All over the country, men are dying. Every kind of man: rich and poor, blue collar and white collar, men of all races, religions and ethnicities. In addition to sex, these dying Americans share another trait: They are no longer young. How can it be that men by the millions are dying while their female counterparts are not — and no one seems to notice or care?

Overall in the United States, males make up 49 percent of the population. But over age 65, the population is 57 percent female — and starting at that age survival differences by sex become more marked. There are only about half as many males as females among people over age 80, and 81 percent of American centenarians are women. According to the United Nations, women outlive men in all but a few of the over 200 nations and territories it monitors.

These differences in aging between sexes raise some interesting questions: Why and from what are older men dying? Does biology favor females for survival, and if so, how and why? Are we doing something socially, culturally or medically that’s killing men? Or are we not doing something that might help?

Although much of the science of sex differences in aging is relatively recent, the longevity disadvantage of males in older age subgroups isn’t new. Human biology appears to favor female survival. This is not consistently true in other species, leading scientists to hypothesize that the advantage may be uniquely human. At the same time, shorter male lives have not been the reality in all places or eras, so biological sex isn’t the sole determinant of life span: Culture interacts with biology.