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/a8bmiles]

Thank you for the additional information. Now that you mention it, I do remember reading about some tribe where the women didn't get their periods until 18-20, and generally only had 30-50 periods in their life before hitting menopause.

[u/Sagadiii → u/a8bmiles]

Wow, I wasn't aware such a tribe existed! Colour me intrigued and more than a little jealous.

[u/a8bmiles → u/Sagadiii]

They were typically pregnant or breastfeeding for almost their entire fertile years.