In defense of evolutionary psychology, part 1: introduction and the pleistocene

Within the skeptic/atheist/rationalist internets, there seems to be a rather striking divide between folks who take for granted the basic ideas of evolutionary psychology and drop off-hand references to Steven Pinker and Cosmides and Tooby, and folks who disagree and drop off-hand references to the fact that evolutionary psychology is evil. I’m very much in the former camp–I mentioned being a big fan of Steven Pinker in my introductory post.

The two camps don’t seem to talk to each other much. Maybe that’s because this is a hard issue to even talk about, in part because of a lack of agreement on what “evolutionary psychology” even means. But if there’s any authoritative source for what evolutionary psychology is, it’s probably the anthology The Adapted Mind, edited by Jerome Barkow, Leda Cosmides, and John Tooby. And here’s how they define their project in the introduction:

The central premise of The Adapted Mind is that there is a universal human nature, but that this universality exists primarily at the level of evolved psychological mechanisms, not of expressed cultural behaviors. On this view, cultural variability is not a challenge to claims of universality, but rather data that can give one insight into the structure of the psychological mechanisms that helped generate it. A second premise is that these evolved psychological mechanisms are adaptations, constructed by natural selection over evolutionary time. A third assumption made by most of the contributors is that the evolved structure of the human mind is adapted to the way of life of Pleistocene hunter-gatherers, and not necessarily to our modem circumstances (p. 5).

I know a lot of people will object to assuming that what the editors call “psychological mechanisms” are adaptations, and I plan on dealing with that issue in a future post. But what actually sticks out at me as the weakest point in this set of three assumptions is the third assumption, about the Pleistocene. There’s a slight nod to doubts people might have about it when the editors say it’s made by “most of our contributors,” a qualification they didn’t make with the first two assumptions. Furthermore, recent studies showing an increase in the rate of human evolution (see here and here, for example) may seem to contradict this assumption.

However, if you read just a bit beyond the section I’ve quoted, I think it becomes clear that this third assumption, taken as the editors intended it, is well-motivated and compatible recent findings about the rate of human evolution since the advent of agriculture. They explain that, “it is unlikely that new complex designs—ones requiring the coordinated assembly of many novel, functionally integrated features—could evolve in so few generations,” which doesn’t rule out adapting to recent changes in subtler ways.

Similarly, they say, “If selection had constructed complex new adaptations rapidly over historical time, then populations that have been agricultural for several thousand years would differ sharply in their evolved architecture from populations that until recently practiced hunting and gathering. They do not.” Again, this doesn’t rule out subtler differences between those human populations as a result of changes in lifestyle (think ability to digest lactose).

Okay, simple issue gotten out of the way. Feel free to use this as a thread for evo psych bashing, but if you’re going to make a claim of the form “evolutionary psychology says X” or “evolutionary psychologists do Y,” tell me whose work you’re referring to. Cosmides and Tooby’s? Donald Symons’? David Buss’? Steven Pinker’s? Robert Trivers’? Geoffrey Miller’s? Whose?

  • Captain Mike

    I have no strong opinions on evo psych, because I don’t know much about it. I’m looking forward to learning more in your future posts.

    In the meantime, here’s a funny cartoon:

    http://xkcd.com/775/

  • Reginald Selkirk

    I should like to point out that the among the leading critics of Evo Psych are those with the best knowledge of biology and evolution. I am thinking of Jerry Coyne, PZ Myers and Larry Moran.

    • Reginald Selkirk

      Larry Moran quotes approvingly from a blurb for Evolutionary Psychology as Maladapted Psychology by Robert C. Richardson:

      The claims of evolutionary psychology may pass muster as psychology; but what are their evolutionary credentials? Richardson considers three ways adaptive hypotheses can be evaluated, using examples from the biological literature to illustrate what sorts of evidence and methodology would be necessary to establish specific evolutionary and adaptive explanations of human psychological traits. He shows that existing explanations within evolutionary psychology fall woefully short of accepted biological standards…

  • jamessweet

    Looking forward to this series of posts, as I don’t fall cleanly into either camp. Probably closer to the pro-EP camp, e.g. I do rather like Pinker, and I think that there is potentially a huge amount to learn from EP, if it can be done right.

