Evolutionary psychology for the masses

January 16, 2011 • 8:11 am

UPDATE: Over at Pharnygula, P.Z. has his own take (negative) on Bering’s paper and the lax standards of evolutionary psychology.  P.Z. notes that the “adaptive” results of the handgrip study cited by Bering have not in fact been replicated by other investigators.   That calls the results into question, something that Bering conveniently omits from his piece.


In the past week I’ve read two “pop” articles on evolutionary psychology.  One, “Social Animal,” in the latest New Yorker, is by New York Times op-ed columnist David Brooks.  It’s apparently an extract from an eponymous upcoming book.  The piece is cleverly framed: it’s the account of a first date by two fictional people, “Harold” and “Erica,” in which all of their conversation, their gestures, and their subsequent courtship and marriage are couched in terms of evolutionary psychology, with Brooks describing the research backing up the story.  Here’s an example:

As Erica and Harold semi-embraced, they took in each other’s pheromones. Smell is a surprisingly powerful sense in these situations. People who lose their sense of smell eventually suffer greater emotional deterioration than people who lose their vision. In one experiment conducted at the Monell Center, in Philadelphia, researchers asked men and women to tape gauze pads under their arms and then watch either a horror movie or a comedy. Research subjects, presumably well compensated, then sniffed the pads. They could somehow tell, at rates higher than chance, which pads had the smell of laughter and which pads had the smell of fear, and women were much better at this test than men.

And so on.  It’s engaging, but how solid are these results, and how much does a study of “fear” and “laughter” really have to do with Erica and Harold’s goodbye hug? The whole article is of this tenor, and I worry that one-off results were being presented as solid findings of evolutionary psychology—uncontestable results of science.
As far as I can see, Brooks has no formal scientific training (he has a bachelor’s degree in history from the University of Chicago), nor any experience as a science journalist.  Does he have the expertise to judge which of these claims are solid, and which mere speculations? There is not a hint in the entire article that the “science” behind Harold’s Dinner with Erica might be tentative or simply speculative.  It’s a cute piece, but an irresponsible one—the fantasy of a journalist who himself has fallen uncritically in love with evolutionary psychology.  You can bet your sweet tuchus that had Carl Zimmer written something like this, it would have included a lot more bet-hedging.  But then it wouldn’t have been published in The New Yorker.

A bit more distressing is a piece in the January 13 Slate, “Darwin’s Rape Whistle“, by Jesse Bering, who should know better. Bering is a psychologist at Queen’s University Belfast, a writer for Scientific American, and author of the forthcoming book, The Belief Instinct: The Psychology of Souls, Destiny, and the Meaning of Life. (He’s also funded by the Templeton Foundation). The subtitle of Bering’s piece is “Have Women Evolved to Protect Themselves from Sexual Assault?”, and you know what the answer is going to be without reading the piece. If it were “no,” the piece wouldn’t have appeared anywhere—so popular are Darwinian explanations of modern human behavior.

Bering’s piece begins by highlighting Randy Thornhill and Craig Palmer’s idea (described in their book A Natural History of Rape: Biological Bases of Sexual Coercion) that the human brain contains an evolved “rape module”: a neuronal circuit that impels men to subdue and copulate with women when they can get away with it.  The idea is that this would have been adaptive in our ancestors, giving disenfranchised males a way to spread their genes when they couldn’t do so through the usual route of pair-bonding.

Thornhill and Palmer’s book was controversial, with many critics claiming that the authors were trying to excuse or justify rape.  Bering takes after these critics, properly noting that “‘adaptive'”does not mean ‘justifiable’,” but rather only mechanistically viable.”  But what he doesn’t mention is that there were strong scientific critiques of the “rape module” idea as well.  I produced two of them myself, a long one in The New Republic and a short one with Andrew Berry in Nature, pointing out not only scientific weaknesses in the evolutionary scenario but Thornhill and Palmer’s unsavory fiddling with statistics, distorting what the primary data on sexual assault really said.  Bering doesn’t mention the scientific controversy, noting only that “it’s debatable that a rape module lurks in the male brain.”

Bering also asserts without question that even the shape of the human penis testifies to pervasive sexual coercion in our ancestors:

In fact, the distinctive, mushroom-capped shape of the human penis is designed to perform the specialized function of removing competitors’ sperm, which indicates an ancestral history of females having sex with multiple males within a 24-hr period.

Note that there is no reservation here, no claim that “there are data supporting this theory but it may be wrong.”  Just a simple factual claim about what science has found. But, as Bering described in Scientific American, the original study used dildos inserted into “realistic latex vagina[s] sold as a masturbation pal for lonely straight men” that had been filled with an artificial substance cooked up to mimic sperm.  This bizarre experiment leaves considerable doubt about why the human penis is shaped like it is!  Yet Bering has no such doubts.  His journalistic certainty in the face of experimental doubt is a hallmark of much reportage on evolutionary psychology. It certainly characterizes David Brooks’s piece as well.

Bering goes on to the centerpiece of his article, the notion of a “rape arms race” that has given human females genetic tools to withstand rape. And by “genetic tools,” I don’t just mean the willingness and desire of women to fight off sexual assault. No, women have specific psychological and physiological modules that supposedly evolved in our ancestors as “anti-rape” tools.  Bering sees four of these:

  1. When threatened by sexual assault, ovulating women display a measurable increase in physical strength.
  2. Ovulating women overestimate strange males’ probability of being rapists.
  3. Ovulating women play it safe by avoiding situations that place them at increased risk of being raped.
  4. Women become more racist when they’re ovulating.

