An Introduction to Tropical Rain Forests (II)

First an update on the issues I mentioned earlier this week: I had a guy come by and ‘fix the internet problem’ yesterday. Approximately an hour after he left I lost my connection, and it was gone for the rest of the day. I have internet now. If the problem is not solved by a second visit on Monday (they’ll send another guy over), the ISP just lost a customer – I’ll give them no more chances, I can’t live like this. The uncertainty is both incredibly stressful and frankly infuriating. I actually lost internet while writing this post. Down periods seem completely random and may last from 5 minutes to 12 hours. I’m much more dependent on the internet than are most people in part because most of my social interaction with others takes place online.

I’ve read four Christie novels within the last week and I finished The Gambler by Dostoyevsky earlier today – in case you were wondering why I’ve suddenly started reading a lot of fiction, the answer is simple: I’m awake for 16+ hours each day, and if I can’t go online to relax during my off hours I have to find some other way to distract-/enjoy-/whatever myself. Novels are one of the tools I’ve employed.

The internet issue is more important than the computer issue also in terms of the blogging context; the computer I’m using at the moment is unreliable, but seems to cause a limited amount of trouble when I’m doing simple stuff like blogging.

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Okay, on to the book. I was rather harsh in my first post, but I did also mention that it had a lot of good stuff. I’ve included some of that stuff in this post below.

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“Forests, because of their stature, have internal microclimates that differ from the general climate outside the canopy. […] In general terms, it is cool, humid, and dark near the floor of a mature patch of forest, progressively altering upwards to the canopy top. Different plants and animal species have specialized to the various forest interior microclimates […] Night is the winter of the tropics, because the diurnal range of mean daily temperature exceeds the annual range and is greater in drier months. […] Rain forests develop where every month is wet (with 100 mm rainfal or more), or there are only short dry periods which occur mainly as unpredictable spells lasting only a few days or weeks. Where there are several dry months (60 mm rainfal or less) of regular occurence, monsoon forests exist. Outside Asia these are usually called tropical seasonal forests. […] To the biologist […] there are major differences, and this book is about tropical rain forests, those which occur in the everwet (perhumid) climates, with only passing mention of monsoon forests.”

“Tropical rain forests occur in all three tropical land areas […]. Most extensive are the American or neotropical rain forests, about half the global total, 4 x 10⁶ km² in area, and one-sixth of the total broad-leaf forest of the world. […] The second largest block of tropical rain forest occurs in the Eastern tropics, and is estimated to cover 2.5 x 10⁶ km². It is centred on the Malay archipelago, the region known to botanists as Malesia. Indonesia[25] occupies most of the archipelago and is second to Brazil in the amount of rain forest it possesses. […] Africa has the smallest block of tropical rain forest, 1.8 x 10⁶ km². This is centred on the Congo basin, reaching from the high mountains at its eastern limit westwards to the Atlantic Ocean, with outliers in East Africa. […] Outside the Congo core the African rain forests have been extensively destroyed.”

“It is now believed that about half the world’s species occur in tropical rain forests although they only occupy about seven per cent of the land area. […] Just how many species the world’s rain forests contain is still […] only a matter of rough conjecture. For mammals, birds, and other larger animals there are roughly twice as many species in tropical regions as temperate ones […]. These groups are fairly well studied, insects and other invertebrates much less so […] The humid tropics are extremely rich in plant species. Of the total of approximately 250 000 species of flowering plants in the world, about two-thirds (170 000) occur in the tropics. Half of these are in the New World south of the Mexico/US frontier, 21 000 in tropical Africa (plus 10 000 in Madagascar) and 50 000 in tropical and subtropical Asia, with 36 000 in Malesia. […] There are similarities, especially at family level, between all three blocks of tropical rain forest, but there are fewer genera in common and not many species. […] In flora Africa has been called ‘the odd man out’;[52] there are fewer families, fewer genera, and fewer species in her rain forests than in either America or Asia. For example, there are 18 genera and 51 species of native palms on Singapore island,[53] as many as on the whole of mainland Africa (15 genera, 50 species) […] There are also differences within each rain forest region. […] meaningful discussions of species richness must specify scale.[60] For example, we may usefully compare richness within rain forests by counting tree species on plots of c. 1 ha. This within-community diversity has been called alpha diversity. At the other extreme we can record species richness of a whole landscape made up of several communities, and this has been called gamma diversity. The fynbos is very rich with 8500 species on 89 000 km². It is made up of a mosaic of different floristic communities, each of which has rather few species. That is to say fynbos has low alpha and high gamma diversity. Within a single floristic community species replace each other from place to place. This gives a third component to richness, known as beta diversity. For example, within lowland rain forest there are differences in species within a single community between ridges, hillsides, and valleys.”

“Most rain forest trees […] exhibit intermittent shoot growth […] The intermittent growth of the shoot tips is seldom reflected by growth rings in the wood, and where it is these are not annual and often not annular either. Rain forest trees, unlike those of seasonal climates, cannot be aged by counting wood rings […] tree age cannot be measured directly. It has [also] been found that the fastest growing juvenile trees in a forest are the ones most likely to succeed, so growth rates averaged from a number of stems are misleading. […] we have very little reliable information on how long trees can live. […] Most of the root biomass is in the top 0.3 m or so of the soil and there is sometimes a concentration or root mat at the surface. […] Roots up to 2 mm in diameter form 20-50 per cent of the total root biomass[79] and their believed rapid turnover is probably a significant part of ecosystem nutrient cycles”

“Besides differences between the three tropical regions there are other differences within them. One major pattern is that within the African and American rain forests there are areas of especially high species richness, set like islands in a sea of relative poverty. […] No such patchiness has been detected in Asia, where the major pattern is set by Wallace’s Line, one of the sharpest zoogeographical boundaries in the world and which delimits the continental Asian faunas from the Australasian […]. These patterns are now realized to have explanations based on Earth[‘s] history […] Gondwanaland and Laurasia were [originally] separated by the great Tethys Ocean. Tethys was closed by the northwards movement of parts of Gondwanaland […]. First Africa and then India drifted north and collided with the southern margin of Laurasia. Further east the continental plate which comprised Antarctica/Australia/southern New Guinea moved northwards, broke in two leaving Antarctica behind, and, as a simplification, collided with the southeast extremity of Laurasia, at about 15 million years ago, the mid-Miocene; this created the Malay archipelago (Malesia) as it exists today. Both super-continents had their own sets of plants and animals. […] Western and eastern Malesia have very different animals, demarcated by a very sharp boundary, Wallace’s line. […] the evolution of the Malay archipelago was in fact more complex than a single collision.[145] Various shards progressively broke off Gondwana from the Jurassic onwards, drifted northwards, and became embedded in what is now continental Asia […]  The climate of the tropics has been continually changing. The old idea of fixity is quite wrong; climatic changes have had profound influences on species ranges.”

“Most knowledge about past climates is for the last 2 million years, the Quaternary period, during which there has been repeated alternation at high latitudes near the poles between Ice Ages or Glacial periods and Interglacials. During Glacial periods tropical climates were slightly cooler and drier, with lower and more seasonal rainfall. During these times rain forests became less extensive and seasonal forests expanded. Most of the Quaternary was like that; present-day climates are extreme and not typical of the period as a whole. Today we live at the height of an Interglacial. […] At the Glacial maxima sea levels were lower by as much as 180 m […] Sea surface temperature was cooler than today, by 5 ° C or more[147] at 18 000 BP in the tropics. […] Rain forests were more extensive than at any time in the Quaternary during the early Pliocene, parts of the Miocene, and especially the early Eocene; so these were all warm periods. Then, in the late Tertiary, fluctuations similar to those of the Quaternary occurred. […] Africa [as mentioned] has a much poorer flora than the other two rain forest regions.[152] This is believed to be because it was much more strongly dessicated during the Tertiary. […] Australia too suffered strong Tertiary dessication. At that time its mesic vegetation became mainly confined to the eastern seaboard. The strip of tropical rain forests found today in north Queensland is only 2-30 km wide and is of particular interest because it contains the relicts of the old mesic flora. This includes the ancestors from which many modern Australian species adapted to hot dry climates are believed to have evolved […] New Caledonia is a shard of Gondwanaland which drifted away eastwards from northeast Australia starting in the Upper Cretaceous 82 million BP. Because it is an island its vegetation has suffered less from the drier Glacial climates so more of the old flora has survived. The lands bordering the western Pacific have the greatest concentration of primitive flowering plants found anywhere […] It is most likely that they survived here as relicts.”

“rain forests have waxed and waned in extent during the Quaternary, and probably in the Tertiary too, and are not the ancient and immutable bastions where life originated which populist writings still sometimes suggest. In the present Interglacial they are as extensive as they have ever been, or nearly so. At glacial maxima lowland rain forests are believed to have contracted and only to have persisted in places where conditions remained favourable for them, as patches surrounded by tropical seasonal forests, like islands set in a sea. In subsequent Interglacials, as perhumid conditions returned, the rain forests expanded out of these patches, which have come to be called Pleistocene refugia. In the late 1960s it was shown that within Amazonia birds have areas of high species endemism and richness which are surrounded by relatively poorer areas. The same was soon demonstrated for lizards.[153] Subsequently many groups of animals have been shown to exhibit such patchiness […] The centres of concentration more or less coincide with each other […] These loci overlap with areas that geoscientific evidence suggests retained rain forest during Pleistocene glaciations […] In the African rain forests four groups of loci of species richness and endemism are now recognized […] Most parts of Malesia today are about as equally rich in species, including endemics, as the Pleistocene refugia of Africa and America. At the Glacial maxima the Sunda and Sahul continental shelves were exposed by falling sealevel. Rain forests were likely to have become confined to the more mountaineous places where there was more, orographic, rain. The main development of seasonal forests in this region is likely to have been on the newly exposed lowlands, and when sea-level rose again at the next Interglacial these and the physical signs of seasonal climates […] were drowned. The parts of Malesia that are above sea-level today probably remained, largely perhumid and covered by rain forest, which explains their extreme species richness and their lack of geoscientific evidence of seasonal past climates. […] Present-day lowland rain forest communities consist of plant and animal species that have survived past climatic vicissitudes or have immigrated since the climate ameliorated. Thus many species co-exist today as a result of historical chance, not because they co-evolved together. Their communities are neither immutable nor finely tuned. This point is of great importance to the ideas scientists have expressed concerning plant-animal interactions […] Those parts of the world’s tropical rain forests that are most rich in species are those that the evidence shows have been the most stable, where species have evolved and continued to accumulate with the passage of time without episodes of extinction caused by unfavourable climatic periods. This is similar to the pattern observed in other forest biomes”

An Introduction to Tropical Rain Forests (I)

This will just be a brief introductory post to the book, which I gave two stars on goodreads – I have internet and the computer seems to not give me too much trouble right now, so I thought I should post something while I have the chance. The book was hard to rate, in a way. Some parts were highly informative and really quite nice. In other parts the author was ‘out of line’, and he goes completely overboard towards the end – the last couple of chapters contain a lot of political stuff. I have included below a couple of examples of some passages the inclusion of which I had issues with:

“It is also fair comment that human-induced extinction today is as great as any of the five previous extinction spasms life on earth has experienced.”

I have read about the human impact on species diversity before, e.g. in Wilson or van der Geer et al.. I have also read about those other extinction events he talks about. I mention this because if you have not read about both, it may be natural to not feel perfectly confident judging on the matter – but I have, and I do. My conclusion is that saying that the human-induced extinction occuring today is “as great as” the Permian extinction event in my mind makes you look really stupid. Either the author doesn’t know what he’s talking about, or he had stopped thinking when he wrote that, which is something that often happens when people get emotional and start going into tribal defence mode and making political points. Which is why I try to avoid political books. Here’s a funny combination of quotes:

i. “The failure of silviculture follows from working beyond the limits of the inherent dynamic capabilities of the forest ecosystem. This is commonly because rules drawn up by silviculturalists are not enforced, often because of political intervention. It may also be because economists, eager to enrich a nation, enforce their dismal pseudoscience to override basic logical principles and dictate the removal of a larger harvest than the forest can sustain without degradation.”

ii. “There have been attempts by campaigning groups in recent years to turn the clock back, sometimes claiming forests have a greater cash value for minor forest products than for timber.[324] A review of 24 studies found that the median annual value per hectare of sustainably produced, marketable non-timber forest products was $50 year⁻¹.[325] As a natural rain forest grows commercial timber at 1-2 m³ year⁻¹ ha⁻¹ or more, and this is worth over $100 m⁻³, sustainable production of timber is of greater value by a factor of at least two to four.”

The word ‘hypocrite’ sprang to mind when I read the second quote. Who does he think conducts such review studies – soil scientists? If economics is pseudo-science, as he himself indicated that he thought earlier in the book, then why should we trust those estimates? On a related note, should evolutionary biologists stop using game theory as well – where does he think core concepts in evolutionary biology like ESS come from? Good luck analyzing equilibrium dynamics of any kind without using tools also used in economics and/or developed by economists.

It actually seems to me to be a general problem in some fields of biology that lots of researchers have a problem separating politics and science – the social sciences really aren’t the only parts of academia where this kind of stuff is a problem. I have a strong preference for not encountering emotional/political arguments in academic publications, and so I tend to notice them when they’re there, whether or not I agree with them. There’s a lot of good stuff in this book and I’ll talk about this later here on the blog, but there’s a lot of problematic stuff as well, and I punish that kind of stuff hard regardless of where I find it. The quotes above are not unique but to me seem to illustrate the mindset reasonably well.

The book covers stuff also covered in Herrera et al., Wilson, and van der Geer et al., and concepts I knew about from McMenamin & McMenamin also popped up along the way. Herrera et al. of course contains entire chapters about stuff only covered in a paragraph or two in this book. The book deals with aspects of ecological dynamics as well through the coverage of the forest growth cycle and gap-phase dynamics as well as related stuff like nutrient cycles, but the coverage in here is much less technical than is Gurney and Nisbet’s coverage – this book is easy to read compared to their text. I mention these things because although I think the book was quite readable I have seen a lot of coverage of related stuff already at this point, so I may not be the best person to ask. My overall impression is however that people reading along here should not have great difficulties reading and understanding this book.

The Emergence of Animals: The Cambrian Breakthrough (II)

I decided to write one more post (this one) about the book and leave it at that. Go here for my first post about the book, which has some general remarks about the book, as well as a lot of relevant links to articles from wikipedia which cover topics also covered in the book. Below I have added some observations from the second half of the book.

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“Use of bedrock geology to reconstruct ancient continental positions relies on the idea that if two separated continents were once joined to form a single, larger continent, then there ought to be distinctive geological terranes (such as mineral belts, mountain chains, bodies of igneous rock of similar age, and other roughly linear to irregularly-shaped large-scale geologic features) that were once contiguous but are now separated. Matching of these features can provide clues to the positions of continents that were once together. […] The main problem with using bedrock geology features to match continental puzzle pieces together is that many of the potentially most useful linear geologic features on the continents (such as volcanic arcs or chains of volcanoes, and continental margin fold belts or parallel mountain chains formed by compression of strata) are parallel to the edge of the continent. Therefore, these features generally run parallel to rift fractures, and are less likely to continue and be recognizable on any continent that was once connected to the continent in question.

Paleomagnetic evidence is an important tool for the determination of ancient continent positions and for the reconstruction of supercontinents. Nearly all rock types, be they sedimentary or igneous, contain minerals that contain the elements iron or titanium. Many of these iron- and titanium-bearing minerals are magnetic. […] The magnetization of a crystal of a magnetic mineral (such as magnetite) is established immediately after the mineral crystallizes from a volcanic melt (lava) but before it cools below the Curie point temperature. Each magnetic mineral has its own specific Curie point. […] As the mineral grain passes through the Curie point, the ambient magnetic field is “frozen” into the crystal and will remain unchanged until the crystal is destroyed by weathering or once again heated above the Curie point. This “locking in” of the magnetic signal in igneous rock crystals is the crucial event for paleomagnetism, for it indicates the direction of magnetic north at the time the crystal cooled (sometime in the distant geologic past for most igneous rocks). The ancient latitudinal position of the rock (and the continent of which it is a part) can be determined by measuring the direction of the crystal’s magnetization. For ancient rocks, this direction can be quite different from the direction of present day magnetic north. […] Paleomagnetic reconstruction is a form of geological analysis that is, unfortunately, fraught with uncertainties. The original magnetization is easily altered by weathering and metamorphism, and can confuse or obliterate the original magnetic signal. An inherent limitation of paleomagnetic reconstruction of ancient continental positions is that the magnetic remanence only gives information concerning the rocks’ latitudinal position, and gives no clue as to the original longitudinal position of the rocks in question. For example, southern Mexico and central India, although nearly half a world apart, are both at about 20 degrees North latitude, and, therefore, lavas cooling in either country would have essentially the same primary magnetic remanence. One of the few ways to get information about the ancient longitudinal positions of continents is to use comparison of life forms on different continents. The study of ancient distributions of organisms is called paleobiogeography.”

“Photosynthesis is generally considered to be a characteristic of plants in the traditional usage of the term “plant.” Nonbiologists are sometimes surprised to learn that [some] animals are photosynthetic […] One might argue that marine animals with zooxanthellae (symbiotic protists) are not truly photosynthetic because it is the protists that do the photosynthesis, not the animal. The protists just happen to be inside the animal. We would argue that this is not an important consideration, since photosynthesis in all eukaryotic (nucleated) cells is accomplished by chloroplasts, tiny organelles that are the cell’s photosynthesis factories. Chloroplasts are now thought by many biologists to have arisen by a symbiosis event in which a small, photosynthetic moneran took up symbiotic residence within a larger microbe […]. The symbiotic relationship eventually became so well established that it became an obligatory relationship for both the host microbe and the smaller symbiont moneran. Reproductive provisions were made to pass the genetic material of the symbiont, as well as the host, on to succeeding generations. It would sound strange to describe an oak as a “multicellular alga invaded by photosynthetic moneran symbionts,” but that is — in essence — what a tree is. Animals with photosynthetic protists in their bodies are able to create food internally, in the same way that an oak tree can, so we feel that these animals can be correctly called photosynthetic. […] Many of the most primitive types of living metazoa contain photosymbiotic
microbes or chloroplasts derived from microbes.”

“The most obvious reason for any organism, regardless of what kingdom it belongs to, to evolve a leaf-shaped body is to maximize its surface area. Leaf shape evolves in response to factors in addition to surface area requirement, but the surface area requirement, in all cases we are aware of, is the most important factor. […] Leaves of modern plants and Ediacaran animals probably evolved similar shapes for the same reason, namely, maximization of surface area. […] Photosymbiosis is not the only possible departure from heterotrophic feeding, the usual method of food acquisition for modern animals. Seilacher (1984) notes that flat bodies are good for absorption of simple compounds such as hydrogen sulfide, needed for one type of chemosymbiosis. In chemosymbiosis as in photosymbiosis, microbes (in this case bacteria) are held within an animal’s tissues as paying guests. The bacteria are able to use the energy stored in hydrogen sulphide molecules that diffuse into the host animal’s tissues. The bacteria use the hydrogen sulfide to create food, using biochemical reactions that would be impossible for animals to do by themselves. The bacteria use some of the food for themselves, but great excesses are produced and passed on to the host animal’s tissues. […] There may be important similarities between the ecologies of
[…] flattened Ediacaran creatures and the modern deep sea vent faunas. […] A form of chemotrophy (feeding on chemicals) that does not involve symbiosis is simple absorption of nutrients dissolved in sea water. Although this might not seem a particularly efficient way of obtaining food, there are tremendous amounts of “unclaimed” organic material dissolved in sea water. Monerans allow these nutrients to diffuse into their cells, a fact well known to microbiologists. Less well known is the fact that larger organisms can feed in this way also. Benthic foraminifera up to 38 millimeters long from McMurdo Sound, Antarctica, take up dissolved organic matter largely as a function of the surface area of their branched bodies”

“Although there is as of yet no unequivocal proof, it seems reasonable to infer from their shapes that members of the Ediacaran fauna used photosymbiosis, chemosymbiosis, and direct nutrient absorption to satisfy their food needs. Since these methods do not involve killing, eating, and digesting other living things, we will refer to them as “soft path” feeding strategies. Heterotrophic organisms use “hard path” feeding strategies because they need to use up the bodies of other organisms for energy. The higher in the food pyramid, the “harder” the feeding strategy, on up to the keystone predator (top carnivore) at the top of any particular ecosystem’s trophic pyramid. It is important to note that the term “hard,” as used here, does not necessarily imply that autotrophic organisms have any easier a time obtaining their food than do heterotrophic organisms. Green plants are not very efficient at converting sunlight to food; sunlight can be thought of as an elusive prey because it is not a concentrated energy source […]. Low food concentrations are a major difficulty encountered by organisms employing soft path feeding strategies. Deposit feeding is intermediate between hard and soft paths. […] Filter feeding, or capturing food suspended in the water, also has components of both hard and soft paths because suspension feeders can take both living and nonliving food from the water.”

“Probing deposit feeders […] began to excavate sediments to depths of several centimeters at the beginning of the Cambrian. Dwelling burrows several centimeters in length, such as Skolithos, first appeared in the Cambrian, and provided protection for filter-feeding animals. If a skeleton is broadly defined as a rigid body support, a burrow is in essence a skeleton formed of sediment […] Movement of metazoans into the substrate had profound implications for sea floor marine ecology. One aspect of the environment that controls the number and types of organisms living in the environment is called its dimensionality […]. Two-dimensional (or Dimension 2) environments tend to be flat, whereas three-dimensional environments (Dimension 3) have, to a greater or lesser degree, a third dimension. This third dimension can be either in an upward or a downward direction, or a combination of both directions. The Vendian sea floor was essentially a two-dimensional environment. […] With the probable exception of some of the stalked frond fossils, most Vendian soft-bodied forms hugged the sea floor. Deep burrowers added a third dimension to the benthos (sea floor communities), creating a three-dimensional environment where a two-dimensional situation had prevailed. The greater the dimensionality in any given environment, the longer the food chain and the taller the trophic pyramid can be […]. If the appearance of abundant predators is any indication, lengthening of the food chain seems to be an important aspect of the Cambrian explosion. Changes in animal anatomy and intelligence can be linked to this lengthening of the food chain. Most Cambrian animals are three-dimensional creatures, not flattened like many of their Vendian predecessors. Animals like mollusks and worms, even if they lack mineralized skeletons, are able to rigidify their bodies with the use of a water-filled internal skeleton called a coelom […] This fluid-filled cavity gives an animal’s body stiffness, and acts much like a turgid, internal, water balloon. A coelom allows animals to burrow in sediment in ways that a flattened animal (such as, for instance, a flatworm) cannot. It is most likely that a coelom first evolved in those Vendian shallow scribble-trail makers that were contemporaries of the large soft-bodied fossils. Some of these Ediacaran burrows show evidence of peristaltic burrowing. Inefficient peristaltic burrowing can be done without a coelom, but with a coelom it becomes dramatically more effective.”

“Bilateral symmetry is important when considering the behavior of […] early coelomate animals. The most likely animal to evolve a brain is one with bilateral symmetry. Concomitant with the emergence of animals during the Vendian was the origin of brains. The Cambrian explosion was the first cerebralization or encephalization event. As part of the increase in the length of the food chain discussed above, higher-level consumers such as top or keystone predators established a mode of life that requires the seeking out and attacking of prey. These activities are greatly aided by having a brain able to organize and control complex behavior. […] Specialized light receptors seem to be a characteristic of all animals and many other types of organisms; […] photoreceptors have originated independently in at least forty and perhaps as many as sixty groups. Most animal phyla have at a minimum several pigmented eye spots. But advanced vision (i. e., compound or image-forming eyes) tied directly into a centralized brain is not common or well developed until the Cambrian. The tendency to have eyes is more pronounced for bilateral than for radial animals. […] some of the earliest trilobites had large compound eyes. Trilobites were probably not particularly smart by modern standards, but chances are that their behavioral capabilities far outstripped any that had existed during the early Vendian. […] Actively moving or vagile predators are, as a rule, smarter than their prey, because of the more rigorous requirements of information processing in a predatory life mode. Anomalocaris as a seek-and-destroy top predator may have been the brainiest Early Cambrian animal.”

