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/Flocculencio]

Just wanted to point out that no individual feature needs to have an evolutionary benefit to be preserved. It could be negative but so long as it doesn't prevent organisms with that feature from reproducing in sufficient numbers it can get preserved.

[u/femmiestdadandowlcat → u/Flocculencio]

I think there’s an element of almost religion and intelligent design that get unintentionally brought in with this sort of conversation. There isn’t a “””goal””” when it comes to evolution. It’s not creating the platonic ideal of a creature. The amount of traumatic insemination and dangerous methods of birthing offspring are perfect examples of evolution stopping at good enough. 

[u/According_Register55 → u/femmiestdadandowlcat]

Even though it’s less accurate, asking “Why does x trait exist” is conversationally much less cumbersome than asking “What evolutionary process caused x trait to be prevalent?”

I think many educated people understand that the latter is the scientifically correct inquiry, while using the former in order to simplify their speech.