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Wednesday, June 9, 2010

Life in the cold, life under the heat

Gathering here a couple of at least curious news I read recently at Science Daily. They have nothing to do with each other except one thing: they both deal with life at extreme temperatures.

Being human is cool... literally so.

Benjamin Passey and colleagues report that temperatures were hellishly high most of the time in one of the most likely cradles of human evolution: the basin of Lake Turkana, including the last three million years.

This may support the thermal hypothesis of human evolution, that would explain why we don't have any fur and sweat so much (intended for cooling) and also maybe why we walk on only two legs, reducing the direct impact of both the Sun and the overheated soil.

The article does not mention it but I recall reading some time ago that even brain size increase has been attributed tentatively to such heat challenge, as larger brains would prevent fainting under the heat allowing our ancestors to exploit the territory at noon, when predators are enjoying their siestas. That would also explain why we keep "natural hats" of hair on our heads, of all bodily places (and I'd dare hunch it might also explain thinly curled hair, still overwhelmingly dominant among tropical peoples, as a means to secure free circulation of air near it).

Source article.

Where water is a rock... methane fills the rivers. Life in Titan?

This in fact was already known. What is new is that astronomer Chris McKay suspects that the chemistry of Titan could well be indicative of the existence of some form of life on it.

Saturn's satellite Titan, as you probably know, has many similitudes with Earth's environment, just that with a much lower temperature range that does not allow water to melt ever. At such freezing temperatures, methane, an organic compound, takes the role of water switching between liquid and gaseous states in the hazy orange atmosphere of this planetoid, the largest moon of the Solar System.

But what is new and interesting is that scientists expected that natural chemistry in Titan would produce lots of acetylene but Cassini has failed to find any of it so far. The most likely chemistry for life without water at such gelid temperatures would be a metabolism of acetylene by hidrolization (reaction with hydrogen instead oxygen, as usually happens on Earth) and, according to McKay, the available data seems to indicate that this is actually happening on Titan.

Still, Mark Allen, says that all non-biological explanations are not still ruled out. Acetylene might be just degraded by solar radiation for example.

But the aboundance of organic compounds on Titan is so overwhelming that it is difficult to think that life has not evolved upon them at the slightest chance. This last is my opinion.

Source article.

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