The “increased racism” module is supposed to have evolved to prevent mixing with outgroups; as Bering says:

In this case, skin color serves as a convenient marker of group identity. (The authors concede that people of different skin colors came into contact with one another only in recent times, evolutionarily speaking, but propose that any physical trait that serves to demarcate an out-group member would be processed by ovulating females as a sort of “hazard heuristic.”)

There is, as far as I can see, exactly one study supporting each of these four points, with at least two of them based on surveys of undergraduates at single American colleges.  Here’s Bering’s summary of the data supporting handgrip strength:

In 2002, SUNY-Albany psychologists Sandra Petralia and Gordon Gallup had 192 female undergraduate students read a story about either a female character being stalked by a suspicious male stranger in a parking lot (ending with: “As she inserts the key into her car door she feels his cold hand on her shoulder …”) or a similar story in which the female character is surrounded by happy people on a warm summer’s day (ending with: “She starts her car, adjusts the stereo, and as she pulls out of the parking lot those nearby can hear her music blasting”). The researchers measured the handgrip strength of each participant before and after she read the story, and compared the scores. Petralia and Gallup also knew from the results of a urine-based ovulation test kit where in their reproductive cycles each participant was, so the researchers could differentiate among women in the menstrual, follicular, ovulatory, and luteal phases. A fifth group consisted of those women who were on contraceptives at the time of the study. The results were unambiguous: Only the ovulating women who read the sexual assault scenario exhibited an increase in handgrip strength. Ovulating women who read the control passage and nonovulatory women who read the sexual assault material grasped with the same intensity as before.

Well, one can debate whether reading a story about rape is the same thing as being sexually assaulted, or whether a marginal increase in handgrip strength would have been sufficient in our ancestors to fight off a rapist.  But the important part of these studies is that they were apparently one-offs—they have not, as far as I know, been replicated by other researchers.  Do we accept single results, based on surveys of American undergraduates at a single university, as characterizing all modern women?

As we know, many studies in science, when repeated, fail to replicate the initial results.  Think of all the reports of single genes for homosexuality, depression, and other behavioral traits that fell apart when researchers tested those results on other groups of people!  And if an author did an initial study (not a replication) of handgrip strength that didn’t show the relationship with ovulation, would that even be publishable? I think not.

I suggest, then, that the results of evolutionary psychology often reflect ascertainment bias. If you find a result that comports with the idea that a trait is “adaptive,” it gets published. If you don’t, it doesn’t.  That leads to the literature being filled with positive results, and gives the public a false idea of the strength of scientific data supporting the evolutionary roots of human behavior.

Nevertheless, Bering, who apparently has never seen a Darwinian explanation he doesn’t like, finds all this very convincing:

I don’t know about you, but I’m riveted, and convinced, by much of the logic in this anti-rape area. And researchers are just getting started.

Well, pardon me if I’m not quite so convinced.  It takes more than a small study on American college women at a single school to convince me that a behavior is an evolved adaptation to prevent rape.

Now I don’t oppose evolutionary psychology on principle. The evolutionary source of our behavior is a fascinating topic, and I’m convinced that the genetic influences are far stronger than, say, posited by anti-determinists like Dick Lewontin, Steve Rose, and Steve Gould.  Evolved adaptations are particularly likely to be found in sexual behavior, which is intimately connected with the real object of selection: the currency of reproduction.  I’m far closer in my views on this topic to Steve Pinker than to Steve Gould.  And there are many good studies in the field, so I don’t mean to tar the whole endeavor.

But, for crying out loud, let’s have the journalists and scientists show a little more responsibility when reporting on evolutionary psychology.  If there are problems with a study, describe them.  If an idea is pure speculation, say it.  If there are other explanations for a phenomenon, give them.  Let’s not gull the public into claiming that we understand something with near certainty when we don’t.   These lax reportorial standards, pervasive in evolutionary psychology, seem to be much tighter in other areas of science, like physics or molecular biology.  And this despite the enormous difficulty of demonstrating that any human behavior is an evolved adaptation.

Every time I write a piece like this, one that’s critical of evolutionary psychology, I get emails from its practitioners, chewing me out for being so hard on their field.  And my response is always the same: I’ll stop being so hard on your field when you guys start being more critical yourselves.  If you policed your own discipline better, I wouldn’t have to.

But since humans are so fascinated by scientific explanations of their own behavior, and so impatient with uncertainty and doubt, there’s not much incentive for the field to clean itself up.

102 thoughts on “Evolutionary psychology for the masses

  1. I accept willingly that, as animals, our evolutionary history affects our present day psychology. But I too worry that there are so many ‘this single behaviour is the result of a single evolutionary pressure’ explanations pulled out of thin air.

    I can think of several other possible evolutionary reasons for the current shape of the penis… including accident and drift. What if the true (as far as we can confirm) reason is a mix of several reasons? An Evolutionary Phallusy perhaps?

    It’s not just scientists that love to find a simple explanation, indeed you could argue that journalists are under the same pressures to find a simple example for many things, and all to a deadline.

