Natural selection maximizes gene reproduction, not health. 

The formation of the organism was not aimed at maximizing health or longevity, but at maximizing the spread of genes. Alleles (different variations of the same gene) that increase the number of offspring will spread in future generations, even if they shorten life and increase suffering. And this is not a hypothesis. Half of humanity was formed by selection to “live fast and die young.”

I, of course, mean the fragile floor. Men live on average seven years less than women. Between the ages of zero and ten, in developed countries, for every hundred girls who die, there are one hundred and fifty boys who die. In adolescence and a little older, this ratio is already three to one (three hundred men per hundred women).

Why? The proximal explanation blames testosterone (and its effects on tissues), immunity, and risk taking. The evolutionary explanation is that in
males, in contrast to females, increased reproduction is facilitated by the waste of resources and energy on competition, and not on tissue repair. The male that wins this fight will attract more mating partners and leave more offspring.

This does not mean that only men have to pay on this bill. Women are also forced to sacrifice health for the sake of reproduction, but not to the same extent as men. Selection tunes all organisms to act in ways that increase fitness, even if this leads to poor health and decreased happiness. Have you ever desperately wanted someone, knowing full well that a relationship with this person can turn into a disaster? Most of us have – sometimes with disastrous consequences.

The same applies to the rest of our desires and the inevitable torments from their unrealizability. We crave recognition, wealth, love, admiration, beauty, power. What for? The joy of success is practically balanced by the bitterness of defeat. Our emotions play into the hands of our genes much more than we do ourselves.