Robert Kurzban

The Evolutionary Psychology Blog

By Robert Kurzban

Robert Kurzban is an Associate Professor at the University of Pennsylvania and author of Why Everyone (Else) Is A Hypocrite. Follow him on Twitter: @rkurzban

Coyne: “No evolutionary psychology hypothesis can be disconfirmed”

Published 24 January, 2011

I don’t want to continue this discussion of the Bering post and the aftermath too much – Bering has himself followed up on Slate and I’ll move on after this post – but I was really quite struck by Coyne’s claim in his more recent post that “there’s no evolutionary psychology hypothesis that can be disconfirmed by data.”

This is obviously a very, very strong claim. If true, the field carries no value as science, given a commitment to falsification.

I thought I’d just talk a little bit about how this view sets Coyne in firm and direct conflict not only with evolutionary psychologists, but some other people as well.

Take, for example, David Buller, about whom I’ve blogged a few times. In his book, Adapting Minds, he challenged Stephen Jay Gould’s concerns about evolutionary psychology, laying out the logic of adaptationism, arguing that he (Gould) “misses the fact that adaptive hypotheses can be supported by the confirmed predictions they make about human psychological mechanisms” (p. 91). (Reminder: That was David Buller I just quoted there.)

Who else…? How about Jerry Fodor? Also a well-known and prominent critic of evolutionary psychology, especially in the context of his arguments surrounding Cosmides and Tooby’s work on detecting cheaters. While Fodor (2008) resists Cosmides and Tooby’s ideas about logical reasoning, he is clear in one of his recent pieces on one thing: what empirical steps would be required to test the theory. (Fodor suggests that the evidence they need is to show there is “no effect of logical form on inferential processes when content is controlled” p. 140. Cosmides and Tooby already ran the tests Fodor demanded, but that’s really not the point) From Coyne’s point of view, Fodor must be very, very deeply confused, since he (Fodor) believes that these evolutionary psychology hypotheses can indeed be falsified. He might think they are, in fact, false, but of course that’s a separate issue.

Speaking of Fodor, responding to his book, What Darwin Got Wrong (with Massimo Piattelli-Palmarini) one biologist recently wrote that “Fodor completely ignores all the examples given by critics (including me) showing that selectionist explanations are not ad hoc and post hoc rationalizations, but can be tested…” (italics original). In that linked article, this biologist argues for the logic of adaptationism, writing that “evolutionary biologists have grappled for decades with the question of how to decide which evolving features of species experience natural selection and which do not. And they’ve devised observational, experimental and statistical ways to make this distinction.” He even makes a functional claim about a human trait, writing: “Individuals who can tan in the sun (and thus prevent melanomas) have an advantage over those whose pigmentation is fixed.” Note the claim that we can infer the function – preventing melanomas – from observations of the trait. No need for fossil evidence, no need to do any genetics. This author even defends evolutionary psychology. Far from believing that “there’s no evolutionary psychology hypothesis that can be disconfirmed,” he writes “much of evolutionary psychology is interesting, worthwhile science.” (He also, I must note, says that the field includes “a speculative fringe…that proposes fanciful stories.”)

You can imagine that I would love to suggest that Coyne read this article, but I won’t. That’s because it would be silly to do so, since – and you probably guessed –  Coyne wrote it.

Why would Coyne defend the field – much of it is science – and attack it with his claim here, that none of it is science?

I don’t really know, but my point is not that Coyne isn’t consistent. I mean, who is…? The question is, I think, why there is such animosity to the idea that the theory of evolution by natural selection can improve research in the social sciences. Evolutionary biologists and evolutionary psychologists use the same principles to achieve similar ends, differing only in terms of the species under study. It’s clear from his other writing that he can’t be endorsing, say, creationist psychology.

So it seems to me we are natural allies, but there seems to be enmity instead of amity. And I even think that the field would welcome “policing” in the sense of constructive suggestions for improvement. Using a blog to declare the entire field unscientific seems less like policing and more like bullying to me. Yes, sure, there is poor work in the discipline. Absolutely. There’s poor work in every field. Are these sorts of public statements helping matters, or just giving an audience an excuse to hold aside the human mind as an organ whose features can’t be studied using the principles of evolutionary biology?