“why didn’t brains and advanced predation develop much earlier that they did? A simple, thought experiment may help address this problem. Consider a jellyfish 1 mm in length and a cylindrical worm 1 mm in length. Increase the size (linear dimension) of each (by growth of the individual or by evolutionary change over thousands of generations) one hundred times. […] The worm will need internal plumbing because of its cylindrical body. The jellyfish won’t be as dependent on plumbing because its body has a higher surface area. […] Our enlarged, 10 cm long worm will possess a brain which has a volume one million times greater than the brain of its 1 mm predecessor (assuming that the shape of the brain remains constant). The jellyfish will also get more nerve tissue as it enlarges. But its nervous system is spread out in a netlike fashion; at most, its nerve tissue will be concentrated at a few radially symmetric points. The potential for complex and easily reprogrammed behavior, as well as sophisticated processing of sensory input data, is much greater in the animal with the million times larger brain (containing at least a million times as many brain cells as its tiny predecessor). Complex neural pathways are more likely to form in the larger brain. This implies no mysterious tendency for animals to grow larger brains; perfectly successful, advanced animals (echinoderms) and even slow-moving predators (sea spiders) get along fine without much brain. But centralized nerve tissue can process information better than a nerve net and control more complex responses to stimuli. Once brains were used to locate food, the world would never again be the same. This can be thought of as a “brain revolution” that permanently changed the world a half billion years ago.”

“There is little doubt that organisms produced oxygen before 2 billion years ago, but this oxygen was unable to accumulate as a gas because iron dissolved in seawater combined with the oxygen to form rust (iron oxide), a precipitate that sank, chemically inactive, to accumulate on the sea floor. Just as salt has accumulated in the oceans over billions of years, unoxidized (or reduced) iron was abundant in the seas before 2 billion years ago, and was available to “neutralize” the waste oxygen. Thus, dissolved iron performed an important oxygen disposal service; oxygen is a deadly toxin to organisms that do not have special enzymes to limit its reactivity. Once the reduced iron was removed from sea water (and precipitated on the sea floor as Precambrian iron formations; much of the iron mined for our automobiles is derived from these formations), oxygen began to accumulate in water and air. Life in the seas was either restricted to environments where oxygen remained rare, or was forced to develop enzymes […] capable of detoxifying oxygen. Oxygen could also be used by heterotrophic organisms to “burn” the biologic fuel captured in the form of the bodies of their prey. […] Much research has focused on lowered levels of atmospheric oxygen during the Precambrian. The other alternative, that oxygen levels were higher at times during the Precambrian than at present has not been much discussed. Once the “sinks” for free oxygen, such as dissolved iron, were saturated, there is little that would have prevented oxygen levels in the Precambrian from getting much higher than they are today. This is particularly so since there is no evidence for the presence of Precambrian land plants which could have acted as a negative feedback for continued increases in oxygen levels” [Here’s a recent-ish paper on the topic – do note that there’s an important distinction to be made between atmospheric oxygen levels and the oxygen levels of the oceans].

Plant-Animal Interactions: An Evolutionary Approach (3)

This will be my last post about the book. You can read my previous posts about the book here and here.

As I have already mentioned, I really liked this book. Below I have covered some of the parts of the book which I have not yet talked about here on the blog, and in particular I’ve included stuff about how plants and animals cooperate with each other. I have of course had to leave a lot of stuff out.

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“The lack of mobility in plants creates a physical obstacle in the dispersal of their genes. In a majority of all plants, this obstacle has been alleviated through the formation of mutualisms with animals that transport pollen grains between stigmas and also disperse seeds. In the case of pollination, the goal for the plant is to receive pollen on its stigma and to have pollen picked up and deposited on conspecific stigmas of other plants. The animal most commonly seeks a food reward. It is important to appreciate that mutualisms such as these represent reciprocal exploitation with an underlying evolutionary conflict. Selection in mutualisms favours selfish behaviour […] One manifestation of such selection […] is the widespread phenomenon of plant species that no longer reward pollinators but instead attract visitors by deception. […] Non-rewarding plants species constitute a substantial portion of all angiosperms, especially among orchids, but they are mostly minor components of the plant community in which they grow. […] Likewise, many flower-visitors (if not most) do not contribute to pollination but do remove floral resources such as nectar and pollen. […] A fair number of plants mimic not flowers but rather pollinator mates or oviposition sites. Flowers of the well-studied European fly orchids (Ophrys) and caladeniine Australian hammer orchids provide visual, olfactory and tactile cues mistaken by naïve wasp males for conspecific females (Stowe 1988), and pollination happens as males attempt copulation with the flowers.” [This sentence made me laugh!]

“pollination mutualisms evolve amid simultaneous antagonistic interactions; the plant is under selection to maximize the net fitness of attracting potentil mutualists at the lowest net cost while minimizing the detrimental effects of non-mutualists or low-quality mutualists. This tradeoff does not exist in antagonistic interactions […] Floral traits are likely to be as much the result of selection for avoidance of some animals as for attraction of others. […] The vast majority of all extant pollination mutualisms […] involve flowering plants, which dominate most biota on earth today.”

“Given that the benefit to plants of animals as pollen vectors is transport across longer distances, it is not surprising that the three extant groups of animals that have evolved flight – insects, birds and bats – contain a very large proportion of all pollinators. Among the insects, flower-visiting species are particularly frequent within the large orders Hymenoptera (bees and wasps), Lepidoptera (moths and butterflies), Diptera (flies) and Coleoptera (bettles). […] The Lepidoptera alone, whose coiling tongues make them flower specialists and effective consumers of nectar, constitute 11% of all described species on Earth […] Among birds, six phylogenetically independent groups have diversified as flower-visitors and often as pollinators […] Together these groups constitute over 10% of all recognized bird species. […] Flowers offer an extraordinary range of shapes, colours and scents, reflecting high rates of evolutionary change in these traits. […] Almost any flower part or even adjacent leaves are modified for the purpose of attracting pollinators. There is arguably more plasticity in these secondary reproductive traits in plants than in any other organismal groups, with the possible exception of birds.”

“Specificity among visitors is a necessity for effective pollination; if animals visit flowers of different species indiscriminately, heterospecific pollen transfer will result, which reduces the probability of pollen reaching a conspecific stigma […] The number of plant species visited varies greatly among flower-visiting species. […] Individual visitors often tend to specialize on a subset of potential flowers during any one foraging bout; in bees perhaps 90% of all visits may be made to a given species, with occasional visits to other species. This short-term specialization is referred to as floral constancy. The dominant flower may vary among simultaneously foraging conspecifics, and within individual visitors on successive foraging bouts. Reasons for such short-term selectivity have been explored in insects, and focus on the effects of foraging rate as a result of memory constraints. Insects must learn by trial and error how to effectively access a reward such as nectar in more complex flowers, as the rewards are concealed and most quickly accessed using a particular approach. Minimum handling time may be approached only after as many as 100 visits to a given zygomorphic flower […] visitors may be unable to keep more than one sensorimotor protocol in active memory, thus making it a superior strategy to focus on one food source at a time […] Specialization is often not in the evolutionary interest of a flower-visiting animal, as its ultimate interest is to optimize the reward harvesting rate over time. A foraging pattern that maximizes the harvesting rate of commodities such as nectar and pollen can include two or more coexisting plant species, especially if their floral structure is fairly similar so that the visitor can use a single visit behaviour protocol. […] The vast majority of all plants are pollinated by two or more species”

“With the […] exception of ants […], invertebrates play only an anecdotal role as seed-dispersers […] All major lineages of vertebrates take part in fruit consumption and seed dispersal, but their importance as dispersal agents is very unequal. Birds and mammals are the only or main dispersers of the vast majority of vertebrate-dispersed plants […] About 36% of 135 extant families of terrestrial birds, and 20% of 107 families of non-marine mammals, are partly or predominately frugivorous […] Fruit consumption by vertebrate dispersers […] has selected for fruit traits that enhance detectability by frugivores […] Although exceptions abound, fruits that are green or otherwise dull-coloured when ripe tends to be associated with seed dispersal by mammals, whereas fruits dispersed by birds tend to be brightly pigmented. The partial dichotomy between ‘bright’ and ‘dull’ ripe fruits has probably been selected for by the contrasting sensory capacities of birds and mammals […] Size is an important attribute of fruits, because it sets limits to ingestion by relatively small-sized dispersers that swallow them whole, like birds. […] Fruits eaten by mammals tend to be larger than those eaten by birds […] Fruit pulp is the reward offered by plants to dispersers, and its nutritional value is a critical element in the plant-disperser interaction. Compared to other biological materials, fruit pulp is characterized, on average, by high water and carbohydrate content, and low protein and lipid content. […] the occurence of secondary metabolites within ripe pulp presumably represents a tradeoff with respect to defence from damaging agents and palatability for dispersers […] A number of studies provide unequivocal support for the ‘palatability-defence tradeoff hypothesis’. […] increased frugivory is quite often associated with increased intestinal length, as an adaptive response for increasing intestinal absorption of the water-diluted nutrients in fruit juice. […] Most fruits are very deficient in nitrogen, which perhaps represents the most important nutritional constraint that frugivorous animals must cope with. Regular ingestion of small amounts of animal food seems to be the commonest way of complementing the poor protein intake associated with frugivory.”

“Abundance of fruit varies markedly among years and seasons, and within as well as between habitats, which generally leads to patchy and unpredictable distributions in time and space […] A distinct suite of behavioural and physiological traits allow frugivores to withstand or escape from temporary situations of fruit scarcity and efficiently locate unpredictable fruit sources. Seasonal migration and habitat shifts are the two most common generalized responses of frugivores to fluctuations in fruit availability. […] Plant-vertebrate dispersal systems are characterized not only by the absence of obligate partnershipts, but also by weak mutual dependence between species of plants and animals, and by the prevalence of unspecific relationships. […] the general picture is one of loose interdependence between species of plants and species of dispersers. […] pollen and seed dispersal by animals are fundamentally dissimilar […], and their differences have manifold evolutionary implications. The two most important distinctions are (i) that a definite target exists for dispersing pollen grains (the conspecific stigma) but not for dispersing seeds; and (ii) that the plant can control pollinators movements by providing incentives at the target site (nectar, pollen), but there are no similar incentives for seed dispersers to drop seeds in appropriate places. These differences are best framed in terms of the departure-related versus arrival-related advantages of dispersal [You can say that seed-dispersal systems work on the basis of ‘advance payment’ alone, whereas pollen dispersal mechanisms also include ‘payment upon delivery’ aspects].”

Finally, ants! Ants are awesome…

“Ants are one of the most abundant, diverse and ecologically dominant animal groups in the world. They make up from 10 to 15% of the entire animal biomass in many habitats, and in the Amazonian rainforest, for example, one hectare of soil may contain 8 million individuals. The impact of ants on the terrestrial environment is correspondingly great. In most habitats they are among the leading predators of other insects and small invertebrates, and in some environments they are the principal herbivores and seed predators. Ants can alter their physical environment profoundly, moving more soil than earthworms, and being major channellers of energy and cyclers of nutrients. […] It is probably fair to say that no other animal group interacts with plants in such diverse ways. Indeed, the fact that ants are the only specific taxa mentioned in the chapter headings of this book reflects their ecological importance in the lives of most plant species. Ants can protect plants directly from herbivores or from competition with other plants. They can also affect plant-community composition and dynamics by selective weeding or ‘gardening’, altering nutrient availability, pollinating flowers, or dispersing and harvesting seeds. Plants provide ants with food and shelter […]. Some relationships between ants and plants appear to be highly coevolved mutualisms and it is these interactions that have received the most study. But the majority of ant and plant species interact in more generalized ways, often through the influence of ants on the chemical and physical properties of soil. […] The oldest ant species, Sphecomyrma freyi, has been dated from amber to be about 80 million years old. [….] there is evidence that ants have been both remarkably diverse and ecologically successful for at least 50 million years”

“Cultivation of fungus by attine ants originated about 50 million years ago. The relationship between the higher attine ants and the symbiotic fungus they cultivate is obligate. Foundress queens propagate the fungus clonally by carrying a pellet of fungus in their mouths during their nuptial flight to establish new colonies. […] The relationship between the attines and their fungus has been termed an ‘unholy alliance’ because it combines the ants’ ability to circumvent plants’ anti-fungal defences with the ability of the fungus to subvert plants’ anti-insect defences. The ants benefit because the fungus breaks down plant tissue such as cellulose, starch and xylan, and possibly detoxifies insecticidal plant compounds. The fungus thus enable them to make use of plant material that would otherwise be unavailable and allows the ants to be truly polyphagous in the midst of diverse flora. […] the relationship between the ants and the fungus has recently been found to be a triumvirate, with evidence that an antibiotic-producing bacterium is an important component of the symbiosis. […] fungus gardens are particularly prone to infection by a group of closely related, highly specialized parasites in the fungal genus Escovopsis. […] Escovopsis is found in gardens of virtually all species of fungus-growing ants, but not elsewhere. The parasite is usually found at low levels, but if the health of the garden is compromised it can quickly take over and destroy the fungal crop. In healthy gardens, Currie et al. (1999) have shown that the fungus is kept in check by specific antibiotics produced by Streptomyces bacteria living on the bodies of the ants […] The bacterium can also promote the growth of the cultivated fungi. The position of the bacterium on the ant integument is genus-specific, indicating that the association with the ants is both highly evolved and of ancient origin […] Attine symbiosis appears to be a coevolutionary arms race between the garden parasite Escovopsis on the one hand, and the tripartite association of the actinomycete, the ant hosts and the fungus on the other. The relationship raises the interesting question of how the attine antibiotics have remained effective against the fungus-garden pathogens for such a long time, given that resistance to antibiotics is a well known problem in human and other populations.”

“The coevolution of ants and plants involving systems of rewards and services has resulted in a variety of elaborate and complex mutualistic interactions collectively known as ant-guard systems. Here the rewards are extra-floral nectar, specialized food bodies and nest sites, while the service is the protection of the plants from herbivory. […] Plant structures known as domatia are developmentally determined and appear to be specific adaptions for ant occupation. They are often formed by the hypertrophy of internal tissue at particular locations in the plant, creating internal cavities attractive to ants […] the plant species that bear them are known as myrmecophytes. […] Some myrmecophytes are actually ‘fed’ by the ants they house. Experiments have shown that two genera in the family Rubiaceae […] absorb nutrients from the wastes of the Iridomyrmex colonies they house in tunnels inside large tubers […] A variety of field studies have shown there is strong competition among ants for dormatia […] Ant-guard systems involving extra-floral nectaries are often complicated by the presence of Homoptera or lepidopteran larvae that secrete nectar-like fluids collectively known as honeydew. In such situations, the ants have a choice of food and the outcome of these three-way interactions between plants, ants and herbivores appears to be extremely variable. The Homoptera include herbivores such as aphids, leafhoppers, scale insects and coccids. Each animal is armed with a proboscis that penetrates plant vascular tissue, tapping into the nutrient supply. With little apparent effort, the sap enters the front end of the homopteran gut, later appearing at the back end as droplets, somewhat depleted in quality but still containing many nutrients, where it is ejected as honeydew. Many ant species harvest the honeydew and, in return, protect the homopterans from predators and parasites […] As a result, ant activity can increase levels of herbivory as well as other forms of damage […] Ant interactions with plant species that produce extra-floral nectaries, food bodies and domatia have evolved both in the presence of homopterans and lepidopteran larvae and the ant behaviour that protects them. For example, homopterans of various kinds are routinely maintained within domatia and they frequently feed on plants that bear extra-floral nectaries. This leads to the situation where plants are providing rewards for ant-guards that attack some of the plant’s enemies but protect others. A solution to this apparent conflict of interest was first proposed by Janzen (1979) who suggested that the presence of homopterans was part of the cost of the ant-guard system […] The evoluation of extra-floral nectaries has itself been viewed as a defence against homopteran attack, weaning ants away from the herbivores […] Homopterans are common herbivores and have been around for a very long time; thus, given their ubiquity, selection for extra-floral nectaries may have resulted in the plants exerting greater control over the ant-guards, provided ants preferred nectar to honeydew.”

Plant-Animal Interactions: An Evolutionary Approach (2)

This is my second post about the book – you can read my first post about the book here; that post includes some more general comments and observations. In this post I’ll cover plant-insect interactions and mammalian herbivory.

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“Herbivory, which is the consumption of plants by animals, encompasses many different types of interactions that differ in their duration and deadliness to the plant. Insect herbivores, like mammals, feed on plants in numerous ways. Seed and seedling herbivory are predatory interactions because herbivores immediately kill individuals in the plant population. Insect herbivores that feed on leaves and other parts of mature plants typically do not cause plant mortality. In the rare cases when they do, it usually requires much time to kill the host plant. Such relationships are closer to parasite-host than predator-prey relationships. […] Insect herbivores differ from mammalian herbivores in their size, numbers, and the kinds of damage they inflict. Because of their small size, insects often have an intimate, lifelong association with the host plant. Moreover, while their associations are lifelong, often their lives are rather short, predisposing them to rapid rates of evolution. On average, insect herbivores are much more specialized than their mammalian counterparts. […] There has long been debate over why specialist feeding habits are widespread in herbivorous insects. […] There are clearly a number of hypotheses, each with some empirical support […] Because specialization is a complex trait, we don’t necessarily expect a single hypothesis to explain the phenomenon.”

“Insect populations frequently fluctuate in size, and this fact has prompted a good deal of speculation as to what factors limit the size of herbivore populations. Hairston, Smith and Slobodkin (1960) reasoned that, since herbivores rarely consume all of their plant resources (the world is green), herbivore populations are likely to be limited by parasites and predators, but not by resource abundance […] However, whether herbivorous insect populations are limited by food (bottom-up forces in a food web) or by predators (top-down forces) remains a hotly debated topic […], and it is unlikely that either force dominates all insect populations”

“The first obstacle that an insect faces is the fact that, on average, only about 10% of the energy available to one trophic level makes it to the next trophic level. Sources of energy loss include the fact that not everything ingested can be assimilated (e.g. lignin, cellulose). […] the chemistry of plant and animal tissues is very dissimilar. Liebig’s law of the minimum states that growth is possible to the extent determined by the nutrient that is in shortest supply. For herbivores, one such nutrient is protein. Because nitrogen is relatively easy to measure and protein is not, protein content is often estimated by assaying organic nitrogen, which comprises from 15 to 18% of plant proteins […] sap-feeding insects, like cicadas and other homopterans, often eat 100 to 1000 times their body weight per day because amino acids make up only a tiny proportion of the sap […] In general, both micro- and macronutrients can limit the growth rate of insect herbivores.”

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I want to interpose an observation here – I find it quite interesting how seemingly unrelated fields can so often become related in ways you do not expect them to. I’m currently reading Mary Barasi’s Nutrition at a glance (which despite its low page count is actually quite a bit of work, as I’ve found out..). It makes sense in retrospect that some things overlap here, but when I started reading Barasi I did not expect stuff covered in this book to be relevant to the coverage in that book (she only deals with humans). It turns out that the stuff above – and some other stuff covered elsewhere in the book as well – is quite relevant to Barasi’s coverage; I’d probably have been somewhat confused by the focus on nitrogen in the protein chapters of Barasi if I had not read the stuff covered in chapter three of this book. When you’re about to learn some new stuff you never really know how that new stuff you’re about to learn may relate to stuff you already know, or for that matter how it may relate to stuff you’ll learn later on. I always love making new connections like these and connect dots I didn’t even know could be connected.

Okay, moving on…

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“Aside from nutritional hurdles and the limited availability of some plant parts, herbivores may also be prevented from feeding as a result of plant defences. […] Adaptions include physical barriers, toxins, anti-feedants, decoys and even other organisms [ants!]. Some defences are always present on the plant; we call these constitutive defences. Many others, including thorns and spikes, are inducible, that is, they are augmented only after the plant is attacked […] The list of chemicals that owe their defensive value to their ability to interfere with insect physiology or behaviour is a very long one. While the elaboration of thorns, spines and hairs is restricted largely to their size and shape, the number of possible combinations, principally of carbon, oxygen, hydrogen, nitrogen and sulfur, is enormous. […] These plant constituents are commonly referred to as ‘secondary’ compounds. […] When the role of a secondary compound is defensive, it is commonly referred to as an ‘allelochemical’. […] Synergists are chemicals that enhance the toxicity of chemicals with which they are mixed. […] Our current understanding is that the presence of secondary compounds can deter many herbivores from using plants, but that almost every plant species has a suite of specialized herbivores that are adapted to use these compounds as attractants, as feeding stimulants or as a source of toxins for use in defence against their enemies. […] As many means as plants have to deter insects, insects have ways of circumventing them. […] The overall responses of plants subjected to herbivory may be viewed as a tradeoff between growth and defence.” [my bold, US]

“As a group, insect herbivores tend to have larger effects than mammalian herbivores on plant growth and reproduction […] when a plant is attacked by one herbivore it may become more or less vulnerable to attack by others. […] the degree to which plants can evolve to become better defended, might be constrained by the preferences of beneficial pollinators. […] While it is clear that herbivores can affect plant community composition and species distribution, the reciprocal effect also exists: plant community composition affects insect herbivore loads. […] The ‘resource concentration hypothesis [states that] herbivores are more likely to find hosts that are concentrated, and herbivores remain longer on hosts growing in dense or pure stands. […] The ‘enemies hypothesis’ [states that] increased diversity of predators and parasitoids in diverse stands may limit population densities of herbivores in these stands. The idea that diverse plant community composition may result in reduced attack by herbivores has been called ‘associational resistance’. […] both community composition and the dispersal abilities of herbivores in relation to the scale of community diversity will affect the degree to which plants receive damage from herbivores.”

“In summary, insect herbivores respond to selection by plant defences and nutritional status. Plants strongly affect insect fitness so that, in general, insect herbivores are relatively specialized with respect to their diet breadth (in comparison with mammalian herbivores). […] Plants affect insect abundance through their defences, which often entail the actions of other species, such as predacious and parasitic enemies of herbivores.
Insects in turn affect plant fitness, and may exert selection on plant defences, both physical and chemical. There is a growing body of evidence suggesting that these defences come at some cost to the plant. On a larger ecological scale, insects affect plant distribution and abundance, as well as the species diversity of plant communities. Frass, honeydew and greenfall from insect outbreaks also alter nutrient cycling regimes in the soil and the availability of nutrients to plants.
Finally, many of the adaptions and counter-adaptions of plants and their insect herbivores support the idea that much of the biodiversity of the earth is a result of the arms race between insect herbivores and their host plants.” [my bold, US]

“The amount of food differs between biomes. The tundra has a primary production of only about 140 g m⁻² yr^–1, while swamps and marshes reach about 3000 g m⁻² yr^–1, i.e. a 20-fold difference between the extremes […] The plant biomass, or standing crop, shows an even greater range between the least and most productive biomes, i.e. a 75 fold difference from about 600 g m⁻² in the tundra to 45 000 in tropical rainforests. Estimates of food resources are vital for understanding the relations between plants and herbivores […] and [there is a] need for estimates that capture both the static and dynamic situations of the food resources. […] Given the large spatial and temporal variation in food abundance and quality, mobility is a valuable trait and the migratory habits of many ungulates represents an adaptive response. There are no strictly sedentary herbivores […] Herbivores have the advantage of feeding on objects that cannot escape, but on the other hand plant food has low nutritive value (it is low in nitrogen and must be digested slowly). […] Diet composition is commonly used to classify animals into functional groups, e.g. predators, omnivores and herbivores. Mammals, like all other living organisms, have a perverse tendency to defy exact classification […] Sixteen different categories of dietary specialization have been proposed, and seven of them refer to herbivores […] a large majority of the [mammalian] herbivores have quite a mixed diet and also feed on animal matter. [my bold, US] […] It is increasingly clear that mammalian herbivory on a given plant species can result in a continuum of responses, depending on the characteristics of the plant, the type of herbivory and the environment. […] there is no simple typical response for a given plant species.”