    1. Why is it “by definition” uncertain?
      Please proffer the exact definition that you are employing, chapter and verse.

  2. the enormous difficulty of demonstrating that any human behavior is an evolved adaptation.

    If it was that simple, something would have come out by now, don’t you think? Maybe all of those are of the “what affects body length” rather than “what affects eye color”.

    As a layman I will sit up and take notice when a solid result was presented. If not, it isn’t a viable area.

    Here’s Bering’s summary

    which is interesting but simply reads like a collection of tell tales for a non-double blind study. Aaand the paper is paywalled of course, sigh! Does anyone know of this?

    Bering also asserts without question that even the shape of the human penis testifies to pervasive sexual coercion in our ancestors

    More people that looks for dicks as the mythical answer!

    When will it ever stop?

    1. Bering also asserts without question that even the shape of the human penis testifies to pervasive sexual coercion in our ancestors

      As a woman, I’d like to say thank you, evolution, for not coming up with copulatory plugs. (Which apparently do exist in Pan and Pongo!)

      Also, let’s hope this “research” doesn’t result in a run on dildos for purposes of morning-after contraception…

  3. I appreciate your criticisms, and I learn from them.

    I would get even more out of this article if it contained more on why the existing self-criticism in evolutionary psychology was not doing the job you feel it should do. Or is there really no existing self-criticism in the field whatsoever?

    I can’t help feeling that some EP journal articles must question their own approach at least in a perfunctory way and offer some way to evaluate its merits.

    Also I don’t see all of the EP articles talking about “modules” at all, and I often don’t see current alternative testable explanations for some of the things they try to explain.

    So my perception is that there is some degree of progress in the field and that it neccessarily entirely built on sand. Do you think that’s an accurate perception, or am I missing something?

    1. Perhaps, but it might be worth remembering that, in EVERY area of science, pop-science articles are typically riddled with hyperbole and an uncritical acceptance of what Coyne calls “one-off” studies. Remember the ‘definitive’ evidence of past microbial life on Mars? How about the press conference on how some bacteria definitely incorporate arsenic into their DNA? Virtually every new finding in human evolution is surrounded by exaggerated claims of importance (think ‘Ardi’).

      Because of the relevance to everyday human behavior and the attendant publicity, it is likely that many practicioners of evolutionary psychology exaggerate or misinterpret their findings, but we can’t paint their entire field with such a broad brush. Pinker is a good example of someone who sifts through the available evidence carefully and thoroughly. This is not to say that I don’t agree with Coyne’s points in these two cases.

      1. Sidenote: I think you meant Ida rather than Ardi. Ardi wasn’t subject to anywhere close to the same media frenzy.

        1. No, I meant Ardi. The first Ardipithecus ramidus specimens were discovered around 15(?) years ago. The recent thorough explication of the findings in Science (Lovejoy and colleagues) was, in my view, greeted with a media frenzy,which included nonsensical statements that Ardi was somehow our “oldest ancestor.” Many popular science writers emphasized that Ardi disproves the idea that the common ancestor of humans and chimps was a chimp (a straw argument in the first place). And other anthropologists thought that some of the inferences by Lovejoy and colleagues about Ardi were quite speculative and trumped up.

  4. I appreciate your non-politicized approach to evolutionary psychology; you seem to be open-minded, yet skeptical. If only more people would take that approach to this complicated subject! You add something constructive to the debate, so here’s a request for you to weigh in more often.

    1. Having spent a few days laid up with a fever, I’ve had a chance to read both of your posts on this subject, as well as the comments and a good many of the links provided by other commentators (and links provided by THOSE links, etc.), and have come to the conclusion that you may not be quite the impartial arbiter I thought you were. Still, you don’t strike me as totally biased either; in this post and it’s follow-up you’ve mentioned that you’re not opposed to evolutionary psychology in principal, and that you believe good work is being done in the field, so I’d still like you to weigh in more often, but I’d amend that and request that you share your views more fully and let your readers know what work you think is good and what conclusions you would at least tentatively support, as well as continuing to critique what you see as bad research and/or reporting. Perspiring minds want to know!

  5. I am so pleased that you wrote about this. I read the “Darwin’s Whistle” piece early this morning, since it was top of the Nota Bene column on the Arts and Letters page. I wondered, then, how reliable the claims were, since it seemed to home in on such very specific things being determined by evolutionary processes, and that kind of specificity seemed, on the face of it, so improbable. It was good to see the thing being torn to bits in this way. As you say, these guys really do need to police their discipline a bit more carefully. It seems strikingly like theology: as long as you can write a grammatically correct sentence about something it seems to pass the requirements for publication. This brings science into disrepute. Is this what they are trying to do?

    1. I concur. Drive-by EP is becoming so pervasive it is vital to keep getting the word out about just how tenuous & often dubious these highly touted experimental “proofs” are.

      And speaking of Lewontin (as JEC briefly was 🙂 ), one of my favorite contributions of his was not in the scientific lit but in the NYBR, when he spoke out about just how unreliable “data” relying on self-reportage by humans can be.

  6. Two points.

    One, I don’t think the term “rape module” is in any way appropriate, but it’s a foregone conclusion that genes which promote a tendency to commit rape are in the pool. To demand evidence for something so patently obvious is nothing more than special pleading.

