This idea has been drifting around in my head for a while now. I recently went to a talk that helped me solidify what I wanted to say about it. Here goes.
Everyone loves to hate evolutionary psychology, particularly the sometimes-garbled versions that make the headlines*. And it’s not just because these headlines sometimes (often) emphasize gender or (less often) racial stereotypes that reasonable people find repellent. There is often genuinely bad science involved, and I think it’s the responsibility of the scientific community to call this out. Now, that’s not the point of this post.
The point is that bad science is often better for advancing a field than good science. Bad science should make us re-check our methods and re-think our reasoning to make doubly sure we’re not doing exactly what we’ve called out. Because sometimes we’re more likely to call out bad science involving humans, because it produces such a distasteful result (sex differences in fruit flies, not a big deal; sex differences in humans, irritating at best, fodder for the patriarchy at worst).
Let’s talk specifically about the kinds of bad science we encounter with so much “pop” evolutionary psych. There are the methodologically questionable forced-choice questionnaires, the “Stone Age brain” assumption, the framing that presumes contemporary Western stereotypes. Now, I’m not going to critique methodology, because I’m not equipped to do it. But I am equipped to criticize some of the assumptions about evolution that go into the framing of the research and subsequent interpretation. What they all boil down to is adaptationism: the search for adaptive stories to explain whatever trait you’re confronted with.** The problem with searching for adaptive stories is that one becomes less likely to consider that the trait in question might not be adaptive at all. Adaptationism tends to become an assumption that what you see got there by adaptation—you just have to explain what it was an adaptation to.
Till very recently I thought that it didn’t exist in such a crude form among pop psychologists, that it was more nuanced; I though that most biologists/psychologists/sociologists/anthropologists accused of believing all traits must be adaptive would vehemently deny it. But on Monday I actually heard a respected anthropologist say it. He said “We can assume traits evolved through adaptation” and that “this assumption is controversial for humans” but “not for other organisms”. (I paraphrase only a little.)
Is this assumption controversial for other organisms? Let’s say it’s controversial in the sense that intelligent design is controversial. That is, there’s no controversy and it’s the other story that’s right. I think most biologists, if they thought about it, would say that it’s best to assume that a trait is not adaptive, and then rule out as many nonadaptive possibilities as you can while you test your adaptive alternative hypothesis.
The crucial bit here is ruling out the nonadaptive possibilities. Not just testing the null hypothesis of non-adaptation against an alternate hypothesis of adaptation. You may rule out drift and phylogenetic inertia, but have you considered allometry? For that matter, have you considered all the plausible adaptive hypotheses? Maybe it’s not sexual selection at all that made your birds sing but confusing predators. Maybe the trait you’re looking at is correlated with something else that’s under selection.
My point is not that evolutionary biologists are getting sloppy about adaptationism. It’s that good scientists hold evolutionary psychology to a high standard, and we should make sure we hold ourselves to that same standard. It never hurts to be reminded.
*Let’s get this out of the way: yes, there is a good way to do evolutionary psychology. It’s entirely reasonable to think that human cognition and behaviour has evolved. But not all approaches to the problem are equal. In the end, the catchphrasiest studies make the headlines, and they’re also the ones that commit the misdemeanors I discuss the most often.
**And thus, I firmly entrench myself on one side of an ugly and ongoing debate.