Ok. On to other matters…


Fodor, J. A., 2008, “Comment on Cosmides and Tooby”, in W. Sinnott-Armstrong (ed.), Moral Psychology: The Evolution of Morality: Adaptations and Innateness, (Moral Psychology, volume 1), Cambridge, MA: MIT Press, pp. 137–141.

  • DiscoveredJoys

    Ah! But what is the source of the enmity?

    If I project my beliefs on to others(!), I see people proud of their rationality and logical thought. But evolutionary psychology has the potential to reveal how little of our behaviour is driven by rationality.

    Just like creationists dislike the Theory of Evolution – it reveals how much of our nature *is* nature, not some sacred soul.

  • miko

    There are real difficulties of falsification in historical sciences (like evolution, where we are often dealing with discrete events they may have occurred only once), but that should disqualify them as science… I won’t defend Coyne’s consistency because I can’t be bothered to read everything he has said, however I agree with the main criticism that EP often engages only superficially and unproductively with evolution (counterproductively if you include the media coverage). At the risk of endlessly repeating myself, to come up with plausible adaptive explanations for a trait is not sufficient to call what you are doing “evolutionary” or to claim that the trait is adaptive. What is the evidence for the selection pressure existing or having existed? What is the evidence (not plausible argument) your trait increases fitness under this selection regime? When? What is the distribution and heritability of the trait in modern populations? I don’t want to patrol disciplinary borders, but I think if you want to call your field “evolutionary X” you have to do evolutionary research–not just use it as a conceptual frame for your data.

    It is true that you will often see a biologist who studies, say, visual encoding, throw out a phrase like “color vision is an adaptive feature of vertebrate sensation, which may have driven the diversification of neuronal adhesion molecules in the retina” and then go on to talk about the genetics of retinal wiring and nothing about fitness and selection. The difference is they aren’t calling it “evolutionary visual neurobiology.” Framing your thinking with evolution just makes you a life scientist (welcome, psychology), it isn’t in itself interesting or support for a particular adaptive hypothesis, however plausible. Before you tell me I am caricaturing EP (guilty), please admit that this is what a lot of EP looks like, particularly the kind that makes headlines, and has unfortunately become its “public” face. You would win more people over by defending only what’s worth defending.

    • miko

      “should NOT disqualify them as science” – sorry

    • Robert Kurzban

      Two small points. I’m not sure, but from your question, “ What is the evidence for the selection pressure existing or having existed?” I think perhaps you’re saying you don’t think that Williams’ logic underlying his argument for the criteria for establishing a functional/adaptationist claim is correct. That’s fine, but if Williams is wrong, then the problem is broader than our field. (This was Fodor went after evolutionary theory; have a look at the end of Coyne’s post.) Secondly, it’s interesting you use vision as an example. On this blog, Brian Scholl wrote “all vision scientists are basically evolutionary psychologists both in theory and practice, but wouldn’t think that is worth noting.” They just assume the logic is correct, and use the ideas without naming them. His comment I think is also worth a read.

      • miko

        I think what I did was restate Williams. Without adherence to strict criteria, such as fitness effects, heritability, population distribution, one cannot assign adaptive significance. Thus my criticism of the adaptive assertions in the genital arousal paper. Williams seems to me inherently conservative… “adaptation is often recognized in purely fortuitous effects, and natural selection is invoked to resolve problems that do not exist.”

        • JdL

          Hi Miko. You are not the only one to have put forward this sort of argument, but to say that you are restating Williams is a bit rich. His proposed criteria for identifying adaptations (in Williams 1966) were without exception functional design criteria. Moreover, Williams was a soft- but outspoken proponent of (methodological) adaptationism – which proceeds by formulating (etiological) function hypotheses, deriving predictions from them, and testing these – and he has explicitly defended ‘adaptationist storytelling’ as a valid part of the scientific process in biology and explicitly rejected Gould’s views on this matter. See, for example, Williams’ Plan and Purpose in Nature (1996) or his writings on evolutionary medicine (e.g., Nesse & Williams 1994). (The Buller quote above recognizes the basic validity of this brand of adaptationism.) The fact that the biological literature is chock-full of etiological function attributions based primarily or exclusively on evidence of functional design but your kind of argument is almost never made in non-EP contexts is, I think, telling. (By this last sentence I did not mean to imply that you are guilty of a double standard, just that some critics of EP are.)