    If I could list my three biggest reservations about EP, in no particular order, and apologizing in advance that I am bending your “name names” rule a bit for the first two:

    1) Lay and popular perceptions of evolutionary biology in general tend to be hyper-adaptationist, and this seems to sort of have a spillover effect into the science itself in that overly adapationist accounts make a bigger impact than they ought. I won’t go nearly as far as Larry Moran, but I believe there’s a hell of contingency involved in evolution, and I think the answer to a disturbingly large number of evolutionary “why” questions is “that’s just the way it worked out”. Evo-psych shares this problem, and while it’s not unique to EP, I wonder if there is the equivalent of a Larry Moran within the field of EP, to act as a counter-balance. I am certainly not aware of one…

    2) EP — and, in fact, any endeavor to study the specific history of how selective forces shaped a single particular species — suffers from some pretty steep challenges regarding testability. It’s easy to say “Trait X could have evolved this way,” but showing that it actually did is another matter entirely, and is very difficult to establish definitively, sometimes even impossible.

    This is not to say that all claims of EP are fundamentally untestable, nor is it to deny that there is value in suggesting possible ways for traits to have evolved even if we know it must remain in the realm of speculation. It just makes EP difficult to get right, is all.

    3) Too many racist misogynist assholes very publicly playing up EP in the media, making up controversial just-so stories and claiming them as absolutely true so as to be all provocative and then hide behind, “Hey, don’t get mad at me, it’s just ‘science’…” I’m looking at you here, Kanazawa!

    That’s not a criticism of EP per se, of course, but it sure helps give it a bad name.

    OTOH, it seems plainly obvious to me that a) many human tendencies are in our nature rather than simply learned; b) if it’s “in our nature”, that means in our genes, so that means there is at least the opportunity for selective pressure to have played a role (even if I think many people underestimate the role of contingency); and c) it would be really cool if we could study that.

    I know some people dispute premise (a), but I feel like the data is pretty firm at this point (and anyway, it’s a rather odd form of human exceptionalism to think that all animals have innate natures except H. sapiens…). I think the most legitimate angle of attack in EP would be to respond to (c) with, “Yes, that would be cool, but we can’t, so shut up.” But that just seems terribly incurious and pessimistic!

    Many of the testability issues regarding EP may turn out to be intractable, but it seems we ought to at least try. With due humility, that is, which is what makes fuckers like Kanazawa so destructive.

    • http://kagerato.net kagerato

      I agree in particular with the point that some evolutionary psychologists seem to repeatedly make particular claims that are nearly impossible to test (or falsify). This doesn’t undermine the entire concept of evolutionary psychology, but it makes people very skeptical when too many supposedly respected practitioners in a field keep raising hypotheses that seem to match personal bias more so than a genuine desire to determine the truth.

      This is something all scientists in every field have to deal with from time to time.

  • Caravelle

    I love evolutionary psychology and I like a lot about Steven Pinker, but practically every detailed complaint about evopsych I’ve seen (i.e. more detailed than just “evopsych is Bad”) was pretty cogent. Pretty much none of those I’ve seen challenged the very premise of evolutionary psychology; they challenged specific studies and assertions made by some evolutionary psychologists as being poor science (poor science that coincidentally tended to support existing prejudices). Those that did write off the whole field seem to do so because they think it’s overrun by poor science, not because they disagree with its premise.

  • Pierce R. Butler

    … it is unlikely that new complex designs—ones requiring the coordinated assembly of many novel, functionally integrated features—could evolve in so few generations…

    Take a look at the specific, complex, and hard-wired behaviors humans have bred into (say) dogs, in fewer canine generations than there have been human generations living ~90% under conditions of peasantry. If the punk-eek model shows us anything, it shows that mere millennia can create significant evolutionary changes.

