Richard Dawkins, the flamboyant British biologist who gave us the phrase "selfish genes," now offers a genetic explanation for President Clinton's alleged foibles with les femmes. Our evolutionary ancestors were harem builders (like seals), Dawkins explains, instead of monogamous (like Canadian geese). Any male monopolizing power and wealth also monopolized the females, thus ensuring the survival of his genes. Clinton's behavior is simply a fossilized remnant from our genetic past.

Well, Dawkins's Just-So story may be good for a chuckle. But reducing human behavior to genetics is serious business these days. The latest fad is an updated version of sociobiology known as evolutionary psychology, which seeks explanations for human behavior in our genes. Surprising numbers of liberals and conservatives are eagerly claiming it as support for their own political philosophies.

Why is evolutionary psychology so popular? It promises to fill a gap in the Darwinist world-view: the need for a workable morality. Ever since Darwin, many have recognized that evolution leads to moral nihilism. For example, Cornell biologist William Provine (himself a loyal Darwinist) acknowledges that Darwinism implies "no free will" and "no ultimate foundation for ethics."

But we all experience the angst of facing moral choices, so evolutionists keep trying new ways to fit morality into the picture. Evolutionary psychology claims that by examining our evolutionary history, we can identify which behaviors have been selected for their adaptive value. These provide the basis for a genuinely scientific morality.

Does this new theory succeed in rescuing evolution from moral nihilism? No. The first problem is that any behavior practiced anywhere can be judged to ...