    • Marco DG

      Two good papers that are relevant to this issue:

      Schmitt & Pilcher (2004). Evaluating Evidence of Psychological Adaptation.
      How Do We Know One When We See One? Psychol Sci, 15.

      Ketelaar & Ellis (2000). Are Evolutionary Explanations Unfalsifiable? Evolutionary Psychology
      and the Lakatosian Philosophy of Science. Psychol Inquiry, 11.

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  • miko

    I’ll think about the first point…the second is my point exactly. Evolutionary and adaptive thinking influences how all life scientists think about problems (on some level). I am saying this does not make all life science “evolutionary biology”, which is explicitly the study of the mechanism and patterns of evolutionary forces, including adaptation, but also drift, linkage, pleiotropy, and all the other genetic and developmental quirks that make biological evolution complex. I rarely, if ever, see EP engage with evolutionary biology, genetics, neuroscience, etc. If EP is just contextualizing psychology with the assumption that our brains evolved: so what? It’s like calling it “Brain Psychology.” What other kind is there? Picking individual cognitive traits and coming up with plausible models for their effects on fitness is fine, but without any measurement (or even estimates!) of effects on fitness, strength of selection, genetic and anatomical bases, etc, you’re just not studying evolution. Why does all the EP I see look like that genital arousal paper instead of like Terence Deacon?

    • Marco DG

      “Why does all the EP I see look like that genital arousal paper instead of like Terence Deacon?”

      Excellent question. My guess is that your main sources are Internet blogs rather than handbooks, academic volumes, and journals such as Evolution & Human Behavior, human Nature, and Evolutionary Psychology.

      • miko

        Well, this is the “official blog of Evolutionary Psychology” and one explicitly devoted to promoting EP, so I guess I would expect to see the good stuff here, for one.

        I don’t have time to look now, but if you can offhand recommend some individual articles, I would like to have a look.

        • Robert Kurzban

          Quick clarification. This blog is formally associated with the journal Evolutionary Psychology, but I absolutely don’t claim that this blog is an “official” blog of the field as a whole. I don’t think that’s what you meant, but I just thought it would be worth clarifying.

    • Marco DG

      Here is a (very short) list of recent academic volumes on various EP topics. I recommend all of them. The authors deal extensively with issues of genetics and epigenetics, neuroscience, endocrinology, primatology and comparative research, and so on. This is the kind of literature that everyone with an interest in EP and a scientific background should become familiar with.

      - Buss & Hawley (2011). The evolution of personality and individual differences.
      - Ellis & Bjorklund (2005). Origins of the social mind.
      - Platek & Shackelford (2009). Foundations in evolutionary cognitive neuroscience.
      - Geher & Miller (2008). Mating intelligence: Sex, relationships, and the mind’s reproductive system.
      - Thornhill, R. & Gangestad, S.W. (2008). The evolutionary biology of human female sexuality.

      • miko

        OK, I promise to get a couple of those from the library at some point, though what I meant was primary literature (since I can get it online)–I will work my way through a current issue of an EP journal and see how that goes.

        • Marco DG

          If you name a topic you’re especialy interested in, I can provide links to some papers.

          Note: keep in mind that some of the best work in EP gets published in high-impact journals like BBS, Proc R Soc B, PNAS, Psych Bull, and so on. The journals I mentioned above are more specialized, and tend to publish empirical studies rather than broad theoretical papers.

    • David P.

      “Evolutionary and adaptive thinking influences how all life scientists think about problems (on some level).”

      I could not disagree more. Psychology is in desperate need of adaptive thinking. As Rob points out in his book (which is great by the way), more than 15,000 articles have been written on the topic of “self-esteem,” which sadly have not enhanced our understanding of the human mind one iota. If only these psychologists had realized that being motivated to feel good runs completely counter to adaptive thinking – because “evolution doesn’t care how happy you are” (a good line from Rob’s book) – they could have channelled all that time and money to more fruitful ends. There is way too much research in psychology that does not map onto adaptive logic and is not progressing because of it. This is sad and needs to change.

