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Thursday, January 20, 2011

The Bankruptcy of Evolutionary Psychology

Evolutionary psychologists never seem to give up. Their latest folly is to pretend that women have a series of evolved behaviors to avoid rape during the time that they're ovulating.

Jerry Coyne has already commented on the study and his follow-up posting is worth reading because it highlights the responses of others who have dissected the papers [The women of Slate take on evolutionary psychology].

The bottom line is that the entire field of evolutionary psychology is in big trouble and it is bound to become a major laughing stock unless evolutionary psychologists clean up their act [Evolutionary Psychology as Maladapted Psychology].

One of Jerry Coyne's comments caught my eye because we've just been reading the Gould & Lewontin Spandrels paper in class. Coyne said,
Like the stories of the Bible, there’s no evolutionary psychology hypothesis that can be disconfirmed by data. If your story doesn’t hold up, simply concoct another story. Of course, there’s no evidence for the alternative stories, either.
In 1979 Gould and Lewontin wrote,
The admission of alternatives in principle does not imply their serious consideration in daily practice. We all say that not everything is adaptive; yet, faced with an organism, we tend to break it into parts and tell adaptive stories as if trade-offs among competing, well designed parts were the only constraint upon perfection for each trait. It is an old habit. As Romanes complained about A.R. Wallace in 1900: "Mr. Wallace does not expressly maintain the abstract impossibility of laws and causes other than those of utility and natural selection... Nevertheless, as he nowhere recognizes any other law or cause... he practically concludes that, on inductive or empirical grounds, there is no such other law or cause to be entertained. The adaptationist programme can be traced through common styles of argument. We illustrate just a few; we trust they will be recognized by all:

(1) If one adaptive argument fails, try another. Zig-zag commissures of clams and brachiopods, once widely regarded as devices for strengthening the shell, become sieves for restricting particles above a given size (Rudwick, 1964). A suite of external structures (horns, antlers, tusks) once viewed as weapons against predators, become symbols of intra-specific competition among males (Davitashvili, 1961). The eskimo face, once depicted as "cold engineered" (Coon, et al., 1950), becomes an adaptation to generate and withstand large masticatory forces (Shea, 1977). We do not attack these newer interpretations; they may all be right. We do wonder, though, whether the failure of one adaptive explanation should always simply inspire a search for another of the same general form, rather than a consideration of alternatives to the proposition that each part is "for" some specific purpose.
Plus ça change, plus c'est la même chose.


  1. It drives the experimental psychologists nuts too.

  2. I can understand criticism of bad research, but I'm not really clear on why evolutionary psych is such a maligned field. The general premise, that our behaviors are influenced by evolutionary adaptions of the brain, seems plausible enough.

  3. Just having a good idea about why things may work the way they do is not enough for the idea to be scientific. E.P. can (maybe uncharitably) be seen as just a collection of disconnected factoids with no testable or modifiable theories, internal to the discipline, to connect them together. The methods of making the E.P. stories of 2050 will be the same as those of 2010.

    It's maligned, partly, because it produces much "research" that ends up being touted in newspapers, tv, and general interest magazines. This, even though many of its hypotheses are untestable, contradictory or otherwise less than scientific. Yet it calls itself a science, and is considered as one by the general public, and so risks besmirching the reputation of the whole of science in eyes of the public. Science is not storytelling with facts.

  4. Mike D says,

    The general premise, that our behaviors are influenced by evolutionary adaptions of the brain, seems plausible enough.

    Indeed, that's a "plausible" idea. But in order to move from "plausible" to science you need a lot more. First, you have to at least consider other plausible evolutionary explanations such as the possibility that the trait evolved but it's maladaptive or neutral. That's hardly ever done.

    But before getting that far, you had to do three things that most evolutionary psychologists shun. (1) You have to demonstrate that the behavior has a strong genetic component. (2) You have to show that there was variation in our ancestral population (different alleles). (3) You have to demonstrate that you sufficiently understand the conditions and culture of our ancient ancestors to be able to construct an adaptive scenario.

    If you skip these steps you are not doing science.

  5. Just following the links from the comments section in the latest ev-psych thread.

    I'm boggling at this latest just-so story. Did they have any women in the research team or colleagues who could have told them that women have a series of conscious strategies for avoiding rape all the time?

    If this conclusion were true, then it would require that women who are ovulating have an unconscious suite of behaviors that they engage in to prevent rape (if they were conscious, they'd wind up in the all-the-time repertoire) and that they're more effective than the steps that women take when they're not ovulating.

    Furthermore, they'd have to show that there is a strong selective advantage to be had in not being raped. Here you'd think that they'd at least learn the wisdom of telling a consistent story. Because it has already been notoriously argued by Thornhill and Palmer that rape is adaptive for men. So if rape is adaptive for men, but not being raped is adaptive for women, then we have an evolutionary arms race and we've been studying the dynamics of those for decades. So what evidence is there that the avoidance behaviors of women have become more elaborate in response to the rapist behavior of men? One would think that if such coevolution were a reality, the effects of it could hardly be missed.