“The metabolic requirements of mammals increase with (body mass)^0.75 (Kleiber 1932), but the capacity of the gastrointestinal tract with (body mass)^1.0 […] Smaller animals thus have higher mass-specific food requirements without any accompanying proportional increase in the gut capacity, which limits the volume of digesta retained and its passage […] There is a tradeoff between the rate of intake and the time allowed for chewing. […] The theory of optimal foraging is based on the assumption that an animal would forage in such a way that it optimizes its fitness […] Food, in terms of quantity or quality, is usually highly variable and is sometimes distributed in more or less discrete patches. Therefore, one crucial point in the optimal foraging concept will be the criteria for when to leave a feeding patch and move to another. The ‘marginal value theorem’ states that a herbivore should stay as long as the extraction rate is above the average for the environment as a whole. […] Understanding the decision rules used by a herbivore requires an understanding of its behavioural responses on various time-scales. It is less probable that an animal optimizes its diet at each bite, but rather that it bases future decisions on an integration over longer periods.” [I found these observations rather funny in a way – some of this stuff is a lot like microeconomic theory, it’s just that in this case the hypotheses made relate to the behaviours of non-human organisms, rather than humans..]

Plant-Animal Interactions: An Evolutionary Approach (1)

“This book, aimed at upper-division undergraduate students and those starting graduate studies, attempts to provide a manageable synthesis of recent developments in the field of terrestrial plant-animal interactions”, they write in the introduction. One of the amazon reviewers claimed that “This is a VERY easy read” – which was actually, in combination with the high ratings it’s got, a large factor leading me to give this book a try; I figured that I shouldn’t be too worried about the fact that this book is written for advanced undergraduates/graduate students in a field I’m not super familiar with.

The book is actually not terribly difficult to read – in the sense that most concepts/terms applied throughout the book are defined along the way, meaning that you’re unlikely to have major issues understanding what’s going on even if you’re not an evolutionary biologist (I’m not, so I should know). It also helps that many of the terms which are not defined along the way will be sort of obvious to you from the context (they never really tell you what coprolite is, but I should think a picture of a dinosaur turd would help… I incidentally read about those things last year, so that particular word did not cause me problems). Although not all ‘potentially problematic terms’ are defined in the book most of them are, and there are a lot of definitions in this book. It’s quite dense; it’s a book where my average reading speed will be around 10 pages per hour, when measured over multiple hours and including necessary reading breaks and so on – perhaps 13-15 when things are going really well. I recently started reading Christie’s Peril at End House, and I’m reasonably sure it’ll take me less time to read that entire book than it took me reading chapter 2 of this book (chapter 2 was, I should perhaps add, significantly longer than the average chapter). I’m well aware that some textbooks are worse than 10-15 pages/hour and I have my eyes on another text dealing with related stuff which I’m reasonably sure will be a bit more work than this one was, and I’m also aware that some books catering to a more advanced audience will presumably take familiarity with many of the terms defined in this book for granted; but even so, calling this ‘a very easy read’ is perhaps a bit much. I should note that although I don’t want to delude anyone into thinking this book is easier to read than it is, I also really don’t want to give people reading along here more excuses not to read this book than is strictly necessary, because I think it’s just a great book.

I have decided to give the book a couple of posts here on the blog, perhaps 3, but I don’t know when I’ll post the others – I have finished the book, and I’ve started reading Kuhn. I’m somewhat behind on the book blogging at the moment, which tends to happen when I’m reading stuff offline; in part because blogging books I’ve read offline is in general a lot more work, among other things because I can’t copy/paste relevant segments when quoting from the books.

I’ve given the book five stars on goodreads simply because as mentioned it’s a really great book – it’s the sort of book which does all those things I’ve been consistently annoyed about popular science books dealing with topics related to the ones covered in this book not doing, and it’s on the other hand also the sort of book which does none of those annoying things the other type of books tend to do. The book doesn’t spend a page talking about how butterflies look nice, ‘you could see the sun setting in the distance…’, or some anecdote about the uncle of the author or crap like that; you have definitions, functional relationships and dynamics explored in detail – a thoroughly analytical approach, without all the infuriating crud. Occasional appreciation, yes, but mainly just the data, the dynamics, the science.

In biology you have two major fields called zoology (dealing with animals) and botany (dealing with plants), but “the knowledge of these two groups of organisms has traditionally progressed along separate lanes, under the leadership of different researchers and independently of each other” (a quote from the introduction). What this means is that there haven’t been a lot of people who’ve done work on ‘the stuff in the middle’ – which is a shame, as “we will never fully understand the evolution of the morphology, behaviour and life history of plants and animals unless we understand in sufficient detail their reciprocal influences in ecological and evolutionary time” (another quote from the introduction). So they’ve written down some of the things they know about these things. The book has nine chapters written by 13 different contributors. The first two chapters are sort of ‘general’ chapters; the first one is about: ‘Species interactions and the evolution of biodiversity’, and the second (much longer) one is about: ‘The history of associations between plants and animals’. In part 2 of the book, dealing with ‘mostly antagonisms’, they talk about plant-insect interactions (chapter 3), mammalian herbivory (chapter 4) and granivory (chapter 5 – “Granivory describes the interaction between plants and the animals (termed granivores or seed-predators) that feed mainly or exclusively on seeds.”). In part 3, dealing with ‘mostly mutualisms’, they talk about pollination by animals (chapter 6) and seed dispersal by vertebrates (chapter 7). In the last part, ‘synthesis’, they talk about ant-plant interactions (chapter 8) and a little bit about ‘future directions’ in research on these matters (chapter 9). In my opinion there were no bad chapters in this book – this is a ‘pure’ five star rating, without any kind of ‘compensatory stuff’ going on. Other people may disagree, but my opinion is that the book is well written, deals with super interesting stuff, and that this stuff is just plain fascinating!

It would be easy to write one post dealing with each of the chapters but I’m not going to do that, and so my posts about this book are going to be another set of those posts where you’ll spend perhaps 10-15 minutes on perhaps 10 hours of material. The book has a lot of stuff I simply cannot cover here, and I highly recommend that you read it if you find the stuff I cover here interesting. It’s been hard to blog this book because it’s in general really difficult to know what to exclude, and very easy to find new things to add. The stuff below covers some of the material from the first two chapters, corresponding to roughly 75 pages.

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“The majority of terrestrial organisms fly. […] The evolution of propelled and passive flight, and their consequences, may well be regarded as the most creative force in the development of biodiversity. Most plants fly at one stage of their life cycle or another, as pollen or as seeds or both. Spores of ferns and fungi fly. Pollen, spores and seeds are carried on the wind by a multitude of winged animals: insects, birds, bats and perhaps pterosaurs in their day. […] the vast majority of terrestrial organisms exist in trophic systems based on plants, be they the plant themselves, herbivores, carnivores, pollinators, frugivores or granivores […] as we climb the trophic ladder, species richness increases by orders of magnitude. A plant species, such as an oak, birch or willow, may be host to 200-300 insect herbivore species. Each herbivorous insect may be utilized by 10-20 carnivores, either predators or parasites. The plant provides both food and habitat for the associated fauna and many microhabitats are available for colonization […] Including undescribed species, there may be 10-100 million species of all kinds living today, over half of them insects, of which 99,5% can fly in the adult stage. […] Add to the insects about 9000 species of birds and 1000 bat species, together making up 80% of the warm-blooded vertebrates, and we see that conquest of the air has been an evolutionary ‘success’ of extreme proportions.”

“The basis for the spectacular radiations of animals on earth today is clearly the resources provided by the plants. They are the major primary producers, autotrophically energizing planet Earth. […] Well over 90% of energy in terrestrial systems is fixed by autotrophic plants (the remainder by algae and bacteria), and almost all terrestrial animals depend on autotrophic production, either directly as herbivores or saprophages, or for shelter and microhabitats, or indirectly as predators and parasites utilizing the second trophic level of herbivores. […] plant-animal interactions are both direct and indirect and ramify throughout the trophic system. […] multitrophic-level interactions are ubiquitous and important both for the understanding of natural interactions and for effective management of landscapes dominated by humans […] while plant hosts and their varied insect herbivores evolve and are constantly replaced in time and space, their associations nonetheless remain constant. A Paleozoic palaeodictyopterid insect imbibing vascular tissue sap from a marattialean tree fern is functionally playing the same role as an aphic today feeding on the same tissues in an angiosperm […] Given the taxonomic turnover of vascular plants and herbivorous insects and yet the survival of persistent ecological associations, the phenomenon of ecological convergence is an important long-term pattern […] multidisciplinary evidence from various geological disciplines, particularly those applied to the earlier part of the fossil record, indicate that the more ancient the ecosystem, the less it resembles the present.”

“Three hypotheses have been proposed for assessing how ecological units, such as functional feeding groups, dietary guilds and mouthpart classes, expand in macroevolutionary time […] The first hypothesis, the ecological saturation hypothesis (ESH), advocated by palaeobiologists, maintains that the total number of ecological positions, or roles, has remained approximately constant through time after an initial exponential rise […] Thus taxa enter and exit the ecological arena of the biological community […], but their associations or roles remain virtually level. By contrast, the expanding resource hypothesis (ERH) is favoured by biologists and states that there is a gradual increase in food resources and availability of niches through time […] the intrinsic trend of diversification hypothesis (ITDH) […] holds that the long-term patterns of ESH and ERH vary among groups of organisms […] This view would imply that the proportion of occupied ecological roles has a globally disjunct pattern according to group, time and space. Of these, the current data favors ESH, if one assumes that the ecological clock was set during the Pennsylvanian and the previous fossil record is too poor for analysis.”

“Taphonomy is the study of the physical, chemical and biotic events that affect organisms after death, including pre-burial processes that transform the original living community into an entombed death assemblage that may be encountered by paleobiologists many aeons later. The fidelity to which the preserved assemblage actually resembles the source community is an issue in dicussions of the quality of the fossil record […] A full appreciation of the fossil associational record [between insects and plants] requires an evaluation of the five major types of qualitative evidence: plant reproductive biology, plant damage, dispersed coprolites, gut contents, and insect mouthparts. […] Collectively, these five types of evidence range from the direct, ‘smoking gun’ of gut contents, where the consumer and consumed are typically identifiable, to the more remote and circumstantial evidence of floral reproductive biology and mouthparts, where inferences are based on functional understanding, usually from modern analogues. […] Of all types of evidence for plant-arthropod associations, plant damage has the most extensive fossil record […] gut contents are the rarest type of evidence for plant-animal associations”

“Functional feeding groups can be sorted into 14 basic ways that insects access food” [I had no idea! And yes, they talk about all of these in the book. Note that you can easily split up those ‘basic ways’ into more subcategories if you like:] “In well-preserved Cretaceous and Caenozoic angiosperm-dominated floras, there are approximately 30 distinct types of external foliage-feeding, ranging from generalized bite-marks on margins to highly stereotyped and often intricate patterns of slot-hole feeding: earlier floras have fewer recognizable types of damage. […] The history of arthropod feeding on plants began during the Late Silurian to early Devonian […] by the close of the Pennsylvanian, the expansion of arthropod herbivory had invaded all plant organisms and virtually all plant tissues […] This expansion of dietary breadth provided a modern cast to the spectrum of insect diets. […] while the overwhelming bulk of the 14 plant-associated diet types was in place during the late Pennsylvanian, it was followed by the addition of 4 novel diet types during the Mesozoic in conjunction with the establishment of freshwater ecosystems and the diversification of advanced seed plants. […] When expressed as a diversity curve spanning the past 400 million years, there is a linear but stepped rise in mouthpart class diversity from the Early Devonian to the Early Jurassic, where it reached a plateau, followed by only a few subsequent additions […] Thus virtually all basic mouthpart innovation, including plant-associated mouthpart classes, was established prior to the angiosperm ecological expansion during the Middle Cretaceous [this was when flowering plants really took off, US], suggesting that mouthpart classes are attributable to basic associations with seed plants, or vascular plants of the more remote past, rather than the relatively late-appearing angiosperms […] Arthropods have used plants extensively for shelter probably since the Early Devonian”

“The amount of live plant tissue assimilated by arthropods is significantly greater than that of vertebrates in virtually all biomes except grasslands […] The fossil evidence indicates that this arthropod dominance has probably been the case since the establishment of the earliest terrestrial ecosystems. In fact, it was not until the latest Devonian that vertebrates emerged on land […], for which evidence indicates obligate carnivory. […] Direct evidence for vertebrate herbivory does not occur until the latest Pennsylvanian to earliest Permian […], about 100 million years after it appeared among mid-Paleozoic arthropods. […] A consequence of large vertebrate size is that consumption of plant organs is frequently complete and not partial as it is among arthropods, leaving minimal evidence from leaves, seeds and other wholly-consumed items. Also, the rarity of vertebrates when compared to arthropods may result in an underestimate of vertebrate importance in their interactions with plants. […] An interesting aspect of Paleozoic tetrapod herbivores is that they were uniformly short-necked and short-limbed browsers that cropped plant material within a metre to perhaps two metres of the ground surface. This trend continued […] into the Late Triassic, at which time basal dinosaur lineages began their diversification into virtually all major terrestrial feeding niches […] While Paleocene to middle Eocene mammalian herbivores were dominated by small to medium-sized forms consuming fruit, seeds and leaves, later herbivores were much larger, and invaded the browsing and eventually grazing adaptive zones […] This shift is related to the mid-Caenozoic origin of savanna and grassland biomes concomitant with the ecological spread of grasses. The oldest grasses reliably documented in the fossil record occur at the Palaeocene/Eocene boundary [~56 mya, US] […], although the earliest evidence for a grassland-adapted mammalian fauna is from the middle Oligocene [~28 mya, US] of Mongolia […] During the Pleistocene (2.65 Ma to 10 000 yr BP), much of the Planet underwent severe climactic pertubations from five major episodes of continental and associated alpine glaciation. Continental faunas were considerably reorganized during and after this interval in terms of dominance and composition of species […] Much evidence now supports a view that continental species did not respond as cohesive assemblages to these major environmental shifts, but rather individualistically […] An important exception to this trend are insects with high host specificity, which responded differently, retaining ancestral plant associations to the present […] or becoming extinct. Herbivorous mammals have less obligate dependence on plant species […] and thus exhibit greater dietary flexibility during times of major environmental stress.”

The Origin and Evolution of Cultures (IV)

“The first half of the book was not easy to read due to the technical nature of the coverage, and so I decided to put it away for a while. However I did pick it up again, and I’m really glad I did as there’s simply no way around the fact that this book is awesome. Some of the chapters in this book are chapters you need to read.

Highly recommended. Probably the best book I’ve read this year.”

I’ve finished the book – the above is my review of it on goodreads. I gave the book five stars.

The last part of it had (at least) two of those must-read chapters which I when I read them feel like I really ought to blog, and they both had a lot of stuff. The first of these chapters was an awesome chapter on agriculture. I wrote some stuff of my own about that stuff in my last post about the book (I’ve incidentally corrected a few minor inaccuracies in that post since it was posted – I thought I should mention this here), but I’m pretty sure I wouldn’t have done this if I’d known what was in that chapter; they cover this topic in a lot of detail and they do it really well. Many of the aspects they cover incidentally do not overlap with what I wrote though some of course do; you’ll surely get a lot out of reading this post despite having read my earlier comments on the topic (at least if you’re interested in these sorts of things). In my archaeology textbook, which is only a few years old, the idea that the dramatic climate change which took place around the Pleistocene/Holocene boundary was a crucial factor in the development of agriculture is taken for granted, but Boyd and Richerson’s coverage reminds us that archaeologists were not always so eager to accept this hypothesis (and it should be noted that other, weaker, hypotheses are mentioned/covered in the archaeology text as well – I was skeptical about some of these while reading the book (I wrote a couple of pretty harsh remarks in the margin) because they seemed implausible to me; Boyd and Richerson illustrates in the chapter e.g. through application of models of population dynamics that I had reason to be skeptical). I forgot to talk about climate in my last post on the topic probably because I assumed people knew this part, but it gets its fair share of the attention in this post anyway so I guess no harm is done.

The other chapter I consider to be best categorized as a ‘must-read’ chapter is chapter 19, on ‘Simple Models of Complex Phenomena’, which relates a little bit – but only a little – to a blog post of mine which has recently got some attention. When reading that chapter I was never in any doubt I’d cover that stuff here – this stuff is pure gold. The ‘Microevolutionary processes give rise to history’-chapter was also really interesting and the last chapter on memes there are probably more than a few people who’d benefit from reading, but I’ll not cover that stuff here; I don’t think I’d have problems writing 4 or 5 posts about the remaining parts of the book, and this is simply too much. I’ll talk about agriculture in this post and then I’ll probably cover the model chapter in a later post. It’s possible that the agriculture coverage in the book is less interesting to people with very limited knowledge of archaeology and human prehistory than it is to me (not that I’d say I know much about this stuff – actually on second thought I probably belong in the group of people with ‘very limited knowledge’ as well…), because a lot of things which relate closely to what they write about are perhaps hard to conceptualize without knowing anything about these things, but anyway I write about what I find interesting, so here we are.

Let’s move on to the book chapter coverage:

…

“Numerous subsequent investigations [after the Braidwood team] now provide a reasonably detailed picture of the origins of agriculture in several independent centers and its subsequent diffusion to almost all of the earth suitable for cultivation. These investigations have discovered no region in which agriculture developed earlier or faster than in the Near East, though a North Chinese center of domestication of millet may prove almost as early. Other centers seem to have developed later, or more slowly, or with a different sequence of stages, or all three. The spread of agriculture from centers of origin to more remote areas is well documented for Europe and North America [a major problem in relation to East Asia/China is incidentally the lack of ‘transitional sites’ dated around 8.000 to 6.000 years BC; we have very early sites and then we have “abundant and widespread evidence for sedentary Neolithic villages” by 6000 BC (Scarre et al.) – but we miss some evidence as to what happened in between – US]. Ethnography also gives us cases where hunters and gatherers persisted to recent times in areas seemingly highly suitable for agriculture, most notably much of western North America and Australia. Attempts to account for this rather complex pattern are a major focus of archaeology.”

“The processes involved in such a complex phenomenon as the origin of agriculture are many and densely entangled. Many authors have given climate change a key explanatory role […] The coevolution of human subsistence strategies and plant and animal domesticates must also play an important role […] Hunting-and-gathering subsistence may normally be a superior strategy to incipient agriculture […], and, if so, some local factor may be necessary to provide the initial impetus to heavier use of relatively low-quality, high-processing-effort plant resources that eventually result in plant domestication. Population pressure is perhaps the most popular candidate […] Quite plausibly, the complex details of local history entirely determine the evolutionary sequence leading to the origin and spread of agriculture in every region. Indeed, important advances in our understanding of the origins of agriculture have resulted from pursuit of the historical details of particular cases […] Nonetheless, we propose that much about the origin of agriculture can be understood in terms of two propositions:
Agriculture was impossible during the last glacial age. During the last glacial age, climates were variable and very dry over large areas. Atmospheric levels of CO2 were low. Probably most important, last-glacial climates were characterized by high-amplitude fluctuations on timescales of a decade or less to a millennium. Because agricultural subsistence systems are vulnerable to weather extremes, and because the cultural evolution of subsistence systems making heavy, specialized use of plant resources occurs relatively slowly, agriculture could not evolve.
In the long run, agriculture is compulsory in the holocene epoch. In contrast to the Pleistocene climates, stable Holocene climates allowed the evolution of agriculture in vast areas with relatively warm, wet climates, or access to irrigation. Prehistoric populations tended to grow rapidly to the carrying capacity set by the environment and the efficiency of the prevailing subsistence system. Local communities that discover or acquire more intensive subsistence strategies will increase in number and exert competitive pressure on smaller populations with less intensive strategies. Thus, in the Holocene epoch, such intergroup competition generated a competitive ratchet favoring the origin and diffusion of agriculture.”

This is the basic idea. But the chapter has a lot more:

“For the last 400,000 years, very high-resolution climate proxy data are available from ice cores taken from the deep ice sheets of Greenland and Antarctica. Resolution of events lasting little more than a decade is possible in Greenland ice 80,000 years old, improving to monthly resolution 3,000 years ago. During the last glacial, the ice core data show that the climate was highly variable on time scales of centuries to millennia […] The last glacial period was arid and extremely variable compared to the Holocene. Sharp millennial-scale excursions occur in estimated temperatures, atmospheric dust, and greenhouse gases. The intense variability of the last glacial carries right down to the limits of the nearly 10-year resolution of the ice core data. […] Even though diffusion and thinning within the ice core progressively erases high-frequency variation in the core […] the shift from full glacial conditions about 18,000 years ago to the Holocene interglacial is accompanied by a dramatic reduction in variation on timescales shorter than 150 years. The Holocene (the last relatively warm, ice-free 11,600 years) has been a period of very stable climate, at least by the standards of the last glacial age.[2] The climate fluctuations recorded in high-latitude ice cores are also recorded at latitudes where agriculture occurs today. Sediments overlain by anoxic water that inhibits sediment mixing by burrowing organisms are a source of low- and mid-latitude data with a resolution rivaling ice cores. Events recorded in North Atlantic sediment cores are closely coupled to those recorded in Greenland ice […], but so are records distant from Greenland. Hendy and Kennett (2000) report on water temperature proxies from sediment cores from the often-anoxic Santa Barbara Basin just offshore of central California. This data shows millennial- and submillennial-scale temperature fluctuations from 60–18 thousand years ago with an amplitude of about 8°C, compared to fluctuations of about 2°C in the Holocene epoch. As in the Greenland cores, the millennial-scale events often show very abrupt onsets and terminations and are often punctuated by brief spikes of warmth and cold.”

“We expect that opportunism was the most important strategy for managing the risks associated with plant foods during the last glacial age. Annual plants have dormant seed that spreads their risk of failure over many years, and perennials vary seed output or storage organ size substantially between years as weather dictates. In a highly variable climate, the specialization of exploitation on one or a few especially promising species would be highly unlikely, because ‘‘promise’’ in one year or even for a decade or two would turn to runs of years with little or no success. However, most years would likely be favorable for some species or another, so generalized plant-exploitation systems are compatible with highly variable climates. […] Plant food-rich diets take considerable time to develop. Plant foods are generally low in protein and often high in toxins. Some time is required to work out a balanced diet rich in plant foods, for example, by incorporating legumes to replace part of the meat in diets. Whether intensification and agriculture always lead to health declines due to nutritional inadequacy is debatable, but the potential for them to do so absent sometimes-subtle adaptations is clear […] The seasonal round of activities has to be much modified, and women’s customary activities have to be given more prominence relative to men’s hunting. Changes in social organization either by evolution in situ or by borrowing tend to be slow […] We doubt that even sophisticated last-glacial hunter-gatherers would have been able to solve the complex nutritional and scheduling problems associated with a plant-rich diet while coping with unpredictable high-amplitude change on timescales shorter than the equilibration time of plant migrations and shorter than actual Holocene trajectories of intensification.”

“Low mean productivity, along with greater variance in productivity, would have greatly decreased the attractiveness of plant resources during the last glacial age. Lower average rainfall and carbon dioxide during the last glacial age reduced the area of the earth’s surface suitable for agriculture […] On present evidence we cannot determine whether aridity, low CO2 levels, millennial-scale climate variability, or submillennial-scale weather variation was the main culprit in preventing the evolution of agriculture. Low CO2 and climate variation would handicap the evolution of dependence on plant foods everywhere and were surely more significant than behavioral or technological obstacles. Hominids evolved as plant-using omnivores (Milton, 2000), and the basic technology for plant exploitation existed at least 10 thousand years before the Holocene […] At least in favorable localities, appreciable use seems to have been made of plant foods, including large-seeded grasses, well back into the Pleistocene […] Significantly, we believe, the use of such technology over spans of last-glacial time that were sufficient for successive waves of intensification of subsistence in the Holocene led to only minor subsistence intensification, compared to the Mesolithic, Neolithic, and their ever-more-intensive successors. […] After 11,600 B.P., the Holocene period of relatively warm, wet, stable, CO2-rich environments began. Subsistence intensification and eventually agriculture followed. Thus, while not perfectly instantaneous, the shift from glacial to Holocene climates was a very large change and took place much more rapidly than cultural evolution could track.”

