Econstudentlog

Stuff

i. “Jesus said to his disciples: “Things that cause people to stumble are bound to come, but woe to anyone through whom they come. It would be better for them to be thrown into the sea with a millstone tied around their neck than to cause one of these little ones to stumble.” (Luke 17, quote found here).

ii. Dimetrodon. Image from the article:

“a predatory synapsid genus that flourished during the Permian period, living between 280–265 million years ago (during the Artinskian to Capitanian stages).

As a synapsid it was more closely related to mammals than to true reptiles such as lizards and snakes. It is classified as a pelycosaur. Fossils of Dimetrodon have been found in North America and Europe. Dimetrodon had a sail on its back, which is known to have been used for regulating body temperature. […]

Dimetrodon has two types of teeth, shearing teeth and sharp canine teeth. Its name, in fact, means “two-measures of teeth”. Dimetrodon was one of the first animals with differentiated teeth and the teeth were suitable for killing animals then tearing them to pieces. […]

The spines of Dimetrodon have grooves on the base that were presumably ingested by blood vessels and thus ensured good bloodflow through the skin of the sail. The theory is that Dimetrodon was active in the early morning when the sun rose. The sail would be pointed towards the sun and would absorb heat allowing rapid warming. This allowed Dimetrodon to hunt at a time when other animals were not sufficiently warmed up and were slow. The sail increased body surface area by 50%. According to calculations by Bramwell Fellgett, it took a 200 kg (440 lb) Dimetrodon approximately one and a half hours for its body temperature to go from 26 to 32 °C (79 to 90 °F) [13] A study by Haack concluded that warming was slower than previously thought and that the process probably took four hours.[14] In order to cool its body in the hot midday sun, Dimetrodon turned its sail away from the sun, causing the heat to drain. The rapid warming using the sail give Dimetrodon an edge over larger animals, weighing over 55 kg. Smaller animals had higher body surface-to-mass ratio, making them hotter than Dimetrodon. The prey of Dimetrodon would therefore have been mostly large animals like Diadectes, Eryops and Ophiacodon. The changing climate during the Permian period, when the temperature increased, is a possible reason for the extinction of Dimetrodon since the sail meant no benefit over other animals and was rather a disadvantage due to its fragility.”

Even though in most Western cultures there seem to be quite a bit of focus on dinosaurs and the Mesozoic and a lot less focus on what came before that, it’s worth remembering that there was a lot of stuff going on before life ever got to the dinosaurs.

iii. A quote:

“My model of this situation is less sanguine than others here, though Yvain and Tetronian hinted at it: it’s identity politics. Humans very naturally associate themselves with many different groups, some of them arbitrarily defined, and often without any conscious thought. Religion, favorite sports teams, the street/neighborhood/city/state/country you live in, and many other things can be the focal point of these groups. The more you associate with one of these groups, the more its part of your identity – i.e. how you see yourself. If you associate with one of these groups particularly strongly, any action which appears to make a rival group look better will personally offend you and elicit a response.”

In general, on a related note I think that the likelihood that an argument will escalate (conflict level will increase) is increasing in n in most naturally occuring settings. When two people argue nobody else is watching – which means that there are nobody else there to impress/defend. The more people are watching, the more people will witness a status loss or a status gain resulting from the argument. Also, once several people are involved coalitions will start to form naturally and you’ll start to not only be defending yourself but also feel that you have a duty (due to implicit community norms ect.) to defend the tribe. Gender also matters; in my (admittedly limited) experience, a male with a female partner arguing with another male will argue ‘more strongly’ for X if the partner is present than if she is not (unless the female makes clear that she considers the argument irrelevant; if she does and the male picks up on that signal, he’ll be likely to ‘fold’ whether or not he ‘was winning’ (…which of course he was)). Also, males are probably likely to a) be more aggresive (conflict-prone) if there are women present, and b) be more -ll- if the gender ratio is skewed ‘against them’ (# males >> # females) and less likely to be -ll- if the gender ratio is skewed ‘in their favour’ (# males << # females).

iv. Square/Cube Law. (see also wikipedia)

“When an object undergoes a proportional increase in size, its new volume is proportional to the cube of the multiplier and its new surface area is proportional to the square of the multiplier.

For example, if you double the size (measured by edge length) of a cube, its surface area is quadrupled, and its volume is increased by eight times.

The point of this law is that with living beings, muscle strength is (more or less) a function of surface area, but weight is a function of volume. And Newton’s famous Second Law (the “force = mass * acceleration” one) means that if you double a critter’s size, you end up with four times the muscle power moving eight times the mass, so instead of having the same relative agility as the original, the double-sized creature actually has only half.

This applies to flyers as well: Double the size, and you get four times the wingpower attempting to keep eight times the weight airborne, so the creature’s ability to fly has actually been cut by half.”

Part of why dung beetles can roll up to 50 times their own weight (/and why we can’t).

v. “The ancient Greeks and Romans used torture for interrogation. Until the 2nd century AD, torture was used only on slaves (with a few exceptions). After this point it began to be extended to all members of the lower classes. A slave’s testimony was admissible only if extracted by torture, on the assumption that slaves could not be trusted to reveal the truth voluntarily.[12]” (wikipedia)

vi. Swaziland

“Swaziland, officially the Kingdom of Swaziland (Umbuso weSwatini), and sometimes called Ngwane or Swatini, is a landlocked country in Southern Africa, bordered to the north, south and west by South Africa, and to the east by Mozambique. The nation, as well as its people, are named after the 19th century king Mswati II.

Swaziland is a small country, no more than 200 kilometres (120 mi) north to south and 130 kilometres (81 mi) east to west. […]

Some 75% of the population are employed in subsistence farming, and 60% of the population live on less than the equivalent of US$1.25 per day. […]

Swaziland’s economic growth and societal integrity is highly endangered by its disastrous HIV epidemic, to an extent where the United Nations Development Program has written that if it continues unabated, the “longer term existence of Swaziland as a country will be seriously threatened.”[5] The infection rate in the country is unprecedented and the highest in the world at 26.1% of adults[6] and over 50% of adults in their 20s.[5] […]

…Swaziland has the highest HIV infection rate in the world […] and also the lowest life expectancy at 32 years, which is 6 years lower than the next lowest average of Angola. From another perspective, the last available World Health Organization data in 2002 shows that 64% of all deaths in the country were caused by HIV/AIDS.[11] […]

In 2004, Swaziland acknowledged for the first time that it suffered an AIDS crisis, with 38.8% of tested pregnant women infected with HIV […] Life expectancy has fallen from 61 years in 2000 to 32 years in 2009.[15]”

January 19, 2012 - Posted by | Africa, biology, data, Geography, Paleontology, Psychology, quotes, wikipedia

1 Comment »

  1. On the Square/Cube law: may I add Metcalfe’s law: http://en.wikipedia.org/wiki/Metcalfe%27s_law (sorry, html linking does not like apostrophes much). Take-away lesson: things almost never scale well and/or easily.

    Comment by Plamus | January 21, 2012 | Reply


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