Here's some stuff that's not from my normal journal reading list, but I none the less find interesting:
Danger! Science jargon ahead!
Chimpanzees adopting unrelated children. (Altruism in Forest Chimpanzees: The Case of Adoption. Boesch et al 2010) So, the question is, is this an evolutionarily adaptive trait, that is to say, in provisioning these young they gain a benefit to their own fitness, or is this a spandrel - a maladaptive piece of behaviour that is the result of a more adaptive behaviour. I can see how the adaptionalist case would work - after all, rearing offspring would be a strong signal as to mate quality - but the argument that it's a spandrel seems more appealing, given the evidence. What I'd put a whole nickel on happening is that chemically, the same brain changes are going on in bonding with these unrelated individuals as it is with their actual offspring. Question: Why the heck isn't this seen in captive situations?
Positive selection in armpit odour? (A Functional ABCC11 Allele Is Essential in the Biochemical Formation of Human Axillary Odor. Martin et al 2010) So, Europeans and Africans have some components to their armpit sweat, and people descended from East Asian populations (which would include the groups that peopled the Americas?) have individuals with subtly different compositions. The frequency of the derived allele can reach upwards of 95% in those populations. Researchers found a DNA substitution that seems to result in a change in odour composition. East Asian (does this follow into American groups?) have a subtly different odorant composition, which the authors argue is the result of positive mate choice. Genomically, the show that it has benefit from strong positive selection. The allele reaches 95% frequency in some populations. I'm totally onboard with the idea that odour drives matechoice in humans (or is a driving factor), but I'm not sold on their description that this is the primary driver of this gene. Problem is, this gene also is a factor in the dry ear wax. Which we strongly suspect is adaptive. So, the adaptive tale of that gene is probably very complex.