“Might we not expect agriculture to have emerged in the last interglacial 130,000 years ago or even during one of the even older interglacials? No archaeological evidence has come to light suggesting the presence of technologies that might be expected to accompany forays into intensive plant collecting or agriculture at this time. Anatomically modern humans may have appeared in Africa as early as 130,000 years ago […], but they were not behaviorally modern. Humans of the last interglacial were uniformly archaic in behavior. Very likely, then, the humans of the last interglacial were neither cognitively nor culturally capable of evolving agricultural subsistence. However, climate might also explain the lack of marked subsistence intensification during previous interglacials. Ice cores from the thick Antarctic ice cap at Vostok show that each of the last four interglacials over the last 420,000 years was characterized by a short, sharp peak of warmth, rather than the 11,600-year-long stable plateau of the Holocene (Petit et al., 1999).”

“Once a more productive subsistence system is possible, it will, over the long run, replace the less-productive subsistence system that preceded it. The reason is simple: all else being equal, any group that can use a tract of land more efficiently will be able to evict residents that use it less efficiently […] More productive uses support higher population densities, or more wealth per capita, or both. An agricultural frontier will tend to expand at the expense of hunter-gatherers as rising population densities on the farming side of the frontier motivate pioneers to invest in acquiring land from less-efficient users. […] Thus, subsistence improvement generates a competitive ratchet as successively more land-efficient subsistence systems lead to population growth and labor intensification. Locally, huntergatherers may win some battles (e.g., in the Great Basin; Madsen, 1994), but in the long run the more intensive strategies will win wherever environments are suitable for their deployment. The archaeology supports this argument […] Societies in all regions of the world undergo a very similar pattern of subsistence efficiency increase and population increase in the Holocene, albeit at very different rates. Holocene hunter-gatherers developed local equilibria that, while sometimes lasting for thousands of years, were almost always replaced by more intensive equilibria.”

“Cohen’s (1977) influential book argued that slowly accumulating global-scale population pressure was responsible for the eventual origins of agriculture beginning at the 11,600 B.P. time horizon. He imagines, quite plausibly, that subsistence innovation is driven by increases in population density, but, implausibly we believe, that a long, slow buildup of population gradually drove people to intensify subsistence systems to relieve shortages caused by population growth, eventually triggering a move to domesticates. Looked at one way, population pressure is just the population growth part of the competitive ratchet. However, this argument fails to explain why pre-agricultural hunter-gatherer intensification and the transition to agriculture began in numerous locations after 11,600 years ago […] Assuming that humans were essentially modern by the Upper Paleolithic, they would have had 30,000 years to build up a population necessary to generate pressures for intensification. Given any reasonable estimate of the human intrinsic rate of natural increase under hunting-and-gathering conditions (somewhat less than 1% yr^-1 to 3% yr^-1, populations substantially below carrying capacity will double in a century or less […] If agricultural technologies were quick and easy to develop, the population pressure argument would lead us to expect Pleistocene populations to shift in and out of agriculture and other intensive strategies as they find themselves in subsistence crises due to environmental deterioration or in periods of plenty due to amelioration. Most likely, minor intensifications and de-intensifications were standard operating procedure in the Pleistocene. However, the time needed to progress much toward plant-rich strategies was greater than the fluctuating climate allowed, especially given CO2- and aridity-limited plant production.”

…

This part is really important to understand, and I know I’ve talked about this before but I’ll say it again: Humans living, say, 25.000 years ago were not stupid. They weren’t monkeys walking around looking for berries in the woods. They probably tried and tried repeatedly to make this kind of stuff work, explore all kinds of creative ways to obtain enough/more food, always slightly adjusting their strategies in order to stay alive and keep having kids – but the climate wouldn’t allow them to ever achieve ‘take off’. As they put it towards the end of the chapter: “If climate variation did not limit intensification during the last glacial age to vanishingly slow rates compared to the Holocene epoch, the failure of intensive systems to evolve during the tens of millennia anatomically and culturally modern humans lived as sophisticated hunter-gatherers before the Holocene is a considerable mystery.” It seems climate is a big part of the explanation why we never got to where we are now before we did. Environmental constraints limit the activities of all lifeforms in all kinds of ways, and it would serve us well every once in a while to recall that we are in fact no different, even if we like to think we are, and that such effects may have played a crucial role in the history of our species.

I’ve added a bit more from the book. Some of the stuff below I talked about in the last post as well (do recall that I wrote that post before I read this chapter), but I figured it wouldn’t hurt to include it here anyway:

…

“The timing of initiation of agriculture varies quite widely […] The exact sequence of events also varies quite widely. For example, in the Near East, sedentism preceded agriculture, at least in the Levantine Natufian sequence, but in Mesoamerica crops seem to have been added to a hunting-and-gathering system that was dispersed and long remained rather mobile […] For example, squash seems to have been cultivated around 10,000 B.P. in Mesoamerica, some 4,000 years before corn and bean domestication began to lead to the origin of a fully agricultural subsistence system […] Some mainly hunting-and-gathering societies seem to have incorporated small amounts of domesticated plant foods into their subsistence system without this leading to full-scale agriculture for a very long time. […] the path forward through the whole intensification sequence varied considerably from case to case.”

“In all known cases, the independent centers of domestication show a late sequence of intensification beginning with a shift from a hunter-gatherer subsistence system based upon low-cost resources using minimal technological aids to a system based upon the procurement and processing of high-cost resources, including small game and especially plant seeds or other labor-intensive plant resources, using an increasing range of chipped and ground stone tools […] The reasons for this shift are the subject of much work among archaeologists […] The shifts at least accelerate and become widespread only in the latest Pleistocene or Holocene. However, a distinct tendency toward intensification is often suggested for the Upper Paleolithic more generally. […] Upper Paleolithic peoples often made considerable use of small mammals and birds in contrast to earlier populations. These species have much lower body fat than large animals, and excessive consumption causes ammonia buildup in the body due to limitations on the rate of urea synthesis […] Consequently, any significant reliance on low-fat small animals implies corresponding compensation with plant calories, and at least a few Upper Paleolithic sites, such as the Ohalo II settlement on the Sea of Galilee […], show considerable use of plant materials in Pleistocene diets. Large-seeded annual species like wild barley were no doubt attractive resources in the Pleistocene when present in abundance and would have been used opportunistically during the last glacial age. If our hypothesis is correct, in the last glacial age no one attractive species like wild barley would have been consistently abundant (or perhaps productive enough) for a long enough span of time in the same location to have been successfully targeted by an evolving strategy of intensification, even if their less intensive exploitation was common. The broad spectrum of species, including small game and plants, reflected in these cases is not per se evidence of intensification (specialized use of more costly but more productive resources using more labor and dedicated technology), as is sometimes argued […] In most hunter-gatherer systems, marginal diet cost and diet richness (number of species used) are essentially independent […], and prey size is far less important in determining prey cost than either mode or context of capture […] For all these reasons, quantitative features of subsistence technology are a better index of Pleistocene resource intensification than species used. We believe that the dramatic increase in the quantity and range of small chipped stone and groundstone tools only after 15,000 B.P. signals the beginning of the pattern of intensification that led to agriculture.”

“Early intensification of plant resource use would have tended to generate the same competitive ratchet as the later forms of intensification. Hunter-gatherers who subsidize hunting with plant-derived calories can maintain higher population densities and thus will tend to deplete big game to levels that cannot sustain hunting specialists […] Once the climate ameliorated, the rate of intensification accelerated immediately in the case of the Near East. In other regions changes right at the Pleistocene-Holocene transition were modest to invisible […] The full working out of agrarian subsistence systems took thousands of years. […] Fully agricultural subsistence systems in the sense of a dominance of domesticated species in the diet typically postdate the origin of agriculture [which they define as “dependence upon domesticated crops and animals for subsistence” – US] by a millennium or more. […] Zvelebil (1996) emphasizes the complexity and durability of frontiers between farmers and hunter-gatherers and the likelihood that in many places the diffusion of both genes and ideas about cultivation was a prolonged process of exchange across a comparatively stable ethnic and economic frontier.”

The Biology of Happiness

(Before I move on to talk about the book, I wanted to add a short unrelated personal note: I have been under a lot of stress over the last few weeks on account of stuff I really didn’t have many realistic ways to deal with (I tried various approaches and I think I was somewhat creative in my attempts, but they were mostly unsuccessful). The main stressor is now gone for the moment, so maybe I’ll blog more in the weeks to come than I have over the last few weeks. However as I’ve decided to participate in a Mensa event this weekend you should not expect me to update this blog between Friday evening and Sunday afternoon, as I assume I’ll not be spending much time near a computer during that time.)

…

“of all political ideals, that of making the people happy is perhaps the most dangerous one. It leads invariably to the attempt to impose our scale of ‘higher’ values upon others, in order to make them realize what seems to us of greatest importance for their happiness; in order, as it were, to save their souls. It leads to Utopianism and Romanticism. We all feel certain that everybody would be happy in the beautiful, the perfect community of our dreams. […] the attempt to make heaven on earth invariably produces hell.”

Let’s just say the author of this book has not read Popper.

Here’s what I wrote on goodreads:

“I’m not rating this as it does not make sense to rate it. Some parts of the last few chapters deserve 0 stars. A few of the first chapters deserve three stars.

The first half of the book has a few problems but is generally of a reasonably high quality. I learned some new stuff there. The last chapters of the book are quite poor.

In general I’d probably if hard-pressed give it two stars as a sort of average rating of the material. But 2 stars would imply that I think the book is ‘okay’. And some parts of it really is not okay. However I also cannot justify giving the book one star.”

…

I’d wish it were this easy, but unfortunately it isn’t so I’m finding myself reading this stuff. It did not take much time to read the book and that the first half to two-thirds of it was reasonably interesting. I don’t regret reading the rest – it’s relevant for how to assess the remainder of the coverage, if nothing else, and the book is so short I never got to dwell on the bad stuff much. Popper’s quote is incidentally relevant because the author seems to think people reading the book care about what he thinks about politics and stuff like that. I don’t, and I tend to assume that I’m not the only one; most people reading Springer publications don’t do so because they’re looking for political coverage of the topics of the day. Anyway I see no need to talk about those aspects here. I also don’t want to talk much about some of the specific advice he gives, which I consider to be … (I don’t really have a good word for it). He’s a proponent of embracing religion because it may make you happier, and he’s also a fan of various forms of ‘positive thinking’-type psychological interventions. Dobson et al. covered that kind of stuff and there was also a bit on that kind of stuff in Leary & Hoyle, and I think Grinde is overestimating how large effects can be derived from such cognitive interventions – in an impact-evaluation framework the evidence for much of the advice he gives is simply either poor or non-existent, and adding a reference to one study or something like that to justify an approach is not going to convince me when review chapters on related topics have failed to do the same. The fact that he seems to systematically (deliberately?) overestimate the prevalence of various mental problems throughout the last part of the book, presumably because he assumes that doing this will make the political suggestions he’s heading towards more palatable, certainly does not help; it makes him look untrustworthy. Which is unfortunate because other parts of the coverage are actually okay.

Enough about the bad stuff. I’d rather talk a little about some of the interesting stuff in the book.

Here’s part of the abstract from the the beginning of the book:

“This book presents a model for what happiness is about—based on an evolutionary perspective. Briefly, the primary purpose of nervous systems is to direct an animal either towards opportunities or away from danger in order to help it survive and procreate. Three brain modules are engaged in this task: one for avoidance and two for attraction (seeking and consuming). While behaviour originally was based on reflexes, the brain gradually evolved into a more adaptive and flexible system based on positive and negative affects (good and bad feelings). The human capacity for happiness is presumably due to this whim of evolution—i.e. the advantages of having more flexibility in behavioural response. A variety of submodules have appeared, caring for a long list of pursuits, but recent studies suggest that they converge on shared neural circuits designed to generate positive and negative feelings. The brain functions involved in creating feelings, or affect, may collectively be referred to as mood modules. Happiness can be construed as the net output of these modules. Neural circuits tend to ‘expand’ (gain in strength and influence) upon frequent activation. This suggests the following strategy for improving mental health and enhancing happiness: To avoid excessive stimulation of negative modules, to use cognitive interference to enhance the ‘turn off’ function of these modules, and to exercise modules involved in positive feelings.”

He uses the term happiness in the book in a way such that both hedonic and eudaimonic elements are included. There are quite a few ways to break down what happiness ‘really is all about’ and philosophers and others have written about these things for thousands of years, but Grinde argues that “Whatever divisions are made, it all seems to come down to activation of nerve circuits designed for the purpose of creating positive affect”. It should also be noted that: “Our knowledge in neurobiology is not yet at the level where we can accurately delegate happiness to particular brain structures.” There are some structures we know to be involved and we know that neurotransmitters involved in these processes in humans and other mammals also serve similar functions in more primitive organisms/neural systems, but of course if you’re taking ‘a broad view’ of happiness the way the author does, demanding that we have the full picture is perhaps a bit much. On a related note:

“There has been considerable work aimed at defining the neuroanatomy of mood modules […] The more ancient, presumably subconscious, neural circuitry involved is situated in the subcortical part of the brain—particularly in the thalamus, hypothalamus, amygdala and hippocampus. The cognitive extension appears to involve circuitry in the orbitofrontal, lateral prefrontal, insular and anterior cingulate parts of the cortex. The subcortical nerve circuits are probably essential for initiating positive and negative feelings, while the cortex enables both the particulars of how they are perceived, and a capacity to modulate their impact. […] the two reward modules (seeking and liking) and the punishment module presumably evolved from simple neurological structures catering to approach and avoidance reflexes in primitive animals.”

The neurobiology stuff relevant to this discussion is covered in much more detail in Clark & Treisman, although that one of course also only really scratches the surface and very different aspects are emphasized there. As for the reflexes mentioned above, they are very useful in some contexts and can from one point of view (the author’s) be considered a forerunner to more complex emotions. Reflexes don’t however always work that well, in particular they don’t necessarily handle change and complexity very well; if different reactions are optimal in different contexts an organism may benefit from upgrading from reflexes only/mainly to more complex information feedback systems. You don’t need emotions for that, but emotions may be a part of such a complex feedback system. Instead of going from the ‘simple to the complex’, one might also ask why e.g. plants never developed a nervous system? This may add a bit to the understanding of why these things are the way they are – Grinde argues that:

“The reason why plants never obtained anything similar to a nervous system is presumably because they (or at least the more complex versions) are sedentary. They do not need to move around to find food”. Animals tend to do, and even if they’re sedentary “their survival requires what we refer to as behaviour […] which may be defined as movements required for survival and procreation. […] The nerve system, and the concomitant use of muscles, was the evolutionary response to this requirement. In complex animals like vertebrates, the nervous system infiltrates all parts of the body. It connects with sense organs, to extract information from the environment, and effector organs (muscles), to orchestrate behaviour. The sense organs offer the organism information that is used to decide on an action, and the muscles set the action in motion. Between these two lies a processing capacity, which in advanced animals is referred to as a brain.”

I think it’s interesting in this context that a lot of what most humans probably consider to be ‘different stuff’ is really dealt with by the same brain structures:

“the three mood modules appear to cater to all sorts of pleasures and pains […] the ups and downs associated with the emotional response to sociopsychological events rely on much the same neural circuitry that underlies the typical pain and pleasures caused by physical stimuli. For example, experiencing envy of another person’s success activates pain-related circuitry, whereas experiencing delight at someone else’s misfortune (what is referred to as schadenfreude), activates reward-related neural circuits […] Similarly, feeling excluded or being treated unfairly activates pain-related neural regions […] On the other hand, positive social feelings, such as getting a good reputation, fairness and being cooperative, offers rewards similar to those one gets from desirable food […] And the same reward-related brain regions are activated when having sex or enjoying music […] Apparently, the ancient reward and punishment circuits of the brain have simply been co-opted for whatever novel needs that arouse in the evolutionary lineage leading toward humans.”

Some parts of the brain are more sensitive to stimuli than others, although we tend to hover around a set point of happiness. The set point is one we may be able to slowly change over time, and for most people it seems to be ‘positive’ in the sense that we tend to be relatively content when negative feelings are not activated – ‘a default state of contentment’, as Grinde terms it. I thought it was interesting that humans seem to be more sensitive to big negative emotional stimuli than to other stimuli (most positive stimuli tend to have relatively short-lived effects), “presumably because a single threat can have a far more drastic effect on genetic fitness (e.g., leading to death), than can a single fortunate event.” As in the case of many other complex traits, there aren’t any major-impact ‘happiness genes’; although genes matter the differences they cause are most likely due to the combined effects of a large number of small-impact genes and their interactions with the environment. This should hardly be surprising.

Thinking about the evolutionary context underlying our emotional responses to various stimuli the way Grinde does in this book of course also leads to questions about whether the enviroment in which humans live today is well-suited for the task of making us happy and related questions such as how we might best go about trying to optimize our environment in order to live a happy life. When looked at from a certain point of view modern humans live lives which are a bit like the lives of zoo animals; the environment we inhabit is very different from the one in which our ancestors evolved, and zoo animals that are not well taken care of tend to be unhappy and engage in various problematic behaviours. I’m not sure I want to go into that discussion in too much detail, but it’s certainly the case that whereas some aspects of modern life have the potential to increase our happiness, e.g. by dealing with stimuli that tends to be make us unhappy (hunger, pain, disease), other aspects probably have the opposite effect (e.g. weaker social bonds). This should not be new to the readers of this blog either as I think I’ve talked about this stuff before; I’ve certainly read stuff which has made me think along similar lines in the past.

There’s some stuff covered in the book which I have not talked about, but I figure I’ll stop here. I really would not recommend the book, but parts of it was actually reasonably interesting.

Wikipedia articles of interest

i. Stirling engine.

“A Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work.^[1][2] Or more specifically, a closed-cycle regenerative heat engine with a permanently gaseous working fluid, where closed-cycle is defined as a thermodynamic system in which the working fluid is permanently contained within the system, and regenerative describes the use of a specific type of internal heat exchanger and thermal store, known as the regenerator. It is the inclusion of a regenerator that differentiates the Stirling engine from other closed cycle hot air engines.

Originally conceived in 1816 as an industrial prime mover to rival the steam engine, its practical use was largely confined to low-power domestic applications for over a century.^[3]

The Stirling engine is noted for its high efficiency compared to steam engines,^[4] quiet operation, and the ease with which it can use almost any heat source. This compatibility with alternative and renewable energy sources has become increasingly significant as the price of conventional fuels rises, and also in light of concerns such as peak oil and climate change. This engine is currently exciting interest as the core component of micro combined heat and power (CHP) units, in which it is more efficient and safer than a comparable steam engine.^[5][6] […]

In contrast to internal combustion engines, Stirling engines have the potential to use renewable heat sources more easily, to be quieter, and to be more reliable with lower maintenance. They are preferred for applications that value these unique advantages, particularly if the cost per unit energy generated is more important than the capital cost per unit power. On this basis, Stirling engines are cost competitive up to about 100 kW.^[56]

Compared to an internal combustion engine of the same power rating, Stirling engines currently have a higher capital cost and are usually larger and heavier. However, they are more efficient than most internal combustion engines.^[57] Their lower maintenance requirements make the overall energy cost comparable. The thermal efficiency is also comparable (for small engines), ranging from 15% to 30%.^[56] For applications such as micro-CHP, a Stirling engine is often preferable to an internal combustion engine. Other applications include water pumping, astronautics, and electrical generation from plentiful energy sources that are incompatible with the internal combustion engine, such as solar energy, and biomass such as agricultural waste and other waste such as domestic refuse. Stirlings are also used as a marine engine in Swedish Gotland-class submarines.^[58] However, Stirling engines are generally not price-competitive as an automobile engine, due to high cost per unit power, low power density and high material costs.”

Sixty Symbols at one point made a neat little video about these engines – you can watch the video here.

…

ii. Doolittle Raid.

“The Doolittle Raid, also known as the Tokyo Raid, on 18 April 1942, was an air raid by the United States on the Japanese capital Tokyo and other places on Honshu island during World War II, the first air raid to strike the Japanese Home Islands. It demonstrated that Japan itself was vulnerable to American air attack, was retaliation for the Japanese attack on Pearl Harbor on 7 December 1941, provided an important boost to U.S. morale, and damaged Japanese morale. The raid was planned and led by Lieutenant Colonel James “Jimmy” Doolittle, U.S. Army Air Forces.

Sixteen U.S. Army Air Forces B-25B Mitchell medium bombers were launched without fighter escort from the U.S. Navy‘s aircraft carrier USS Hornet deep in the Western Pacific Ocean, each with a crew of five men. The plan called for them to bomb military targets in Japan, and to continue westward to land in China—landing a medium bomber on the Hornet was impossible. Fifteen of the aircraft reached China, and the other one landed in the Soviet Union. All but three of the crew survived, but all the aircraft were lost. […]

The raid caused negligible material damage to Japan, only hitting non-military targets or missing completely […] but it succeeded in its goal of helping American morale and casting doubt in Japan on the ability of its military leaders. It also caused Japan to withdraw its powerful aircraft carrier force from the Indian Ocean to defend their Home Islands, and the raid contributed to Admiral Isoroku Yamamoto‘s decision to attack Midway—an attack that turned into a decisive strategic defeat of the Imperial Japanese Navy (IJN) by the U.S. Navy near Midway Island in the Central Pacific. […]

Immediately following the raid, Doolittle told his crew that he believed the loss of all 16 aircraft, coupled with the relatively minor damage to targets, had rendered the attack a failure, and that he expected a court-martial upon his return to the United States. Instead, the raid bolstered American morale to such an extent that Doolittle was awarded the Medal of Honor by President Roosevelt, and was promoted two grades to brigadier general, skipping the rank of colonel. […]

Following the Doolittle Raid, most of the B-25 crews who had reached China eventually achieved safety with the help of Chinese civilians and soldiers. Of the 80 airmen who participated in the raid, 69 escaped capture or death. When the Chinese helped the Americans escape, the grateful Americans in turn gave them whatever they had on hand. The people who helped them, however, paid dearly for sheltering the Americans.”

The Japanese were pretty pissed afterwards:

“The Japanese military began the Zhejiang-Jiangxi Campaign to intimidate the Chinese from helping the American airmen. All airfields in a range of some 20,000 square miles (50,000 km²) in the areas where the Raiders had landed were torn up.^[28] Germ warfare was used and atrocities committed, and those found with American items were shot. The Japanese killed an estimated 250,000 Chinese civilians during their search for Doolittle’s men.^[29][30] […] On 28 August 1942, pilot Hallmark, pilot Farrow and gunner Spatz faced a war crimes trial by the Japanese for allegedly strafing Japanese civilians. At 16:30 on 15 October 1942 they were taken by truck to Public Cemetery Number 1, and executed by firing squad. The other captured airmen remained in military confinement on a starvation diet, their health rapidly deteriorating. In April 1943, they were moved to Nanking, where Meder died on 1 December 1943. The remaining men, Nielsen, Hite, Barr and DeShazer, eventually began receiving slightly better treatment and were given a copy of the Bible and a few other books. They were freed by American troops in August 1945.”

…

iii. Missouri Executive Order 44.

“Missouri Executive Order 44, also known as the Extermination Order in Latter Day Saint history,^[1][2] was an executive order issued on October 27, 1838 by the governor of Missouri, Lilburn Boggs. It was issued in the aftermath of the Battle of Crooked River, a clash between Mormons and a unit of the Missouri State Guard in northern Ray County, Missouri, during the Mormon War of 1838. Claiming that the Mormons had committed “open and avowed defiance of the laws”, and had “made war upon the people of this State,” Boggs directed that “the Mormons must be treated as enemies, and must be exterminated or driven from the State if necessary for the public peace—their outrages are beyond all description”.^[2]

While Executive Order 44 is often referred to as the “Mormon Extermination Order” due to the phrasing used by Boggs, no one is known to have been killed by the militia or anyone else specifically because of it. There were, however, other associated deaths: the militia and other state authorities used Boggs’ missive as a pretext to expel the Mormons from their lands in the state, and force them to migrate to Illinois. This forced expulsion in difficult, wintry conditions posed a substantial threat to the health and safety of the affected Mormons, and an unknown number died from hardship and exposure. Furthermore, a group of men and boys were killed by Livingston County militia in the Haun’s Mill massacre three days after the order was issued; however, there is no evidence that the militiamen had any knowledge of it, nor did they ever use the order to justify their actions.

Mormons did not begin to return to Missouri until 25 years later, when they found a more welcoming environment and were able to establish homes there once more. […] Boggs’ extermination order, long unenforced and forgotten by nearly everyone outside the Latter Day Saint community, was formally rescinded by Governor Christopher S. Bond on June 25, 1976, 137 years after being signed.”

