By the age of 85, there are 6 women for every 4 men. By 100, the ratio is 2 to 1.
Today in Scientific American, gerontologist Thomas Kirkwood breaks down the science behind these facts.
One of the theories to explain women’s longevity is that men have historically had more stressful lives — hunting, gathering, and so forth. But with that reasoning, you’d think that as the gender gap in working conditions has narrowed, so would the gap between lifespans of men and women. Not so.
Plus, anyone who has taken care of an infant — not to mention the many babies and little kids our ancestor moms probably cared for — knows it stacks up quite nicely (read: it’s harder) with the stress of working.
So what is it that makes women live longer?
The answer probably relates to why we age in the first place, says Kirkwood. Our bodies’ cells are always making tiny mistakes — a little DNA and protein damage here and there — and at the same time, it also repairs cells and keeps us going.
But as we get older, our body gets slower at the repair part, and the damage overtakes the regeneration.
Women, from an evolutionary standpoint, might be less disposable than men, because they need to nurture and feed an infant — our bodies might need to drive more energy towards staying healthy. The same adaptations that have led women to be strong enough to carry and care for a baby might also make them better at repairing damaged cells and keeping ahead of the damage-repair curve.
Kirkwood is clear in saying that men aren’t disposable, though. He cites research about the important role fathers play in producing healthy kids too.
But on balance, he thinks women are better at repair. In fact, some of the biological forces that drive men from a reproductive standpoint — like testosterone — aren’t so good for overall health. And he says (don’t try this at home. not intended for health-promotion purposes) that castration has actually been shown to make men live longer.
More from Heather Turgeon