Someone called my attention to a short post about evolutionary psychology at Pharyngula:

Well, ignoring the obligatory and customary reference to “douchebags,” I was curious about the article that inspired this post. Clicking on the link, I found a piece at the science/tech site io9 called “The rise of the evolutionary psychology douchebag” by Annalee Newitz.

Newitz happens to be the editor-in-chief of io9, so I guess she can write anything she wants. Unfortunately, she decided to take on evolutionary psychology. That was a mistake. Her post is godawful: a combination of tarring evolutionary psychology with a few ad hominems that have nothing to do with the field as a whole, and then a poorly informed argument for the impossibility of studying the evolutionary roots of human behavior.

Let me first give a disclaimer. I’ve been a critic of evolutionary psychology, particularly some of its earliest excesses, and attracted some attention with my two published and highly critical reviews (one co-authored with Andrew Berry) of Palmer and Thornhill’s dubious theory that the human brain contains a “rape module” prompting males to rape isolated females. That was a bad example of the genre, largely because their work was tendentious and because the authors twisted their statistics in an inappropriate way to support the supposed “adaptive” nature of rape.

But the field has moved on and improved, and has made some important advances. I’ve detailed some of these in a previous post, “Is evolutionary psychology worthless?“. These belie the claim that “The fundamental premise of evolutionary psychology is worthless.” As I’ve pointed out, that “fundamental premise” is only this: “the human brain, like the human body, still shows traces of its evolutionary ancestry.” Disputing that on principle is equivalent to disputing evolution as a whole, for it would be odd indeed if our behavior did not reflect at least some of the selective pressures that molded it during the 6 million years of hominin evolution preceding the rise of civilization. Evolutionary psychology shows enormous promise for helping understand where we came from.

That said, there is of course still a bad strain in the field, one mainly seized upon by the popular press, which loves stories about how this or that behavior reflects our ancient evolutionary history. And some evolutionary psychologists, like Satoshi Kanazawa, have catered to this appetite, eroding their credibility in the process. But dismissing an entire field because of a few miscreants is a serious mistake, for it waves away the possibility that we can really learn something about what evolutionary forces molded our behavior. It’s like dismissing evolutionary morphology in humans because, after all, how could it be possible that modern bodies reflect ancient selection pressures? Remember, brains are part of our body.

Nevertheless, Newitz wants to brush aside the whole field as fatally flawed. Her reasons are fatuous:

1. Two evolutionary psychologists committed fraud. As she notes:

Evolutionary psychology has often been a field whose most prominent practitioners get embroiled in controversy — witness the 2010 case of Harvard professor Marc Hauser, whose graduate students came forward to say he’d been faking evidence for years. Then there was the case of Diederik Stapel, whose social psychology work shared a lot of territory with evopsych. He came forward in late 2011 to admit that most of his data was sheer invention.

I don’t know much about the story of Stapel, but I do know about the Hauser tale, and the fact is that he was caught by fellow evolutionary psychologists, who (like Frans de Waal) called him out for his misdeeds.

But this is just dumb, for scientists in many other fields have committed fraud as well. It’s like dismissing molecular biology because at least a dozen practitioners have committed fraud. Newitz is simply smearing a field for bad reasons—probably ideological ones.

2. One evolutionary psychologist made a stupid remark on Twitter. That was Geoffrey Miller from the University of New Mexico, who made this misguided tweet that Newitz reproduces:

Yep, that was stupid, and Miller was rightfully called out on it. But what on earth does it have to do with evolutionary psychology? Nothing. Newitz is making a purely ad hominem argument here. If one stupid remark by a scientist is sufficient to denigrate a field, then the entirety of science should be discarded. Newitz also notes that Miller has published some other hypotheses that seem bizarre, and I’ll agree with her here: sometimes I think Miller speculates far beyond the bounds of data, as he did in his book The Mating Mind. But that doesn’t mean that human thoughts and behaviors weren’t molded in part by sexual selection. Lots of scientists toss out bizarre hypotheses (Bill Hamilton in evolutionary biology was one of these), but sometimes they turn out to be correct.

Regardless, it’s journalistically irresponsible to smear a field the way Newitz has done. So let’s get to her only “substantive” argument against evolutionary psychology:

3. Humans evolve too fast to bear behavioral traces of ancient evolution.

This is all part of [Miller’s] and many other evopsych researchers’ project to prove that humans haven’t changed much since we were roaming east Africa 100,000 years ago. Evolutionary biology researchers like Marlene Zuk have explored some the scientific problems with this idea. Most notably, humans have continued to evolve quite a lot over the past ten thousand years, and certainly over 100 thousand. Sure, our biology affects our behavior. But it’s unlikely that humans’ early evolution is deeply relevant to contemporary psychological questions about dating, or the willpower to complete a dissertation. Even Steven Pinker, one of evopsych’s biggest proponents, has said that humans continue to evolve and that our behavior is changing over time. But the classic evopsych douchebag, like Miller, absolutely wants to believe that humans are still in thrall to the same psychological forces that shaped our behavior much earlier in Homo sapiens evolution.

