I have disturbed and distressed Jerry Coyne, because I have dissed the entire field of evolutionary psychology. I find this very peculiar, because in my field, Jerry Coyne has a reputation for dissing all of evo devo, so it can’t possibly be that we’re supposed to automatically respect every broad scientific endeavor. There has to be something more to it than just an academic defense of a discipline. And there is, unfortunately. Here’s his prelude.

I’ve been known for a while as a critic of evolutionary psychology, particularly when it first began as “sociobiology” in the Seventies. At that time there was a lot of unsupported speculation being bruited about as “science” (i.e., human males evolved to have “rape modules”, a view that I criticized strongly). But over the decades, evolutionary psychology has matured, and I now see it as a valuable way of studying the origins of human behavior. Not that it’s all perfect—the “pop” versions, such as those produced by Satoshi Kanazawa, seem pretty dire to me, debasing a field that’s striving for scientific rigor. But even Kanazawa has been rejected by serious evolutionary psychologists.

Sadly, some self-professed skeptics have decided to debunk the entire field of evo-psych, and for reasons that I see not as scientific, but as ideological and political. That is, like the opponents of sociobiology thirty years ago, these skeptics object to the discipline because they see it as both motivated by and justifying conservative political views like the marginalization of women. Well, that may be the motivation of some people, but not, I think, of most well-known workers in evo psych, who are merely trying to study the evolutionary roots of human behavior. It pains me that skeptics are so dogmatic, so ideological, in viewing (and rejecting wholesale) a legitimate scientific field.

That second paragraph? Pure ad hominem, unsupported by evidence. I detest evolutionary psychology, not because I dislike the answers it gives, but on purely methodological and empirical grounds: it is a grandiose exercise in leaping to conclusions on inadequate evidence, it is built on premises that simply don’t work, and it’s a field that seems to do a very poor job of training and policing its practitioners, so that it primarily serves as a dump for bad research that then supplies tabloids with a feast of garbage science that discredits the rest of us. I’d like to see the evolutionary psychologists who propose that there is a high quality core to their discipline spending more effort ripping into their less savory colleagues than on the indignant sniffing at critics of evolutionary psychology. I’d have more respect for the field if there was more principled internal striving.

There is also a tactic I really dislike; I call it the Dignified Retreat. When criticized, evolutionary psychologists love to run away from their discipline and hide in the safer confines of more solidly founded ideas. Here’s a perfect example:

…the notion that “the fundamental premises of evo psych are false” seems deeply misguided. After all, those premises boil down to this statement: some behaviors of modern humans reflect their evolutionary history. That is palpably uncontroversial, since many of our behaviors are clearly a product of evolution, including eating, avoiding dangers, and the pursuit of sex. And since our bodies reflect their evolutionary history, often in nonadaptive ways (e.g., wisdom teeth, bad backs, the coat of hair we produce as a transitory feature in fetuses), why not our brains, which are, after all, just bits of morphology whose structure affects our behaviors?

You know what? I agree entirely with that. The brain is a material product of evolution, and behavior is a product of the brain. There are natural causes for everything all the way down. And further, I have great respect for psychology, evolutionary biology, ethology, physiology, anthropology, anatomy, comparative biology — and I consider all of those disciplines to have strong integrative ties to evolutionary biology. Does Coyne really believe that I am critiquing the evolved nature of the human brain? Because otherwise, this is a completely irrelevant statement.

Evolutionary psychology has its own special methodology and logic, and that’s what I criticize — not anthropology or evolutionary biology or whatever. Somehow these unique properties get conveniently jettisoned whenever a critic wanders by, only to be re-adopted without reservation within the exercise of the discipline. And that’s really annoying.

