It's no secret that women generally live longer than men, often by as much as ten years. Check out any senior center or nursing home and chances are you'll find more (sometimes many more) women. Widows far outnumber widowers in this country and others. But why is there such a discrepancy? After all, a married couple who live in the same house, eat the same foods, and engage in the same activities should have life expectancies that are equal, shouldn't they?

Perhaps, if you're only considering external forces when it comes to the lifespan. Scientists, however, believe that some of the gender difference in longevity has to do with biological processes, although exactly what they are is unclear. Specifically, women tend not to develop heart problems or suffer strokes until well into their sixties or seventies, unlike men who experience these conditions a decade earlier. For years estrogen was thought to have a protective effect on the heart while testosterone raised harmful cholesterol levels, although recent research reveals that giving estrogen to a woman past menopause may put her more at risk for heart problems, not less. Boston University's New England Centenarian Study data suggest that iron may play a role in the gender gap in longevity. Iron may help cells create damaging free radicals, and since women tend to have less iron in their bodies thanks to years of menstruation, they may have an advantage in that area. Scientists also theorize that the XX (female) chromosome itself may offer more protection than the XY (male) chromosome, but acknowledge that nothing is certain.

More important than biological factors in determining longevity, however, are behavioral ones. And here, men unequivocally fall short. Men do more to bring about their own demises earlier than women do, mainly in the form of smoking, drinking, eating poorly, and getting into car accidents. Older men also commit suicide in greater numbers than women do when they're depressed, and they tend not to deal with stress as well, which may contribute to disease. Adopting better health habits and learning how to manage their emotions can give men a much-needed boost when it comes to moving gracefully into old age.

Sources: Boston University Medical School,; Harvard University Gazette,