…

iv. Ug99. This is probably the kind of thing you’d prefer most people never to learn anything about. At least I’d say that if something like this ever becomes a household name, this is very bad news:

“Ug99 is a lineage of wheat stem rust (Puccinia graminis f. sp. tritici), which is present in wheat fields in several countries in Africa and the Middle East and is predicted to spread rapidly through these regions and possibly further afield, potentially causing a wheat production disaster that would affect food security worldwide.^[1] It can cause up to 100% crop losses and is virulent against many resistance genes which have previously protected wheat against stem rust.

Although Ug99-resistant varieties of wheat do exist, a screen of 200 000 wheat varieties used in 22 African and Asian countries found that only 5-10% of the area of wheat grown in these countries consisted of varieties with adequate resistance.^[1]”

…

v. Egyptian temples (featured).

Some quotes from the article:

“Each temple had a principal deity, and most were dedicated to other gods as well.^[9] However, not all deities had temples dedicated to them. Many demons and household gods were involved primarily in magical or private religious practice, with little or no presence in temple ceremonies. There were also other gods who had significant roles in the cosmos but, for uncertain reasons, were not honored with temples of their own.^[10] Of those gods who did have temples of their own, many were venerated mainly in certain areas of Egypt, though many gods with a strong local tie were also important across the nation.^[11] Even deities whose worship spanned the country were strongly associated with the cities where their chief temples were located. In Egyptian creation myths, the first temple originated as a shelter for a god—which god it was varied according to the city—that stood on the mound of land where the process of creation began. Each temple in Egypt, therefore, was equated with this original temple and with the site of creation itself.^[12] As the primordial home of the god and the mythological location of the city’s founding, the temple was seen as the hub of the region, from which the city’s patron god ruled over it.^[13]

Pharaohs also built temples where offerings were made to sustain their spirits in the afterlife, often linked with or located near their tombs. These temples are traditionally called “mortuary temples” and regarded as essentially different from divine temples. However, in recent years some Egyptologists, such as Gerhard Haeny, have argued that there is no clear division between the two.” […]

“The earliest known primitive shrines appeared in Egypt by the late Predynastic Period, in the late fourth millennium BC. […] Temple-building continued down until the 4th century AD.^[63] However, with the rise of the Christian Roman Emperors temples lost their traditional state funding, had their treasures melted down, and the proceeds redirected towards the building of churches.^[64] In AD 391 all pagan cults were banned by Theodosius I and in this same year the Serapeum of Alexandria was destroyed by Christians.^[65] Attacks on pagans and temples were widespread throughout Egypt.^[66] A few temples, such as Luxor, were converted into churches, while many others went completely disused.^[67] In AD 550, Philae, the last functioning temple in Egypt, was closed.^[68]”

“Some estimate that by the New Kingdom period, temples owned about 33% of the arable land.^[44]”

“A temple needed many people to perform its rituals and support duties. Priests performed the temple’s essential ritual functions, but in Egyptian religious ideology they were far less important than the king. As temple decoration illustrates, all ceremonies were, in theory, acts by the king, and priests merely stood in his place. The priests were therefore subject to the king’s authority, and he had the right to appoint anyone he wished to the priesthood. In fact, in the Old and Middle Kingdoms most priests were government officials who left their secular duties for part of the year to serve the temple in shifts.^[125] Once the priesthood became more professional, the king seems to have used his power over appointments mainly for the highest-ranking positions, usually to reward a favorite official with a job or to intervene for political reasons in the affairs of an important cult. […] Besides its priests, a large temple employed singers, musicians, and dancers to perform during rituals, plus the farmers, bakers, artisans, builders, and administrators who supplied and managed its practical needs.^[133] A major cult […] could have well over 150 full or part-time priests,^[134] with tens of thousands of non-priestly employees working on its lands across the country.^[135] These numbers contrast with mid-sized temples, which may have had 10 to 25 priests, and with the smallest provincial temples, which might have only one.^[136]” […]

“After their original religious activities ceased, Egyptian temples suffered slow decay. Many were defaced or dismantled by Christians trying to erase the remnants of paganism. Over time locals carried off their stones to use as material for new buildings.^[67] What humans left intact was still subject to natural weathering. Temples in desert areas could be covered by drifts of sand, while those near the Nile, particularly in Lower Egypt, were often completely buried under layers of river-borne silt. Thus, some major temple sites like Memphis and Heliopolis were reduced to ruin, while many temples far from the Nile and centers of population remained mostly intact. […] Nineteenth-century Egyptologists studied the temples intensively, but their emphasis was on collection of artifacts to send to their own countries, and their slipshod excavation methods often did further harm.^[174] Slowly, however, the antique-hunting attitude toward Egyptian monuments gave way to careful study and preservation efforts. […] Today there are dozens of sites with substantial temple remains,^[177] although many more once existed, and none of the major temples in Lower or Middle Egypt are well preserved.^[178] […] Archaeological work continues as well, as many temple remains still lie buried and many extant temples are not yet fully studied.”

…

Glycolysis.

(Actually I’m not sure this one is really that interesting, but it was one of the articles I was browsing a couple of days ago while reading McPhee et al. When I had had a brief look at this article, I concluded that I really didn’t need to understand the specific line of reasoning in the book that had made me look up that stuff..).

Dinosaurs past and present (2)

You can read my first post about the book here. I ended up giving it three stars on goodreads. I’m closer to two stars than four. It’s an old book, and although this ads to the reading experience at some points (see also some of the quotes below) it subtracts elsewhere. I wouldn’t recommend it, but it was okay and at times somewhat interesting. Some quotes from the last half of the book:

“Failure to recognize the full potential of trackways and track sites has frequently been a contributing factor in the proliferation of incorrect reconstructions of dinosaur activity. Even where good trackway evidence existed and was well known the interpretation rarely was adequate. For example, the Texan track sites reviewed here tell us that sauropods did not drag their tails, yet probably ninety-nine percent of all sauropod reconstructions made in the last fifty years have suggested that they did.”

“The widely debated issue of dinosaur endothermy and ectothermy has a direct bearing on the question of whether smaller dinosaurs like dromacosaurids or hypsilophodontids should be shown with an outer insulating fur or featherlike pelt. To date no direct evidence exists that any known dinosaur had such a covering…” (As many of you would probably know, we do have such evidence today. See e.g. this and this.)

“Until recently most restored dinosaurs were either drab gray, drab brown, or drab green. The assumption was that since the actual colors were unknown, these were “safe” colors. […] At present there is no proof for pattern or colors in dinosaurs. Considering the likelihood that their lives were governed by the same behavioral principles as modern vertebrates, it seems probable that most of these animals may have had patterns and colors of almost any kind rather than being drab and patternless. […] most baby dinosaurs would almost certainly have needed cryptic markings to help them hide from predators.”

“[A] fascinating possibility would be to re-create as a computer-animated simulation an event like the Glen Rose Sauropod Migration or Lark Quarry Dinosaur Stampede from Australia described by Thulborn and Wade (1979). To do so a map of the trackway assemblage would be recorded on a data tablet and programmed as a perspective view on a computer screen. Since the size, depth, and angle of the tracks can often furnish information about the size, weight, and approximate speed of an animal, the data from a single indivdual’s footprints, if these could be isolated, could be used to construct and program dinosaur images that would fit the size of each set of tracks. Combined with texture mapping and shading techniques, these images could be animated to show the sauropod herd migrating from a moving “camera-eye” vantage point in a simulated Jurassic landscape.” (…just 6 years later people could watch Jurassic Park in movie theatres around the world – I know this was not what the author had in mind, but…)

“During the Mesozoic era herbaceous plants were less abundant than they are now. Larger plants produce less new growth in proportion to their weight than do herbs. Plant biomass must therefore have been more highly visible in dinosaurian landscapes and imparted much “character” to ancient terrestrial ecosystems. Complete plants are seldom found in the fossil record, and whole-plant restorations are rarely made. It is thus very difficult to estimate the appearance of ancient plantscapes.”

“Relative to six other international groups (Hoffman and Nitecki 1985), vertebrate paleontologists are the least supportive of the asteroid-impact hypothesis and the most confident that there was not a Cretaceous mass extinction. In a survey taken during the annual Society of Vertebrate Paleontology meetings in the fall of 1985 (Browne 1985), twenty-seven percent of the respondents saw no evidence for a mass extinction at the end of the Cretaceous and forty-three percent believed that the approximately coincidental impact of an asteroid did not cause the extinctions. […] The point of view I hold cannot have been popular, for only four percent of the respondents at the 1985 meeting (I was unable to attend) felt that an asteroid impact resulted in the extinction of the dinosaurs.”

…

In case some of you have a desire to read a little more about ‘this kind of stuff’, I’ve posted a few links below:

Coelophysis.
Petrified Forest National Park (featured wikipedia article).
Phytosaur.
Dicynodont.
Paleobotany.
Triassic.
Mesozoic.
Thecodontia.

The Incas and their Ancestors: The archaeology of Peru (1)

Here’s the link, the average goodreads rating is 3.55. I found the book via the AskAnthropology reading list.

It’s not the first book I read on this specific subject (THP also covers some of this stuff, but in much less detail), however we know a lot more now than we did when Métraux wrote his book (as Moseley puts it in the introduction, “Due to a tremendous escalation in Andean studies, more archaeological, historical, and anthropological research has been carried out during the current generation than during all prior centuries.”) so I’m learning a lot. A really nice thing about the book is that although it deals only with a very specific group of people, it still has some focus on highlighting general principles regarding human development. Of course a book like Boyd and Richerson’s The Origin and Evolution of Cultures (I’m planning on reading this at some point..) presumbly deals with such matters in much more detail, but it’s still nice to have at least some big-picture stuff in a book like this.

Some stuff from the first half or so of the book, as well as a few comments:

“Just as the historical accounts of Tahuantinsuyu are not without prejudice, the archaeological record did not remain unbiased by the Spanish arrival. The conquering forces quickly learned that great stores of precious metal existed in the ground. Much was purely geological in context, but the tombs of past lords and nobles also contained enormous stores of gold and silver. Within a generation of the conquest, looting operations grew so large and financially rewarding that they became legally synonymous with mining. Ancient monuments were divided into claim areas with titles registered in notarial archives. Title holders established chartered corporations to mobilize massive work forces and systematically quarry ruins. As with geological mines, the Castilian king was entitled to a 20 percent tax on all wealth extracted from the ground. Within a short span the Crown established a royal smelter in the Moche valley, not because of any local geological wealth but because the royal mausoleums of Chan Chan had been discovered and looting of the nearby Pyramid of the Sun was underway. […] the Andean Cordillera is probably the most intensively looted ancient center of civilization in the world.”

“Thanks to the rugged Cordillera, which is characterized by global extremes in environmental conditions, Andean civilization differs from other great civilizations of antiquity. If thriving civilizations had matured atop the Himalayas while simultaneously accomodating a Sahara desert, a coastal fishery richer than the Bering Sea, and a jungle larger than the Congo, then Tahuantinsuyu might seem less alien. Fundamental contrasts in the Andean Cordillera’s habitats confronted humans with radically disparate conditions and dissimilar ressources. […] The mountain, marine, desert and jungle habitats required distinctive adaptive strategies and promoted different evolutionary pathways, called Arid Montane, Maritime-Oasis, and Tropical Forest lifeways. The Incas were a montane society, but the land of the four quarters incorporated people adapted to other conditions.” (Many large civilizations of the past have had huge environmental variation within their borders, so I think Moseley may be overemphasizing here how unique the Inca empire was in this regard (see e.g. here), but it seems beyond argument that environmental factors played a major role in the structure and development of the Inca state.)

“About 90 percent of Andean runoff descends to the Atlantic watershed, while only 10 percent descends to the Pacific.”

“cold and anoxia oblige people to eat more, and highlanders are estimated to need around 11.5 percent more calories than lowlanders. Consequently, it costs measurably more to support life and civilization in mountains than in lowlands. Life is also more precarious because comparable food shortages, caused by drought and other disasters, exert greater nutritional duress at higher elevations than at lower ones. […] [But on the other hand…] High-altitude rainfall farming fluctuates less severely than low-elevation runoff farming and irrigation. Arid mountain soils, like sponges, absorb fixed amounts of moisture and must reach saturation before rainfall will produce runoff. […] if rainfall fluctuates by 10 percent […] then runoff [may] fluctuate on the order of 36 percent. […] the flow of Andean rivers fluctuates dramatically from year to year. […] Normally, runoff farming generates much higher yields than rainfall farming. […] During drought, rainfall farming is depressed less severely than runoff farming and coastal irrigation suffers the most because it is furthest away from mountain precipitation.”

“Seasonal variation increases with elevation, and plant-growth cycles are successively shorter at progressively higher altitudes. In the towering mountains, ecological zones are compressed and stacked atop one another. Andean people can trek 100 km as the crow flies and go from hilly jungle to alpine tundra, crossing counterparts of the major continental life zones. Mountain populations around the world pursue farming, herding, and the exploitation of multiple ecological zones because stacked habitats with different growing seasons are close together and the productivity of different zones fluctuates from year to year. In the Andes, this exploitation pattern moves people and produce up and down the mountains, and it is called ‘verticality’ in contrast to ‘horizontality’ which typifies lowland movement.
Verticality and horizontality are associated with different means of procuring resources. Mountain families typically exploit three or more ecological zones […] Consequently, they directly procure commodities from a series of habitats by moving produce along a vertical or elevational axis […] Alternatively, in desert and tropical lowlands people generally make their living in a single continental life zone. Because major zones are far apart, resources from distant habitats are procured indirectly by trade, barter, or exchange with other people […] In the world’s highest mountains many forces of natural selection are similar, including anoxia, cold temperatures, frost, hail, poor soils, short growing seasons, very limited crop diversity [few crops can survive in very high altitudes – US], rugged topography, and marked fainfall variation over short distances. Consequently, human populations in the Alps, Himalayas, and Andes exhibit many parallel adaptions, including symbiotic integration of agricultural and pastoral production, exploitation of multiple ecological zones, reliance on different crops from different altitudes, sequential timing of work in different ecological tiers, dependence upon dung fertilizer, frequent fallowing of fields, emphasis on long-term storage of food products, relatively little sexual division of labor in subsistence tasks, and a mixture of household and communal control of land use.”

“Mountain political centers, such as Cuzco, Huari, and Tiwanaku, expanded both through the uplands as well as down into the lowlands where resource diversity was greatest. In contrast, coastal centers, such as Chimor and Moche, expanded along the Pacific littoral, with little penetration into the highlands above 2000 m”

“Labor was the coin of the realm and the imperial economy extracted tribute in the form of work. […] [There were] three types of labor for the state that can be called agricultural taxation, mit’a service, and textile taxation. […] Agricultural taxation extracted work from both men and women. Commoners did not own land – it belonged to the ayllu. It was Inca practice to divide conquered agricultural land into three categories, ideally of equal size, all of which the peasantry was obliged to farm. The first category was dedicated to the support of the gods […] These lands were cultivated first, before other categories of fields. Yields went to support religious functionaries, priests, and shrine attendants […] The second category of fields belonged to the emperor […] Imperial fields were tended after religious ones, and yields went to support the imperial court and the needs of government. […] agrarian tribute from both religious and imperial lands was largely under Cuzco’s direct control. […] The third category of land was assigned to the local community for its support, redistributed annually to village members by the local kuraka. This allotment was not in equal parts, but proportional to the size of a family and the number of dependents under each head-of-household. As households grew or shrank, their share of land changed. […] Puna pasture lands and llama and alpaca resources were organized in a similar three-fold manner.”

The Ancestor’s Tale (II)

I finished the book yesterday, after having put it away for almost a month. According to a count I did after finishing the book, this was the 40th book I’ve completed this year so far, meaning that I’ve read roughly five and a half books per month on average, or roughly one book per five and a half days (such an average is deceiving though, as the amount of book reading varies widely throughout the year; more than half the books I’ve read this year I’ve read during the summer, i.e. since the beginning of June…). Let’s just say that getting to 50 (or 52?) before the end of the year should not be an impossible task at this point – I didn’t realize I was that far already.

Back to the book – below is my goodreads review of the Dawkins book:

“Parts of this book is pure awesome, and the best parts are really among the greatest things I’ve read on the subject.

But other parts are not quite so great. The treatment is not as systematic as I’d have liked. At one point an (in my opinion) off-topic political rant in the middle of a book about the evolutionary past of our species made me so angry I simply put the book away for almost a month. I’d pretty much decided not to finish it at that point.

I eventually did pick it up again though, and I’m glad I did. But some parts are much better than others, and it’s a damn shame the variation in the quality of the material is as high as it is.”

…

I gave it 4 stars, but it was difficult to pick a rating. I really liked the last 100-200 pages. Incidentally I pointed out in my first post that “he talks about different speciation methods/mechanisms throughout the pages, but he doesn’t mention what they are called” – and I should probably add here that he does add the names later on, though the last half of that original comment still applies (“his coverage is non-systematic and spread out over many pages”). I think if you’re the kind of curious mind who’d enjoy reading a book about the history of life on Earth, you have to read this. I think it could have been a bit better, and that’s basically why I didn’t end up with a five star rating – but this account is still probably about as good as it’s going to get, so I think if you’re limiting yourself to one book on the subject, this is probably the book to read. Even if it isn’t, I’m sure you could do a lot worse.

Below I’ve added some quotes from the last few hundred pages; I’ve tried to quote from ‘the good stuff’ only. The book has 600+ pages, so naturally a lot of good stuff didn’t make the cut, and in fact much of the best stuff I decided not to include here because it was too hard to quote out of context, because ‘too much stuff’ had to be included in each quote in order to make sense of it for someone who’d not read the rest of the book – indeed in a few cases basically the rest of the book had been building up to it (the last quote included in the post below is sort of like this, but it can stand on its own as well):

…

“A mutant animal has a certain probability of being better off as a consequence of its new mutation. ‘Better off’ means better compared to the premutated parental type. […] the smaller the mutation, the more likely it is to be an improvement. […] The essential point, as I have put it before, is that there are many more ways of being dead than of being alive. […] In the multidimensional landscape of all possible animals, living creatures are islands of viability separated from other islands by gigantic oceans of grotesque deformity. Starting from any one island, you can evolve away from it one step at the time, here inching out a leg, there shaving the tip of a horn, or darkening of a feather. Evolution is a trajectory through multidimensional space, in which every step of the way has to represent a body capable of surviving and reproducing as well as the parental type […] Almost inevitably, a megamutation […] will land in the middle of the ocean of inviability …” […]

“The key to efficient digestion is to expose a large area of absorptive surface to the food. We achieve that by chewing the food into small pieces and passing the fragments through a long coiled gut whose already large area is compounded by a forest of tiny projections, or villi, covering its lining. Each villus in turn has a brush border of hair-like micro-villi, so the total absorptive area of an adult human intestine is millions of square centimeters. A fungus such as the well-named Phallus […] spreads its mycelium over a similar area of soil, secreting digestive enzymes and digesting the soil material where it lies. The fungus doesn’t walk about devouring food and digesting it inside its body as a pig or a rat would. Instead it spreads its ‘intestines’, in the form of thread-like mycelia, right through the food and digests it on the spot. From time to time hyphae come together to form a single solid structure with recognisable form: a mushroom (or toadstool, or bracket). This structure manufactures spores that float high and far on the wind, spreading its genes for making new mycelium and, eventually, new mushrooms.” […]

“By far the largest single organisms that ever lived are plants, and an impressive percentage of the world’s biomass is locked up in plants. This doesn’t just happen to be so. Some such high proportion follows necessarily from the fact that almost* all biomass comes ultimately from the sun via photosynthesis, most of it in green plants, and the transaction at every link of the food chain is only about 10 per cent efficient. The surface of the land is green because of plants, and the surface of the sea would be green too if its floating carpet of photosynthesisers were macroscopic plants instead of microorganisms too small to reflect noticeable quantities of green light. It is as though plants are going out of their way to cover every square centimetre with green, leaving none uncovered. And that is pretty much what they are doing […] From a plant’s point of view, a square centimetre of the Earth’s surface that is anything but green amounts to a negligently wasted opportunity to sweep up photons.” […]

“The really astonishing thing about Kleiber’s Law is that it holds good from the smallest bacterium to the largest whale. That’s about 20 orders of magnitude. You need to multiply by ten 20 times – or add 20 noughts – in order to get from the smallest bacterium to the largest mammal, and Kleiber’s Law holds right across the board. […]
A very small organism has such a large surface area compared to its volume that it can get all the oxygen it needs through its body wall. […] But a large organism has a transport problem because most of its cells are far away from the supplies they need. They need to pipe stuff from place to place. […] if you double the number of cells that need to be supplied, the network volume more than doubles because more pipes are needed to plumb the network into the main system, pipes which themselves occupy space. […] whether you are a mouse or a whale, the most efficient transport system – the one that wastes the least energy in moving stuff around – is one that takes up a fixed percentage of your body. That’s how the mathematics works out […] For example, mammals, whether mice, humans, or whales, have a volume of blood (i.e. the size of the transport system) which occupies between six and seven per cent of their body.
Taking these two points together, it means that if we wish to double the number of cells to be supplied, but still keep the most efficient transport system, we need a more sparsely distributed supply network. And a more sparse network means that less stuff is supplied per cell, meaning that the metabolic rate must go down.” […]

“A nucleus is huge compared to an electron but tiny compared to an electron’s orbit. Your hand, consisting mostly of empty space, meets hard resistance when it strikes a block of iron, also consisting mostly of empty space, because forces associated with the atoms in the two solids interact in such a way as to prevent them passing through each other. Consequently iron and stone seem solid to us because our brains most usefully serve us by constructing an illusion of solidity.” […]

“one of the most momentous events in the history of life was the formation of the eukaryotic cell. Eukaryotic cells are the large and complex cells, with walled nuclei and mitochondria, that make up the bodies of all animals, plants, and indeed […] all living creatures except the true bacteria and the archaea, which used to be called bacteria.” […] […a big exception, it turns out:] “bacteria and archaea are biochemically more versatile than the rest of the living kingdoms put together. Animals and plants perform a fraction of the biochemical mix of tricks available to bacteria. […] At least as a chemist would see it, if you wiped out all life except bacteria, you’d still be left with the greater part of life’s range. […] For the great majority of its career on this planet life has been nothing but prokaryotic life. We animals are a recent afterthought.” […]

“Depriving somebody of oxygen is a swift way to kill them. Yet our own cells, unaided, wouldn’t know what to do with oxygen. It is only mitochondria, and their bacterial cousins, that do.
As with chloroplasts, molecular comparison tells us the particular group of bacteria from which mitochondria are drawn. Mitochondria sprang from the socalled alpha-proteo bacteria and they are therefore related to the rickettsias that cause typhus and other nasty diseases. Mitochondria themselves have lost much of their original genome, and have become completely adapted to life inside the eukaryotic cells. But, like chloroplasts, they still reproduce autonomously by division, making populations within each eukaryotic cell.”

Of course he couldn’t help himself in the end from adding the remarks below in his conclusion (with which I of course agree):

“If it’s amazement you want, the real world has it all. […] although this book […629 pages, US…] has been written from a human point of view, another book could have been written in parallel for any of 10 million starting pilgrims. […] My objection to supernatural beliefs is precisely that they miserably fail to do justice to the sublime grandeur of the real world. They represent a narrowing-down from reality, an impoverishment of what the real world has to offer.”

Wikipedia articles of interest

i. Otto I, Holy Roman Emperor.

“Otto I (23 November 912 – 7 May 973), also known as Otto the Great, was the founder of the Holy Roman Empire, reigning from 936 until his death in 973. The oldest son of Henry I the Fowler and Matilda of Ringelheim, Otto was “the first of the Germans to be called the emperor of Italy”.^[1]

Otto inherited the Duchy of Saxony and the kingship of the Germans upon his father’s death in 936. He continued his father’s work to unify all German tribes into a single kingdom and greatly expanded the king’s powers at the expense of the aristocracy. Through strategic marriages and personal appointments, Otto installed members of his own family to the kingdom’s most important duchies. This reduced the various dukes, who had previously been co-equals with the king, into royal subjects under his authority. Otto transformed the Roman Catholic Church in Germany to strengthen the royal office and subjected its clergy to his personal control.

