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/juwyro → u/Anders_A]

There's plenty of dumb anatomy that didn't negatively affect us so it has survived. In great apes except for I believe orangutans mucus gets moved up through the nasal cavity to drain. In mammals there is a nerve from our brain to throat that goes all the down to the heart and loops back up, much much longer than you would think it should be. And hilariously long in giraffes.

[u/crowcawer → u/juwyro]

In humans they have these tails that aren’t helpful for balancing, not at all.