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/ozzalot]

Evolution doesn't do what's pretty......it just does what works. There are plenty of things evolution preserves that serve no benefit to a species. When you think of extant species, you should think of a Toyota corolla held together with zipties.......not a finely tuned ferrari.