    Two, how on earth could they come up with a theory and conduct an experiment that presupposes circumcision, something our evolving ancestors certainly did not do? The presence of a foreskin would pretty severely impact competitive sperm removal.

    1. it’s a foregone conclusion that genes which promote a tendency to commit rape are in the pool. To demand evidence for something so patently obvious is nothing more than special pleading.

      How would that be certain? Are we to assume that rape is somehow beneficial for differential reproduction in every species? Controversial interpretations and implications aside (see Sociobiological theories of rape), sex in a forceful or apparently coercive context has also been documented in a variety of species. But a variety of species isn’t all of them.

      Putting the general *FAIL* that follows most or all claims of “obviousness” in science aside, there seems to be no theory to support that coercive sex would be a common trait. (Or would a “rape module” supply that? Does that go back to, say, nematodes then?) So to not test it would be special pleading, surely?

      1. Oops, quote *FAIL*: “Controversial interpretations and implications aside (see Sociobiological theories of rape), sex in a forceful or apparently coercive context has also been documented in a variety of species.”

    2. “Two, how on earth could they come up with a theory and conduct an experiment that presupposes circumcision, something our evolving ancestors certainly did not do? The presence of a foreskin would pretty severely impact competitive sperm removal.”

      ^That! I was thinking the same thing.

      1. Me too. But, being Jewish, I don’t possess that tissue, and so don’t know if it would have any effect on how the mushroom-shaped head of the penis would remove the sperm of previous males.

        1. One of the (many) functions of the foreskin may well be to act as a seal to keep semen in. Wouldn’t retention of one’s own sperm take priority over pumping out rivals’, given that the rivals would be relatively rare and that the penis can’t tell the difference?

          1. Some species have sperm removal mechanisms on the ends of their penises, but the only ones I’m aware of are insects, not mammals.

            1. Wouldn’t the insect ones be much closer to the size of the sperms, almost able to deal with them one by one?

              Considering the most threatening sperms would be far into the uterus or Fallopian tubes, clearing out the vagina seems a fairly futile pastime. (I assume this does not apply to insects.)

              Would one not expect such behaviour to be better tuned to its necessity – more vigorous pumping, perhaps enlarged flare, in the presence (and especially smell) of rival sperm? This could be tested relatively easily.

              1. No clue. With mammals, the dominant strategy that seems to have arisen is simply to keep other males from mating with the female in the first place.

        1. Guys, you sound like the ladies from Sex and the City. If the foreskin doesn’t slide back penetration is (close to) impossible.

          When an uncircumcised man has sex the mushroom head is in full display. However, the effect sometimes is diminished when the body is wider than the head.

          And I imagine back then it was just sex; society made it rape.

          1. …the effect sometimes is diminished when the body is wider than the head.

            Isn’t that the point? That it bunches up about where the supposed mushroom edge would be pulling out all that foreign sperm?

            1. Well, unless one of us has a foreskin and has copulated with a woman after another man has, or the study I described used dildos with foreskins (highly doubtful!), I don’t think any of us can gauge the effect of not being circumcised on sperm competition. But that renders the original study pretty much useless.

              1. The things atheists chat about on Sunday evenings! 😀

                (Oops, wrong post category…make that evolutionists…)

              2. I hope you’re not suggeesting that the experience of one of us could be generalised to all (non-circumcised) human males everywhere.

                There are didloes with foreskins, but they’re far from realistic.

          2. If the foreskin doesn’t slide back penetration is (close to) impossible.

            I have to question this, both from personal experience and from plausibility. Close to impossible?

      2. An alternative hypothesis for the mushroom flange would be to increase cervical air pressure, in the manner of a pump diaphragm, to move the copulator’s sperm along.

  7. Even if we grant those studies robustness, the more parsimonious explanation that is consistent with all of those results is simply increased risk aversion during ovulation, rather than some specific anti-rape behavior. Haven’t read the piece by if Bering didn’t mention that possibility at all, shame on him. Wonder if ovulating women fold more often in a game of poker…

  8. I’m pleased to see this addressed here. I do think that serious science journalists have explored the theme of too much attention being given to one-off results but, seeing as David Brooks can get away with in it in the New Yorker, the message obviously isn’t getting through to editors. I suspect a look at their balance sheets would explain a lot.

    I’d also like to see more skepticism of pop neuroscience, fMRIs and such.

    1. The New Yorker is a great magazine for book reviews, short stories, commentary on current events, and cartoons. However it is a very unreliable source of reliable scientific information And David Brooks is never a reliable source of information on any subject in my opinion.

      1. The New Yorker is a great magazine for book reviews, short stories, commentary on current events, and cartoons.

        Typically, I only ever seem to have a problem with the New Yorker’s accuracy when it comes to science. Does this mean the New Yorker lacks science literacy or does it mean that, as a scientist, I’m biased and only notice the science pieces? For all I know it’s just as bad with social commentary.

    2. …fMRIs…

      Oh, absolutely. The detailed leaps of hypothesizing that result from those images drive me absolutely batty.