This is not only disingenuous, but reflects Newitz’s ignorance of evolution.

First of all, no evolutionary psychologist claims that human behavior hasn’t evolved at all since we roamed the savannas. Indeed, Pinker has pointed that out, and I can give my own examples. Within the last 10,000 years, for example, pastoral populations—those that raise sheep, goats, or cows for milk—have evolved a tolerance for lactose, for animal milk provides a valuable source of nutrition. They’ve achieved this by simply accruing mutations that keep the “lactase” enzyme turned on, an enzyme that is usually inactivated after humans finish weaning. Genetic analysis shows, too, that this inactivation occurred within the last 10,000 years. So if you consider “milk drinking as an adult” as a behavioral trait (which it is, militated by our physiological tolerance for milk), then yes, it’s evolved recently. And surely other traits have, too. But remember that lactose intolerance is a behavior that many humans frequently show, and one that is an evolutionary holdover from our past—a time when milk was available only to babies from their mother’s breasts, and when it was probably disadvantageous to produce an enzyme beyond the time when it was needed. Anybody who is lactose intolerant and avoids milk, then, is showing a behavior that is an evolutionary holdover from our ancestors.

Our penchant for fats and sweets can be seen the same way. It’s certainly not good for us—at least those of us who live in carb- and fat-laden cultures—but we still crave that stuff. This is an evolutionary holdover from a time when fat and sugar were valuable resources. Contra Newitz, this behavior almost certainly does reflect the deep relevance of early evolution to contemporary behavior.

The fact is that we diverged from our common ancestor with chimps about 6,000,000 years ago, but “civilization” with its novel selective pressures has been around only 20,000 years. That’s only 0.3% of the total time encompassed by our lineage. If one estimates, say, 20 years per generation, that’s about 1000 generations of human evolution: an eyeblink compared to the three hundred thousand generations in which we experienced selection within small bands of hunters and gatherers. Do we really expect that one thousand generations will completely efface behaviors evolved during 99.7% of the duration of the hominin lineage?

One way to answer this question is to look at whether we retain morphological traits that are holdovers from our “early evolution.” If that’s the case, then one can infer that we probably still show behavioral holdovers from our past as well. And the answer here is unequivocal. Here are some morphological traits no longer seem adaptive but haven’t yet evolved away, or can’t because of evolutionary constraints.

wisdom teeth

bad backs

fetal yolk sacks (which are empty)

our tailbone

goosebumps (adaptive in our relatives for erecting hairs)

skin fold at the corner of our eye (remnant of nictitating membrane)

I could go on, but the point is that these morphological traits are not useful (some are positively harmful), but persist as evolutionary remnants.

Why shouldn’t behavior be the same? After all, evolved behaviors actually reflect evolved morphology: morphological and developmental patterns of our brain’s wiring. Here are a couple of behavioral traits that, I think, reflect our deep evolutionary past:

Higher variance in male than in female reproductive success due to differential behavior of the sexes



Weaning conflict between mothers and their infants



Preference for relatives over nonrelatives (kin selection), and xenophobia (useful for when we lived in small groups)



Fear of spiders and snakes

Some of these can in principle be tested: for example one could do studies to show whether the fear of spiders is innate or learned. And there are other tests as well, and also some evolutionary psychology theories that have been falsified.

It’s simply nonsense to dismiss the field on the grounds that there’s no way that human behavior could show traces of its deep evolutionary past. We already know that some behaviors apparently show such traces, and morphology certainly does. Yes, it may often be hard, or even impossible, to show with great certainty that some of our behavior reflect ancient selection pressures. But are we really going to say that evolutionary psychology is bunk?

The real reason why people like Newitz and others (that includes P. Z., I think) dismiss evolutionary psychology in toto is because they find it ideologically unpalatable: they don’t like its supposed implications. They presume that evo-psych somehow validates misogyny or the marginalization of women and minorities. They will deny this to their dying breath, of course, and pretend that it’s purely a scientific issue, citing a few anecdotal studies that are indeed laughable. But I think we know where these people are coming from. Evolutionary biology itself has been used to justify racism or the sterilization of supposedly “defective” humans, but we don’t dismiss evolutionary biology because of that. Likewise, we shouldn’t dismiss evolutionary psychology just because some cranks draw “oughts” from “is”s.

When you read a statement like this:

“Developmental plasticity is all. The fundamental premises of evo psych are false”,

then you know you are dealing with ideology rather than science. The fundamental premise of evolutionary psychology is simply that some modern human behaviors reflect an ancient evolutionary history. It would be odd if that were completely false. And developmental plasticity is not all. If that were the case, then why do we still have wisdom teeth and bad backs?