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New study: natural selection is getting rid of mutations that shorten human life

posted by Jason Kottke   Sep 11, 2017

A massive genetic study led by Hakhamanesh Mostafavi, an evolutionary biologist at Columbia, suggests that evolution is weeding out certain genetic mutations in humans that shorten people’s lives.

Mostafavi and his colleagues tested more than 8 million common mutations, and found two that seemed to become less prevalent with age. A variant of the APOE gene, which is strongly linked to Alzheimer’s disease, was rarely found in women over 70. And a mutation in the CHRNA3 gene associated with heavy smoking in men petered out in the population starting in middle age. People without these mutations have a survival edge and are more likely to live longer, the researchers suggest.

This is not, by itself, evidence of evolution at work. In evolutionary terms, having a long life isn’t as important as having a reproductively fruitful one, with many children who survive into adulthood and birth their own offspring. So harmful mutations that exert their effects after reproductive age could be expected to be ‘neutral’ in the eyes of evolution, and not selected against.

But if that were the case, there would be plenty of such mutations still kicking around in the genome, the authors argue. That such a large study found only two strongly suggests that evolution is “weeding” them out, says Mostafavi, and that others have probably already been purged from the population by natural selection.