  9. For what it’s worth, this hypothesis about rape was also mentioned in Daniel Bergner’s NY Times Magazine piece two years ago:

    >> …in an attempt to understand arousal in the context of unwanted sex, Chivers, like a handful of other sexologists, has arrived at an evolutionary hypothesis that stresses the difference between reflexive sexual readiness and desire. Genital lubrication, she writes in her upcoming paper in Archives of Sexual Behavior, is necessary “to reduce discomfort, and the possibility of injury, during vaginal penetration. . . . Ancestral women who did not show an automatic vaginal response to sexual cues may have been more likely to experience injuries during unwanted vaginal penetration that resulted in illness, infertility or even death, and thus would be less likely to have passed on this trait to their offspring.” <<


      1. Beware of some guy writing about women…it will end up being about their fantasy life instead of something scientific.

  10. I think Brooks’ piece was fun in presenting pedestrian human behavior with a sort of meerkat manor behaviorist commentary overlaid on it, but absolutely it was irresponsible to present any of these interpretations as anything other than loose guesses based on limited, poor-quality data.

    “Does he have the expertise to judge which of these claims are solid, and which mere speculations?”

    It is obviously all speculation, as this is all grabby pop evo-psych, the magical bubble of reasoning where vague plausibility and concrete certainty merge seamlessly into one.

    I get the feeling that the promoters of pop-EP do not even have a concept of what evidence in behavioral genetics or evolutionary biology looks like.

    “where is the real science being done?”

    As usual, animal models.

  11. In terms of human male reproduction, it seems to me that there are three evolutionary strategies, each with their own advantages and disadvantages:

    1. committed relationship with one or more females
    2. sowing your wild oats (consensually)
    3. rape

    Given that human children are completely dependent and reliant on the mother for several years and still partially reliant for up to 15 or so years. There is likely to be an advantage to being a present and active father to ensure that that your female(s) and offspring are protected. So one can see why option 1 would be advantageous

    The sowing your wild oats option #2, requires that you seduce and impregnate as many women as possible and hope that they are raised to adulthood in your absence, potentially by another (#1) male.

    Then there is option #3 is similar to #2 requiring the impregnating as many woman as possible. Though has the added danger to the male that the woman is unwilling and may retaliate, also a #1 male may want to protect said female, and either could result in your injury or death, a riskier option. Not to mention the negative effect on the physical and mental health of the female, which would likely reduce the prospect of a child of such a union reaching adulthood.

    This “rape module” seems to imply that all men in the population possess the gene(s) that predispose them to being rapists, which I think is unlikely (assuming if these traits are genetically encoded – which I don’t think there is enough evidence for at this stage). It could be possible that a small proportion of men in the human population would carry a combination of genes that could result in a predisposition to this kind of behavior. But if this is true, I would think that the vast majority males would be likely to have genes making them male of type 1 or 2 or some combination of the two. A certain reasonably large proportion of the male population would have to be type 1 in order improve the odds of anyones offspring reaching adulthood.

    I think that this is supported by the fact that most cultures have family units including males. Also most cultures include a tradition of marriage, partnering one or more women to a man. This usually includes the cultural expectation that the woman remains faithful to said male, and often (thought not always) the cultural expectation that females remain virgins until they are partnered with a male. A strategy that makes it more likely that the #1 male produces the majority of the offspring, allowing only a small proportion of these offspring to be the product of the most cunning and seductive #2 and the strongest, most vicious, #3 type males.

    Therefore I think it is unlikely that rape would be a highly significant force behind human evolution. However I don’t have any data to back this up, and I am not even sure how one would one would test such a hypothesis.

    I am not sure why it would be advantageous for a woman to only have an increase in strength at the prospect of sexual assault when she was ovulating. Surely the risk of injury is high at any time, and it would be evolutionarily advantageous for a woman to defend herself whether she was ovulating or not? Just to ensure her own survival?

    All of this evolutionary psychology is pretty wishy-washy anyway. It is hard enough to identify genes associated with mental traits such as mental illness. How does one separate genetic psychological traits from environmental influenced ones anyway? Especially given the strong impact on society on sexual behavior.

    1. Your thinking is much more in line with some of the animal research I’ve heard of. I’ve read that the degree of sexual dimorphism in apes, for instance, reflects the relative frequency of monogamous mating strategies vs. harem-type social groups. Gibbons, the least dimorphic group, live mostly as monogamous couples…Gorillas, one of the most dimorphic, live in mixed groups with a dominant silverback much larger than the females, etc. The average percentage difference in size between human sexes was deemed to fall in the “slightly polygynous” area.

      Your other point is also well taken. When JEC wrote:

      Bering takes after these critics, properly noting that “‘adaptive’”does not mean ‘justifiable’,”…

      …I so wanted to add, “nor does it mean universal!” One of the most routinely lost concepts in the discussion of natural selection is the importance of variation, and the related idea that not all “traits” are adaptive under all conditions, and that some are maintained in populations at relatively low frequencies depending on how often conditions exist in which they are adaptive (among other reasons!). The absolutism of all this pop-psych popularization is one of its worst characteristics.

    2. Good points.

      One nitpick:

      A certain reasonably large proportion of the male population would have to be type 1 in order improve the odds of anyones offspring reaching adulthood.

      That might be true if we knew the survival rate of offspring to reproductive age from type 2 versus type 1 sexual encounters. But I’m not aware of any actual data for this.