What I object to in evolutionary psychology is that their stock in trade is to make observations of behavior in a single species, often in a single population, and then to infer an evolutionary history from that data point. You don’t get to do that. It’s not that the observations are invalid (they’re often interesting in their own right), or that it’s not possible that human behaviors carry a strong genetic component — it’s that you simply can’t draw an evolutionary conclusion from the simple existence of a trait in a population. Yet evolutionary psychologists do, all the time.

I had a second objection that Coyne briefly addresses: developmental and neuroplasticity obscure the genetic basis of behaviors.

… “developmental plasticity” does not stand as a dichotomous alternative to “evolved features.” Our developmental plasticity is to a large extent the product of evolution: our ability to learn language, our tendency to defer to authorities when we’re children, our learned socialization—those are all features almost certainly instilled into our brains by natural selection as a way to promote behavioral flexibility in that most flexible of mammals.

That’s a cop-out. Yes, developmental plasticity is an evolved property, but to study it, you study development. Not psychology. It’s a different level of the problem.

The reason plasticity is a serious (and far too ignored) issue for evolutionary psychology is that if you’re trying to identify a genetic basis for a specific behavior, it represents a huge amount of confounding noise. It’s HARD WORK to isolate the genetic core of a behavior (assuming there is one) from the learned properties of the organism.

For instance, I’m really interested in the behaviors of zebrafish, and one of the things I’ve done is tried to identify different behaviors in different lines of fish — they exist, and it would be really cool to identify alleles involved in the differences. Feeding behaviors, for instance, vary in different lines. One line may carry out what we think are wild-type patterns: they feed by darting to the surface, carrying the food down to the bottom, and gulping it down there. Another may indulge in stupid lab-bred behaviors: wallowing at the surface, chowing down on floating flakes — something that would get them eaten quickly by birds in the wild.

It turns out to be really hard to maintain that behavior in the lab. Raising fry to adults is actually a wonderful exercise in selection (wallowing babies get lots of food, cautious babies get less) and training. We really had to struggle to develop feeding regimens that were neutral to the behavior we wanted to study. That’s why plasticity is such an important factor in these kinds of studies — it’s really, really, really hard to separate learned behavior from genetically predisposed behavior. It demands a huge amount of rigor and all kinds of controls — the kinds of things you simply cannot do with humans.

Again, this is not to say that one can’t do good psychology. What I’m saying is that taking that next huge step of linking behavior to genes to evolution demands data and methods that are not present in our toolbox right now, making most of the claims of evo psych fallacious.

In our presentation at Convergence, Greg Laden mentioned being present at early seminars by Cosmides and Tooby in which they laid out their goals. They drew a big box and in one top corner, they wrote “behavior”; in a lower corner, they put “genes”. The idea was that this field would strive to connect the two words together — which I consider a wonderful goal and something I’d like to see, too. Unfortunately, the space between the two words is filled with handwaving right now. I’m much more respectful of science that tries to incrementally bring the two together, but evolutionary psychology prematurely tries to stitch them together with transparent guesswork. That’s not science.

Coyne closes with a couple more ad hominems.

One gets two impressions when listening to the skeptics’ criticism of evolutionary psychology. First, they haven’t read widely in the discipline, and are criticizing either pop-culture versions of the field or a caricature (born of ignorance, possibly willful) of EP. Even I know that EP advocates don’t often publish studies that rely solely on undergraduates.

As I mentioned, I’m very interested in the connection between genes and behavior — I’ve actually read quite a bit in this field. I’ve also read a fair amount of the evolutionary psychology literature, and the source of my animus is that in comparison to good science on the biological basis of behavior, it suffers abominably. It doesn’t even come close to evolutionary biology (my own work is more genetics and brain development, and I’ll be the first to tell you that work on lab-bred zebrafish is a piss-poor way to do evolution…so I find it particularly appalling to see human psychology touted as evolutionary).

As for the claim that EP doesn’t often publish studies solely on undergraduates — it’s worse. Stephanie Zvan looked at recent publications in the journal Evolutionary Psychology.

