Zombie Psychology: Bad Ideas That Simply Refuse to Die

At the risk of reopening a can of worms, Jerry Coyne’s recent post I think helps clarify why he dislikes the field of evolutionary psychology so much.

Coyne is responding to someone he refers to as a “lurker” on his blog who asked him to give an example of a an evolutionary psychology study he (Coyne) thought was good. I of course applaud Coyne for taking the time to do this. I think that it’s a very useful way to try to move forward.

What can we learn about Coyne’s choice of a “good” paper in evolutionary psychology? It is a paper published in The New England Journal of Medicine in 2004 by two medical doctors, William Reiner and John Gearhart. Briefly, the paper reports an investigation of genetically XY babies with a particular disorder that affects the genitals. The babies are surgically made female and raised as female. This study (N=16) asked the question of whether these individuals – genetically male but raised as females, with vaginas rather than penises – identified as males or females when they got older. Briefly, many of the subjects self-identified as males.

One could quibble about the identification of a study with a small N, in which double blinding is impossible, and so on, but I think that would miss the point, except insofar as it illustrates that Coyne doesn’t object to studies on these grounds per se, but simply applies these criticisms when he dislikes research for some other reason.

The important point is that I think that there is a lot of information in this choice. Obviously, it’s interesting that he doesn’t select a study conducted by people who self-identify as evolutionary psychologists, or is published in an evolutionary psychology journal. He passes over Joe Henrich’s award-winning work, to take just one example.

My sense is that he sees this work as distinguishing whether gender identity is “biological/genetic” as opposed to “cultural/learned.” You can see Coyne’s views on this when he writes: “The results show that, to a large extent, the roots of gender-specific behavior are biologically rather than socially based, and are present at birth,” drawing the biology/culture distinction, which evolutionary psychologists explicitly reject. (See below.) (Coyne mentions that he got into this work because Pinker referred to it in The Blank Slate. Pinker concludes from this and related work that the hypothesis that “boys and girls are born identical except for their genitalia” is “not looking good,” a claim about the origin of variation between the sexes.)

From his choice, then, one might infer that Coyne thinks evolutionary psychology is about showing that traits are “genetic” or “innate” as opposed to “learned,” a very common misconception among people unfamiliar with the field.

Another way to see why he objects to the field is his view of ultimate explanations in evolutionary psychology. He writes that what he likes about this particular study in JAMA is that is “comprises a simple test of a simple hypothesis, and does not involve telling tortuous adaptive “stories” to rationalize the results.” I don’t know what he means by “rationalize” there (let alone “tortuous”), but I take it from this that he thinks explanations in the case of humans are preferable if they include only a proximate explanation as opposed to a proximate and ultimate explanation.

So it seems to me that this choice is very helpful in illustrating the origin of his irritation with the field. He thinks, I infer, that the agenda of evolutionary psychology is to claim that human behavior is innate, fixed, genetic and biological rather than learned, flexible, and cultural. A sensible person who thought this, and observed human variation, would quite reasonably conclude that there are problems with the field. Of course, this gets the commitments of the field wrong, which is why these conversations recur with regularity. Similarly, it’s true that the field commits to the value of both proximate and ultimate explanations, just as evolutionary biology does. Of course if he thinks that ultimate explanations are a liability rather than an asset, he finds the field that much worse.

Future conversations will be limited in their usefulness until we can at least agree on what it is that we disagree about. While (many) evolutionary psychologists think the productive axis of debate is the specificity of cognitive mechanisms, interlocutors such as Coyne still seem to want to have the debate about nature versus nurture. True, that’s not the only issue. There remains the question of why he thinks that an adaptationist analysis and ultimate explanations are useful for seahorses but unwanted “stories” for humans, but my sense is that the first order of business is to agree about the axis of debate.

And, maybe just for completeness, here is a passage on this issue from Cosmides and Tooby in their online primer:

Debates about the “relative contribution” during development of “nature” and “nurture” have been among the most contentious in psychology. The premises that underlie these debates are flawed, yet they are so deeply entrenched that many people have difficulty seeing that there are other ways to think about these issues.

Evolutionary psychology is not just another swing of the nature/nurture pendulum. A defining characteristic of the field is the explicit rejection of the usual nature/nurture dichotomies — instinct vs. reasoning, innate vs. learned, biological vs. cultural. What effect the environment will have on an organism depends critically on the details of its evolved cognitive architecture. For this reason, coherent “environmentalist” theories of human behavior all make “nativist” claims about the exact form of our evolved psychological mechanisms. For an EP, the real scientific issues concern the design, nature, and number of these evolved mechanisms, not “biology versus culture” or other malformed oppositions.

02. February 2011 by kurzbanepblog
Categories: Blog | 7 comments

Comments (7)

  1. Agreed on all counts save one: “tortuous” ≠ “torturous.” The lack of an r makes all the difference (and makes his comment make sense…well, syntactical sense, anyway).

