Somewhere, in most women's conscious or unconscious minds, is the unspoken expectation that, if their marriages or relationships last, they will most likely outlive their partners. They know that their children, for whom they're primarily in charge, will grow up and leave. And they face a barrage of advertising and other societal cues that subtly but ever so steadily suggest that they're not getting older, they're getting invisible.

But whether expected or a bolt from the blue, each loss, each change, each transition, offers a woman the chance to slightly alter course — or even try an entirely new path.

Credit stamina, stoicism — or what researchers call resilience, meaning the ability to come back from serious adversity such as war, rape or the devastation of a hurricane. Regardless of the name, science is beginning to examine its source — a powerful combination of biology, social behavior and psychology, all of which conspire to give women some boosts that men don't have.

Certainly, suffering and change aren't the exclusive domain of women. But this mix of physical and mental stuff that makes a female, combined with a woman's typical life experiences, helps explain how some teenage, poverty-stricken mothers get an education, a job and raise the kids; how some midlife dumpees and young widows are able to dry their tears, roll up their sleeves and learn to change a tire; how some long-cared-for wives learn, when their husbands die, where the money is and how to balance a checkbook.

Those 5.3 bonus years that women, who live to an average age of 80.1, have over men are a mixed blessing, often leading to decreased mobility and increased loneliness. "It's the price we pay for survival," says Barbara Migeon, geneticist at Johns Hopkins University Medical School.

Not only do women live longer than men in the United States, this year, for the first time, the longevity gap will likely become a worldwide phenomenon.

Thanks to advances in maternal care, women in every corner of the globe will outlive their male compatriots, according to projections published in the April 8 issue of the British Medical Journal.

Their health advantage has long been chalked up to hormones. Now scientists are starting to explore the DNA within each cell, and they're finding some protective benefits to having a double dose of the X chromosome, as females do, compared with the X-Y combination that males have.

But biology alone can't keep a human being moving forward through heartbreak. Social and behavioral scientists, too, are finding that the networking skills first picked up in caves and passed on through millenniums of grain- and berry-gathering serve women today in getting through abuse, abandonment, infertility, divorce, widowhood.

The fall of the former Soviet Union in 1991 gave social scientists a tragic laboratory of research material to study gender differences.

"They found that single men were the most vulnerable. On average, they lived about six or seven years shorter than before the fall. Most of these men couldn't find work, they hung out with each other, they drank and smoked and were belligerent," says Shelley E. Taylor, social neuroscientist at the University of California-Los Angeles and author of "The Tending Instinct."

Times were just as tough for the women, but while there was a slight drop in their life expectancy, females didn't die off in droves. Nor did they drink, smoke and fight. "The women created informal social networks. One person would stand in line for bread, another would take care of children while another looked for work," says Taylor.

GENETIC EDGE

A female's biological advantage begins in the womb.

There, the fertilized egg that becomes a girl gets a double dose of the X chromosome, while the egg that becomes a boy gets an X and a Y chromosome. In both sexes, each cell carries the individual's genetic code. In men, that's made up of genes on 22 pairs of chromosomes, and one pair of mismatched sex chromosomes, an X and a Y. It's the same for women, except each cell carries two copies of the X chromosome. Yet no one can survive with two working versions of the X.

"Females aren't allowed to have twice as much gene product, so we turn off one chromosome," says Migeon, whose work on the topic was published in the March 22-29 issue of the Journal of the American Medical Association. "It's random. In half your cells, it's the mother's X, in the other half it's the father's."

So women end up with two types of cells. A number of genetic diseases originate on the X chromosome, such as color blindness, muscular dystrophy and hemophilia. With only one X, boys might get just the defective cells, while girls get a mixture of normal and defective cells — a kind of backup system to prevent some diseases.

The system that protects women from some disorders can also backfire. If one of the two types of cells comes to dominate, the other type might escape recognition by immune system cells that recognize "self," triggering an internal attack. That might be why women are more likely to suffer from autoimmune diseases such as lupus. "There's no proof of this yet, but this is the implication," says Migeon.

Whatever the health problem, women almost invariably discover it sooner. Their bodies send them to doctors' offices regularly for Pap tests, contraception prescriptions or prenatal care.

