Mental mismatches

A Primate of Modern Aspect (“The sexuality wars, featuring apes”) writes about some of the reactions to the new book, Sex at Dawn: The Prehistoric Origins of Modern Sexuality. As the subtitle suggests, the book is an account of human sexuality from the viewpoint of evolutionary psychology, written by Christopher Ryan and Cacilda Jeth. Ryan blogs at Sex at Dawn, I’m a frequent reader.

Anyway, I loved this point about comparative studies:

[F]or some reason, the only time primate sexuality gets any attention is when we turn it into a debate about how humans should be having sex.
We never say, Hey, those muriquis are too promiscuous. Dont they know that all of their close evolutionary cousins are polygynous? If they just did what came naturally to them, theyd have a lot less psychological stress. Or, Those gibbons are so sexually repressed. If they just gave in to their natural predilection for promiscuity, I bet those nasty gibbons would have fewer territorial disputes and gibbon society would be much more peaceful.

Why worry about the “echoes” of psychic distress that may linger after the mating system changes? That’s a very interesting point; there are unexplored assumptions here about the nature of adaptation and the structure of genetic causation of mental states. Clearly if major aspects of human social life change, we cannot expect people’s minds to be perfectly optimized to the new regime. But what is the force of selection? What are the mental “rough spots” that differential fertility will ultimately iron out? How much “mismatch” between mental and social adaptations can persist?

Primates may not be the best non-human model for such questions. Some domesticates have undergone social changes as great as humans, with strong selection against individuals who buck their human masters. But for many wild primates we may reasonably wonder, to what extent are social dynamics constrained by mental adaptations, and how quickly can mental lives shift under selection to fit a new social system?