Conventionally, it is assumed that the reason for the remarkably persistent gap between men’s and women’s lifespans is cultural. Men are less likely to seek physical or mental health care when they’re in pain or injured or ill, less likely to get routine preventative care, less likely to eat nutritionally and exercise regularly and floss their teeth and all the rest of it.
However, some scientists suggest that part of the reason for the difference in men’s and women’s lifespans may, in fact, be biological.
Across species, mitochondrial DNA is only inherited from the mother: the egg has all the parts of a cell, including the mitochondria (which has different DNA from the rest of the cell), while the sperm only provides DNA. Therefore, natural selection only screens for mitochondrial DNA that is helpful (or at least not harmful) to females. If a mutation is only harmful to males, then it is passed along– even though it reduces the lifespan of males. That may be part of the reason that the lifespan gap remains so stubborn.
Of course, this is based on a study of fruit flies, so it may not generalize to humans (although there’s no reason to believe that it doesn’t) and we don’t know how large the effect size is. And it’s certainly not to say that we oughtn’t change cultural norms so that it’s acceptable for men to take care of their health the same way that women do (while avoiding forcing men to endure the pernicious body-policing that women face). However, it does suggest that maybe this is another case where biology means that equity is not equality. Just like nearly all deaths in childbirth will be of women, just like most women have to put up with periods or menopause when men won’t, just like women as a whole will be less strong than men as a whole, just like many men can pee standing up and most women can’t, just like most men will get far less input than women about what happens after a child is conceived, men may tend to live less long than women do. The unfairness of biology.