Thursday, August 30, 2007
Every year, Medical Hypotheses, an Eselvier publication, gives out a prize to honour those who think outside of the box. In 2006 the prize was given for this paper "Parental selection: a third selection process in the evolution of human hairlessness and skin color". Now the first part of that title actually makes sense, parental selection undoubtedly plays a role in evolution, including human evolution. Often in birds, parents will favor one of the offspring and let the others die. It's all a matter of opportunity cost. The metabolic cost of making a second egg, while high for the female, is still outweighed by the potential cost of losing one egg and not being able to reproduce for one season, especially if life expectancy is short. In other words, two birds in the nest is better than none in the bush. For birds, this selection may depend on cracking out of the egg a few minutes earlier, or being noisier, or having a bigger redder beak. In humans the situation is quite different. For one, twin births are relatively rare so there is no competition for milk. This means the most likely mechanism of parental selection would probably be infanticide. It is not hard to imagine that this could happen on the basis of the sex of the baby, or perhaps if there is a malformation or mental retardation. But the authors go further, much further, and they crossed the line, in fact they are so far from the line, they can't even see the line. They argue that babies had to look cute otherwise their mothers would abandon them, so they became all pink and lost their hair, so has to not be confused with Neanderthals. WHAAT? First of all, if anything, genes that would make mothers find their baby attractive no matter what are more likely to be positively selected than genes which makes them choosy. For eutherian mammals, the maternal investment leading to birth is huge, they wouldn't just throw the baby with the bathwater because he is too hairy, or not pink enough. In fact the stupidity is even greater, because if you assume that our ancestors started out hairy, then the difference in hair compared to Neanderthals does not help to discriminate the two. I mean you just have to look at the face, that's enough to differentiate them. Some people even argue that the two species might have interbred. That also seems odd to me, I mean when I see a monkey, the last thing I want is to have sex with it. I don't know about you. Plus, imagine how technically difficult that would be, first you would have to catch it in the trees. Anyways, there are definitely better theories for hairlessness such as having less parasites, especially since we humans are such poor social groomers... So I'll put that theory in the same garbage bin as the we're hairless because we had an "aquatic ape" phase bullshit.