After putting down a brief civil war among the rebellious duchies, Otto defeated the Magyars in 955, thus ending the Hungarian invasions of Europe. The victory against the pagan Magyars earned Otto the reputation as a savior of Christendom and secured his hold over the kingdom. By 961, Otto had conquered the Kingdom of Italy and extended his realm’s borders to the north, east, and south. In control of much of central and southern Europe, the patronage of Otto and his immediate successors caused a limited cultural renaissance of the arts and architecture. Following the example of Charlemagne‘s coronation as “Emperor of the Romans” in 800, Otto was crowned Emperor in 962 by Pope John XII in Rome.

Otto’s later years were marked by conflicts with the Papacy and struggles to stabilize his rule over Italy. Reigning from Rome, Otto sought to improve relations with the Byzantine Empire, which opposed his claim to emperorship and his realm’s further expansion to the south. To resolve this conflict, the Byzantine princess Theophanu married his son, Otto II, in April 972. Otto finally returned to Germany in August 972 and died of natural causes in 973. Otto II succeeded him as Emperor.”

This part made me scratch my head: “Otto called the feuding parties to his court at Magdeburg, where Eberhard was ordered to pay a fine, and his lieutenants were sentenced to carry dead dogs in public, a particularly dishonoring punishment.” Carry dead dogs in public? Seriously? The article incidentally has many examples of how ‘the game of thrones’ was played by Otto and his comtemporaries (strategic marriages, hidden agreements, banquets held where the people who showed up got massacred, …). Here’s a little more stuff from the article:

“In the early summer of 951, before his father marched across the Alps, Otto’s son Liudolf, Duke of Swabia, invaded Lombardy in northern Italy. From his stronghold in Swabia located just north of the Alps, Liudolf was in closer proximity to the Italian border than his father in Saxony. While the exact reason for Liudolf’s actions are unclear, dynastic concerns and family ties to Adelaide may have been a factor. Adelaide’s mother, Bertha of Swabia, was a daughter of Regelinda, the mother of Liudolf’s wife Ida, from her first marriage to Burchard II, Duke of Swabia. Liudolf, therefore, may have intervened in the Italian campaign at the request of Adelaide’s relatives. Additionally, Liudolf, 19 years old himself, did not view the idea of a young step-mother as in his best interests. Though Otto had named him as his successor, Liudolf feared any potential step-brother may usurp his claim to the German throne.

The purpose of Liudolf’s Italian campaign was to overthrow Berengar II and therefore render unnecessary Otto’s own expedition into Italy, and thus his marriage to Adelaide. While Liudolf was preparing his expedition, the Bavarian Duke Henry, Otto’s brother and Liudolf’s uncle, conspired against him; Swabia and Bavaria shared a long common border and the two dukes were involved in a border dispute. Henry influenced the Italian aristocrats not to join Liudolf’s campaign. When Liudolf arrived in Lombardy, he found no support and was unable to sustain his troops. His army was near destruction until Otto’s own army crossed the Alps. […] With the humiliating failure of his Italian campaign and Otto’s marriage to Adelaide, Liudolf became estranged from his father and planned a rebellion. […]

Word of the rebellion reached Otto at Ingelheim. In order to secure his position, he traveled to his stronghold at Mainz. The city was also the seat of Archbishop Frederick of Mainz, who acted as the spokesman for the rebels and offered himself as a mediator between Otto and the rebels, who quickly arrived in Mainz. Recorded details of the meeting or the negotiated treaty do not exist, but Otto soon left Mainz with a peace treaty favorable to the conspirators, most likely confirming Liudolf as heir apparent and approving Conrad’s original agreement with Berengar II, making the treaty contrary to the desires of Adelaide and Henry.

When Otto returned to Saxony, Adelaide and Henry persuaded the king to void the treaty. Convening the Imperial Diet at Fritzlar, Otto declared Liudolf and Conrad as outlaws in absentia.^[25] […] Otto’s actions at the Diet prompted the people of Swabia and Franconia into civil war against their king. […] The Hungarians invaded Otto’s domain as part of the larger Hungarian invasions of Europe and ravaged much of Southern Germany during Liudolf’s civil war. Though Otto had installed the Margraves Hermann Billung and Gero on his kingdom’s northern and northeastern borders, the Principality of Hungary to the southeast was a permanent threat to German security.”

These were ‘interesting times’…

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ii. Enceladus (moon) (featured).

“Enceladus is the sixth-largest of the moons of Saturn.^[12] It was discovered in 1789 by William Herschel.^[13]

Enceladus seems to have liquid water under its icy surface. Cryovolcanoes at the south pole shoot large jets of water ice particles into space. Some of this water falls back onto the moon as “snow”, some of it adds to Saturn’s rings, and some of it reaches Saturn. The whole of Saturn’s E ring is believed to have been made from these ice particles. Because of the apparent water at or near the surface, Enceladus may be one of the best places for humans to look for extraterrestrial life.”

It’s not very big, here’s a to-scale size comparison made by NASA:

“In 2005 the Cassini spacecraft performed several close flybys of Enceladus, revealing the moon’s surface and environment in greater detail. In particular, the probe discovered a water-rich plume venting from the moon’s south polar region. This discovery, along with the presence of escaping internal heat and very few (if any) impact craters in the south polar region, shows that Enceladus is geologically active today. Moons in the extensive satellite systems of gas giants often become trapped in orbital resonances that lead to forced libration or orbital eccentricity; proximity to the planet can then lead to tidal heating of the satellite’s interior, offering a possible explanation for the activity.

Enceladus is one of only three outer Solar System bodies, with Jupiter‘s moon Io‘s sulfur volcanoes and Neptune‘s moon Triton‘s nitrogen “geysers” where active eruptions have been observed. Analysis of the outgassing suggests that it originates from a body of subsurface liquid water, which along with the unique chemistry found in the plume, has fueled speculations that Enceladus may be important in the study of astrobiology.^[14] The discovery of the plume has added further weight to the argument that material released from Enceladus is the source of the E ring. […]

Because it reflects so much sunlight, the mean surface temperature at noon only reaches −198 °C (somewhat colder than other Saturnian satellites).^[8] […]

Images taken by Cassini during the flyby on July 14, 2005 revealed a distinctive, tectonically deformed region surrounding Enceladus’s south pole. This area, reaching as far north as 60° south latitude, is covered in tectonic fractures and ridges.^[2][40] The area has few sizable impact craters, suggesting that it is the youngest surface on Enceladus and on any of the mid-sized icy satellites; modeling of the cratering rate suggests that some regions of the south polar terrain (SPT) are possibly as young as 500,000 years, or younger.^[2]”

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iii. Pax Mongolica (‘good article’).

“The Pax Mongolica (less often known as Pax Tatarica)^[1] is a Latin phrase meaning “Mongol Peace” coined by Western scholars to describe the stabilizing effects of the conquests of the Mongol Empire on the social, cultural, and economic life of the inhabitants of the vast Eurasian territory that the Mongols conquered in the 13th and 14th centuries. The term is used to describe the eased communication and commerce the unified administration helped to create, and the period of relative peace that followed the Mongols’ vast conquests. The term was coined in parallel to Pax Romana.

The conquests of Kublai Khan and his successors effectively connected the Eastern world with the Western world, ruling a territory from Southeast Asia to Eastern Europe. The Silk Road, connecting trade centers across Asia and Europe, came under the sole rule of the Mongol Empire. It was commonly said that “a maiden bearing a nugget of gold on her head could wander safely throughout the realm.”^[2][3] The end of the Pax Mongolica was marked by political fragmentation of the Mongol Empire and the outbreak of the Black Death in Asia which spread along trade routes to much of the world.”
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iv. Marco Polo (‘good article’).

“Marco Polo (ⁱ/ˈmɑrkoʊ ˈpoʊloʊ/; Italian pronunciation: [ˈmarko ˈpɔːlo]; c.1254 – January 8–9, 1324)^[1] was an Italian merchant traveler from the Republic of Venice^[2][3] whose travels are recorded in Livres des merveilles du monde, a book which did much to introduce Europeans to Central Asia and China. He learned the mercantile trade from his father and uncle, Niccolò and Maffeo, who traveled through Asia, and apparently met Kublai Khan. In 1269, they returned to Venice to meet Marco for the first time. The three of them embarked on an epic journey to Asia, returning after 24 years to find Venice at war with Genoa; Marco was imprisoned, and dictated his stories to a cellmate. He was released in 1299, became a wealthy merchant, married and had three children. He died in 1324, and was buried in San Lorenzo.

His pioneering journey inspired Christopher Columbus^[4] and many other travellers.”

Do note that the version of the Fra Mauro map included as an illustration to the article is ‘upside down’; in the original version of that map south was at the top and north at the bottom…

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v. Royal Navy. All you ever wanted to know about the Royal Navy of Britain and its history. Well, not really, but that’s probably also a bit much to ask for; for example the article never even mentions the Singapore Strategy. I should point out that there are many featured articles in these areas of wikipedia even if this article is not one of them (the Singapore Strategy article however is); specific warships which saw action during the World Wars for example often have very detailed and well-written (i.e. featured-) articles (see e.g. German Battleship Bismarck, HMS Furious, HMS Eagle, HMS Royal Oak, … – here’s a list of WW2 ships…) and the coverage of ship-classses is often great too (see e.g. Dreadnought, Ironclad warship, Battleship, Yamato-class battleship, Courageous-class battlecruiser …).

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vi. Mount Kenya (‘good article’).

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vii. Meristem.

“A meristem is the tissue in most plants containing undifferentiated cells (meristematic cells), found in zones of the plant where growth can take place.

Meristematic cells give rise to various organs of the plant and keep the plant growing. The Shoot Apical Meristem (SAM) gives rise to organs like the leaves and flowers. The cells of the apical meristems – SAM and RAM (Root Apical Meristem) – divide rapidly and are considered to be indeterminate, in that they do not possess any defined end fate. In that sense, the meristematic cells are frequently compared to the stem cells in animals, which have an analogous behavior and function.

The term meristem was first used in 1858 by Karl Wilhelm von Nägeli (1817–1891) in his book Beiträge zur Wissenschaftlichen Botanik.^[1] It is derived from the Greek word merizein (μερίζειν), meaning to divide, in recognition of its inherent function.

In general, differentiated plant cells cannot divide or produce cells of a different type. Therefore, cell division in the meristem is required to provide new cells for expansion and differentiation of tissues and initiation of new organs, providing the basic structure of the plant body.”

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viii. Wieferich prime.

“In number theory, a Wieferich prime is a prime number p such that p² divides 2^p − 1 − 1,^[4] therefore connecting these primes with Fermat’s little theorem, which states that every odd prime p divides 2^p − 1 − 1. Wieferich primes were first described by Arthur Wieferich in 1909 in works pertaining to Fermat’s last theorem, at which time both of Fermat’s theorems were already well known to mathematicians.^[5][6]

Since then, connections between Wieferich primes and various other topics in mathematics have been discovered, including other types of numbers and primes, such as Mersenne and Fermat numbers, specific types of pseudoprimes and some types of numbers generalized from the original definition of a Wieferich prime. Over time, those connections discovered have extended to cover more properties of certain prime numbers as well as more general subjects such as number fields and the abc conjecture.

Despite a number of extensive searches, the only known Wieferich primes to date are 1093 and 3511 (sequence A001220 in OEIS).”

It’s worth having these guys in mind when you’re thinking about limits – “It has been conjectured (as for Wilson primes) that infinitely many Wieferich primes exist” – but only two (2!) such numbers are currently known, and: “It is now known, that if any other Wieferich primes exist, they must be greater than 6.7×10¹⁵.” Sometimes it takes a lot of time to get to infinity… Incidentally only 48 Mersenne primes, a different type of primes, are known and it’s also hypothesized that there’s an infinite number of those…

Khan Academy videos of interest

I assume that not all of the five videos below are equally easy to understand for people who’ve not watched the previous ones in the various relevant playlists, but this is the stuff I’ve been watching lately and you should know where to look by now if something isn’t perfectly clear. I incidentally covered some relevant background material previously on the blog – if concepts from chemistry like ‘oxidation states’ are a bit far away, a couple of the videos in that post may be helpful.

I stopped caring much when I reached the 1 million mark (until they introduced the Kepler badge – then I started caring a little again until I’d gotten that one), but I noticed today that I’m at this point almost at the 1,5 million energy points mark (1.487.776). I’ve watched approximately 400 videos at the site by now.

Here’s a semi-related link with some good news: Khan Academy Launches First State-Wide Pilot In Idaho.

Wikipedia articles of interest

i. Globular cluster (featured). What a thing like that looks like:

“A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is derived from the Latin globulus—a small sphere. A globular cluster is sometimes known more simply as a globular.

Globular clusters, which are found in the halo of a galaxy, contain considerably more stars and are much older than the less dense galactic, or open clusters, which are found in the disk. Globular clusters are fairly common; there are about 150^[2] to 158^[3] currently known globular clusters in the Milky Way, with perhaps 10 to 20 more still undiscovered.^[4] Large galaxies can have more: Andromeda, for instance, may have as many as 500.^[5] Some giant elliptical galaxies, particularly those at the centers of galaxy clusters, such as M87,^[6] have as many as 13,000 globular clusters. These globular clusters orbit the galaxy out to large radii, 40 kiloparsecs (approximately 131,000 light-years) or more.^[7]

Every galaxy of sufficient mass in the Local Group has an associated group of globular clusters, and almost every large galaxy surveyed has been found to possess a system of globular clusters.^[8] The Sagittarius Dwarf and Canis Major Dwarf galaxies appear to be in the process of donating their associated globular clusters (such as Palomar 12) to the Milky Way.^[9] This demonstrates how many of this galaxy’s globular clusters might have been acquired in the past.

Although it appears that globular clusters contain some of the first stars to be produced in the galaxy, their origins and their role in galactic evolution are still unclear.”

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ii. Srinivasa Ramanujan (‘good article’). If you’ve seen Good Will Hunting the name will probably ring a bell. An interesting life, but much too short.

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iii. Gastropoda.

“The Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomic class within the phylum Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to large. There are many thousands of species of sea snails and sea slugs, as well as freshwater snails and freshwater limpets, as well as land snails and land slugs.

The class Gastropoda contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Late Cambrian. There are 611 families of gastropods, of which 202 families are extinct, being found only in the fossil record.^[3]

Gastropoda (previously known as univalves and sometimes spelled Gasteropoda) are a major part of the phylum Mollusca and are the most highly diversified class in the phylum, with 60,000 to 80,000^[3][4] living snail and slug species. The anatomy, behavior, feeding and reproductive adaptations of gastropods vary significantly from one clade or group to another. Therefore, it is difficult to state many generalities for all gastropods. […]

At all taxonomic levels, gastropods are second only to the insects in terms of their diversity.^[5] […]

Although the name “snail” can be, and often is, applied to all the members of this class, commonly this word means only those species with an external shell large enough that the soft parts can withdraw completely into it. Those gastropods without a shell, and those with only a very reduced or internal shell, are usually known as slugs.”

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iv. Borel-Cantelli lemma.

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v. Vijayanagara Empire. (featured)

“The Vijayanagara Empire referred to as the Kingdom of Bisnagar by the Portuguese, was an empire based in South India, in the Deccan Plateau region. It was established in 1336 by Harihara I and his brother Bukka Raya I of Sangama Dynasty.^[1][2][3] The empire rose to prominence as a culmination of attempts by the southern powers to ward off Islamic invasions by the end of the 13th century. It lasted until 1646 although its power declined after a major military defeat in 1565 by the Deccan sultanates. The empire is named after its capital city of Vijayanagara, whose ruins surround present day Hampi, now a World Heritage Site in Karnataka, India.^[4] ”

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vi. Donner Party (featured).

“The Donner Party was a group of 87 American pioneers who in 1846 set off from Missouri in a wagon train headed west for California, only to find themselves trapped by snow in the Sierra Nevada. The subsequent casualties resulting from starvation, exposure, disease, and trauma were extremely high, and many of the survivors resorted to cannibalism.

The wagons left in May 1846. Encouraged to try a new, faster route across Utah and Nevada, they opted to take the Hastings Cutoff proposed by Lansford Hastings, who had never taken the journey with wagons. The Cutoff required the wagons to traverse Utah’s Wasatch Mountains and the Great Salt Lake Desert, and slowed the party considerably, leading to the loss of wagons, horses, and cattle. It also forced them to engage in heavy labor by clearing the path ahead of them, and created deep divisions between members of the party. They had planned to be in California by September, but found themselves trapped in the Sierra Nevada by early November.

Most of the party took shelter in three cabins that had been constructed two years earlier at Truckee Lake (now Donner Lake), while a smaller group camped several miles away. Food stores quickly ran out, and a group of 15 men and women attempted to reach California on snowshoes in December, but became disoriented in the mountains before succumbing to starvation and cold. Only seven members of the snowshoe party survived, by eating the flesh of their dead companions. Meanwhile, the Mexican American War delayed rescue attempts from California, although family members and authorities in California tried to reach the stranded pioneers but were turned back by harsh weather.

The first rescue group reached the remaining members, who were starving and feeble, in February 1847. Weather conditions were so bad that three rescue groups were required to lead the rest to California, the last arriving in March. Most of these survivors also had resorted to cannibalism. Forty-eight members of the Donner Party survived to live in California. Although a minor incident in the record of westward migration in North America, the Donner Party became notorious for the reported claims of cannibalism. Efforts to memorialize the Donner Party were underway within a few years; historians have described the episode as one of the most spectacular tragedies in California history and in the record of western migration.^[1] […]

The group became lost and confused. After two more days without food, Patrick Dolan proposed that one of them should volunteer to die, to feed the others. Some suggested a duel, while another account describes an attempt to create a lottery to choose a member to sacrifice.^[88][89] Eddy suggested they keep moving until someone simply fell, but a blizzard forced the group to halt. Antonio, the animal handler, was the first to die; Franklin Graves was the next casualty.^[90][91]

As the blizzard progressed, Patrick Dolan began to rant deliriously, stripped off his clothes and ran into the woods. He returned shortly afterwards and died a few hours later. Not long after, possibly because 12-year-old Lemuel Murphy was near death, some of the group began to eat flesh from Dolan’s body. Lemuel’s sister tried to feed some to her brother, but he died shortly afterwards. Eddy, Salvador and Luis refused to eat. The next morning the group stripped the muscle and organs from the bodies of Antonio, Dolan, Graves, and Murphy and dried it to store for the days ahead, taking care to ensure that nobody would have to eat his or her relatives.^[92][93]

After three days rest they set off again, searching for the trail. Eddy eventually succumbed to his hunger and ate human flesh, but that was soon gone. They began to take apart their snowshoes to eat the oxhide webbing, and discussed killing Luis and Salvador for food; after Eddy warned the Indians they quietly left.^[94] During the night Jay Fosdick died, leaving only seven members of the party. Eddy and Mary Graves left to hunt, but when they returned with deer meat, Fosdick’s body had already been cut apart for food.^[95][96] After several more days—25 since they had left Truckee Lake—they came across Salvador and Luis, who had not eaten for about nine days and were close to death. William Foster, believing the flesh of the Indians was the group’s last hope of avoiding imminent death from starvation, shot the pair.^[97]

On January 12, the group stumbled into a Miwok camp looking so deteriorated that the Indians initially fled. The Miwoks gave them what they had to eat: acorns, grass, and pine nuts.^[97] After a few days, Eddy continued on with the help of a Miwok to a ranch in a small farming community at the edge of the Sacramento Valley.^[98][99] A hurriedly assembled rescue party found the other six survivors on January 17.”

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vii.  Endosymbiont.

“An endosymbiont is any organism that lives within the body or cells of another organism, i.e. forming an endosymbiosis (Greek: ἔνδον endon “within”, σύν syn “together” and βίωσις biosis “living”). Examples are nitrogen-fixing bacteria (called rhizobia) which live in root nodules on legume roots, single-celled algae inside reef-building corals, and bacterial endosymbionts that provide essential nutrients to about 10–15% of insects.

Many instances of endosymbiosis are obligate; that is, either the endosymbiont or the host cannot survive without the other, such as the gutless marine worms of the genus Riftia, which get nutrition from their endosymbiotic bacteria. The most common examples of obligate endosymbiosis are mitochondria and chloroplasts. Some human parasites, e.g. : Wucherichia bancrofti and Mansonella perstans thrive in their hosts because of an obligate endosymbiosis with Wolbachi spp.. They can both be eliminated from their host by treatments that target this bacterium. However, not all endosymbioses are obligate. Also, some endosymbioses can be harmful to either of the organisms involved.

It is generally agreed that certain organelles of the eukaryotic cell, especially mitochondria and plastids such as chloroplasts, originated as bacterial endosymbionts. This theory is called the endosymbiotic theory, and was first articulated by the Russian botanist Konstantin Mereschkowski in 1905.^[1]“

Wikipedia articles of interest

1. Star fort.

“A star fort, or trace italienne, is a fortification in the style that evolved during the age of gunpowder, when the cannon came to dominate the battlefield, and was first seen in the mid-15th century in Italy.

Passive ring-shaped (enceinte) fortifications of the Medieval era proved vulnerable to damage or destruction by cannon fire, when it could be directed from outside against a perpendicular masonry wall. In addition, an attacking force that could get close to the wall was able to conduct undermining operations in relative safety, as the defenders could not shoot at them from nearby walls. In contrast, the star fortress was a very flat structure composed of many triangular bastions, specifically designed to cover each other, and a ditch. In order to counteract the cannon balls, defensive walls were made lower and thicker. Although this made their climbing easier, the ditch was widened, so that attacking infantry was still exposed to fire from a higher elevation for a while, including enfilading fire from the bastions. The outer side of the ditch was usually provided with a glacis to deflect cannon balls aimed at the lower part of the main wall. Further structures, such as ravelins, tenailles, hornworks or crownworks, and even detached forts could be added to create complex outer works to further protect the main wall from artillery, and sometimes provide additional defensive positions. They were built of many materials, usually earth and brick, as brick does not shatter on impact from a cannonball as stone does.

Star fortifications were further developed in the late fifteenth and early sixteenth centuries primarily in response to the French invasion of the Italian peninsula. The French army was equipped with new cannon and bombards that were easily able to destroy traditional fortifications built in the Middle Ages. Star forts were employed by Michelangelo in the defensive earthworks of Florence, and refined in the sixteenth century by Baldassare Peruzzi and Scamozzi. The design spread out of Italy in the 1530s and 1540s. It was employed heavily throughout Europe for the following three centuries. […]

Fortifications of this type continued to be effective while the attackers were armed only with cannons, where the majority of the damage inflicted was caused by momentum from the impact of solid shot. While only low explosives such as black powder were available, explosive shells were largely ineffective against such fortifications.

The development of mortars, high explosives, and the consequent large increase in the destructive power of explosive shells and thus plunging fire rendered the intricate geometry of such fortifications irrelevant. Warfare was to become more mobile. It took, however, many years to abandon the old fortress thinking.”

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2. Byzantine Empire (featured). This seems to be one of the topics that Wikipedia covers very well – there’s a lot of stuff here, and lots of links both to other articles and to external sources.

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3. Lyapunov stability.

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4. Tornado (featured).

From the article:

“The United States averages about 1,200 tornadoes per year. The Netherlands has the highest average number of recorded tornadoes per area of any country (more than 20, or 0.0013 per sq mi (0.00048 per km²), annually), followed by the UK (around 33, or 0.00035 per sq mi (0.00013 per km²), per year),^[64][65] but most are small and cause minor damage. In absolute number of events, ignoring area, the UK experiences more tornadoes than any other European country, excluding waterspouts.^[61]

Tornadoes kill an average of 179 people per year in Bangladesh, the most in the world. This is due to high population density, poor quality of construction and lack of tornado safety knowledge, as well as other factors.^[66][67] Other areas of the world that have frequent tornadoes include South Africa, parts of Argentina, Paraguay, and southern Brazil, as well as portions of Europe, Australia and New Zealand, and far eastern Asia.^[7][68]

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5. Formal system (logic).

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6. Ferdinand I, Holy Roman Emperor.

“Ferdinand I (10 March 1503, Alcalá de Henares, Spain – 25 July 1564, Vienna, Habsburg domain [now in Austria]) was Holy Roman Emperor from 1558, king of Bohemia and Hungary from 1526, and king of Croatia from 1527 until his death.^[1][2] Before his accession, he ruled the Austrian hereditary lands of the Habsburgs in the name of his elder brother, Charles V, Holy Roman Emperor.

