WASHINGTON—Women, take care: After more than a century of living longer than men, your advantage is starting to shrink. Men are gaining on you.
That's the conclusion of scientists who study the puzzling question of why females generally outlive males in the United States and other advanced nations.
"Women live longer than men for reasons that are still not completely understood," said Richard Hodes, director of the National Institute on Aging in Washington.
But it's certainly changing: A female born in 1975 could expect to live 7.8 years longer than a male. Now the gender gap is down to 5.4 years, smaller than at any time since 1950.
The main reason is that women are "smoking more and dying earlier as a result," said Fred Pampel, a demographer at the University of Colorado in Boulder. Until the 1960s, far more men than women smoked.
There also are other causes—biological, social and behavioral—for the difference in male and female life spans, experts say.
For example, women have two X chromosomes in their DNA, while men have one X and one Y. If one of a woman's X chromosomes is damaged by radiation or toxic chemicals, the other one can take its place. Men have no such safety net and thus are more susceptible to certain diseases.
Men tend to collect fat around their bellies, increasing the danger of a heart attack. Women put their extra pounds on their thighs, which distresses but doesn't kill them.
The female hormone estrogen also may reduce the risk of heart disease in women, said Robert Hummer, the director of the Population Research Center at the University of Texas in Austin.
The male hormone testosterone drives boys and men to "higher rates of vigorous physical activity and physical aggressiveness, which contribute to their higher rates of injury mortality," said Ingrid Waldron, a biologist at the University of Pennsylvania in Philadelphia.
"The gender gap in mortality is probably due more to behavioral and social factors than to strictly biological factors," Hummer said in an e-mail.
"Women tend to behave in more healthy ways than men," he said. "Women tend to smoke less, drink less, use fewer dangerous drugs, use their seat belts more often, drive less recklessly and use less violence than men."
Statistics show that men are more likely than women to be employed in dangerous occupations, such as construction and mining, Waldron said. Gun use is more common among males, leading to higher mortality for gun accidents, suicide and homicide.
"Men die more often from destroying themselves with cigarettes, drugs, alcohol, driving fast," said Royda Crose, the author of a 1997 book titled "Why Women Live Longer Than Men."
"We teach our boys to be strong, independent, never admit you need help, and then they suffer throughout life," Crose, a retired psychologist at Ball State University in Muncie, Ind., said in a telephone interview.
As a result, men are almost five times as likely as women to commit suicide. "Women attempt suicide more often," she said, "but it's usually a cry for help and not lethal. Men just decide to end their life."
Crose said women generally take better care of their health than men, who often put off going to doctors or hospitals when they're sick or depressed.
Men often go downhill when they retire and lose their positions of power, Crose said. "Also, when they lose a spouse, they're really lost. They don't have the same social skills as women or a circle of intimate friends."
Nevertheless, "the single most important behavioral cause of men's higher mortality has been men's higher rates of cigarette smoking," Waldron said.
As a result, the average boy born in 2002, the latest year for which statistics are available, will live for 74.5 years, but the average girl for 79.9 years, according to the National Center for Health Statistics in Hyattsville, Md.
A typical 65-year-old man can expect another 16.4 years of life—a woman 19.4 more years. "The number of elderly women is 50 percent larger than the number of elderly men," Waldron said.
In recent decades, the gender gap has been shrinking. "After widening for nearly 100 years, the sex differential in mortality has over the last decade or two begun to narrow," Pampel said.
"In the 1960s, men's smoking started to fall and women's to increase—they kind of converged," Pampel said. The effects started to show up in the 1980s, when lung cancer started killing women nearly as often as men.
Pampel cautioned, however, that women's advantage in longevity may expand again soon because more women are quitting smoking or never starting.
"The likely decline of smoking among women in the future implies that the recent narrowing of the differential will reverse," he said.
The gender gap used to be much smaller. In 1900, life expectancy at birth was only two years longer for females—who frequently died in childbirth—than for males: 48.3 years versus 46.3 years. Women's lead peaked at almost eight years in the 1970s.
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(c) 2005, Knight Ridder/Tribune Information Services.
GRAPHIC (from KRT Graphics, 202-383-6064): 20050119 LONGEVITY
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