Wednesday, October 05, 2005

Orangutans gone wild   posted by Razib @ 10/05/2005 08:13:00 PM

I suspect most readers have perused Demonic Males at some point, and stumbled upon the concept of developmentally arrested orangutan males who mate with females by raping them (in contrast to the bigger males whose entreaties are welcomed). Here are two papers that readers might find of interest in relation to this topic....

Male orangutan subadulthood: a new twist on the relationship between chronic stress and developmental arrest:

...These results imply that the arrest of secondary sexual development in some male orangutans is not stress-induced, but instead perhaps an adaptation for stress avoidance during the adolescent or "subadult" period. These data, together with previously reported data on levels of gonadotropins, testicular steroids, and growth-related hormones, define endocrine profiles associated with alternative reproductive strategies for males with and males without secondary sexual features.

So why is this strategy hanging around? Well, Male bimaturism and reproductive success in Sumatran orang-utans:

Fecal samples were collected from a well-studied population in Indonesia, and eight human microsatellites were analyzed for 30 individuals that have been behaviorally monitored for up to 27 years. By carrying out paternity analysis on 11 offspring born over 15 years, we found that unflanged males fathered about half (6) of the offspring. Relatedness between successful unflanged males and resident dominant males was significantly lower than 0.5, and for some unflanged/flanged male pairs, relatedness values were negative, indicating that unflanged males are not offspring of the flanged males....

The data set is very small (though there aren't really that many orangutans to sample from out there, are there?). But I think it makes it clear that alternative reproductive strategies for complex organisms isn't unfathomable. It makes Henry's old ideas about father absence seem more plausible I think. Unfortunately the current ascendency of Evolutionary PsychologyTM allows the scientifically interested lay public to buy into the idea of phenotypic monomorphism, that there is one strategy to rule them all. And of course this results in bitch-fests between conservatives and liberals (or whatever typology you want to set up) aiming to lay claim to the mantle of ideology most in keeping with the Most Perfect Human Behavior.