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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

A Coyne Flip?

Published 27 June, 2011

John Horgan recently penned a little rant about biological determinism, stemming from the recent discussion of the paper suggesting that Gould erred in one of the analyses he presented in The Mismeasure of Man. This led me back to Jerry Coyne’s blog because Horgan – somewhat amusingly – lumped Coyne together with people like Richard Wrangham and Rose McDermott, both of whom take an evolutionary approach to their respective fields. Now, as Coyne properly pointed out, Horgan sort of bundles together an odd collection of ideas under the banner of “biological determinism,” but my interest isn’t in either Gould’s putative error or in Horgan’s.

Instead, looking at Coyne’s blog, I was interested to see that he had some favorable remarks to make about Darwinian Medicine.  (This connects well to current events, as Randy Nesse will be the keynote speaker at the Human Behavior and Evolution Society meeting taking place this coming week in Montpellier, France, from where I am writing this post. I hope this post is less stinky than I am, given that Air France seems to have decided against putting my luggage on the plane and, 36 hours later, still cannot locate it.)

In any case, in addition to the post about Darwinian Medicine, Coyne also recently discussed an interesting behavior by sloths (see also the post here) – they come down out of their trees to poop. In his post on May 23rd, he writes about why they might do this:

By “why”, of course, I mean what were the advantages of any genes that produced this behavior?  I’m assuming here that this behavior is genetically based rather than simply learned, which seems a reasonable supposition.

First, it’s interesting to note the learned/genetic dichotomy he favors, but more interestingly, he then suggests four ideas about the function of this behavior and he is very explicit about the fact that one can test the function of this behavioral pattern, writing (as if he had to defend the claim) that “in principle these theories are testable.” (By the way elsewhere he has written that to show that a trait is an adaptation, “we must show that it enhances reproduction.”) In any case, he continues:

We could see, for example, how sloths manage to find each other at mating time.  We could also do mock-defecation studies from branches, using model sloths, to see if the noise attracts predators.

He’s saying that one can use observations about the organism and various sorts of experiments to arbitrate different hypotheses about the evolved function of behavior. For some reason, I feel like repeating that. He’s saying that one can use observations about the organism and various sorts of experiments to arbitrate different hypotheses about the evolved function of behavior.

I might note that in the post responding to Horgan, he defends Richard Wrangham – also, interestingly, lumped in with Coyne and the others, this way:

As for Wrangham’s hypothesis about the biological basis of human aggression, I see it as plausible, or at least not immediately worth dismissing on the grounds of ideology.  If our altruistic and cooperative traits are partly built on the genes of our ancestors, as perhaps Horgan agrees (I do, too), why not the aggressive and pernicious traits as well?

Taken together, it seems that we can infer that Coyne takes positions along the lines of the following

  1. Hypotheses about the function of non-human behavior are not uncritical and untestable storytelling, but can be tested. (This is clear from the sloth post.)
  2. Hypotheses about the function of physiology in humans are not uncritical and untestable storytelling, but can be tested. (This is clear from the Darwinian Medicine post.)

On the joining of those two –hypotheses about the function of behavior in the case of humans – it’s a bit less clear. One might expect that, to be consistent, he would take the view that hypotheses of evolved function of human behavior – a key feature of evolutionary psychology – are not untestable just-so stories, but can, indeed, be tested.

But, on the other hand, for Coyne, no opportunity to burnish his anti-evolutionary psychology credentials is to be passed up. In his post about Horgan he writes: “I share Horgan’s dismay at rampant biological determinism: I have been a pretty strong critic of evolutionary psychology and sociobiology, for example,” as if the two fields are equivalent to biological determinism. And, in the Darwinian Medicine post, he similarly couldn’t seem to resist taking a swipe:

While I now think that Darwinian medicine is a useful and intriguing discipline, its practitioners must be careful not to fall into the same trap that’s snared many evolutionary psychologists: uncritical and untestable storytelling.

This is especially interesting in a historical sense; Nesse is considered by many (including me) as one of the founders of evolutionary psychology. So it seems that at least this part of the discipline is useful and intriguing but, at the same time, he thinks that “No evolutionary psychology hypothesis can be disconfirmed.”

For what it’s worth, I continue to like Coyne’s blog, and I’ll even plug his book again. I also continue, however, to think his antipathy to evolutionary psychology is misplaced. If you think that we can discover the function of fever, puking, and pooping at the base of a tree, why are other patterns of behavior not susceptible to a similar analysis?

  • http://jmsb.concordia.ca/~GadSaad/ gad saad

    Nice post Rob. The hypocrisy implicit to those who can offer adaptationist explanations for all but one animal (humans) is astonishing.


  • http://vertebratesocialbehavior.blogspot.com Clara B. Jones

    1. It seems virtually impossible to critique EP without arousing defensiveness and/or disclaimer from it’s practitioners.
    2. For Coyne to say that “behavior is genetically based” is not evidence that he is guilty of commiting the nature-nurture fallacy. It, rather, reflects a difference between Modern Synthesis biologists and Extended Synthesis biologists. Clear explications of these views, including their similarities & differences, can be found in Pigliucci & Muller (eds), 2010, MIT Press.
    3. Perhaps I am mistaken in interpreting you to suggest that an understanding of “function” explains adaptive significance; however, it should be clear that knowledge of/information about either one does not necessarily clarify the other.

    • Jesse Marczyk

      It’s one thing to critique a specific hypothesis; it’s quite another to declare that a field is based upon untestable speculations, call it a religion, and use the word “science” in scare quotes.

      Of course, people who like evolutionary psychology defend it when the latter claim is made. In much the same way, people who support the theory of evolution more generally tend to get defensive about the field when others try to dismiss the entire theory as a fanciful and false tale.

      Coyne himself may or may not commit the nature-nurture fallacy at times; I happen to think he does now and again. There are multiple examples throughout his blog where he talks about behavior being “genetically hard-wired”, as well as multiple examples where he seems to also disavow such thoughts. More importantly, however, Coyne appears to feel that evolutionary psychologists think along those lines; labels like “genetic determinism” get thrown around a lot.

  • Jesse Marczyk

    What I find very interesting is how Coyne flips back and forth between saying one of these two things:

    1) These speculations in evolutionary psychology are untestable stories
    2) These speculations in evolutionary psychology are unsupported/refuted by the current evidence

    The first is a statement that there is no evidence he would find convincing; the second is a statement that either there is the possibility of supporting some hypothesis, but he hasn’t seen it yet, or that evidence is capable of refuting a story.

    More curious is that these claims only seem to apply to adaptive hypotheses; non-adaptive hypotheses for behavior or psychology are not seen as unreasonable speculation.


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