Pharyngula

I have annoyed Jesse Bering

That’s what I do, after all. I strongly criticized his uncritical analysis of a set of rape-related evolutionary psychology studies, and now he responds with a rebuttal. It’s not a very good rebuttal, but I highly recommend his second paragraph in which he lists a good collection of links to several people who also ripped into his article. That part is excellent!

But then let’s get into the part where he argues with me.

P.Z. Myers is not, of course, the undisputed public ambassador of his discipline (although I’ve no doubt he sees himself as such), and by no means does the following apply to all biologists, or even all those who are critical of evolutionary psychology. But Myers’ affect-laden views regarding evolutionary psychology do represent those of at least a significant and vocal minority.

Not an auspicious start to accuse me of regarding myself as “the undisputed public ambassador of” biology, which certainly isn’t the case. This is a blog written by a professor in a small town in rural Minnesota. I’m kind of aware of exactly what it is, and lack the airs Bering wants to assign to me. But then, this isn’t surprising, since most of his following arguments rely on telling me what I intended, and he also gets that wrong. Except this little bit, where he does get the overall objections right.

Critics are particularly irritated by the fact that evolutionary psychologists do not test for genetic inheritance of the very traits they argue are adaptive but instead rely on behavioral or self-report measures to evaluate their theories. They also believe that evolutionary psychologists take too many story-telling liberties in reconstructing the ancestral past, since we can never know for certain what life was like hundreds of thousands of years ago, when such traits would have, theoretically, been favored by natural selection. (This is a point also stressed by Rennie in his critique of my Slate essay.) According to Myers, the whole messy endeavor, therefore, “is a teetering pyramid of stacked ‘couldas’ and guesses that it woulda had an influence on evolution.”

This is actually a reasonable summary of my general disagreements with evolutionary psychology. They are quite fond of inventing evolutionary stories about phenomena that don’t even have an iota of evidence for being genetic, and can come up with truly awesome causal accounts for even the most trivial observations.

He picks out one of my objections to argue why the evolutionary psychology crowd can’t do one of the experiments I didn’t suggest doing, which is a little odd, but OK.

In his post, Myers uses my discussion of the evolution of the human penis as a prime example of the sloppy work being done in the study of evolution and human behavior. He pillories psychologist Gordon Gallup’s famous “dildo study,” which suggests that the distinctive mushroom-capped shape of the penis might serve to scoop a competitor’s semen out of the vagina. (I described this work at long, intimate length in two prior articles in Scientific American.) Myers calls this penis study “tripe” because Gallup and his colleagues failed to show how variations in penis shape within a population–and variations in how the penis is used for coital thrusting–directly affect fertilization rates. Instead, the researchers relied on dildos of different designs, surveys of college students’ detailing their sexual behaviors, and a batch of artificial semen.

Now, I can only assume that Myers has not had to face a university human-research ethics committee in the past several decades. If he had, he would realize that his suggested empirical approach would be unilaterally rejected by these conservative bureaucratic gatekeepers. Does Myers really believe that these seasoned investigators wouldn’t rather have done the full experiment he describes–if only they lived in a less prudish and libellous university world? The fact of the matter is that research psychologists studying human sexuality are hamstrung by necessary ethical constraints when designing their studies. Perhaps Myers would be happy enough to allow investigators into his bedroom to examine the precise depth and vigor to which he plunges into his wife’s vaginal canal after they’ve been separated for a week, but most couples would be a tad more reticent. Gallup’s dildo study, and his related work on penis evolution, offered an ingenious–ingenious–way to get around some very real practical and ethical limitations. Is it perfect? No. Again, the perfect study, conceptually speaking, is often the least ethical one, at least as deemed by research ethics committees. But was it driven by clear, testable, evolutionary hypotheses? Yes. And it offered useful information that was otherwise unknown.

Telling me that they can’t do an experiment that I didn’t suggest doing doesn’t really undermine anything I said. I’m perfectly aware of the ethical limitations of human research, which is one reason why I work on animal models. The problem is that what I actually offered as shortcomings of the work wasn’t their failure to wire up my genitals, but this:

They don’t have any evidence that this behavior actually affects the fertilization rate of one partner’s sperm over another, they don’t have any indication of morphological differences in human populations that make some individuals better semen-scoopers, they don’t have any evidence that this behavior has had a differential effect in human history.

Those are the criteria I would expect to see met in order to discuss this issue as an evolutionary problem; what Bering’s sources were studying were mechanical and physiological aspects of some plumbing (which can be interesting!), and then tacking on unwarranted conclusions about evolutionary history. In fact, I don’t see how Bering’s strange and unexecutable experiment of logging the details of my personal sexual behavior would even touch my evolutionary objections.

He also skips over another relevant point I emphasized. I read the research papers he cited. These were studies that had him “riveted, and convinced”, but when I looked at, for instance, the study that found an increase in women’s handgrip strength during ovulation, the paper itself mentioned that there were many other studies that showed no variation in strength over the menstrual cycle. Which is it? Do you just pick the result that favors your interpretation?

Jerry Coyne has a summary of reactions, too, and mentions several instances where the papers aren’t as clear in their support of the evo-psych hypotheses as is claimed. These are very noisy data that sometimes support and sometimes contradict their claims, and it seems that whatever result they pluck out of the mess, it’s always in support of some purported evolutionarily significant effect on behavior or physiology.

As I said in my previous article, I think the general claim of evolutionary psychology, that our current behavior has been shaped by our biological history, is true. I think much of the research in the field is damaging to their thesis, though, not because it demonstrates the opposite, but because it flits over tiny details, like monthly variations in how a woman moves her hips or how she feels about men, and pretends that they’re all examples of the power of natural selection in sculpting a genome that encodes every pelvic wobble and every nerve impulse. It’s become a kind of modern ornithomancy, where each dip and swirl and change in direction of a flight of birds is interpreted as directly connected to the fate of nations. I remain unconvinced.