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.

Because of this ideologically-motivated critique, last December I published a defense of the field, “Is evolutionary psychology worthless?“, pointing out a dozen areas of evo-psych research—most of them not involving gender differences—that I saw as valuable, interesting, and productive.

Nevertheless, the dissing of evo-psych by skeptics continues. The latest critique occurred at the Convergence 2013 conference on a panel described in a post by P. Z. Myers at Pharyngula:

First panel: Evolutionary Psychology, with Stephanie Zvan moderating, and Greg Laden (a biological anthropologist), me (neuroscience by training, evo devo by occupation), and Indre Viskontas (neuroscience) (and who I met for the first time, and who was on a panel at an SF con for the first time…she’s good). My main point: Developmental plasticity is all. The fundamental premises of evo psych are false.

This paragraph disturbed me for two reasons. First, 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?

Second, “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.

I haven’t listened to the entire Convergence panel because the audio is apparently quite bad, but I was distressed by the comments P.Z. made in the ensuing discussion, in which he expands his reasons for rejecting evolutionary psychology. I sent P.Z.’s post and comments to my friend Steve Pinker, whose books have engaged quite deeply with evolutionary psychology, to get his reaction. Steve sent me an email with his responses, and then gave me permission to publish them. (I add the caveat, at Steve’s request, that this was an informal email, and he’s not to be held responsible for slips of grammar or punctuation!)

I post P. Z.’s comments (with links) below in italics (and an “M”), and Steve’s responses in bold type (with a “P”)

A comment P. Z. made in the ensuing discussion:

M: Fundamental assumptions of evo psych: That you can infer an adaptive history from the distribution of current traits — that they are adaptations at all is an assumption usually not founded in evidence (this is not to deny that that there are features that are clearly the product of selection, but that you can’t pick an arbitrary attribute and draw elaborate scenarios for its origins). . . P: Of course “arbitrary” and “elaborate” are the straw-man giveaways here. What about carefully selected attributes, and minimal assumptions about phylogeny with a focus on function, as we do for other organs? You can ask what the spleen is for – and it would be perverse to do physiology without asking such a question – without “drawing elaborate scenarios for its origins.” M:. . . That behavioral features that have been selected for in our history are represented by modular components in the brain – again with rare exceptions, you can’t simply assign a behavioral role to a specific spot in the brain, just as you can’t assign a behavior to a gene. P: No one in Ev Psych points to specific spots in the brain – that’s cognitive neuroscience, not evolutionary psychology. The only assumption is that there are functional circuits, in the same way that a program can be fragmented across your hard drive. M: . . . That the human brain is adapted to a particular environment, specifically the African savannah, and that we can ignore as negligible any evolutionary events in the last 10,000 years, that we can ignore the complexity of an environment most of the evo psych people have never seriously studied, and that that environment can dictate one narrow range of outcomes rather than permit millions of different possibilities. P: The savannah is a red herring – that’s just a convenient dichotomization of the relevant continuum, which is evolutionary history. A minimal commitment to “pre-modern” gives you the same conclusions. By saying that the brain could not have been biologically adapted to stable government, police, literacy, medicine, science, reliable statistics, prevalence of high-calorie food, etc., you don’t need to go back to the savannah; you just need to say that these were all relevantly recent in most people’s evolutionary history. The savannah is just a synechdoche. M: I’d also add that most evo psych studies assume a one-to-one mapping of hypothetical genes to behaviors. . .

P: Completely untrue – this was Gould’s claim in the 1970s, which confused a “gene for x” (indispensable in any evolutionary thinking, given segregation) in the sense of “increases the probability of X, averaging over environments and other genes” with “a gene for X” in the sense of “necessary and sufficient for X.” Every honest biologist invokes “gene for X” in the former sense; evolution would be impossible if there were no additive effects of genes. No one believes the latter – it’s pure straw. M [continuation of previous sentence]:. . . and never actually look at genes and for that matter, ignore most human diversity to focus on a naive typological simplicity that allows them to use undergraduate psych majors at Western universities as proxies for all of humanity” P: It’s psychologists, not evolutionary psychologists, who focus on Western undergrads –field research and citations of anthropology are vastly more common in ev psych than in non-ev-psych. PZ is engaging in prosecution here, not analysis – he’s clearly ignorant of the sociology of the fields. As for diversity – is he arguing for genetic differences among human groups, a la Herrnstein & Murray?

P.Z. then made a second comment:

M: Developmental plasticity vitiates most of the claims of evo psych. Without denying that some behaviors certainly have a strong biological basis, the differences in human behaviors are more likely to be a product of plasticity than of genetic differences. . .

P: Plasticity is just learning at the neural level, and learning is not an alternative to innate motives and learning mechanisms. Plasticity became an all-purpose fudge factor in the 1990s (just like “epigenetics” is today). But the idea that the brain is a piece of plastic molded by the environment is bad neuroscience. I reviewed neural plasticity in the chapter “The Slate’s Last Stand” in The Blank Slate, with the help of many colleagues in neuroscience, and noted that the plasticity that allows feedback during development and learning during ontogeny is superimposed on an innate matrix of neural organization. For example if you silence *all* synaptic activity in the brain of a developing mouse with knock-outs, the brain is pretty much normal. M: . . . I think good evo psych would focus on human universals (much more likely to be driven by genetic properties!) than all this stuff seeking justifications for cultural differences between the sexes or the races or arbitrary subgroups.

Steve didn’t respond to this last bit, but I did ask him to tell me what he thought were the greatest accomplishments of evolutionary psychology. This was in response to one remark (made, I think, by a panel member) that the discipline had produced no substantive accomplishments. Steve’s response:

P: On accomplishments – there are vast numbers of topics in psychology that were barely studied before EP came along, and in which you just can’t formulate sensible hypotheses without giving some thought to function – they’d include sexuality, violence, religion, beauty, play, emotions, and parenting. Even other areas, like perception and memory, have always been evolutionary in the sense that researchers had a vague idea about “function” – the difference being that common-sense is enough when it comes to seeing in 3D, whereas you need to give some more thought to function in the case of, say, beauty. For me there shouldn’t even be a field called “evolutionary psychology” for the same reason there shouldn’t be a field called “cognitive neuroscience” – you can’t understand any biological system without considering each of Tinbergen’s four levels of mechanism, development, adaptation, and phylogeny. “Ev psych” is simply the attempt to take adaptation/function seriously, just as “cog neuro” is the attempt to sharpen mechanism.

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.

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.

And the differences in sexual behavior between males and females do parallel those seen in many animals. Is that just cultural construction, or are there genes and selection pressures involved? One can surely study such things scientifically, just as one studies differences between the sexes of other mammals, without being committed to sexism. There are, after all, testable predictions involved.

No, 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.