  12. Somebody above has mentioned Pinker, rightly I think, as a responsible evolutionary psychologist. I have certainly found much to respect and like in his books, but I should like to see a scientist seriously address his assertions that the arts are no different from pornography or cheesecake. The literary critic Joseph Carroll, in Literary Darwinism, took Pinker apart over this very effectively, I thought, in his book Literary Darwinism, remarking in the course of this on Pinker’s obvious insensitivity to the arts, and his ignorance of them. I should nevertheless like to see a scientist weigh in on this.

    1. How can you scientifically prove that pornography and cheesecake are not “artistic”? That sounds like proving that orange is a better color than purple.

      What would it mean for art to not have a common psychological origin with pornography? That it came from the gods?

      While the bulk of EP is indeed bunk (or at least fishy) it hardly seems a mystery how it came to be that the standard subjects for painting are nudes. It’s ‘cuz we like looking at them! (Especially in a clothed society.) And that in turn isn’t much of an evolutionary mystery.

  13. Palmer and Thornhill respond to critics here, and I found it interesting reading. Right or wrong, their ideas are considerably more nuanced than they often strawmanned.

    1. Thanks for that link–I didn’t know it was available online. I’ll be reading that when time permits (i.e.–after kids are in bed…)

      I’ve not read their book, but here is David Buss on their theory in the most recent edition (2008) of his Evolutionary Psychology textbook (bought to read to myself, not for taking a class–again, I am self-taught. *dang* textbooks are expensive…):

      The section is titled “Do Men Have Evolved Rape Adaptations?” (my bolding)

      “The rape-as-adaptation theory proposes that selection has favored ancestral males who raped in certain circumstances. Proponents of this theory advance the hypothesis that at least six specialized adaptations might have evolved in the male mind (Thornhill & Palmer, 2000)…(I won’t list them here, but I can if you’re interested)…”

      Buss continues:

      “In contrast, the by-product theory of rape proposes that rape is a nondesigned and nonselected-for by-product of other evolved mechanisms, such as the male desire for sexual variety, a desire for sex without investment, a psychological sensitivity to sexual opportunities, and the general capacity to use physical aggression to achieve a variety of goals.”

      He continues:

      “Unfortunately, clear-cut evidence bearing on these competing theories is lacking. Rape is a common occurence during war, but theft, looting, property damage, and cruelty to the defeated are also common. Are there specialized adaptations for each of these behaviors, or are they by-products of other mechanisms? Definitive studies have not been conducted.”

      Throughout the textbook, Buss is careful to note that for *everything* he discusses, follow-up studies need to be done, or studies involving more subjects, and so on. But, anyway, I took those sections to mean that he didn’t give *too* much credence to the rape-as-adaptation theory.

  14. Jerry’s comment:

    “Every time I write a piece like this, one that’s critical of evolutionary psychology, I get emails from its practitioners, chewing me out for being so hard on their field. And my response is always the same: I’ll stop being so hard on your field when you guys start being more critical yourselves. If you policed your own discipline better, I wouldn’t have to.”

    I am going to frame this and put it on my wall. I am a behavioral ecologist studying animals, but am interested in human behavior and evolution, especially around gender issues. My own experience has been virtually identical to Jerry’s, either when I review manuscripts for evo-psych journals (which I have flat out given up on because of aforementioned problem) or when I am at conferences.

    1. Maybe the EP people are defensive as a holdover from the attempts by the Left to censor the early incarnation of human sociobiology.

      A real problem of EP is the disproportionate ease of generating interesting hypotheses compared with the difficulty of testing them. I have a personal list of over a dozen EP project ideas although my research was never even close to that area.

  15. We need to study the human species in a way that is coherent with the rest of biology, just as chemistry is coherent with the atomic theory of physics. Instead, we’re making up a lot of bullshit. I wonder what science historians will say about it in a hundred years.

  16. I can’t help grinding my teeth and muttering whenever pheromones are associated with humans – humans generate no pheromones whatsoever nor are there any equivalents.

    The whole of evolutionary psychology at the moment looks to me like nothing more than Freudianism by another name. For example, in the first example quoted, how much ‘better than chance’ are the numbers? Anyone with a rudimentary knowledge of statistics should be extremely suspicious when such statements are made without showing the data and explaining the experimental conditions. (Unfortunately such nonsense still exists in the medical literature as well though it’s not as bad as 50 years ago.) There is also the issue of disproving alternative explanations – I’m betting that alternative explanations weren’t even considered. That’s not to say that ‘evolutionary psychology’ will be nothing but a crock, but they have a hell of a way to go before any of their ideas can be accepted as demonstrated.

    1. humans generate no pheromones whatsoever nor are there any equivalents.

      I’m suddenly curious how far down the family tree you have to go before you reach pheromones. Do other primates produce them? What about other mammals?

      1. I haven’t read the literature for almost 20 years, but if I remember correctly, pheromones are an adaptation in the insect kingdom. According to the Wikipedia, plants and some animals also make pheromones – but the article looks really weak to me and I was never aware of any credible paper making such claims. The fact that the Wikipedia mentions “human pheromones” is something I consider a dead giveaway that the article is not credible.

  17. I enjoy reading Jerry Coyne’s blog and agree with him on many things science- and atheism-related but his writings on evolutionary psychology are IMHO a mess.

    Coyne: “Every time I write a piece like this, one that’s critical of evolutionary psychology, I get emails from its practitioners, chewing me out for being so hard on their field. And my response is always the same: I’ll stop being so hard on your field when you guys start being more critical yourselves. If you policed your own discipline better, I wouldn’t have to.”