The key events during his reign were the contest with the Ottoman Empire, whose great advance into Central Europe began in the 1520s, and the Protestant Reformation, which resulted in several wars of religion.

Ferdinand’s motto was Fiat iustitia, et pereat mundus: “Let justice be done, though the world perish”.

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7. Wheat.

“Wheat (Triticum spp.)^[1] is a cereal grain, originally from the Levant region of the Near East and Ethiopian Highlands, but now cultivated worldwide. In 2010 world production of wheat was 651 million tons, making it the third most-produced cereal after maize (844 million tons) and rice (672 million tons).^[2] In 2009, world production of wheat was 682 million tons, making it the second most-produced cereal after maize (817 million tons), and with rice as close third (679 million tons).^[3]

This grain is grown on more land area than any other commercial crop and is the most important staple food for humans. World trade in wheat is greater than for all other crops combined.^[4] Globally, wheat is the leading source of vegetable protein in human food, having a higher protein content than either maize (corn) or rice, the other major cereals. […]

“Unlike rice, wheat production is more widespread globally though China’s share is almost one-sixth of the world.” [roughly corresponding to the Chinese share of the global population. I was also surprised to learn that China in 2010 produced almost twice as much wheat (115 million metric tons) as the United States (60 -ll-) did.] […]

“In the 20th century, global wheat output expanded by about 5-fold, but until about 1955 most of this reflected increases in wheat crop area, with lesser (about 20%) increases in crop yields per unit area. After 1955 however, there was a dramatic ten-fold increase in the rate of wheat yield improvement per year, and this became the major factor allowing global wheat production to increase. Thus technological innovation and scientific crop management with synthetic nitrogen fertilizer, irrigation and wheat breeding were the main drivers of wheat output growth in the second half of the century. There were some significant decreases in wheat crop area, for instance in North America.^[60]

Better seed storage and germination ability (and hence a smaller requirement to retain harvested crop for next year’s seed) is another 20th century technological innovation. In Medieval England, farmers saved one-quarter of their wheat harvest as seed for the next crop, leaving only three-quarters for food and feed consumption. By 1999, the global average seed use of wheat was about 6% of output.”

Wikipedia articles of interest

i. Shannon–Hartley theorem. Muller talked a little bit about this one in one of the lectures, I don’t remember which, but it’s probably one of the wave-lectures. His coverage is less technical than wikipedia’s. I was considering not including this link because I previously linked to wikipedia’s closely-related article about the Noisy-channel coding theorem, but I decided to do it anyway. From the article:

“In information theory, the Shannon–Hartley theorem tells the maximum rate at which information can be transmitted over a communications channel of a specified bandwidth in the presence of noise. It is an application of the noisy channel coding theorem to the archetypal case of a continuous-time analog communications channel subject to Gaussian noise. The theorem establishes Shannon’s channel capacity for such a communication link, a bound on the maximum amount of error-free digital data (that is, information) that can be transmitted with a specified bandwidth in the presence of the noise interference, assuming that the signal power is bounded, and that the Gaussian noise process is characterized by a known power or power spectral density. […]

Considering all possible multi-level and multi-phase encoding techniques, the Shannon–Hartley theorem states the channel capacity C, meaning the theoretical tightest upper bound on the information rate (excluding error correcting codes) of clean (or arbitrarily low bit error rate) data that can be sent with a given average signal power S through an analog communication channel subject to additive white Gaussian noise of power N, is:

where

C is the channel capacity in bits per second;

B is the bandwidth of the channel in hertz (passband bandwidth in case of a modulated signal);

S is the average received signal power over the bandwidth (in case of a modulated signal, often denoted C, i.e. modulated carrier), measured in watts (or volts squared);

N is the average noise or interference power over the bandwidth, measured in watts (or volts squared); and

S/N is the signal-to-noise ratio (SNR) or the carrier-to-noise ratio (CNR) of the communication signal to the Gaussian noise interference expressed as a linear power ratio (not as logarithmic decibels).”

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ii. Expansion joint. Also covered by Muller, this is important stuff that people don’t think about:

“An expansion joint or movement joint is an assembly designed to safely absorb the heat-induced expansion and contraction of various construction materials, to absorb vibration, to hold certain parts together, or to allow movement due to ground settlement or earthquakes. They are commonly found between sections of sidewalks, bridges, railway tracks, piping systems, ships, and other structures.

Throughout the year, building faces, concrete slabs, and pipelines will expand and contract due to the warming and cooling through seasonal variation, or due to other heat sources. Before expansion joint gaps were built into these structures, they would crack under the stress induced.”

If you have any kind of construction of a significant size/length, thermal expansion will cause problems unless you try to deal with it somehow. To use expansion joints to deal with this problem is another one of those hidden ‘good ideas’ people don’t think about, because they probably weren’t even aware there was a problem to be solved.

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iii. Beaufort scale.

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iv. Belle Gunness. Not all serial killers are/were male:

“Personal – comely widow who owns a large farm in one of the finest districts in La Porte County, Indiana, desires to make the acquaintance of a gentleman equally well provided, with view of joining fortunes. No replies by letter considered unless sender is willing to follow answer with personal visit. Triflers need not apply.^[2]” […]

“The suitors kept coming, but none, except for Anderson, ever left the Gunness farm. By this time, she had begun ordering huge trunks to be delivered to her home. Hack driver Clyde Sturgis delivered many such trunks to her from La Porte and later remarked how the heavyset woman would lift these enormous trunks “like boxes of marshmallows”, tossing them onto her wide shoulders and carrying them into the house. She kept the shutters of her house closed day and night; farmers traveling past the dwelling at night saw her digging in the hog pen.” Guess what they found buried in the hog pen later?

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v. English garden.

“The English garden, also called English landscape park (French: Jardin anglais, Italian: Giardino all’inglese, German: Englischer Landschaftsgarten, Portuguese: Jardim inglês), is a style of Landscape garden which emerged in England in the early 18th century, and spread across Europe, replacing the more formal, symmetrical Garden à la française of the 17th century as the principal gardening style of Europe.^[1] The English garden presented an idealized view of nature. They were often inspired by paintings of landscapes by Claude Lorraine and Nicolas Poussin, and some were Influenced by the classic Chinese gardens of the East,^[2] which had recently been described by European travelers.^[2] The English garden usually included a lake, sweeps of gently rolling lawns set against groves of trees, and recreations of classical temples, Gothic ruins, bridges, and other picturesque architecture, designed to recreate an idyllic pastoral landscape. By the end of the 18th century the English garden was being imitated by the French landscape garden, and as far away as St. Petersburg, Russia, in Pavlovsk, the gardens of the future Emperor Paul. It also had a major influence on the form of the public parks and gardens which appeared around the world in the 19th century.^[3]”

A few images from the article (click to view full size):

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vi. Aquifer.

“An aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, or silt) from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology. Related terms include aquitard, which is a bed of low permeability along an aquifer,^[1] and aquiclude (or aquifuge), which is a solid, impermeable area underlying or overlying an aquifer. If the impermeable area overlies the aquifer pressure could cause it to become a confined aquifer.” The article has much more.

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vii. Great Tit.

“The Great Tit (Parus major) is a passerine bird in the tit family Paridae. It is a widespread and common species throughout Europe, the Middle East, Central and Northern Asia, and parts of North Africa in any sort of woodland. It is generally resident, and most Great Tits do not migrate except in extremely harsh winters. Until 2005 this species was lumped with numerous other subspecies. DNA studies have shown these other subspecies to be distinctive from the Great Tit and these have now been separated as two separate species, the Cinereous Tit of southern Asia, and the Japanese Tit of East Asia. The Great Tit remains the most widespread species in the genus Parus.

The Great Tit is a distinctive bird, with a black head and neck, prominent white cheeks, olive upperparts and yellow underparts, with some variation amongst the numerous subspecies. It is predominantly insectivorous in the summer, but will consume a wider range of food items in the winter months, including small hibernating bats.^[2] Like all tits it is a cavity nester, usually nesting in a hole in a tree. The female lays around 12 eggs and incubates them alone, although both parents raise the chicks. In most years the pair will raise two broods. The nests may be raided by woodpeckers, squirrels and weasels and infested with fleas, and adults may be hunted by Sparrowhawks. The Great Tit has adapted well to human changes in the environment and is a common and familiar bird in urban parks and gardens. The Great Tit is also an important study species in ornithology. […]

Great Tits combine dietary versatility with a considerable amount of intelligence and the ability to solve problems with insight learning, that is to solve a problem through insight rather than trial and error.^[9] In England, Great Tits learned to break the foil caps of milk bottles delivered at the doorstep of homes to obtain the cream at the top.^[24] This behaviour, first noted in 1921, spread rapidly in the next two decades.^[25] In 2009, Great Tits were reported killing and eating pipistrelle bats. This is the first time a songbird has been seen to hunt bats. The tits only do this during winter when the bats are hibernating and other food is scarce.^[26] They have also been recorded using tools, using a conifer needle in the bill to extract larvae from a hole in a tree.^[9] […]

The Great Tit has generally adjusted to human modifications of the environment. It is more common and has better breeding success in areas with undisturbed forest cover, but it has adapted to human modified habitats. It can be very common in urban areas.^[9] For example, the breeding population in the city of Sheffield (a city of half a million people) has been estimated at 17,164 individuals.^[45] In adapting to human environments its song has been observed to change in noise-polluted urban environments. In areas with low frequency background noise pollution, the song has a higher frequency than in quieter areas.^[46]“

Wikipedia articles of interest

i. Alternation of generations. It’s a bit technical, but I thought the article was interesting:

“Alternation of generations (also known as alternation of phases or metagenesis) is a term primarily used to describe the life cycle of plants (taken here to mean the Archaeplastida). A multicellular sporophyte, which is diploid with 2N paired chromosomes (i.e. N pairs), alternates with a multicellular gametophyte, which is haploid with N unpaired chromosomes. A mature sporophyte produces spores by meiosis, a process which results in a reduction of the number of chromosomes by a half. Spores germinate and grow into a gametophyte. At maturity, the gametophyte produces gametes by mitosis, which does not alter the number of chromosomes. Two gametes (originating from different organisms of the same species or from the same organism) fuse to produce a zygote, which develops into a diploid sporophyte. This cycle, from sporophyte to sporophyte (or equally from gametophyte to gametophyte), is the way in which all land plants and many algae undergo sexual reproduction.

The relationship between the sporophyte and gametophyte varies among different groups of plants. In those algae which have alternation of generations, the sporophyte and gametophyte are separate independent organisms, which may or may not have a similar appearance. In liverworts, mosses and hornworts, the sporophyte is less well developed than the gametophyte, being entirely dependent on it in the first two groups. By contrast, the fern gametophyte is less well developed than the sporophyte, forming a small flattened thallus. In flowering plants, the reduction of the gametophyte is even more extreme; it consists of just a few cells which grow entirely inside the sporophyte.

All animals develop differently. A mature animal is diploid and so is, in one sense, equivalent to a sporophyte. However, an animal directly produces haploid gametes by meiosis. No haploid spores capable of dividing are produced, so neither is a haploid gametophyte. There is no alternation between diploid and haploid forms. […] Life cycles, such as those of plants, with alternating haploid and diploid phases can be referred to as diplohaplontic (the equivalent terms haplodiplontic, diplobiontic or dibiontic are also in use). Life cycles, such as those of animals, in which there is only a diploid phase are referred to as diplontic. (Life cycles in which there is only a haploid phase are referred to as haplontic.)

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ii. Lightning. Long article, lots of stuff and links:

“Lightning is an atmospheric electrical discharge (spark) accompanied by thunder, usually associated with and produced by cumulonimbus clouds, but also occurring during volcanic eruptions or in dust storms.^[1] From this discharge of atmospheric electricity, a leader of a bolt of lightning can travel at speeds of 220,000 km/h (140,000 mph), and can reach temperatures approaching 30,000 °C (54,000 °F), hot enough to fuse silica sand into glass channels known as fulgurites, which are normally hollow and can extend as much as several meters into the ground.^[2][3]

There are some 16 million lightning storms in the world every year.^[4] Lightning causes ionisation in the air through which it travels, leading to the formation of nitric oxide and ultimately, nitric acid, of benefit to plant life below.

Lightning can also occur within the ash clouds from volcanic eruptions,^[5] or can be caused by violent forest fires which generate sufficient dust to create a static charge.^[1][6]

How lightning initially forms is still a matter of debate.^[7] Scientists have studied root causes ranging from atmospheric perturbations (wind, humidity, friction, and atmospheric pressure) to the impact of solar wind and accumulation of charged solar particles.^[4] Ice inside a cloud is thought to be a key element in lightning development, and may cause a forcible separation of positive and negative charges within the cloud, thus assisting in the formation of lightning.^[4]

The irrational fear of lightning (and thunder) is astraphobia. The study or science of lightning is called fulminology, and someone who studies lightning is referred to as a fulminologist.^[8] [I had no idea there was a name for this!] […]

An old estimate of the frequency of lightning on Earth was 100 times a second. Now that there are satellites that can detect lightning, including in places where there is nobody to observe it, it is known to occur on average 44 ± 5 times a second, for a total of nearly 1.4 billion flashes per year;^[101][102] 75% of these flashes are either cloud-to-cloud or intra-cloud and 25% are cloud-to-ground.^[103]

Approximately 70% of lightning occurs in the tropics where the majority of thunderstorms occur. The place where lightning occurs most often (according to the data from 2004–2005) is near the small village of Kifuka in the mountains of eastern Democratic Republic of the Congo,^[105] where the elevation is around 975 metres (3,200 ft). On average this region receives 158 lightning strikes per 1 square kilometer (0.39 sq mi) a year.^[102]

Above the Catatumbo river, which feeds Lake Maracaibo in Venezuela, Catatumbo lightning flashes several times per minute, 140 to 160 nights per year, accounting for 25% of the world’s production of upper-atmospheric ozone. Singapore has one of the highest rates of lightning activity in the world.^[106] The city of Teresina in northern Brazil has the third-highest rate of occurrences of lightning strikes in the world.”

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iii. Dreadnought (featured).

“The dreadnought was the predominant type of battleship in the early 20th-century. The first of the kind, the Royal Navy‘s Dreadnought, had such an impact when launched in 1906 that similar battleships built after her were referred to as “dreadnoughts”, and earlier battleships became known as pre-dreadnoughts. Her design had two revolutionary features: an “all-big-gun” armament scheme and steam turbine propulsion. The arrival of the dreadnoughts renewed the naval arms race, principally between the United Kingdom and Germany but reflected worldwide, as the new class of warships became a crucial symbol of national power. […]

While dreadnought-building consumed vast resources in the early 20th century, there was only one battle between large dreadnought fleets. At the Battle of Jutland, the British and German navies clashed with no decisive result. The term “dreadnought” gradually dropped from use after World War I, especially after the Washington Naval Treaty, as all remaining battleships shared dreadnought characteristics; it can also be used to describe battlecruisers, the other type of ship resulting from the dreadnought revolution.^[1] […]

The building of Dreadnought coincided with increasing tension between the United Kingdom and Germany. Germany had begun to build a large battlefleet in the 1890s, as part of a deliberate policy to challenge British naval supremacy. With the conclusion of the Entente Cordiale between the United Kingdom and France in April 1904, it became increasingly clear that the United Kingdom’s principal naval enemy would be Germany, which was building up a large, modern fleet under the ‘Tirpitz’ laws. This rivalry gave rise to the two largest dreadnought fleets of the pre-war period.^[93]

The first German response to Dreadnought came with the Nassau class, laid down in 1907. This was followed by the Helgoland class in 1909. Together with two battlecruisers—a type for which the Germans had less admiration than Fisher, but which could be built under authorization for armored cruisers, rather than capital ships—these classes gave Germany a total of ten modern capital ships built or building in 1909. While the British ships were somewhat faster and more powerful than their German equivalents, a 12:10 ratio fell far short of the 2:1 ratio that the Royal Navy wanted to maintain.^[94]

In 1909, the British Parliament authorized an additional four capital ships, holding out hope Germany would be willing to negotiate a treaty about battleship numbers. If no such solution could be found, an additional four ships would be laid down in 1910. Even this compromise solution meant (when taken together with some social reforms) raising taxes enough to prompt a constitutional crisis in the United Kingdom in 1909–10. In 1910, the British eight-ship construction plan went ahead, including four Orion (1910)-class super-dreadnoughts, and augmented by battlecruisers purchased by Australia and New Zealand. In the same period of time, Germany laid down only three ships, giving the United Kingdom a superiority of 22 ships to 13. […]

The dreadnought race stepped up in 1910 and 1911, with Germany laying down four capital ships each year and the United Kingdom five. Tension came to a head following the German Naval Law of 1912. This proposed a fleet of 33 German battleships and battlecruisers, outnumbering the Royal Navy in home waters. To make matters worse for the United Kingdom, the Imperial Austro-Hungarian Navy was building four dreadnoughts, while the Italians had four and were building two more. Against such threats, the Royal Navy could no longer guarantee vital British interests. The United Kingdom was faced with a choice of building more battleships, withdrawing from the Mediterranean, or seeking an alliance with France. Further naval construction was unacceptably expensive at a time when social welfare provision was making calls on the budget. Withdrawing from the Mediterranean would mean a huge loss of influence, weakening British diplomacy in the Mediterranean and shaking the stability of the British Empire. The only acceptable option, and the one recommended by First Lord of the Admiralty Winston Churchill, was to break with the policies of the past and make an arrangement with France. The French would assume responsibility for checking Italy and Austria-Hungary in the Mediterranean, while the British would protect the north coast of France. In spite of some opposition from British politicians, the Royal Navy organised itself on this basis in 1912.^[96]

In spite of these important strategic consequences, the 1912 Naval Law had little bearing on the battleship force ratios. The United Kingdom responded by laying down ten new super-dreadnoughts in her 1912 and 1913 budgets—ships of the Queen Elizabeth and Revenge classes, which introduced a further step change in armament, speed and protection—while Germany laid down only five, focusing resources on the Army.^[97]”

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iv. Travelling salesman problem.

“The travelling salesman problem (TSP) is an NP-hard problem in combinatorial optimization studied in operations research and theoretical computer science. Given a list of cities and their pairwise distances, the task is to find the shortest possible route that visits each city exactly once and returns to the origin city. It is a special case of the travelling purchaser problem.

The problem was first formulated as a mathematical problem in 1930 and is one of the most intensively studied problems in optimization. It is used as a benchmark for many optimization methods. Even though the problem is computationally difficult, a large number of heuristics and exact methods are known, so that some instances with tens of thousands of cities can be solved.

The TSP has several applications even in its purest formulation, such as planning, logistics, and the manufacture of microchips. Slightly modified, it appears as a sub-problem in many areas, such as DNA sequencing. In these applications, the concept city represents, for example, customers, soldering points, or DNA fragments, and the concept distance represents travelling times or cost, or a similarity measure between DNA fragments. In many applications, additional constraints such as limited resources or time windows make the problem considerably harder. […]

The most direct solution would be to try all permutations (ordered combinations) and see which one is cheapest (using brute force search). The running time for this approach lies within a polynomial factor of O(n!), the factorial of the number of cities, so this solution becomes impractical even for only 20 cities. One of the earliest applications of dynamic programming is the Held–Karp algorithm that solves the problem in time O(n²2ⁿ).^[13] […]

An exact solution for 15,112 German towns from TSPLIB was found in 2001 using the cutting-plane method proposed by George Dantzig, Ray Fulkerson, and Selmer M. Johnson in 1954, based on linear programming. The computations were performed on a network of 110 processors located at Rice University and Princeton University (see the Princeton external link). The total computation time was equivalent to 22.6 years on a single 500 MHz Alpha processor. In May 2004, the travelling salesman problem of visiting all 24,978 towns in Sweden was solved: a tour of length approximately 72,500 kilometers was found and it was proven that no shorter tour exists.^[16]

In March 2005, the travelling salesman problem of visiting all 33,810 points in a circuit board was solved using Concorde TSP Solver: a tour of length 66,048,945 units was found and it was proven that no shorter tour exists. The computation took approximately 15.7 CPU-years (Cook et al. 2006). In April 2006 an instance with 85,900 points was solved using Concorde TSP Solver, taking over 136 CPU-years […]

Various heuristics and approximation algorithms, which quickly yield good solutions have been devised. Modern methods can find solutions for extremely large problems (millions of cities) within a reasonable time which are with a high probability just 2–3% away from the optimal solution.”

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v. Ediacara biota (featured).

“The Ediacara ( /ˌiːdiˈækərə/; formerly Vendian) biota consisted of enigmatic tubular and frond-shaped, mostly sessile organisms which lived during the Ediacaran Period (ca. 635–542 Ma). Trace fossils of these organisms have been found worldwide, and represent the earliest known complex multicellular organisms.^{[note 1]} The Ediacara biota radiated in an event called the Avalon Explosion, 575 million years ago,^[1][2] after the Earth had thawed from the Cryogenian period’s extensive glaciation, and largely disappeared contemporaneously with the rapid appearance of biodiversity known as the Cambrian explosion. Most of the currently existing body-plans of animals first appeared only in the fossil record of the Cambrian rather than the Ediacaran. For macroorganisms, the Cambrian biota completely replaced the organisms that populated the Ediacaran fossil record.

The organisms of the Ediacaran Period first appeared around 585 million years ago and flourished until the cusp of the Cambrian 542 million years ago when the characteristic communities of fossils vanished. The earliest reasonably diverse Ediacaran community was discovered in 1995 in Sonora, Mexico, and is approximately 585 million years in age, roughly synchronous with the Gaskiers glaciation.^[3] While rare fossils that may represent survivors have been found as late as the Middle Cambrian (510 to 500 million years ago) the earlier fossil communities disappear from the record at the end of the Ediacaran leaving only curious fragments of once-thriving ecosystems.^[4] Multiple hypotheses exist to explain the disappearance of this biota, including preservation bias, a changing environment, the advent of predators and competition from other life-forms.

Determining where Ediacaran organisms fit in the tree of life has proven challenging; it is not even established that they were animals, with suggestions that they were lichens (fungus-alga symbionts), algae, protists known as foraminifera, fungi or microbial colonies, to hypothetical intermediates between plants and animals. The morphology and habit of some taxa (e.g. Funisia dorothea) suggest relationships to Porifera or Cnidaria.^[5] Kimberella may show a similarity to molluscs, and other organisms have been thought to possess bilateral symmetry, although this is controversial. Most macroscopic fossils are morphologically distinct from later life-forms: they resemble discs, tubes, mud-filled bags or quilted mattresses. Due to the difficulty of deducing evolutionary relationships among these organisms some paleontologists have suggested that these represent completely extinct lineages that do not resemble any living organism. One paleontologist proposed a separate kingdom level category Vendozoa (now renamed Vendobionta)^[6] in the Linnaean hierarchy for the Ediacaran biota. If these enigmatic organisms left no descendants their strange forms might be seen as a “failed experiment” in multicellular life with later multicellular life independently evolving from unrelated single-celled organisms.^[7]”

Terms like ‘may have’ (9), ‘perhaps’ (3) and ‘probably’ (3) are abundant in the article, but think about how long time ago this was. I think it’s frankly just incredibly awesome that we even know anything at all.

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vi. Three Emperors Dinner. Yes, there’s a Wikipedia article about a dinner that happened more than 100 years ago. Wikipedia is awesome!

“The Dîner des trois empereurs or Three Emperors Dinner was a banquet held at Café Anglais in Paris, France on 7 June 1867.

It was prepared by chef Adolphe Dugléré at the request of King William I of Prussia who frequented the cafe during the Exposition Universelle. He requested a meal to be remembered and at which no expense was to be spared for himself and his guests, Tsar Alexander II of Russia, plus his son the tsarevitch (who later became Tsar Alexander III), and Prince Otto von Bismarck. The cellar master, Claudius Burdel, was instructed to accompany the dishes with the greatest wines in the world, including a Roederer champagne in a special lead glass bottle, so Tsar Alexander could admire the bubbles and golden colour.^[1]

The banquet consisted of 16 courses with eight wines served over eight hours. The cost of the meal was 400 francs per person^[2] (about €8,800 in 2012 prices).”

