Thursday, June 25, 2009

my kind of inspiring science news

As a romantic, I've always despised evolutionary psychology. It feels too much like an atheist's form of original sin: we behave badly because bad behavior helped our ancestors survive. I understand why its adherents like it: it explains everything. People are consoled by belief systems that explain everything.

But I'm really glad human behavioral ecology is the next step in understanding what we are. A few excerpts from a fascinating article, Can We Blame Our Bad Behavior on Stone-Age Genes?
Hill had something almost as good as a time machine. He had the Ache, who live much as humans did 100,000 years ago. He and two colleagues therefore calculated how rape would affect the evolutionary prospects of a 25-year-old Ache. (They didn't observe any rapes, but did a what-if calculation based on measurements of, for instance, the odds that a woman is able to conceive on any given day.) The scientists were generous to the rape-as-adaptation claim, assuming that rapists target only women of reproductive age, for instance, even though in reality girls younger than 10 and women over 60 are often victims. Then they calculated rape's fitness costs and benefits. Rape costs a man fitness points if the victim's husband or other relatives kill him, for instance. He loses fitness points, too, if the mother refuses to raise a child of rape, and if being a known rapist (in a small hunter-gatherer tribe, rape and rapists are public knowledge) makes others less likely to help him find food. Rape increases a man's evolutionary fitness based on the chance that a rape victim is fertile (15 percent), that she will conceive (a 7 percent chance), that she will not miscarry (90 percent) and that she will not let the baby die even though it is the child of rape (90 percent). Hill then ran the numbers on the reproductive costs and benefits of rape. It wasn't even close: the cost exceeds the benefit by a factor of 10. "That makes the likelihood that rape is an evolved adaptation extremely low," says Hill. "It just wouldn't have made sense for men in the Pleistocene to use rape as a reproductive strategy, so the argument that it's preprogrammed into us doesn't hold up."
...If the environment, including the social environment, is instead dynamic rather than static—which all evidence suggests—then the only kind of mind that makes humans evolutionarily fit is one that is flexible and responsive, able to figure out a way to make trade-offs, survive, thrive and reproduce in whatever social and physical environment it finds itself in.
...Called behavioral ecology, it starts from the premise that social and environmental forces select for various behaviors that optimize people's fitness in a given environment. Different environment, different behaviors—and different human "natures." That's why men prefer Ms. 36-25-36 in some cultures (where women are, to exaggerate only a bit, decorative objects) but not others (where women bring home salaries or food they've gathered in the jungle).