      Agreed, though, that evolutionary psychologists ought to engage more with genetics, biology, and neuroscience. But I think this is mostly a problem that is due to the small number of evolutionary psychologists, the limited opportunity they have to study these fields as part of their training, and the taboo that is placed on the discipline in general. If there were more people in EP, more interdisciplinary ties, more required biology courses in curricula, and less disdain of EP such that collaboration with biologists (like Jerry Coyne) could be possible, this problem would not exist. The way I see it, the problem is not EP itself, but rather EP’s nascent and oppressed status.

      And actually, Steven Pinker used genetics to bolster his case that language is an adaptation, which I found to be utterly convincing:

      • miko

        Thanks, that’s an interesting perspective. I think I have misunderstood the field of psychology to some extent. My dad was one of the earlier generations of people trained as psychologists who decided that if you wanted to understand the mind you have to look at the brain, as opposed to drawing flowcharts of hypothetical functional entities. I thought that revolution was over… So, yeah, partly psychology uncomfortably straddles social sciences and biology.

        I hate to keep bringing up Terence Deacon, but his ideas on language evolution are several levels of explanatory richness and scientific rigor (neuro- and evo-) beyond anything I have ever seen Pinker write or say… The Symbolic Species to me renders The Language Instinct pretty much completely dispensable.

  • miko


    Well, I’ve only superficially looked at Williams, but even the summaries of the first two chapters in his table of contents seem to counter to your comment.

    1. Function (fitness benefit to the organism) is insufficient evidence for adaptation.
    2. Natural selection, the only mechanism for producing adaptation, requires particular conditions to be operate (i.e. there must be an appropriate selective environment, the trait must have certain structural features)

    Whether he thought it was useful to use adaptive storytelling in understanding biological systems is not the same as saying the ease of coming up with an adaptive story makes a particularly evolutionary claims more likely to be true. I think Dennett summarizes this spectrum pretty well, and points out the pitfalls of “greedy” adaptationism.

    You are right that most fields of biology aren’t held to high standards of evolutionary reasoning, because although normally informed and framed in the context of evolution, it often does not really matter what the “adaptive” status of the trait they are studying is. I need make no argument about the fitness benefits of eyes or transcription factors to study the mechanisms of retinal cell fate specification. Evolutionary biology does have a much higher standard, because they are examining traits specifically to understand the evolutionary mechanisms that produced them. EP should be held to at least the same standards of evidence and reasoning as evolutionary biology if it claims to study the evolution of human behavior rather than to merely frame psychological studies with adaptive arguments. I don’t have a strong opinion about this, but I see why some people would argue that the bar should be even higher for EP because of the complexities and contingencies of human cultures, and the fact that psychological traits are poorly defined biologically.

    Ultimately I think everyone would be willing to grant more storytelling leeway if we weren’t bombarded with weekly EP stories in the press about the evolutionary underpinnings of thong underwear or the clothing color choices of professional athletes. From the outside, it is a discipline that often doesn’t even seem to take itself seriously. I realize this is not the fault of the whole field. However, evolutionary biologists fight like wolverines and regularly denounce and decry what they perceive as shoddy work or reasoning. It can be ugly, but the arguments are difficult and do move forward. I do not see this level of internal policing in EP, or indication that they engage much with empirical evolutionary biology.

    • JdL

      Williams’ concept of function is explicitly etiological (and I was very clear about this): a trait’s function is to do what it was designed to do (by NS). The definition of function you give above, which equates function with fitness benefit to organism, does NOT in any way, shape or form represent Williams’ view. (Had you actually read any of his work rather than just look at the table of contents, you would know this.)

      Williams argued that (etiological) functional hypotheses – H: T was designed (by NS) to do F – give rise to TESTABLE predictions, which is manifestly true. (Even Buller, one of the harshest critics of EP, concedes this point.)