Wikipedia articles of interest

i. Song Dynasty. [featured, great article with lots of links)

“The Song Dynasty (Chinese: 宋朝; pinyin: Sòng Cháo; Wade-Giles: Sung Ch’ao; IPA: [sʊ̂ŋ tʂʰɑ̌ʊ̯]) was a ruling dynasty in China between 960 and 1279; it succeeded the Five Dynasties and Ten Kingdoms Period, and was followed by the Yuan Dynasty. It was the first government in world history to issue banknotes or paper money, and the first Chinese government to establish a permanent standing navy. This dynasty also saw the first known use of gunpowder, as well as first discernment of true north using a compass. […]

The population of China doubled in size during the 10th and 11th centuries. This growth came through expanded rice cultivation in central and southern China, the use of early-ripening rice from southeast and southern Asia, and the production of abundant food surpluses.^[4][5] […]

The Song Dynasty was an era of administrative sophistication and complex social organization. Some of the largest cities in the world were found in China during this period (Kaifeng and Hangzhou had populations of over a million).^[1][48] People enjoyed various social clubs and entertainment in the cities, and there were many schools and temples to provide the people with education and religious services.^[1] The Song government supported multiple forms of social welfare programs, including the establishment of retirement homes, public clinics, and pauper‘s graveyards.^[1] The Song Dynasty supported a widespread postal service that was modeled on the earlier Han Dynasty (202 BC – AD 220) postal system to provide swift communication throughout the empire.^[49] The central government employed thousands of postal workers of various ranks and responsibilities to provide service for post offices and larger postal stations.^[50] […]

The Song military was chiefly organized to ensure that the army could not threaten Imperial control, often at the expense of effectiveness in war. Northern Song’s Military Council operated under a Chancellor, who had no control over the imperial army. The imperial army was divided among three marshals, each independently responsible to the Emperor. Since the Emperor rarely led campaigns personally, Song forces lacked unity of command.^[89] The imperial court often believed that successful generals endangered royal authority, and relieved or even executed them (notably Li Gang,^[90] Yue Fei, and Han Shizhong.^[91])

Although the scholar-officials viewed military soldiers as lower members in the hierarchic social order,^[92] a person could gain status and prestige in society by becoming a high ranking military officer with a record of victorious battles.^[93] At its height, the Song military had one million soldiers^[22] divided into platoons of 50 troops, companies made of two platoons, and one battalion composed of 500 soldiers.^[94][95] Crossbowmen were separated from the regular infantry and placed in their own units as they were prized combatants, providing effective missile fire against cavalry charges.^[95] The government was eager to sponsor new crossbow designs that could shoot at longer ranges, while crossbowmen were also valuable when employed as long-range snipers.^[96] Song cavalry employed a slew of different weapons, including halberds, swords, bows, spears, and ‘fire lances‘ that discharged a gunpowder blast of flame and shrapnel.^[97]

Military strategy and military training were treated as science that could be studied and perfected; soldiers were tested in their skills of using weaponry and in their athletic ability.^[98] The troops were trained to follow signal standards to advance at the waving of banners and to halt at the sound of bells and drums.^[95] […]

The economy of the Song Dynasty was one of the most prosperous and advanced economies in the medieval world. […] The Song economy was stable enough to produce over a hundred million kilograms (over two hundred million pounds) of iron product a year.^[133] […] The annual output of minted copper currency in 1085 alone reached roughly six billion coins.^[4] The most notable advancement in the Song economy was the establishment of the world’s first government issued paper-printed money, known as Jiaozi […] The size of the workforce employed in paper money factories was large; it was recorded in 1175 that the factory at Hangzhou employed more than a thousand workers a day.^[135] […]

The innovation of movable type printing was made by the artisan Bi Sheng (990–1051), first described by the scientist and statesman Shen Kuo in his Dream Pool Essays of 1088.^[179][180] The collection of Bi Sheng’s original clay-fired typeface was passed on to one of Shen Kuo’s nephews, and was carefully preserved.^[180][181] Movable type enhanced the already widespread use of woodblock methods of printing thousands of documents and volumes of written literature, consumed eagerly by an increasingly literate public. The advancement of printing had a deep impact on education and the scholar-official class, since more books could be made faster while mass-produced, printed books were cheaper in comparison to laborious handwritten copies.^[67][71] The enhancement of widespread printing and print culture in the Song period was thus a direct catalyst in the rise of social mobility and expansion of the educated class of scholar elites, the latter which expanded dramatically in size from the 11th to 13th centuries.^[67][182]”

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ii. Tidal flexing.

“Tidal acceleration is an effect of the tidal forces between an orbiting natural satellite (e.g. the Moon), and the primary planet that it orbits (e.g. the Earth). The acceleration is usually negative, as it causes a gradual slowing and recession of a satellite in a prograde orbit away from the primary, and a corresponding slowdown of the primary’s rotation. The process eventually leads to tidal locking of first the smaller, and later the larger body. The Earth-Moon system is the best studied case.

The similar process of tidal deceleration occurs for satellites that have an orbital period that is shorter than the primary’s rotational period, or that orbit in a retrograde direction. […]

Because the Moon‘s mass is a considerable fraction of that of the Earth (about 1:81), the two bodies can be regarded as a double planet system, rather than as a planet with a satellite. The plane of the Moon’s orbit around the Earth lies close to the plane of the Earth’s orbit around the Sun (the ecliptic), rather than in the plane perpendicular to the axis of rotation of the Earth (the equator) as is usually the case with planetary satellites. The mass of the Moon is sufficiently large, and it is sufficiently close, to raise tides in the matter of the Earth. In particular, the water of the oceans bulges out along both ends of an axis passing through the centers of the Earth and Moon. The average tidal bulge closely follows the Moon in its orbit, and the Earth rotates under this tidal bulge in just over a day. However, the rotation drags the position of the tidal bulge ahead of the position directly under the Moon. As a consequence, there exists a substantial amount of mass in the bulge that is offset from the line through the centers of the Earth and Moon. Because of this offset, a portion of the gravitational pull between Earth’s tidal bulges and the Moon is perpendicular to the Earth-Moon line, i.e. there exists a torque between the Earth and the Moon. This boosts the Moon in its orbit, and decelerates the rotation of the Earth.

As a result of this process, the mean solar day, which is nominally 86400 seconds long, is actually getting longer when measured in SI seconds with stable atomic clocks. (The SI second, when adopted, was already a little shorter than the current value of the second of mean solar time.^[9]) The small difference accumulates every day, which leads to an increasing difference between our clock time (Universal Time) on the one hand, and Atomic Time and Ephemeris Time on the other hand: see ΔT. This makes it necessary to insert a leap second at irregular intervals. […]

Tidal acceleration is one of the few examples in the dynamics of the Solar System of a so-called secular perturbation of an orbit, i.e. a perturbation that continuously increases with time and is not periodic. Up to a high order of approximation, mutual gravitational perturbations between major or minor planets only cause periodic variations in their orbits, that is, parameters oscillate between maximum and minimum values. The tidal effect gives rise to a quadratic term in the equations, which leads to unbounded growth. In the mathematical theories of the planetary orbits that form the basis of ephemerides, quadratic and higher order secular terms do occur, but these are mostly Taylor expansions of very long time periodic terms. The reason that tidal effects are different is that unlike distant gravitational perturbations, friction is an essential part of tidal acceleration, and leads to permanent loss of energy from the dynamical system in the form of heat.”

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iii. Error function. Somewhat technical, but interesting (the article has a lot more):

“In mathematics, the error function (also called the Gauss error function) is a special function (non-elementary) of sigmoid shape which occurs in probability, statistics and partial differential equations. It is defined as:^[1][2]

(When x is negative, the integral is interpreted as the negative of the integral from x to zero.) […]

The error function is used in measurement theory (using probability and statistics), and although its use in other branches of mathematics has nothing to do with the characterization of measurement errors, the name has stuck.

The error function is related to the cumulative distribution , the integral of the standard normal distribution (the “bell curve”), by^[2]

The error function, evaluated at    for positive x values, gives the probability that a measurement, under the influence of normally distributed errors with standard deviation , has a distance less than x from the mean value.^[3] This function is used in statistics to predict behavior of any sample with respect to the population mean. This usage is similar to the Q-function, which in fact can be written in terms of the error function.”

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iv. Lake Vostok

“Lake Vostok (Russian: озеро Восток, lit. “Lake East”) is the largest of more than 140 sub-glacial lakes and was recently drilled into by Russian scientists. The overlying ice provides a continuous paleoclimatic record of 400,000 years, although the lake water itself may have been isolated for 15^[3][4] to 25 million years.^[5]

Lake Vostok is located at the southern Pole of Cold, beneath Russia‘s Vostok Station under the surface of the central East Antarctic Ice Sheet, which is at 3,488 metres (11,444 ft) above mean sea level. The surface of this fresh water lake is approximately 4,000 m (13,100 ft) under the surface of the ice, which places it at approximately 500 m (1,600 ft) below sea level. Measuring 250 km (160 mi) long by 50 km (30 mi) wide at its widest point, and covering an area of 15,690 km² (6,060 sq mi), it is similar in area to Lake Ontario, but with over three times the volume. The average depth is 344 m (1,129 ft). It has an estimated volume of 5,400 km³ (1,300 cu mi).^[2] The lake is divided into two deep basins by a ridge. The liquid water over the ridge is about 200 m (700 ft), compared to roughly 400 m (1,300 ft) deep in the northern basin and 800 m (2,600 ft) deep in the southern. […]

The coldest temperature ever observed on Earth, −89 °C (−128 °F), was recorded at Vostok Station on 21 July 1983.^[3] The average water temperature is calculated to be around −3 °C (27 °F); it remains liquid below the normal freezing point because of high pressure from the weight of the ice above it.^[30] Geothermal heat from the Earth’s interior may warm the bottom of the lake.^[31][32][33] The ice sheet itself insulates the lake from cold temperatures on the surface. […]

The lake is under complete darkness, under 350 atmospheres (5143 psi) of pressure and expected to be rich in oxygen, so there is speculation that any organisms inhabiting the lake could have evolved in a manner unique to this environment.^[19][36] These adaptations to an oxygen-rich environment might include high concentrations of protective oxidative enzymes.

Living Hydrogenophilus thermoluteolus micro-organisms have been found in Lake Vostok’s deep ice core drillings; they are an extant surface-dwelling species.^[35][40] This suggests the presence of a deep biosphere utilizing a geothermal system of the bedrock encircling the subglacial lake. There is optimism that microbial life in the lake may be possible despite high pressure, constant cold, low nutrient input, potentially high oxygen concentration and an absence of sunlight.^[35][41][42]

Jupiter‘s moon Europa and Saturn‘s moon Enceladus may also harbor lakes or oceans below a thick crust of ice. Any confirmation of life in Lake Vostok could strengthen the prospect for the presence of life on icy moons.^[35][43]”

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v. Nicosia

“Nicosia (/ˌnɪkəˈsiːə/ NIK-ə-SEE-ə), known locally as Lefkosia (Greek: Λευκωσία, Turkish: Lefkoşa), is the capital and largest city in Cyprus, as well as its main business center.^[2] After the collapse of the Berlin Wall, Nicosia remained the only divided capital in the world,^[3] with the southern and the northern portions divided by a Green Line.^[4] It is located near the center of the island, on the banks of the Pedieos River.

Nicosia is the capital and seat of government of the Republic of Cyprus. The northern part of the city functions as the capital of the self-proclaimed Turkish Republic of Northern Cyprus, a disputed breakaway region whose independence is recognized only by Turkey, and which the rest of the international community considers as occupied territory of the Republic of Cyprus since the Turkish Invasionin 1974. […]

The Turkish invasion, the continuous occupation of Cyprus as well as the self-declaration of independence of the TRNC have been condemned by several United Nations Resolutions adopted by the General Assembly and the Security Council. The Security Council is reaffirming their condemnation every year.^[40]”

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vi. Perennial plant

“A perennial plant or simply perennial (Latin per, “through”, annus, “year”) is a plant that lives for more than two years.^[1] The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials. More correctly, woody plants like shrubs and trees are also perennials.

Perennials, especially small flowering plants, grow and bloom over the spring and summer and then die back every autumn and winter, then return in the spring from their root-stock, in addition to seeding themselves as an annual plant does. These are known as herbaceous perennials. However, depending on the rigors of local climate, a plant that is a perennial in its native habitat, or in a milder garden, may be treated by a gardener as an annual and planted out every year, from seed, from cuttings or from divisions. […]

Although most of humanity is fed by seeds from annual grain crops, perennial crops provide numerous benefits.^[3] Perennial plants often have deep, extensive root systems which can hold soil to prevent erosion, capture dissolved nitrogen before it can contaminate ground and surface water, and outcompete weeds (reducing the need for herbicides). These potential benefits of perennials have resulted in new attempts to increase the seed yield of perennial species,^[4] which could result in the creation of new perennial grain crops.^[5] Some examples of new perennial crops being developed are perennial rice and intermediate wheatgrass.”

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vii. Anaconda Plan.

“The Anaconda Plan or Scott’s Great Snake is the name widely applied to an outline strategy for subduing the seceding states in the American Civil War. Proposed by General-in-Chief Winfield Scott, the plan emphasized the blockade of the Southern ports, and called for an advance down the Mississippi River to cut the South in two. Because the blockade would be rather passive, it was widely derided by the vociferous faction who wanted a more vigorous prosecution of the war, and who likened it to the coils of an anaconda suffocating its victim. The snake image caught on, giving the proposal its popular name.”

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viii. Caesar cipher (featured).

“In cryptography, a Caesar cipher, also known as Caesar’s cipher, the shift cipher, Caesar’s code or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a shift of 3, A would be replaced by D, B would become E, and so on. The method is named after Julius Caesar, who used it in his private correspondence.

The encryption step performed by a Caesar cipher is often incorporated as part of more complex schemes, such as the Vigenère cipher, and still has modern application in the ROT13 system. As with all single alphabet substitution ciphers, the Caesar cipher is easily broken and in modern practice offers essentially no communication security.”

If you don’t really know much about cryptography but would like a quick and accessible introduction to the subject matter, I recommend Brit Cruise’ videos on the subject at Khan Academy.

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ix. Water purification. From the article:

“It is not possible to tell whether water is of an appropriate quality by visual examination. Simple procedures such as boiling or the use of a household activated carbon filter are not sufficient for treating all the possible contaminants that may be present in water from an unknown source. Even natural spring water – considered safe for all practical purposes in the 19th century – must now be tested before determining what kind of treatment, if any, is needed. Chemical and microbiological analysis, while expensive, are the only way to obtain the information necessary for deciding on the appropriate method of purification.

According to a 2007 World Health Organization (WHO) report, 1.1 billion people lack access to an improved drinking water supply, 88 percent of the 4 billion annual cases of diarrheal disease are attributed to unsafe water and inadequate sanitation and hygiene, and 1.8 million people die from diarrheal diseases each year. The WHO estimates that 94 percent of these diarrheal cases are preventable through modifications to the environment, including access to safe water.^[1] Simple techniques for treating water at home, such as chlorination, filters, and solar disinfection, and storing it in safe containers could save a huge number of lives each year.^[2] Reducing deaths from waterborne diseases is a major public health goal in developing countries.”

Here’s a related paper on ‘Global Distribution of Outbreaks of Water-Associated Infectious Diseases‘ which I’ve previously blogged here.

Wikipedia articles of interest

i. British anti-invasion preparations of World War II. From the article:

“Any German invasion of Britain would have to involve the landing of troops and equipment somewhere on the coast, and the most vulnerable areas were the south and east coasts of England. Here, Emergency Coastal Batteries were constructed to protect ports and likely landing places. They were fitted with whatever guns were available, which mainly came from naval vessels scrapped since the end of the First World War. These included 6 inch (152 mm), 5.5 inch (140 mm), 4.7 inch (120 mm) and 4 inch (102 mm) guns. These had little ammunition, sometimes as few as ten rounds apiece. At Dover, two 14 inch (356 mm) guns known as Winnie and Pooh were employed.^[25] There were also a small number of land based torpedo launching sites.^[26]

Beaches were blocked with entanglements of barbed wire, usually in the form of three coils of concertina wire fixed by metal posts, or a simple fence of straight wires supported on waist-high posts.^[27] The wire would also demarcate extensive minefields, with both anti-tank and anti-personnel mines on and behind the beaches. On many of the more remote beaches this combination of wire and mines represented the full extent of the passive defences.

Portions of the Romney Marsh, which was the planned invasion site of Operation Sea Lion, were flooded^[28] and there were plans to flood more of the Marsh if the invasion were to materialise.^[29]

Piers, ideal for landing of troops, and situated in large numbers along the south coast of England, were disassembled, blocked or otherwise destroyed. Many piers were not repaired until the late 1940s or early 1950s.^[30]

Where a barrier to tanks was required, Admiralty scaffolding (also known as beach scaffolding or obstacle Z.1) was constructed. Essentially, this was a fence of scaffolding tubes 9 feet (2.7 m) high and was placed at low water so that tanks could not get a good run at it.^[31] Admiralty scaffolding was deployed along hundreds of miles of vulnerable beaches.^[32]

An even more robust barrier to tanks was provided by long lines of anti-tank cubes. The cubes were made of reinforced concrete 5 feet (1.5 m) to a side. Thousands were cast in situ in rows sometimes two or three deep.

The beaches themselves were overlooked by pillboxes of various types (see British hardened field defences of the Second World War). These were sometimes placed low down to get maximum advantage from enfilading fire whereas others were placed high up making them much harder to capture. Searchlights were installed at the coast to illuminate the sea surface and the beaches for artillery fire.^[33][34][35]”

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I also thought this article, on British hardened field defences (pillboxes), was quite fascinating. It seems to me that at least a few of the models were not much more than poorly constructed deathtraps, whereas some others were remarkably well constructed.

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ii. Bradford-Hill criteria. I was waiting a long time for these to be brought up (/mentioned?) during this lecture; they were never mentioned and along the way the lecturer made me start doubting whether he even knew the difference between a p-value and a correlation coefficient. Either way, the criteria are “a group of minimal conditions necessary to provide adequate evidence of a causal relationship between an incidence and a consequence” – here’s the list from the article:

1. Strength of association (relative risk, odds ratio)
2. Consistency
3. Specificity
4. Temporal relationship (temporality) – not heuristic; factually necessary for cause to precede consequence
5. Biological gradient (dose-response relationship)
6. Plausibility (biological plausibility)
7. Coherence
8. Experiment (reversibility)
9. Analogy (consideration of alternate explanations)

Do have these in mind the next time you come across an article on reddit (or wherever) explaining how ‘drinking X two times a week will prevent cancer’ or how ‘doing Y will minimize your risk of getting disease Z’ (or whatever). Of course in 1965, when the criteria were formulated, people had never even heard about stuff like Granger causality tests, vector autoregressive models and instrumental variable models. Establishing any kind of reasonably strong argument for a causal relationship between two sets of variables is very hard.

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iii. Minamata disease. Via mercury and mercury poisoning. It’s a horrible story and I think it’s pretty much certain that quite a few comparable disasters are unfolding right now elsewhere, e.g. in China. From the article:

“Minamata disease […] is a neurological syndrome caused by severe mercury poisoning. Symptoms include ataxia, numbness in the hands and feet, general muscle weakness, narrowing of the field of vision and damage to hearing and speech. In extreme cases, insanity, paralysis, coma, and death follow within weeks of the onset of symptoms. A congenital form of the disease can also affect foetuses in the womb.

Minamata disease was first discovered in Minamata city in Kumamoto prefecture, Japan, in 1956. It was caused by the release of methylmercury in the industrial wastewater from the Chisso Corporation‘s chemical factory, which continued from 1932 to 1968. This highly toxic chemical bioaccumulated in shellfish and fish in Minamata Bay and the Shiranui Sea, which when eaten by the local populace resulted in mercury poisoning. While cat, dog, pig, and human deaths continued over more than 30 years, the government and company did little to prevent the pollution.

As of March 2001, 2,265 victims had been officially recognised (1,784 of whom had died)^[1] and over 10,000 had received financial compensation from Chisso.^[2] By 2004, Chisso Corporation had paid $86 million in compensation, and in the same year was ordered to clean up its contamination.^[3] On March 29, 2010, a settlement was reached to compensate as-yet uncertified victims.^[4]

A second outbreak of Minamata disease occurred in Niigata Prefecture in 1965. The original Minamata disease and Niigata Minamata disease are considered two of the Four Big Pollution Diseases of Japan.”

See also Patio process, a historically quite significant technique which improved the yields of silver mines in South America.

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iv. Recovery position.

“The recovery position refers to one of a series of variations on a lateral recumbent or three-quarters prone position of the body, in to which an unconscious but breathing casualty can be placed as part of first aid treatment.

An unconscious person (GCS <8) in a supine position (on their back) may not be able to maintain an open airway as a conscious person would.^[1] This can lead to an obstruction of the airway, restricting the flow of air and preventing gaseous exchange, which then causes hypoxia, which is life threatening. Thousands of fatalities occur every year in casualties where the cause of unconsciousness was not fatal, but where airway obstruction caused the patient to suffocate.^[2][3][4] The cause of unconsciousness can be any reason from trauma to intoxication from alcohol.”

You never know when you need to know stuff like this.

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v. Cassava.

“Cassava (Manihot esculenta), also called yuca, mogo, manioc, mandioca and kamoting kaoy a woody shrub of the Euphorbiaceae (spurge family) native to South America, is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy, tuberous root, a major source of carbohydrates. It differs from the similarly-spelled yucca, an unrelated fruit-bearing shrub in the Asparagaceae family. Cassava, when dried to a starchy, powdery (or pearly) extract is called tapioca, while its fermented, flaky version is named garri.

Cassava is the third-largest source of food carbohydrates in the tropics.^[1][2] Cassava is a major staple food in the developing world, providing a basic diet for around 500 million people.^[3] Cassava is one of the most drought-tolerant crops, capable of growing on marginal soils. Nigeria is the world’s largest producer of cassava.

Cassava root is a good source of carbohydrates, but a poor source of protein. A predominantly cassava root diet can cause protein-energy malnutrition.^[4]

Cassava is classified as sweet or bitter. Like other roots and tubers, Cassava contains anti-nutrition factors and toxins.^[5] It must be properly prepared before consumption. Improper preparation of cassava can leave enough residual cyanide to cause acute cyanide intoxication and goiters, and may even cause ataxia or partial paralysis.^[6] Nevertheless, farmers often prefer the bitter varieties because they deter pests, animals, and thieves.^[7] The more-toxic varieties of Cassava are a fall-back resource (a “food security crop”) in times of famine in some places.^[8]”

Using the toxic varieties as fall-back ressources is of course not exactly optimal. It can actually, and has, lead to really terrible outcomes (here’s the study Rosling talks about, I have not been able to find a non-gated version):

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vi. Solon. I’m sure that for most readers the name rings a bell, but what do you actually know about the guy? If you click the link, you’ll know more…

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vii. Emulsion.

“An emulsion is a mixture of two or more liquids that are normally immiscible (un-blendable). Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion is used when both the dispersed and the continuous phase are liquid. In an emulsion, one liquid (the dispersed phase) is dispersed in the other (the continuous phase). Examples of emulsions include vinaigrettes, milk, and some cutting fluids for metal working. The photo-sensitive side of photographic film is an example of a colloid.”

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viii. Onomatopoeia. Included because that’s just a neat word for something I didn’t know had a name:

An onomatopoeia or onomatopœia […] from the Greek ὀνοματοποιία;^[1] ὄνομα for “name”^[2] and ποιέω for “I make”,^[3] adjectival form: “onomatopoeic” or “onomatopoetic”) is a word that imitates or suggests the source of the sound that it describes. Onomatopoeia (as an uncountable noun) refers to the property of such words. Common occurrences of onomatopoeias include animal noises, such as “oink” or “meow” or “roar”. Onomatopoeias are not the same across all languages; they conform to some extent to the broader linguistic system they are part of; hence the sound of a clock may be tick tock in English, dī dā in Mandarin, or katchin katchin in Japanese.”

(And now you know…)

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ix. Chemokine. It’s a technical article, but you can’t read it and not at least get the message that the human body is almost unbelievably complex.