Why Haven't Bald Men Gone Extinct?

By Jamie Condliffe on at

Lots of men worry about losing their hair. But instead of fretting about their beauty, it might make sense for them to count their blessings—because, by rights, bald men should probably be extinct by now. So why aren't they?

New Scientist has taken at look a that particularly interesting question in a wonderful feature, that tries to get to the bottom of why baldness should still be so widespread amongst the males of our species. From the article:

The hair on our heads may protect us from the noonday sun, maintain body heat when it is cold, and even attract a mate. If so, men who lose their hair are at a disadvantage, and you would expect natural and sexual selection to have weeded them out. So why haven't bald men like me, or at least our versions of genes, gone extinct?

One early stab at answering this question rested on the idea that a man's genetic predisposition to baldness is found in genes he inherited from his mother. Since she would not have suffered baldness and its concomitant ill effects, natural selection would have no cause to remove these genetic variants. But think about it carefully and the logic fails - mothers are just as likely to have sons as daughters and every time they do, if these males are less likely to procreate, these variants should become rarer. In any case, science has shown that this mother-based hypothesis is wrong.

Instead, scientists have recently been positing many theories about why baldies aren't dying out—and most revolve around making some attempt to argue that baldness offers some kind of evolutionary advantage. Some researchers suggest, for instance, that it signals dominance and status, while others suggest that it shows people that they offer maturity, wisdom and nurturance.

Or maybe, just maybe, there's a physiological explanation. One recent study rather boldly suggests that baldness allows more sun to penetrate through the skulls of aging men, in turn diminishing the odds of developing prostate cancer. That's interesting, sure, but also completely unproven.

In all honesty, nobody knows for certain why bald men still exist, any more than they can account for your pinky toe hanging around. But I can heartily recommend the New Scientist's article as a fascinating—and entertaining—journey through some of the more interesting hypotheses. [New Scientist]

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