Women live longer than men. Why? The answer is certainly not that they endure less stress, as was once assumed when men went to work and women tended the home. Nor does it seem to be that women live healthier lives, given that they spend more of their old age in poor health.
Under the pressure of natural selection to make the best use of scarce energy supplies, our species gave higher priority to growing and reproducing than to living forever. Our genes treated the body as a short-term vehicle, to be maintained well enough to grow and reproduce, but not worth a greater investment in durability when the chance of dying an accidental death was so great. In other words, genes are immortal, but the body - what the Greeks called soma - is disposable...
Could it be that women live longer because they are less disposable than men? This notion, in fact, makes excellent biological sense. In humans, as in most animal species, the state of the female body is very important for the success of reproduction. The fetus needs to grow inside the mother’s womb, and the infant needs to suckle at her breast. So if the female animal’s body is too much weakened by damage, there is a real threat to her chances of making healthy offspring. The man’s reproductive role, on the other hand, is less directly dependent on his continued good health.
Women's bodies, Kirkwood hypothesizes, are better at repairing damage and warding off degenerative buildup. He notes there is evidence that castration can help the male body improve in these areas - but he wisely concludes that few "men - myself included - would choose such a drastic remedy to buy a few extra years."
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