    For a more complete picture, it should be added that the public responses of practitioners of evolutionary psychology to Coyne’s writings on the subject include explicit accusations of gross misrepresentation. While Coyne may think of himself as policing, as a stout defender of proper science, some regard him as a crooked cop (if that metaphor works).

    See for example: http://www.psych.ucsb.edu/research/cep/tnr.html and http://www.epjournal.net/filestore/ep07288294.pdf

    Take the following example (see second link to Liddle & Shackelford 2009):

    “Another misconception about evolutionary psychology presented in WEIT is revealed in the description of the “Environment of Evolutionary Adaptedness,” or EEA. According to Coyne, evolutionary psychologists claim that, “over the millions of years of human evolution, the environment, both physical and social, was relatively constant” (p. 245). This is not what evolutionary psychologists claim. The EEA does not refer to the entire evolutionary history of humans. Rather, there is a distinct EEA for each adaptation. A more accurate definition of an EEA is “a statistical aggregate of selection pressures over a particular period of time that are responsible for the emergence of an adaptation” (Buss, Haselton, Shackelford, Bleske, and Wakefield, 1998, p. 536). This definition is consistent with the fact that the environment did not remain constant in every way over the millions of years of human evolution. Moreover, it is not the environment as a whole that must remain constant for an adaptation to be constructed, but rather the selection pressures that construct each particular adaptation.”

    Anyone familiar with the primary evolutionary psychological literature knows that, on this point, Liddle and Shackleford are right and Coyne is plain wrong; and anyone with access to the primary literature and some time on their hands can easily check this assertion. (Unfortunately, many people’s views on EP are second-hand and common misrepresentations abound (e.g., EP as panadaptationism).)

    Sometimes Coyne’s arguments are just poor. Consider his take on by-product hypotheses in his NR review of T&P:
    “The real problem with the by-product hypothesis is its banality. It explains everything about human beings.
    Since we have an evolutionary history, everything that we are and everything that we do can be furnished
    with an evolutionary explanation.” And: “The key phrase in the passage [from Thornhill & Palmer] that I [Coyne] have just adduced is ‘whether evolution applies is never a question.’
    This is an explicit admission that the by-product hypothesis lacks the defining property of any scientific
    theory–the property of falsifiability, the ability to be disproven by some conceivable observation. An unfalsifiable theory is not a scientific theory. It is a tautology, or an article of faith.”

    This criticism is simply confused. The assumption that all biological phenomena have an evolutionary explanation of some kind – in addition to proximate explanations – follows from the distinction between ultimate and proximate explanations and the fact that evolutionary explanations are the only kind of ultimate explanation recognized as scientifically valid (see Mayr on the distinction between proximate and ultimate/evolutionary explanations). The only people who subscribe to the idea that we should consider non-evolutionary alternatives to evolutionary explanations are 1) creationists/ID adherents (because they recognize divine`will as an ultimate cause) and 2) those who do not get the ultimate/proximate distinction (e.g., Coyne) and suggest proximate explanations as alternatives to evolutionary ones (a category mistake). Coyne’s criticism of by-product hypotheses is equivalent to saying that physics is not a science because physicists do not consider non-physical explanations.

    This criticism is even more bizarre given the fact that, as Coyne surely knows, by-product hypotheses are standard fare in evolutionary biology. Spandrels are by-products, allometric effects are by-products, consequences of trade-offs are by-products, etc.(Note the irony: a critic of evolutionary psychology effectively arguing that by-product hypotheses are unfalsifiable just-so stories.)

    Sorry for rambling, but I just wanted to point out that the implicit assumption of many posters here that Coyne is a good guide on evolutionary psychology is very debatable.

    1. San Marco wrapped around itself. As with any blog, the rule is caveat leitor. Dr. Coyne is presumably comfortable with some loosey-goosey, questionable presentations, such as he put out here, and with the pro-gun control post that ignored all the empirical studies on the results of gun bans.

      If he is willing to be criticized by folks like you and me, then the blog is nevertheless worthwhile: Coyne sometimes as guru, occasionally as foul-up. But clearly I prefer more of the former, less of the latter. Primarily because any lack of rigor may provide an opening for creationists.

      Oh yes, Dr. Coyne do you really want to call 80% of Republicans morons, given that their party controls the grant-money purse strings? I hope they read your presidential disclaimer.

  18. Certainly agree with most of the criticism expressed by Coyne in this blog, yet cannot help but feel that both he and P.Z. Myers are applying research journal article standards to popular science media.
    Do they apply the same standards of accuracy and documentation for popular media articles in other fields, or are they being unduly harsh on EP?

    1. I think I’ve been just as tough on science reporting involving other things: take a look at my posts on epigenetics, for example. And at least one of the authors I mentioned in the post is actually working in the field.

      Take a look at the artificial penis article if you want to see bad standards in journals!

  19. I wrote a rebuttal to you. It made me tired.

    It is clear that your (political) feelings have been hurt. It’s really silly, though, for you to pretend that that’s an argument.

    I do not doubt that you are a Republican, and one who feels wronged by Dr. Coyne’s politics, but what does being a Republican have to do with what Dr. Coyne said about this article?

  20. The recent book, “Sex at Dawn: The Prehistoric Origins of Modern Sexuality” provides answers to many questions posed here.

