Why do women outlive men? Science zeroes in on answer

Women tend to live longer than men. But it wasn't always that way, a new study says.

Adults born in the late 19th century were the first to see men dying at much higher rates than women. So the gender difference in life expectancy is fairly recent, and probably isn't based on anatomy alone, researchers say.

In medical and public health circles, women's long lives relative to men's have often been considered "a given," said Hiram Beltran-Sanchez, a demographer at the University of Wisconsin in Madison and the lead author of the study published this week in the Proceedings of the National Academy of Sciences. He decided to look back at population data to see whether that had always been true.

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