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Joining the crowd may be an evolutionarily productive practice. And people will often band together by whatever means available. In a 2001 study, for example, John Tooby and colleagues concluded that no part of the human cognition is designed to encode race as a group identifier (not the case with age or gender). During humans' evolutionary history, the researchers reasoned, people did not often encounter other races. As they showed using team jerseys, categorizing by race is a byproduct of the actual objective set by natural selection: categorizing by coalitional affiliation. (Kurzban et al., Proc Natl Acad Sci, 98:15387–92, 2001.)
Perhaps music serves as a mating display or a means of coordinating social interactions. Maybe religiosity serves as a group-level adaptation, allowing some to persevere over others. Some researchers, known generally as evolutionary psychologists, seek rigorous ways to investigate such complex human traits. In...
KIPLING'S UNINTENDED LEGACY
Twenty-five years ago, paleontologist Stephen Jay Gould and biologist Richard Lewontin3 criticized the so-called adaptationist program, charging that overeager biologists labeled some organisms' traits adaptations without real evidence. Many traits, they said, were actually byproducts, associated with adaptations, but not the result of natural selection. The bridge of one's nose will hold up one's glasses, but it's not an adaptation for such.
This so-called science, argued Gould and Lewontin, boiled down to little more than just-so stories – referring to Rudyard Kipling's century-old children's fables that offered imaginative explanations for certain animals' distinctive qualities.
"That was just a foolish paper," says Wilson. "All scientists deal in hypotheses and in scenarios. That's how they formulate and identify the problem that they hope to solve. [Gould and Lewontin] confused hypothesis formation with what they thought was just empty story-telling."
But as evolutionary psychologists address more complex cultural features, justly or unjustly, they haven't escaped the just-so criticism. Nevertheless, the field has become more accepted. Hires of evolutionary psychologists at psychology and anthropology departments are more common, says psychology professor Martin Daly, McMaster University, Hamilton, Ontario, editor-in-chief of the journal
"What we're after is mapping the properties of universal human nature," explains John Tooby, codirector of the Center of Evolutionary Psychology at the University of California, Santa Barbara, and coeditor of
The evolutionary psychologist's role, explains Tooby, is to identify byproducts
Regardless, whether or not the field can yet claim any significant advances in scientists' study of human behavior is still debatable. Even some practitioners aren't certain how fruitful EP will be. "Except for very few things, mostly to do with sex and violence, there haven't been really any cognitive breakthroughs that are the result of evolutionary psychology," says Scott Atran, senior research scientist at the National Center for Scientific Research in Paris.
Atran, however, calls it a wonderful enterprise with opportunities to generate potentially fruitful hypotheses. But like Darwin's theory when first presented, most of EP, says Atran, currently entails consistency arguments: plausible but unproven rationales. It remains to be seen, he argues, whether EP will blossom into a fecund area of study like Darwin's work or go the way of phrenology.
MURDER, MUSIC, AND MASS APPEAL
The field does have some obvious inherent methodological drawbacks. Focusing on the human as the primary object of study is both a blessing and a curse. Investigators can communicate with their subjects like no other; but resulting data often can be misleading. People are biased and have imperfect self-knowledge, says Daly.
He contends that the field has gotten better at zeroing in on the factors underlying people's judgments. The key, suggests University of Texas evolutionary psychologist David Buss, is to use multiple methods, including observations, physiological recordings, and comparisons with demographic data. Buss is studying the evolution of homicidal tendencies. He's asked normal subjects about the frequency, duration, and nature of any homicidal thoughts they've experienced, but he's also looked at police reports and eyewitness testimonies of 350 known killers. Using imaging technologies to isolate brain functions related to EP hypotheses is also becoming increasingly prevalent.
EP is no more speculative, argue proponents, than any branch of psychology. Indeed, EP may be less speculative since it incorporates evolutionary constraints. One important means of improving the field, says Marc Hauser, codirector of the Mind, Brain and Behavior program at Harvard, is to incorporate comparative animal data, particularly primate cognition data, something that hasn't been particularly commonplace in a human-centric field.
Limits exist as to what can be approached scientifically, says Steven Pinker, Harvard psychology professor and author of
But Hauser and others are tackling the topic. His lab studies consonant versus dissonant music in monkeys versus humans. They discovered that while human subjects preferred harmonious rather than unpleasant sounds, the animals were indifferent. Now, the question: Did a perceptual bias for linking sound structures with emotions evolve uniquely in our species or in other animals as well? "It begins to open the door and point out a method so that you can begin to ask that question," says Hauser, whose group also studies the evolutionary origins of language, mathematics, and morality.
Regarding the evolutionary significance of religious behavior, David Sloan Wilson, in
The scope of EP will likely become clearer as the field continues to grow. "There's a lot of fashion to evolutionary psychology," says Atran. "A lot of people are getting into this because they think it's easy science. And the result is there's so much nonsense. My fear is that it's turning off some of the really good scientists."
Others take inconsistencies in the field in stride. "There's no question there's crap in the field," says Hauser. "But there's crap in a lot of fields."