  21. Dr. Coyne cites two articles, one of them in the popular press, declares them bogus and then opines that the field of evolutionary psychology is a mess and that this is fault of evolutionary psychologists. I’m curious: if I were to cite two articles (one from the popular press) on the subject of speciation, declare them bogus, would that then justify my assertion that the science of phylogenetics is a mess and that is the fault of phylogeneticists?

    1. Sorry, but you haven’t been reading this website. I’ve posted a lot of stuff on evolutionary psychology in the past two years, showing that the field is in SOMEWHAT of a mess. It’s not just these two articles that demonstrate it. And yes, the practitioners are partially responsible.

      Perhaps your snarky comment reflects unfamiliarity with a position I’ve maintained all along, for which I’ve adduced lots of evidence. I’d also suggest you read the comment by Dr. Zuk above.

      1. And I’d suggest you read the comment by JdL. Every field of science has journals that publish dubious results, which are then criticized by people with professional knowledge in the field. Indeed, that’s the point: you do your studies, you publish the results, and then 1) see if anybody can replicate it, and 2) see if they think it makes sense, given the growing theoretical structure of the field.

        What you don’t do (not if you are a responsible scientist) is reject an entire field of study because a single journal article can’t be replicated. No, you reject the hypothesis presented in the article and then move on. What Bering did is just what you’re supposed to do in any empirical science. What happened after Bering’s results weren’t replicated is also just what you’re supposed to do in any empirical science.

        As for Dr. Zuk “giving up” on the unenviable task of peer-reviewing papers in evolutionary psychology because some of them are bogus, perhaps it’s Dr. Zuk (and people like her) you should blame for what you perceive to be the lack of “self-policing” by evolutionary psychologists.

        1. Sorry, I meant to type “Petralia” (the lead author of the ‘hand-grip’ study) when I typed “Bering” (the author of the Slate article describing the study by Petralia and Gallup.

        2. It’s specifically the place where responsible critics of a field go from legitimately pointing out replication failures and providing expert criticism of patterns of evidence in a field … to making broad generalizations and expressing their attitudes … that they are most vulnerable to subjective bias.

          I perceive that to be the point that JdL and MacNeill are pointing out.

          Taking the additional step of claiming that attitudes about a field are supported by evidence makes for a tricky slope where I think responsible scientists and scholars take special care and let the less responsible “debunkers” unleash their humor for rhetorical purposes.

          To me, mixing these things quickly becomes problematic because in a sense it turns a legitimate scientific inquirer into more of a committed position advocate.

        3. I see your point about “giving up” on reviewing EP papers not being the best solution, I do. But at the same time, I have my own work to do, in a field that I think is more rigorously vetted. And I haven’t felt that my reviews of EP have ever helped, however constructive they have tried to be.

          On one occasion I painstakingly outlined what I thought was a clearly fatal flaw in the reasoning of the paper from the outset. I then found substantive errors in the methodology, the analysis, and the conclusions (seriously, I considered keeping the paper as a model of what not to do for my students, but decided it would be too hard to maintain confidentiality). I tried *extremely* hard to avoid sounding confrontational.

          The outcome? The paper was accepted with revisions, because the other reviewers, neither of whom were biologists, liked it, and the editor thought it was interesting stuff.

          It’s not that this kind of thing can’t happen to other sorts of scientific papers, because of course it can. I am only saying that having this experience and others similar to it far more often in EP has led me to, well, find something more constructive to do.

  22. But the ideas are interesting and plausible! They’re both of those things to the max! What could possibly be your problem?

    / sarcasm

  23. I am a bit confused JDL-

    Your explanation of the EEA is “a statistical aggregate of selection pressures over a particular period of time that are responsible for the emergence of an adaptation.”

    It seems to me, from what I have read of the literature involved with Evo-Psych, that this statistical aggregate of selection pressures is assumed to have been constant over our entire history- that is, traits arose and were shaped by selective pressure early on in our evolutionary history, and have remained relatively constant since.

    That is, unless I am mistaken, EP postulates that the traits themselves arise out of a certain EEA at a certain time, but then remain relatively similar even after their emergence. Is this incorrect?

    Basically, I am curious whether or not EP asserts that Homo sapiens has been, or is currently, subject to selective pressure that is constant across our history.

    1. Don’t know if you’ll read this, but I’ll give a quick response anyway.

      Every adaptation has its own EEA, consisting of the selection pressure that caused it to evolve. For example, the EEA of adult lactase persistence (a fairly recent physiological adaptation) is a nutritional environment with milk from domesticated animals. This is the sense of EEA that is relevant to the research literature. This notion of the selective environment (or adaptively relevant environment as it’s also been termed) is operative throughout evolutionary biology. The EEA, in this sense, is not a new idea peculiar to evolutionary psychology. (I am in favor of dropping the term altogether since it so easily leads to misdirected criticisms.)

      Since different adaptations have different EEAs, THE EEA *can* be thought of as “a statistical aggregate [bla bla bla]”. That said, this kind of EEA is a useless fiction which has no role to play in guiding scientific research.

      I’m not saying that some evolutionary psychologists have never implied that there is a specific time and place that we can identify as THE human EEA, but this is not, I think, an idea with much traction in the evolutionary psychological research literature.

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