      Further, my point was not that other fields of biology are not held up to the same standards of evolutionary reasoning. Many EVOLUTIONARY fields of biology, such as behavioral ecology paleobiology, also make frequent use of this kind of methodologial adaptationism. It is a legitimate research strategy with a stellar track record.

      What you might be objecting to is the idea that functional design is taken as evidence of NS (maybe this looks circular to you).

      • miko

        JdL, if a trait’s function is what it was designed to do by NS, that it is tautological that it contributes to fitness, there is no other way for NS to design anything. Not that it matters particularly what one author thinks, but I’ve read a bit more and Williams is absolutely explicit that observing that a trait’s benefit to the organism is not in itself evidence of adaption, which is obviously not the same thing as allowing one to make “testable hypotheses.” Which is what I was saying…I am not interested in the semantics of the word “function.”

        I think my critique of EP in this light is that apparent beneficial function IS often asserted to be or tacitly treated as evidence for adaptation. The papers I have read in the primary EP literature (n<10, I'm working on it), do not engage with the basic conditions required for adaptive natural selection to take place on their trait of interest, they simply assert their plausibility and move on with the story. I think you are wrong to assert that evolutionary biologists treat adaptive explanations as cavalierly. But, I've decided to do a comparison…I'm taking the current issue each of an EP journal and an evolutionary biology journal and will attempt summarize them for comparative purposes.

        • JdL

          Miko, a last reply, just to clear things up. I think we’ve been largely talking past each other. (I really don’t recognize my characterization of Williams in your replies at all.)

          We agree that adaptiveness (conferring a fitness benefit) is insufficient grounds to conclude that we are dealing with an adaptation (who doesn’t?). And if your critique of EP is that evolutionary psychologists often leap to quickly from adaptiveness to adaptation, then that is at least a coherent critique – good luck on the literature review! We also agree that many different kinds of evidence are often required to test adaptation hypotheses. Of course, many different kinds of testable predictions follow from adaptation hypotheses other than predictions about functional design. The key question is what evidentiary standards should be employed to test adaptation hypotheses (and what standards are, as a matter of fact, being employed) (see the Andrews et al. ref given by Marco DG on this). I see no point in arguing about these matters any further here, since there is a huge academic literature on the topic, but I suspect that we would be largely in agreement on many of these issues.

          A word of warning though (offered in a constructive spirit). It is fine not to be interested in the semantics of the word ‘function’, but you should realize that it is one of the central concepts in these debates and that many participants (including Williams and probably the majority of philosophers of biology and evolutionary psychologists) always mean etiological function by ‘function’. (I should not have assumed that you were familiar with this term. My bad.) In a nutshell, the etiological function of a biological item are those of its effects that were naturally selected for. If you accept this definition, then all adaptations have functions and only adaptations have functions. ‘Function’, to these authors (and I’ve followed their usage), simply does not mean anything like ‘fitness benefit to the organism’ (in contrast to your statement in an earlier post), as they are only willing to attribute functions to adaptations. To them, all hypotheses about biological function ARE by definition hypotheses about adaptation.

          Many of our apparent disagreements stem from the fact that I use the term ‘function’ in this restricted sense while you use it more loosely. Being aware of this semantic issue will probably prevent a lot of confusion during your expeditions into the academic literature.


          • miko

            Thanks, that does make sense. And you are correct that that is my fundamental criticism of the EP I have been exposed to.

    • Marco DG

      miko, JdL:

      I’ll try to push your discussion beyond Williams by (re)suggesting two recent papers on (1) the kinds of evidence for adaptation in psychology and (2) the epistemological status of evolutionary psychology:

      Schmitt & Pilcher (2004). Evaluating Evidence of Psychological Adaptation. How Do We Know One When We See One? Psychol Sci, 15.

      Ketelaar & Ellis (2000). Are Evolutionary Explanations Unfalsifiable? Evolutionary Psychology and the Lakatosian Philosophy of Science. Psychol Inquiry, 11.

      See also:

      Andrews et al. (2002). Adaptationism – how to carry out an exaptationist program. Behav Brain Sci, 25.

