Econstudentlog

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.”

August 9, 2013 - Posted by | biology, books, evolution

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