After more than a century of living longer than men, the advantage that favors women is starting to shrink.
That is the conclusion of scientists who study the question of why females generally outlive males in the United States and other nations.
“Women live longer than men for reasons that are still not completely understood,” said Richard Hodes, the director of the National Institute on Aging in Washington.
But it is 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 said.
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.