      • JdL

        Thanks for the refs, although I’ve read most of these (K&E and Andrews et al.); but I should point out that I was not trying to engage in a debate about adaptationism, just trying to correct some misunderstandings about Williams’ position because it is so often misunderstood/misrepresented.

        I am certainly not going to spend any time debating adaptationism on the web. (Actually, I don’t think I’ll be spending any more time debating scientific/philosophical issues online, feels like a complete waste of time.)

      • miko

        Thanks, Marco, I enjoyed the Schmitt/Pilcher paper and can now articulate my gripes with the EP papers I have read in new language: the nomological networks used to support their evolutionary arguments lack evidentiary depth and breadth. Their network diagram, while specific to human pyschological traits, can be adapted to be a handy score sheet for my comparative analysis.

  • miko

    Well, it looks like they did the nomological analysis (qualitatively, at least) for me! And now I can no longer say I have not seen substantive criticism of EP from within the field itself.

    “Evolutionary psychologists too often focus on only one evidentiary box, working solely with college undergraduates,
    foragers, genetics, or cross-species studies, for instance. Even so,
    despite a very limited nomological network of evidence, many evo-
    lutionary psychologists make broad and unwarranted claims about the positive identification of human adaptations. It is our contention that psychological science would be better served if evolutionary researchers think outside their usual ‘‘box’’ and that, as a field, evolutionary psychology should expend more scholarly effort building cross-disciplinary networks of evidence for adaptation.”

  • Andy

    On to other matters indeed.

    Here you questioned the inconsistency in the critic’s reasoning. You also wondered “why there is such animosity to the idea that the theory of evolution by natural selection can improve research in the social sciences.”

    I think we can find a good place to start looking in the idea of “The Ideological Immune System” , this brilliant piece just arrived in my Reader from Skeptic Magazine.

    Some choice quotes…

    “Those who attack, however, the most confirmed and verified truths, may not always do so out of fear. Their assault upon truth may be motivated by high ideals and a zeal for the preservation of some — as they perceive it — greater truth.”

    “We are not surprised when these new truths are attacked by those who fear the advance of science or who, for an array reasons, may hold the scientist and his science in contempt. But we are stunned when those who honor science and its achievements (who may even earn their bread within the realm of science) attack the most verified and confirmed scientific truths.”

    It goes on to talk a lot about how our feelings about causality color our ability to accept and observe new theories about causality.

    Since this exact phenomenon is universal in the history of science, I think it bears repeating that we can actually study this phenomenon in the light of EP. The evolution and function of our ideological immune system.

    Great food for thought in any case.

    • Marco DG

      The example I love most is the reception of the theory of continental drift when it was first proposed. The story is well told by R. Jordan here:

      The theory was denounced by geologists as preposterous, antiquated, footloose, dangerous, “utter, damned rot”, and a “fairy tale.” Of course, it is nearly useless to judge the truth of an idea by its critical reception; still, the violence of the reaction of expert peers to ideas that were eventually accepted is something one should bear in mind.

  • Robert Kurzban

    Marco, Andy,
    Thanks for these. Very interesting.

  • miko

    Maybe I’m wrong, but I don’t think there is animosity, at least among most biologists, about evolutionary psychology as a concept. In substance I think most of the critiques are based in something closer to the quote above by Schmitt & Pilcher. If S&P do represent something close to the consensus view of evidentiary standards within EP, then I think it’s fair for EP’s critics to ask why so much of it seems to fall so ridiculously short of these standards, as S&P acknowledge.

    Anyway, I think you guys should disown David Brooks before it’s too late, because from the excerpt I read, it’s not going to make you look good, or like science.

    • Andy

      “I don’t think there is animosity, at least among most biologists, about evolutionary psychology as a concept. ”

      To be fair, you’re right. I don’t want to draw a false comparison, especially because Coyne and Myers et al are great people, but that’s the same thing the vaccine dissenters say. “I’m not against vaccines, but…” The problem is emotionalism.

      It’s very easy to point out the logical fallacies that our feminist friends employ. The ones that our scientist friends employ are much harder to pinpoint. It’s (imo) splitting hairs over who gets the credit for discovering the causation.

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