It must be “Let’s all beat up Evo Psych” Day!

Earlier, when I was writing up that criticism of Rybicki and Stangroom, I read through that article on shopping and foraging and evolution that he had cited in defense of his views. There was something in it that drove me to distraction and made me want to find a match and light the whole paper on fire (a bit of indulgent exorcism of annoying work that is getting increasingly difficult to do; I was reading it on my iPad). It’s something that afflicts almost all of the evo-psych work on the evolution of sex differences, and it rankles. So let me try to purge my irritation in a way other than incinerating an expensive bit of electronics. Let me instead pretend to be an evolutionary psychologist.

First, let me stipulate that everything is a product of selection; that the only interesting features in human evolution are adaptive ones. This one really, really hurts, because I’m by no means a panadaptationist, and think a lot of features are far easier to explain as a product of pure chance rather than having to come up with an elaborate just-so story to rationalize them. But have no fear, I’ll return to a pluralist view at the end.

Second, the paper included this nice chart on the differences in roles in hunter-gatherer societies (it’s relevance to a paper on shopping preferences in 19 year old American college students is still in question).

I will stipulate that every single cell in that table is true. I’ll go further and stipulate that the correlation with the sexes is absolute and perfect: in all hunter-gatherer societies, women never hunt and use those hunting skills, and men never gather and use those gathering skills. I’m not an anthropologist, so that table could be totally crackers and there could be a thousand exceptions, but I’m not going to worry about it; we’re stacking the odds to favor the evo-psych hypotheses as much as possible right now.

Further, I will stipulate that many of those skills are biologically based and founded on genetically determined cognitive abilities, and that they have no overlap. That is, for instance, hunters need a theory of mind that is built on an elaborate cortical substrate in order to more efficiently predict the behavior of prey; this ability is not used by gatherers when they’re searching for tubers. Gatherers, on the other hand, need very precise sensitivities to color and nuances of shape to assist in pattern-matching while searching, abilities that hunters do not use.

I will also stipulate that these specific cognitive and perceptual abilities have no utility outside hunting or gathering. There are no social circumstances, for instance, in which these abilities might be an exaptation.

Finally, I stipulate that the circumstances that produce these adaptations are still relevant today, and that 95,000 years of human evolution in hunter-gatherer societies completely dominates and makes irrelevant the last 5,000 years of evolution in agricultural and urban societies; we can ignore any processes that might have undone prior adaptations.

Is that enough yet? Have I given enough of the store away? ‘Cause I’m really feeling a little psychic stress here, since giving up some of those premises makes me want to claw them back and stab them a few times, until they’re bleeding and dead. But I’m playing the game, let’s give evo-psych every possible advantage, and grant them every assumption they make as a default.

Now here’s the part that infuriates me when reading these sex difference papers. They almost always act as if they’re discussing two independent breeding populations facing different selection pressures.

But…

Every hunting man had a gatherer mother; every gathering woman had a hunting father.

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