[Eli5] Why do people get bald on the back or front of their head rather than their face, chest or genitals?
In: 35
There’s quite a few good mechanistic answers here. In terms of the evolution drivers there’s a few possibilities.
It could be this is a secondary trait that has been selected for. That is, it might be that being hairier on the chest has been selected for, and balding is just a side effect of the way that the mechanism works.
Or baldness itself could confer a fitness advantage. Given that males of other closely related primates develop obvious physical features to show they are older, you could have the same thing in humans. It might be a social signal to indicate ‘I’ve been around awhile. My genes are good and I probably have decent social standing now too.’
Or it could be genetic ‘drift’. That is mutation over time has resulted in baldness, and although there’s no advantage there’s also no disadvantage, so it ends up a part of the population for no reason except that it happened to occur.
There are probably some other possibilities too.
Edit, typos
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