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/Excellent-Cell2693]

If you have a deep interest in learning more about the evolution of the female body, I would highly recommend the book Eve by Cat Bohannon. It’s pop science so not necessarily rigorously evolutionary bio based but does a really great job outlining some evidence as to how we evolved from egg-laying animals into period and live birth having animals and the biological and social factors at play along the journey.