Let's talk about sex

Whenever a couple of curious kids play a behind-the-woodshed game of doctor, they discover that male and female bodies are different. Later, they learn that nature designed masculine and feminine organs for particular functions, although the specifics can be confusing even for adults. Roseanne Barr says husbands think a uterus is a tracking device. Why else would they ask their wives to locate a milk carton hiding in plain sight in the refrigerator?

Last week, a team of scientists from Duke and Pennsylvania State universities published the results of a study of the X chromosome, which women and men have, and the Y chromosome, which only men carry. The research, part of an international effort to map the human genome, may illuminate some of the biological differences between the sexes, especially, one would expect, those not obvious to recreational investigators.

The hope is that a greater understanding of genes that affect disease might yield new therapies and even cures. That's terrific. But what's much more fun, on the shallow level of talk radio discourse and newspaper column blather, is the influence of biology on personality, the notion that DNA transmits to one gender the ability to belch at will.

Evolutionary psychologists have been beating the Darwinian drum for years, invoking the Victorian scientist's name to explain everything from trophy wives to infanticide. In "The Moral Animal," Princeton scholar Robert Wright illustrates how humans can overcome the sloth, greed, lust and covetousness dictated by their DNA by being aware of which maladaptive traits they're fighting. "We don't understand much about the linkages that ultimately translate from genes to behavior," he says. "Right now, the causal chain between genes and behavior is still a black box."

When the new X and Y studies were made public in the journal Nature, it was widely reported that differences between men and women, on the genetic level, were greater than previously thought. In other words, men and women are not alike. Tell us, oh genetic experts, something we didn't know.

What was heralded as the more surprising finding came from zooming in on the X chromosome. The X, apparently, is one complex little number -- much more complicated than the Y. Therefore, the truth about the aberrant X provides scientific proof that women are different from each other. Forget PMS. A biology-is-destiny believer would conclude that a plethora of genetic variations explains feminine unpredictability.