I don't think most men like to talk about feelings," an acquaintance of mine said recently. "Gay men like to talk about feelings."

It wasn't an astounding insight, except that it came from a 13-year-old. His mother had been recounting the breakup of another couple's marriage, explaining that the wife had deep feelings but was often lonely because the husband showed little interest in sharing them. The youngster realized this was not just one couple's dilemma. Though barely a teen, he knew from experience that the Mars-Venus paradigm holds a piece of truth--that men and women approach love differently.

Rarely has popular wisdom been studied so extensively or documented so well. Wherever researchers go to study differences between men and women, the same pattern emerges. Men are more open to sex with strangers, more likely to commit adultery, less insistent on emotional intimacy as the foundation of a relationship--and less likely to talk about their feelings.

Is this disparity simply an outgrowth of cultural traditions, as some psychologists maintain, or is it rooted in human biology? There is no doubt that child rearing, education, peer pressure and media models help shape our behavior.

But as science reveals more about our neurological makeup, the power of biology becomes ever harder to dismiss. When you get down far enough, there are few things that are irreducibly male or female. The challenge is to manage our differences--especially those that are toxic to relationships--without naively trying to eradicate them.

In evolutionary terms, it would be very surprising if women and men were not wired for different approaches to intimacy. If your body tosses off sperm cells like confetti and bypasses the burdens of pregnancy and lactation, you can afford to be shallow. Your reproductive potential is limited only by your access to fertile eggs.

A woman, as the keeper of those sought-after eggs, faces very different incentives. The challenge, biologically, is not to find a partner but to find a high-quality partner, and keep his attention throughout the long process of pregnancy and child rearing. Her challenge, in other words, is to forge a relationship and nurture it, fending off a breakup that would jeopardize her huge physiological investment.

Critics often dismiss these arguments as "just-so stories" intended to justify traditional sex roles as biological imperatives. But predictions don't justify anything. They are simply a starting point for deeper inquiry. If you suspect that men and women are wired for different kinds of thought and behavior, one way to find out is to examine the wiring itself. Do male and female brains differ in meaningful ways?

As it turns out, they do. During fetal development, the two sexes encounter different levels of testosterone in the womb. Animal studies suggest that the hormone has lasting effects on the hypothalamus, a small brain structure that influences sexual and aggressive behavior throughout life. Likewise, human studies have turned up sex differences in a frontal-lobe region responsible for emotional reasoning. And researchers have found evidence that the corpus callosum, a massive bridge of fibers connecting the two halves of the brain, may be larger in women than in men. If so, the extra fibers may help integrate the language centers and emotional centers of women's brains, enabling them to verbalize feelings more readily than men.

Whatever its precise underpinnings, la différence lives--and while it's not always something to celebrate, accommodating it sometimes makes more sense than resisting it. If a man forgets an anniversary or neglects to say "I love you," it doesn't necessarily mean his heart is cold. If he finds conversations about "the relationship" as enticing as fingernails on a blackboard, it doesn't mean he is psychologically defective. At some level, it simply means he isn't female.

Women in traditional societies, and traditional women in ours, tend to accept such differences and work around them. They don't expect their husbands to have deep conversations about feelings; they have women friends for that. The woman who tries to make a man into something he is not can succeed a little, but to carry this too far can be folly. Many a marriage has foundered not so much on lack of communication as on unrealistic hopes for it.

That's not to say that our differences are all unbridgeable. Studies find consistently that marital counseling can foster good will and help struggling couples avoid separation and divorce. Men and women may feel things differently and express themselves differently, but we're still capable of learning from each other.

Men have gained immeasurably from the feminist revolution, both as partners and as parents. Those of us who have been coaxed into intimate relationships with our children can now pity the generations of men who missed this sweet and vital part of life.

As for romance, it has figured in Western marriage for more than a century, but we are perhaps the first generation that has endeavored to keep it alive. It will always be a challenge, but we may yet find a way.

This essay first appeared in the June 16, 2003, edition of Newsweek and is reprinted with permission.