How many of these studies were done only using college students? More than half. In 33 studies, the population whose preferences were used as a proxy for human universals was a population of college students. Another six studies used a combination of college students and other populations. One of these additional study populations was young, educated Israeli adults. Two were populations from around the university attended by the student populations.

Other university town populations were used on their own, without student populations, but many of the studies that did not use college students could not. Studies of blind dates, cyclists, criminals, pregnant women, sleep deprivation, parents of premature babies, younger children, soccer referees, musicians, and severely disabled people all drew from specialized populations.

More striking than the use of college students, however, was the geographic restriction on the populations used. Out of 60 studies, 51 drew their samples entirely from the U.S., Canada, and Europe. The exceptions were (mostly students) from Japan, Singapore, China, Israel, World Cup countries, St. Kitts, Mexico, historical records from around the world, and an international sample drawn from Amazon’s Mechanical Turk. While not all the samples were “Western” (in the odd, non-directional meaning that word has accrued), only those last four–7% of the total–were distinctly non-WEIRD.

Ooops. Really, look over the papers — they’re already restricted to one species, and it’s an exceptional work that even tries to reach out to different subpopulations. The study of the genetic basis of behavior is an extraordinarily complex problem, and I don’t see any adequate efforts being made to constrain the variables; and once you’ve got a genetic basis, identifying an evolutionary history for that is yet another non-trivial problem.

And then we get the ideology-bashing again.

Second, it’s pretty clear that the opposition to evolutionary psychology from these quarters is ideologically rather than scientifically motivated. One gets the feeling that research on gender differences shouldn’t be done at all because it’s either designed to repress women, motivated by the desire to do that, or has the likely outcome of promoting discrimination. Well, sexist scientists may try to do that, but I haven’t seen much of that since the Seventies. And gender differences are fascinating. There’s a reason, for instance, why human males are larger and hairier than females, and have more testosterone. Are we supposed to say “You can’t work on that—could have bad repercussions!” Sure, scientific results can always be misused, but I don’t see that as a reason to put up roadblocks against scientific research. After all, what field is more misused and misquoted than evolutionary biology? I am a frequent recipient of emails from Jews trying to convince me to reject evolution because Darwin ultimately caused the Holocaust.

Please. Have I ever said that we shouldn’t study gender or racial differences? No. We know there are going to be differences. The catch is that they have to be studied very, very well, with rigor and careful analysis, because they are socially loaded and because science has a deeply deplorable history of using poor methods to reach bad conclusions that are used as ideological props for the status quo. I’m not putting up roadblocks against scientific research; I would like to put up roadblocks to sloppy, lazy ideological nonsense touted as scientific research. I should think every scientist would want that.

To return to Coyne’s prior criticism of evo devo: that’s exactly what I appreciated about it. He took a strong stance, demanding hard evidence to support evo devo’s claims of the importance of regulatory mutations in evolution. And he was right to do so! If you’re going to make claims about genes and evolution, you had better be prepared to show the supporting evidence at all levels of the problem. I’m not sure why he’s gotten more soft on the demand for rigor from evolutionary psychology when he was far more demanding on evo devo.

Maybe it was ideology.

And this is just silly.

…the fundamental premise of evolutionary psychology is absolutely sound: our brains, like the rest of our bodies, are the product of evolution and natural selection over the past six million years, and some of our current behaviors reflect that evolution. To deny that is ideologically motivated nonsense. To parse out the evolutionary component of such behaviors is the goal of evolutionary psychology.

That’s another Dignified Retreat. Evolutionary Psychology is not synonymous with Evolutionary Biology. I can reject bad science in the form of evolutionary and genetical claims about behavior; it does not imply that I think evolution played no role in our brains.

Coyne has a long section where he solicited responses from Steven Pinker, as well. This is long enough so I’ll defer that for a different day, but I did note that there’s a lot of this ideological ad hominem in there, too, and some of it is even contradictory!