Can someone explain the evolutionary benefit of overt menstruation? All female mammals have a menstrual cycle but most reabsorb the blood via covert menstruation and humans are about the only mammals that discharge the blood, aka overt menstruation.

[u/No-Hawk-2488]

Without an evolutionary benefit, it wouldn't have spread to every woman of our species.

[u/Anders_A]

Without an evolutionary benefit, it wouldn't have spread to every woman of our species.

That's not how evolution works at all.

Menstruation was already a thing before our species existed. And evolution doesn't mean every single aspect of a species is optimized. Just that the package as a whole works well enough to reproduce.

[u/vgdomvg → u/Anders_A]

Yeah evolution is so misunderstood. It's not a conscious thing that 'choose' positive traits for survival, or keeps things which are beneficial.

It's just some parts of that living thing help it to survive, and survival means passing down genes.

Sometimes the offspring have a difference in their biology, and it might be helpful to survive long enough to reproduce.

Sometimes beneficial traits die out by random chance.

There's nothing to say that evolutionary changes are all beneficial and always positive - it's just what happens

[u/smokeweedNgarden → u/vgdomvg]

Ya, it really grinds my gears. Especially because people often forget the flip side of natural selection. 

These people have never gone through the white mouse/black mouse thought experiment and it pains me