Nothing animates the conversation of women like talk about how they're stereotyped by men. The stereotypes are rarely consistent. Some men still rage at the look of an emancipated career woman with long hair twisted severely in a bun. But he's eager to forgive when she lets it down over a glass of wine and fluffs it suggestively.

Some American men are so disillusioned with changes wrought by radical feminism that they seek an Asian or Eastern European bride through a marriage broker or dating sites on the Internet, egged on by wild fantasies that they'll meet a submissive housewife by day who becomes a wild and crazy sexpot by night. This is not the mail-order bride of the Old West populated by manly men and womanly women. On the frontier, men and women were expected to work hard and were equal opportunity offenders of good hygiene.

But as the city and suburbs replaced the frontier, so did expectations, and women began to work against stereotypes of their own making. You can find them abundantly in the Mommy Wars, where working mothers attack stay-at-home mothers and vice versa. Freud famously asked, "What do women want?" Today women pose that very question to themselves.

Gone is the feminist bravado of sharpshooter Annie Oakley: "Anything you can do, I can do better." Or at least as good. Women are beginning to realize that sexual differences, though not immutable, determine what men and women do best.

Feminist studies still blame the environment (read men) for creating the culture that makes it difficult for them to enter the workplace, but the latest research on male-female differences suggests that the brains of men and women are wired so differently that dramatic sexual distinctions begin in the womb. An appreciation for the maternal instinct is enjoying a revival.

This does not mean that male chauvinists can revert to piggy behavior, suggesting that women return only to a place in the home. But it does allow women to validate their strengths for doing what comes naturally in motherhood.

The scientific phenomenon changing male-female perceptions is a book called "The Female Brain," by Louann Brizendine, a neurologist, all about new brain imaging technology. It ought to help (but probably won't) both men and women find a commonsense understanding of the roots of sexual differences and how to deal with them.

My favorite finding of Dr. Brizendine's is her description of the different way the brains of girls and boys determine thinking about the opposite sex after puberty. The part of a boy's brain that controls sexual thought is twice the size of a girl's. Once his brain is flooded with testosterone, the boy is likely to think about sex every 52 seconds. Surges of estrogen may lead a teenage girl to obsess over her style and her need to look desirable, but that's as far as she wants to go. She buys, he lies.

"It's hard to believe that something as tiny as a little hormone could have such a robust behavioral effect for all of us," Dr. Brizendine tells ABC News' "20/20." Hormonal changes that occur in a woman after she gives birth reorient her behavior toward her husband. "The dad is there only in a supporting role now," she says. "Whereas he is used to being the main course, he's now like a side dish." (But maybe a sweet potato?)

We've long known that women are more verbal than men, but we've only recently established that the female emotional memory is longer. Women use 20,000 words in a day where a man is likely to use only 7,000 (and often says just as much). Add her long memory to his laconic reticence and you can understand how men and women argue differently. A man is nearly always at a disadvantage when a woman recalls every argument they've ever had. He doesn't remember any of them, or so he says.

But men and women change as they grow older. Baby boomers, now entering their 60s, still work out at the gym as a way to stay fit, but the latest trend for seniors may reflect changing hormones and diminished aggression. They're returning to ballroom dancing as an alternative to exercise. Dancing burns from 250 to 400 calories an hour. Membership in USA Dance, a ballroom dancing organization, has doubled to 20,000 members over the last decade. Dancing cheek to cheek to "Heart and Soul" doesn't have the intensity of rocking to "You Ain't Nothin' But a Hound Dog," but it has a soothing intimacy and emotional memory, and it can eliminate some of the 20,000 words that most couples can usually do without. Nature will out.