Writing in The New York Review, Richard Lewontin takes up a question that interests me: how the slow pace of adaptive evolution cannot keep up with the rapidly changing human world. Indeed, selection has no chance to operate on traits that do not manifest until after the age of reproduction. Lewontin uses the example of surfer boys who may be susceptible, in the sixth or seventh decade of life, to aggressive skin cancers. The surfers who are resistant to skin cancer do not reproduce at different rates. (They're all alive and potent at 30.) If you were determined to increase the human life span and were given a lot of time to work with, you should consider outlawing reproduction among people under, say, 35. If memory serves, Richard Dawkins makes this point in The Selfish Gene.
Along the same line, it is worth observing that the increase in life expectancy is due mainly to losing fewer people along the way. It is not that the elderly are living longer; it's that the young are. The most intractable diseases are those of old age--partly on account, probably, of the fact that nature cares for your genes but not for you. Once your reproductive years have passed, medical science is not aided in its efforts by an elemental force of nature.
Then there are nearly universal and destructive emotions to consider. If people, no matter how successful and admired (think: Tolstoy), nevertheless feel restless and unhappy, it might be because in the biological past of our species the well-adjusted, happy ones were not roaming the territory, ejaculating in as many women as possible. Genes predisposing one toward quiet and contented reflection did not therefore fare very well. Or, to take up an emotion that seems to have been much on the mind of Will Shakespeare, there is the related case of sexual jealousy. Othello's killed him before he could procreate, and it is the motivating agent in a lot of the sordid crimes reported in the local news. So why hasn't evolution rooted out this harmful emotion? Because in the youthful days of our race, when our character was being formed, the jealous ones were more successful at passing on their genes, and conditions have changed far too quickly for evolution to be of any help. We're stuck with dangerous and violent impulses that, before the invention of criminal law and birth control, helped our forebears pass on their genes to the next generation. It seems lke an impossibly long time ago to us but nature has different measures.
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