I’ve been on a bit of tear about EvoPsych recently, haven’t I? While you might think that’s just because I’m a feminist, and therefore opposed to the subject on principle, my beef has less to do with brute tribalism than brute facts. For instance, many if not most studies have poor controls and fail to look for confounding factors.

Everyone has always assumed — and early research had shown — that women desired fewer sexual partners over a lifetime than men. But in 2003, two behavioral psychologists, Michele G. Alexander and Terri D. Fisher, published the results of a study that used a “bogus pipeline” — a fake lie detector. When asked about actual sexual partners, rather than just theoretical desires, the participants who were not attached to the fake lie detector displayed typical gender differences. Men reported having had more sexual partners than women. But when participants believed that lies about their sexual history would be revealed by the fake lie detector, gender differences in reported sexual partners vanished. In fact, women reported slightly more sexual partners (a mean of 4.4) than did men (a mean of 4.0).

In 2009, another long-assumed gender difference in mating — that women are choosier than men — also came under siege. In speed dating, as in life, the social norm instructs women to sit in one place, waiting to be approached, while the men rotate tables. But in one study of speed-dating behavior, the evolutionary psychologists Eli J. Finkel and Paul W. Eastwick switched the “rotator” role. The men remained seated and the women rotated. By manipulating this component of the gender script, the researchers discovered that women became less selective — they behaved more like stereotypical men — while men were more selective and behaved more like stereotypical women. The mere act of physically approaching a potential romantic partner, they argued, engendered more favorable assessments of that person.

Another problem is way too much emphasis on adaptation, and not enough on chance.

You have to consider chance as far more important, and far more likely to produced elaborations.

Do these phenomena operate in the real world, rather than just hypothetical scenarios? Yes. For example, look at the globin genes. These are found in two clusters, an α cluster with seven genes (including two pseudogenes) and a β cluster with five genes. All the genes are related and similar and function — these are all proteins with heme and oxygen-carrying functions — where each gene has slightly different functions (one may have a higher affinity for oxygen than another) and patterns of expression (one may be expressed at a different stage of development than another, or in a different range of tissues), and we can see specific functional adaptations for each, but their origin has to be in a selectively neutral condition.

A fetal hemoglobin with a high affinity for oxygen is an adaptation when expressed in a fetus, but detrimental when expressed in a pregnant woman (it wouldn’t share oxygen as readily with the fetus). The selective advantage could only arise after the different globins had evolved, and when differential gene expression mechanisms had been coupled to them to assure that they would only be expressed under appropriate conditions. The origin was not a selection event, but the refinement to specific roles probably was.

Also, they assume adaptation has infinite power, and can work against even the slightest disadvantage or promote the faintest advantage. Not so.

Being unable to discriminate differences in a particular range of wavelengths is a disadvantage — probably a very small one, but it’s clear that having trichromatic vision swept to near-fixation in old world monkeys and apes fairly rapidly, and fairly thoroughly…and not having it is a step backwards. So why hasn’t natural selection culled it from our populations? This isn’t a recent innovation that hasn’t had time to be corrected; trichromacy arose sometime after the split between the old and new world monkeys, 30-40 million years ago. It’s X-linked in those other primates, too. Shouldn’t this defective allele have been long gone from the primates?

No, and there’s a simple explanation: color blindness is a defect that’s below the threshold for a strong selection pressure to work against it (all you colorblind readers can heave a sigh of relief—Nature isn’t going to come gunning for you).

And if color-blindness is invisible to selection, I’m going to be pretty damned skeptical when an evolutionary psychologist tries to tell me that girls’ fondness for pink colors is or was a functional adaptation: a product of a 100,000 years of natural selection. It’s not impossible that pink preference could confer a benefit, but the idea that a pink preference was so strongly selected for that we can infer that it must have had a selective advantage is so unlikely that it can be dismissed as totally bogus, in the absence of exceptionally strong evidence for such an improbable circumstance.

And finally, it argues against plasticity in behavior and pretends we aren’t a big-brained social species.

the word “evolutionary” is doing a bit more work here than it may seem at first blush.  Indeed, the word seems to encode, in this context, a series of propositions that most people actually working in human evolution believe to be false, if not ridiculous.  Foundationally, where students of human evolution have generally emphasized the adaptability of the human mind, evolutionary psychologists have rather attempted to call attention to the adaptedness of the human mind.

From these opposed starting points, other divergences quickly accumulate. For example, the idea that there is an instinctual  “human nature” that is analytically separable from human culture.  Whether or not you believe it, the idea has far stronger roots in Aristotle than in Darwin. But what our knowledge of human evolution tells us is that even our most fundamental evolutionary instincts, walking and talking, are  also learned and highly cultural.  Moreover, any familiarity with the history of the subject can show that assertions about “human nature” have a great deal of political valence.  They consequently must endure high degrees of scrutiny to be taken seriously; the propositions that regularly emerge from evolutionary psychology tend to wither under the merest criticism.

As someone who’s read the above, as well as studies by David Buss and other proponents, I’m forced to conclude the vast majority of it is rank pseudo-science.

Ultimately, the biggest problem with EP may be that it underestimates the power of evolutionary forces—both to tinker continually with the human brain, and to have created ingenious and flexible problem-solving structures in the first place. There’s a nice irony here, since for years EP-ers have ridiculed opponents for not appreciating evolutionary theory’s core tenets. Buller goes so far as to note an eerie resemblance between EP and intelligent design, which also treats human nature as fixed and complete.