It leads you out of the maze into a new gaudy lecture-room where MacCann, with one hand on The Origin of Species and the other hand on the new testament, tells you that you admired the great flanks of Venus because you felt that she would bear you burly offspring and admired her great breasts because you felt that she would give good milk to her children and yours. —James Joyce, A Portrait of the Artist as a Young Man
The appeal of evolutionary psychology is easy to grasp. Just think of Annie Hall. The last few decades have left us so profoundly disoriented about the most urgent personal matters–gender roles, sexual norms, the possibility of creating lasting romantic relationships, not to mention absolutely everything to do with family structure–that it's no surprise to find people embracing a theory that promises to restore order. Once we had religion to tell us who we are. Then, for a while, we had Freud. Now we have evolutionary psychology, which, as an attempt to construct a science of human nature on Darwinian principles, marshals two of the most powerful ideas in contemporary culture: science, our most authoritative way of knowing, and nature, our highest ground of moral appeal. No wonder the field is catnip to journalists and armchair theorists alike. Equip yourself with a few basic concepts–natural selection, inclusive fitness, mating choice–and you, too, can explain the mysteries of human existence. That evolutionary psychology has no real intellectual credibility, that mainstream biology regards it as a house of sand, rarely seems to come up. EP is the Malcolm Gladwell of science: facile and glib, but so persuasive and charming that no one wants to ruin the fun.
To be fair, the problem lies less in the field's goals than in its claims. Much of its opposition is misguided and out-of-date. For a long time, evolutionary approaches to human behavior were discredited by the specter of Social Darwinism. More recently, the concept of a unitary human nature has been condemned as a form of bourgeois universalism–that is, of disguised ethnocentrism. But those who reject the notion of human psychology as a product of evolution (that is, of nature rather than culture) would undoubtedly recoil at the idea that human physiology is not a product of evolution. The only alternative is creationism. And if our bodies have evolved, then so have our minds, which a materialist philosophy (one that doesn't depend on supernatural entities like the Christian soul) must regard as products of our bodies–of our brains, nerves, sense organs and so forth. Surely no one would dispute that there is a universal bee nature or dog nature or chimpanzee nature. Why not then acknowledge, at least in principle, a universal human nature, however various its elaborations in culture?
The question is, What does it consist of, how did it arise and can we discover it? Here is where evolutionary psychology falls down. EP claims that the human mind evolved in the Pleistocene, the 1.6 million years during which Homo sapiens emerged on the African savanna. EP seeks to identify apparently innate and cross-culturally universal aspects of human behavior (like speech), then tries to construct scenarios to explain why such behaviors would have been adaptive–would have promoted individual or collective survival and reproduction–in the Pleistocene environment. This all sounds reasonable until you discover that: (1) we don't actually know what the Pleistocene environment looked like; (2) we don't know how our Pleistocene ancestors lived; and (3) we now believe that evolution might happen a lot faster than we used to think, so much of our psychology may not be a product of the Pleistocene at all but of the 10,000 years since the emergence of civilization. There are other problems with the stories that EP likes to make up about how we got to be the way we are. They still have no support in genetics. If something's not genetic, it's not evolved. Also, not all behaviors (or physiological structures) are the result of selection pressures. Some are byproducts of other capacities, as literacy clearly is. Some are the result of functional shifts (insects' wings, for example, seem to have developed at first to regulate heat). Finally, there are some deeply ingrained human behaviors that seem very hard to justify in adaptive terms.