Genetic determinism? Not so fast.

June 26, 2009 • 7:27 am

There are several items in the news today relevant to evolutionary psychology.  First, David Brooks, in The New York Times, has an op-ed piece on the excesses of evolutionary psychology.  Apparently “inspired” by a new book by Geoffey Miller, Brooks resists evo-psycho’s exaggerated claims:

Now Miller has published another book, “Spent,” in which he takes evolutionary psychology to the mall. The basic argument is that each of us is born with our own individual level of six big traits: intelligence, openness to new things, conscientiousness, agreeableness, emotional stability and extraversion. These modules are built into humans and other animals (apparently squid can be shy).

We are all narcissists, Miller asserts. We spend much of our lives trying to broadcast our excellence in these traits in order to attract mates. Even if we’re not naturally smart or outgoing, we buy products and brands that give the impression we are.

According to Miller, driving an Acura, Infiniti, Subaru or Volkswagen is a sign of high intelligence. Driving a Cadillac, Chrysler, Ford or Hummer is a sign of low intelligence. Listening to Bjork is a sign of high intelligence, while listening to Lynyrd Skynyrd is a sign of low intelligence. Watching Quentin Tarantino movies is a sign of high openness. He theorizes that teenage girls may cut themselves as a way to demonstrate their ability to withstand infections.

Evolutionary psychology has had a good run. But now there is growing pushback. Sharon Begley has a rollicking, if slightly overdrawn, takedown in the current Newsweek. And “Spent” is a sign that the theory is being used to try to explain more than it can bear.

This critique, along with Sharon Begley’s (see below), is a welcome sign that people won’t credulously accept the excessive claims of evolutionary psychology. Miller, in particular, has made a name (and some bucks) with ludicrous and insupportable claims about the genetic basis of human nature.  Now, Brook’s own critique is not perfect. He says, for example:

The second problem is one evolutionary psychology shares with economics. It’s too individualistic: individuals are born with certain traits, which they seek to maximize in the struggle for survival.

But individuals aren’t formed before they enter society. Individuals are created by social interaction. Our identities are formed by the particular rhythms of maternal attunement, by the shared webs of ideas, symbols and actions that vibrate through us second by second. Shopping isn’t merely a way to broadcast permanent, inborn traits. For some people, it’s also an activity of trying things on in the never-ending process of creating and discovering who they are.

This really says almost nothing, and ignores the fact that humans certainly evolved in a social milieu, and that some of our evolved traits must have been adaptive only in a social milieu.  How else can you explain an inborn facility to learn language?  Brooks would have been better off making the most trenchant critique of evolutionary psychology:  the tendency for many advocates to make speculations completely unsupported by evidence.  Do young girls really cut themselves to demonstrate a resistance to infection? Why isn’t it young men who do the cutting? After all, it’s the men who compete for women, and the “handicap” view of sexual selection posits that ornaments like the peacock’s tail are there to show females that males have the genes or constitution able to deal with (or at least produce) a debilitating but attractive feature.  When it comes to speculations about human behavior, we also have to worry that they could have unintended social consequences. Promoting the notion that self-mutilation might be adaptive may, for example, have the side effect of promoting its spread.

Apropos, Sharon Begley of Newsweek has just published a long critique of evolutionary psychology, a critique that is surprising for a mainline magazine. Begley beings with a critique of Thornhill and Palmer’s “adaptive rape,” hypothesis, which I also attacked in a New Republic article.  Begley then discusses some data that refute evo-psycho’s more popular claims, noting that these refutations get far less press than the original, sensationalistic claims.

Evolutionary psychology is not going quietly. It has had the field to itself, especially in the media, for almost two decades. In large part that was because early critics, led by the late evolutionary biologist Stephen Jay Gould, attacked it with arguments that went over the heads of everyone but about 19 experts in evolutionary theory. It isn’t about to give up that hegemony. Thornhill is adamant that rape is an adaptation, despite Hill’s results from his Ache study. “If a particular trait or behavior is organized to do something,” as he believes rape is, “then it is an adaptation and so was selected for by evolution,” he told me. And in the new book Spent, evolutionary psychologist Geoffrey Miller of the University of New Mexico reasserts the party line, arguing that “males have much more to gain from many acts of intercourse with multiple partners than do females,” and there is a “universal sex difference in human mate choice criteria, with men favoring younger, fertile women, and women favoring older, higher-status, richer men.” . . .

Yet evo psych remains hugely popular in the media and on college campuses, for obvious reasons. It addresses “these very sexy topics,” says Hill. “It’s all about sex and violence,” and has what he calls “an obsession with Pleistocene just-so stories.” And few people—few scientists—know about the empirical data and theoretical arguments that undercut it. “Most scientists are too busy to read studies outside their own narrow field,” he says.

It’s about time something like this was published in a place where people can see it.   Bravo, Ms. Begley!

Speaking of research whose initial lurid claims get far more press than their later refutation, consider human “behavior genes.” Case after case in which researchers claim to have found genes for depression, novelty-seeking, alcoholism, schizophrenia, and the like have later been shown to be nonrepeatable in bigger data sets, or in data from other populations.  But the failures to replicate get far less media attention than do the original claims.  One example this week: a new “meta-analysis” study in the Journal of the American Medical Association that refutes an earlier claim that a gene involved in serotonin transport causes depression.    (See here and here for popular reports about the failure to replicate).  At least in this case, Newsweek (are they on a good science kick?) highlighted the refutation.  There are, naturally, evolutionary hypotheses about why genes for depression may be adaptive; I discuss some of these in WEIT.

All this goes to show that when it comes to assertions about the genetic/evolutionary basis of human behavior, caveat emptor.