"Women look after themselves from the age of 11 because they start to bleed," says Sebastian Kraemer, a child and adolescent psychiatrist in London whose research on the flip side of resilient females, "The Fragile Male," was published in the British Medical Journal in December 2000. "A tendency for care is really forced on a woman."

Biology and medical visits get women off to a good start. Then a woman's psychological need to "tend and befriend," Taylor found, can protect her through hard times far more effectively than the much-studied counterpart impulse in men: "fight or flight." The lucky children benefit from the caretaking. But some of those who aren't so lucky, remarkably, figure out how to compensate.

It was Evelyn Gonzalez-Figueroa's mother who tended her two children during a long journey through Mexico from El Salvador, calmed their fears as they were smuggled over the border in a bus and reunited the family with their father in Los Angeles. It was her mother, who, as a housekeeper, networked her way into better housing. She befriended a client who offered a house for rent in a safe neighborhood.

It was her mother, too, who insisted her children learn English within six months, and pounded the message like a drumbeat that there were reasons they took the risks of immigration: a good education and better life for the children.

"We were here to make ourselves better. It was expected. It wasn't an option," Gonzalez-Figueroa says. She now holds a doctorate and does research at UCLA on cultural barriers. She and her family are U.S. citizens. To call her mother's contribution "nurturing" is an understatement.

EFFECT ON KIDS

After 25 years of research and analyzing more than 1,000 studies, Taylor found that early maternal nurturing can have an extraordinary effect on children.

"A mother's tending can completely eliminate the potential effects of a gene," she says. Risk for a disease, such as depression, can fail to materialize, and so can an inborn propensity to crumble under stress.

But females themselves, as early as infancy, start acting in ways that could well protect them later. As babies, they send out stronger signals than males that they're open for communication. "Little girls raise their eyebrows, open their eyes wide, and give people the impression that they really want to talk," says Kraemer. Wanting to talk, and learning to speak about intimate feelings, serves women well for a lifetime, even in the most dire circumstances.

Angela Kennedy, assistant professor at the school of social work at Michigan State University, extensively interviewed 10 young women who grew up in Chicago's ghettos. All of them had witnessed violence, some had been its victims, all were teenage mothers and none had good family support. Yet four of the young women managed to go to school, get jobs and escape the cycle of poverty. One thing they had in common was an ability to connect with someone outside the circle of trouble.

"These are the kids that a teacher or a neighbor is drawn to," Kennedy says.

An innate belief that one is somehow special, Kennedy found, was also a common element in children who work their way out of terrible circumstances.

Genetic research is confirming that some people are, indeed, special. They may have inherited a particular gene that programs them for added resilience in the face of adversity. Simply put, those with advantageous DNA, including what's called the 5HTT gene, bounce back better.

But for those who lack the gene, all may not be lost. MarySue Heilemann, professor in the school of nursing at UCLA, studied 315 women who had emigrated from Mexico. If resilience is in part an inborn personality trait, attitude and circumstance can give it a shot in the arm. "What some theoreticians imply is that you either have it or you don't," says Heilemann. "Even if that's the truth, what if you have a little bit of resilience? Is there something that can boost it?"

Her study found, not surprisingly, that money is a resiliency booster. But the amount necessary to keep on truckin' doesn't conform to the usual definitions of poverty or wealth. "Women who said that their finances were adequate to meet their needs during the last month coped well," she says. Enough money to meet monthly obligations, whether that's a $500 rent check or a $5,000 mortgage payment, can ignite a spark of resilience.

Biology, psychology and instinct can take women a long way. But Heilemann's research is a reminder that, though friends, support and nurturing count a great deal, when a crisis intrudes, even strong, resilient women have to be able to cover the bills.

Men, women and children, for the most part, seek their comfort from women. And, unless the demands become overwhelming, the nurturer's health and well-being are aided by the very act of helping. "If you look at people who give a lot of social support and compare them over time, the givers as well as the recipients are healthier," says Taylor.

So a woman with young ones in tow, or aging parents who need help, or a husband who depends on her for his social and conversational support is getting back at least some of what she's giving.