    • Caravelle

      Under very high and consistent selection pressure. Is there evidence human psychology has been under high consistent selection pressure lately ? As far as I can tell there are cases of “high”, and cases of “consistent”, but not really both. As Chris points out this doesn’t preclude subtler changes.

  • Daniel Engblom

    I’m biased towards evolutionary psychology (I accuse Dawkins, as he was the first biologist I read from). Mainly because the explicit assumption made within it that many other sub-disciplines don’t make at the offset, that of our animal-nature and historical ancestry.

    And it pains me how people always makes the polarisation (straw man) of optimistic-naive-adaptationist-story-telling versus realist-skeptical-scientist-critical: Pinker has heavily leaned on cognitive psychology – And Robert Trivers’ theory of self-deception lies on the firm evidence of our self-serving biases.

    But, I have noticed that, apart from Pinker, Symons and Judith Rich Harris, there are not many Evolutionary Psychologists criticizing each others ideas and weeding out the weak, poorly thought-out and badly justified hypotheses that others like to make (think folk-psychology-turned-masquerade-evolutionary-babble). This easily to our apish us-them mentality (and essentialist intuitions) ‘taints’ the whole discipline that others who see themselves as outsiders use to dismiss the whole.

    So I see that evolutionary psychology needs more people that test each others ideas and evaluates them, but I’m sure some other evo-psych has also made this observation (I vaguely recall reading this from some Evolutionary psychologist – Dennett?).

    But I hope I’m wrong! If someone can think of some other EvoPsych who has evaluated, criticized, tested – and in general been scientific about the ideas coming ‘from their ranks’, then I hope everyone will bring them up to attention for all of us.

    Side note: Roger Bingham had so weak reasons to “turn his coat” (http://www.edge.org/q2008/q08_15.html#bingham) the only one I could find was that there’s not enough neuroscience in EvoPsych, which I can sort of sympathize with, but it’s still no reason (you could bring neuroscience into it instead of acting like a dick about it). He merely redressed some thoughts from evolutionary psychology (like the importance of learning) and merely accused the rest as dogma.

  • scenario

    I haven’t read enough about it to give an informed opinion about the subject.

    Does Human nature have to be universal in order for evolutionary psychology to work? Could there be several sets of genes that influence peoples psychology in slightly different ways?

    Different dog breeds have been selected for different behavior for many years. If the environmental selection pressures were different in different areas slightly different human natures could evolve. We’ve been mixing and matching genes for a long time. People could be hardwired for certain behaviors, but not always exactly the same set.

    From my understanding, human population increased dramatically once farming started. Wouldn’t there be more variation possibly leading to faster evolution in a population of 100 million than 100 thousand?

    For example, some people have genes that predispose them to believing in some sort of higher being, other people don’t. How it is expressed depend on the environment. If the biological tendency and environment reinforce each other, you could either get a fundy or an atheist from an early age. If they work against each other and you have other environmental forces, you might get someone who is at least superficially religious but always has doubts. I’m not sure how you could test something like this.

  • http://www.facebook.com/gojaejin jeremygoard

    I should like to point out that the among the leading critics of Evo Psych are those with the best knowledge of biology and evolution. I am thinking of Jerry Coyne, PZ Myers and Larry Moran.

    And among it’s most influential figures, Richard Dawkins, Steven Pinker and Daniel Dennett. The former group have yet to demonstrate the willingness and ability to even summarize the relevant views of the latter accurately, and I’m not holding my breath.

    Francis Collins believes in transubstantiation. Coyne, Myers and Moran have done great work, but they’re just as capable of being shortsighted and irrational on specific issues.

    • http://www.modernpsychologist.ca Brad

      The defensive comments from EP’s effectively saying: “you fail to understand our theory…” is getting tiresome. It seems that no one is acknowledged to have understood the paradigm unless it is accepted. All critics, it seems, ‘have it wrong,’ which is a very bad attitude to have and is suggestive of a pseudoscience at work. Kuhn and Popper would be rolling in their graves if they were to know of these kinds of theories given serious consideration by such otherwise intelligent people.

      Here are some things that I have written on EP:

      Critique of Evolutionary Psychology
      Follow up discussion

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