Sunday, December 23, 2007

Hairlessness, kin selection and sexual selection   posted by Asher @ 12/23/2007 12:50:00 PM

Would it be possible that hairlessness and skin color evolved to allow fathers to identify their direct biological offspring, so as not to have to support another male's genes. In many other species, when a new male/group of males takes over they kill the existing pups, so there seems to be pretty good evidence for parents to prefer their direct offspring to the offspring of others. Now it's difficult to say that this is natural selection as there's no particular reason to think that the existing brood has "less fit" genes than the new brood would provide. It would also be interesting to see whether or not there is greater morphological variation in appearance in humans than in other great apes. This would seemingly bolster the argument that much of human culture evolved around allowing fathers to identify their specific offspring and prefer them over other male's offspring. Men would tend to prefer women with greater morphological variation and hairlessness because these women's children would tend to exhibit features that would allow the male to more readily identify parentage. I have done a fair amount of googling and have not been able to find anyone else making this hypothesis but I would be happy if someone could provide any insight into prior references to this sort of theory, namely that hairlessness was sexually selected so that fathers could identify their specific biological offspring.

The one hypothesis posited by Judith Rich Harris seems to assert post-modernist sounding psychological factors; her "us hairless/them hairy" sounds like something straight out of post-colonialist theory or the Frankfurt School. If we are going to seriously consider the role of genetics and evolutionary history in current human affairs we need to prefer strict genetic causes over psychological-ideal "causes", which are really manifestations of the ghost-in-the-machine mentality.

My interest in genetics comes from my interest in ethical philosophy and economics, so I'll admit up-front that I have no expertise here and I'll ask for your indulgence. As I understand it sexual selection for dimorphism takes a long time. However, traits that are sexually monomorphic can manifest relatively quickly in a population. Significant selective pressure for less hairy females would result in offspring of both sexes exhibiting lower levels of fur over probably a relatively short period of time. I just wanted to add that last part because I want to state up-front that I have no specific expertise in this area.

If there is one thing that I believe that I cannot yet demonstrate it's that much of varieties of human life and culture evolved to allow human beings to identify their kin and prefer those kin to non-kin.

A final note: most people agree that sexual selection takes place on the male which is why males in almost every attribute exhibit. This is true. But imagine a situation where a particular region has developed high rates of pair-bonding and males and females raise their offspring as a pair. Males might not be willing to care for a child that they could not specifically recognize as their own, therefore, the female would continue eliminating children until she produced an individual child for which a specific male would/could identify as his own and take responsibility. So, what I am doing is taking a cue from Harris and combining parental selection as a cognitively complex variation on sexual selection; this is kin selection plus sexual selection.

P.S. this is my first post so be gentle