  2. 1. I had not heard of Henrich (an undergraduate degree in engineering!); he is currently @UBC. While I’ve not read any of his work, the topics and collaborators are certainly impressive. Thank you for informing me of this young scientist. However, I don’t note any paper/chapter/book topics or descriptions of his work that identify him primarily as an EPer. EP is mentioned only once as an interest among many others.
    2. Certainly Jerry Coyne can speak for himself; however, it is simply absurd to suggest, as Kurzban does, that JC advances the outmoded nature vs. nature dichotomy. I suspect that what RK is not taking into consideration is that JC may be a “classical” geneticist whereby one BEGINS WITH the genotype for an understanding of the phenotype. I would not think that the classical view is in any manner inconsistent with epigenetics and methylation; however, it is certainly inconsistent with the position taken by Mary Jane West-Eberhard in her 2003 tome (OUP).
    3. Referring to the LC/JT paragraphs that RK quotes, I “just don’t get it”, as my oldest granddaughter said to me once when she was struggling with an algebra problem. Maybe EP is “over my head”; on the other hand, JC’s critiques may be worth taking very seriously, indeed.

    • On your second point, given his remark that the behaviors are “biologically rather than socially based,” I don’t know what else one is to infer other than that these two are in some type of zero sum conflict, so I’m not sure I see your objection.

  3. The problem with Coyne’s view is that people do not understand the implications of such a study. If we establish that there are some innate sex differences in one domain, that it imply that at least there is a good possibility that other sex differences exist. However, when other studies suggest this exact point, the same people will dismiss these studies and attach the whole paradigm. The default assumption for most people and researchers is that any sex differences are cultural and any biological sex differences need to be proven way beyond doubt. This sort of bayesian reasoining put ev psych claims at a disadvantage, even though a-priori we shouldn’t give any culture explanation any more weight unless there are data to support it.

  4. It’s not the size of a study per se that’s the issue. You don’t need much more than a sample of two to substantiate a hypothesis that, say, that 250mg of cyanide is a fatal . (The fact being established one wishes there was no further impromptu experimentation!) On the other hand for very obvious reasons it would be very, very problematic to use a sample of two to substantiate a hypothesis that women are incapable of mastering linear commutative nonassociative algebras over the complex numbers.

    As for whether there are real differences between men and women I’m pretty sure you can tell that (if by no other means) by assaying products of gonadal steroid breakdown in urine over 24-hour periods. Even if you had a hard time distinguishing testosterone from progesterone you’d figure out pretty quickly that male steroids rise and fall daily in a way that female steroids don’t. So bingo. And even if you were to contend that testosterone and progesterone were pretty analogous hormones the impact of daily vs. monthly cycling would result in pretty measurable behavior differences. Bingo again. Nor would you need very large samples to detect the differences, although the larger, longer, and more diverse your sample the more variation you’d begin to notice, especially in relation to illness, external stress, interpersonal interaction, and age (especially as subject age varied away from the late teens and early twenties.) Oh, and substances consumed. But even with all those confounding factors you’d still be able to detect differences with a great degree of confidence. Bingo one last time, there are differences between men and women, they’re innate, they’re genetically determined, and the hormonal differences can result in behavioral differences.

    I think the quibbling starts when assertions arise that the differences in behavior are themselves adaptive and adapted for, as opposed to being side effects. The idea that men get crabby or aggressive and women get “pms” when their respective hormone levels drop below a certain point is kind of indisputable. It would be harder to say, however, that the crankiness men sometimes develop as their hormone levels drop with age, and the crankiness women sometimes develop as their hormone levels drop in the days before their cycles end, are both cognitive behaviors that have been specifically selected for and (presumably) the result of adaptation to different environmental pressure.

    Anyway, one would have to be silly to say there’s no evolved behavior — crankiness is too easily observed for all manner of insufficiency (sex hormones, blood sugar, etc.) to believe it could be anything else.

    Because it’s easily and reliably reproduced I’d be comfortable with research findings based on small sample sizes and with less meticulous attention paid to other variables. But again, for far more complex behaviors I think it’s reasonable to ask for bigger samples as well as way better controls over other possibly confounding variables. When people say “extraordinary claims require extraordinary evidence” that’s usually what they mean. Not that there can be no convincing evidence, just that it needs to be really convincing.


  5. Regarding the “above the fray,” and somewhat unctuous blurb by Cosmides and Tooby, e.g.,

    “Debates about the ‘relative contribution’ during development of ‘nature’ and ‘nurture’ have been among the most contentious in psychology. The premises that underlie these debates are flawed, yet they are so deeply entrenched that many people have difficulty seeing that there are other ways to think about these issues.”

    I doubt that such a debate has ever actually taken place, at least among thinkers anyone has ever heard about. To have such a debate, it would be necessary for both sides to be represented. It’s plausible that there have been, and still are, advocates for the “nurture” side, but the “nature” side? I think not. Who, of any intellectual repute, has ever said “that traits are ‘genetic’ or ‘innate’ ” without adding the usual caveats favored by evolutionary psychologists? I doubt that such “genetic determinists” have ever existed as other than ideologically useful myths, although it’s quite true that one does appear in an episode of “The Three Stooges.”

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