Evolutionary Psychology Blog Archive

Could Evolutionary Psychology’s Critics Pass Evolutionary Psychology’s Midterms?

Back in October of last year, Larry Moran wrote a critique of an article about domestic abuse, which I subsequently responded to, pointing out an error in Moran’s post. Moran later responded in turn on his blog, writing, in part:

Robert Kurzban was upset by my critique of science journalism and evolutionary psychology [Evolutionary Psychology Crap in New Scientist]. You might recall that my criticism is based on many common features of evolutionary psychology but the most important are the unwarranted assumptions that: (1) a particular specific behavior has a strong genetic component. (2) that the behavior is adaptive, and (3) that we know how our ancestors behaved.

Remarks in the comments were salty. From his reading of my web site, for instance, he draws the inference that I am not a genuine scientist, but he helpfully tells me how I could become one, which it turns out has to do with picking the right collaborators, writing:

… evolutionary psychologists seem to avoid doing real science. They prefer to just assume that their model is correct and look for good stories to “confirm ” it.

Robert Kurzban’s website is a good example of that. A scientist would write ….

We are interested in testing whether certain human behaviors have a strong genetic component and, if so, whether the behavior is adaptive. If the answers to those question are “yes” then we’d like to do some work to find out when such traits might have evolved. 

We are collaborating with geneticists to identify potential adaptive behavior alleles and to see if there’s any evidence of a selective sweep of the corresponding region of the genome.

With that as background, my interest is that at the time I read Moran’s post, I recall being struck by his claims about the three assumptions that characterize the field. Not only were they wrong, but they were wrong in such a basic way that it seemed  to me that he probably hadn’t read anything at all about the field.

This semester I am teaching Psychology 272, Evolutionary Psychology, to about 100 University of Pennsylvania undergraduates. Their first exam was last week, so I thought I would put my guess to the test, presenting Moran’s assumptions as the topic of an essay question.

I had to edit slightly, but I preserved his actual words as well as I could. Here is the essay question as my students saw it on the exam:

Recently, someone writing about evolutionary psychology wrote that the field makes a set of assumptions. In particular, the writer claimed that evolutionary psychologists who are studying a particular behavior assume that (1) the behavior “has a strong genetic component,” (2) the behavior “is adaptive,” and (3) we know how our ancestors behaved.

For TWO of the three assumptions above (5 points for each), based on your readings and the material presented in lecture, indicate whether or not each of the three assumptions is indeed made by evolutionary psychologists. If the assumption is correct, provide a justification for the assumption. If it is not, explain why it is wrong and how you would change the assumption to make it correct.

My interest was in measuring how much instruction someone would need to be able to identify (and therefore not make) the errors in Moran’s post. At the time of the exam, my students had had 8 lectures of 1 hour and 20 minutes, or about 11 hours total. (I put the readings that were assigned at the end of this post.) This is an undergraduate class, with Sophomores, Juniors, and Seniors. The only prerequisite is introductory psychology.

Before I give the results, I want to be clear that my argument here isn’t about whether the assumptions are themselves correct; my interest is in what evolutionary psychology as a field assumes. How much time and effort would it take to learn enough about the field to avoid making the mistakes that Moran makes, even if it turns out that the assumptions themselves are problematic?

Here are the data. The results were that 53 of 76, or 70% answers to assumption (1) indicated that the assumption was false. For the second and third assumptions these numbers were 30 of 40 (74%) and 33 of 41 (82%). To summarize, a clear majority of my students, with four weeks of instruction in my undergraduate course, were able to recognize that Moran’s claims about what evolutionary psychology assumes were wrong.

These values actually underestimate a little bit. In the case of the first assumption, many students who said that the assumption was right reinterpreted the statement to make it more reasonable, emphasizing that all traits are jointly caused by genes interacting with the environment. (This is not to say that some students did not get it wrong, just that 70% doesn’t properly capture the fraction that got it right.) Also, I want to sound a note of thanks to Jennifer DeSantis, my superlative TA, who, I should say, actually did all the heavy lifting on the grading of the essays.

To give a sense of what they said, here are some excerpts from their essays. (I received permission to post from the authors of the answers.)

On the first assumption, Kathryn Raynor writes: “When studying a particular behavior, evolutionary psychologists do not make the assumption that the behavior has a strong genetic component. This would be an example of the gene vs. environment [dichotomy] that evolutionary psychologists try to avoid. The notion of genes vs. environment is a bad dichotomy because each heavily influences the other. An organism’s behavior results from the complex interplay between genes and environment…”

On the second assumption, that behavior is “adaptive,” Kathryn Raynor, again, writes: “Evolutionary psychologists also do not [her underline] automatically make the assumption that a particular behavior is adaptive. This  is a very strong claim; in order to assert that some behavior is adaptive, there must be evidence that the behavior serves a function, that is, it solves an adaptive problem, AND that it is specialized or well-designed to perform that function….” Laura Micu similarly penned: “Evolutionary psychologists don’t assume that a behavior is an adaptation, they study it to find out whether it is an adaptation, a by-product or a ‘cheap’ left-over…”

Finally, on the third assumption, Laura Micu, again, writes “…we don’t know, or are able to say for sure, what our ancestors’ behavior might have been. We can only speculate given historical and present-day social observations, as well as observations of animals that are closely related to us…” Similarly, Geoffrey Bass writes: “The above assumption is incorrect. It would be absurd to assume that we could determine with a great deal of accuracy how our prehistorical ancestors actually behaved, and evolutionary psychologists make no such claim. They are interested,  to some extent, in the origin and development of adaptive behaviors… it requires that we can identify or speculate about specific challenges our ancestors might have faced…”

Again, I want to be clear that the issue for this purpose is not whether the assumptions are good ones. Perhaps there is a logical flaw in the adaptationist analysis that I asked my students to entertain. Perhaps we can know for sure what our ancestors did. What I’m saying is that my students, by and large, correctly identified the assumptions of the discipline, a feat that Moran was unable to accomplish.

The broader point is that Moran is only one instance of a larger phenomenon, and critics of evolutionary psychology frequently demonstrate innocence of the field’s basic assumptions and theoretical commitments. As I’ve said in the past, an interesting question is why critics feel comfortable voicing such strong objections to the field, given their lack of background, even to the point, as in this case, of accusations of the discipline not being a science. I don’t pretend to understand the motives, but it’s an area that merits closer study. I’m afraid that we can be confident that there will be plenty of additional data along the same lines from our voluble critics of evolutionary psychology.

Required Reading for Psychology 272, through Week 4

Cartwright (2008), pp. 1-91, 145-170, 191-228, Dawkins (2006), pp. 1-165; Miller (2007); Kurzban, 2010, Chapter 2; Tooby & Cosmides (2005)

Cartwright, J. (2008). Evolution and Human Behavior: Darwinian perspectives on human nature (2^nd ed.).Cambridge,MA: MIT Press.

Dawkins, R. (2006). The Selfish Gene: 30th Anniversary Edition. Oxford: Oxford University Press.

Kurzban, R. (2010). Why everyone (else) is a hypocrite: Evolution and the modular mind. Princeton, NJ: Princeton University Press.

Miller, G. F. (2007). Sexual selection for moral virtues. Quarterly Review of Biology, 82(2), 97-125.

Tooby, J. & Cosmides, L. (2005). Conceptual foundations of evolutionary psychology. In D. M. Buss (Ed.), The Handbook of Evolutionary Psychology (pp. 5-67). Hoboken, NJ: Wiley.

17. February 2012 by kurzbanepblog
Categories: Blog | 27 comments