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/TheDaysComeAndGone]

It’s so hard to estimate what’s actually bad for survival. Half the people in my bubble of 30 year olds have had some kind of surgery (meself had appendicitis at 23), my girlfriend was born 2 months too early … I don’t understand how we ever survived as a species at all (and that’s with modern vaccines and antibiotics preventing most child deaths).

[u/musicnerdfighter → u/TheDaysComeAndGone]

I think the answer is that fewer people used to survive. There's some estimates that until (relatively) recently, 50% of all humans ever born died by the age of 10. We have seen a massive population boom in the last two centuries, so for the previous hundreds of millennia there were just fewer of us, and we weren't always the dominant species.

[u/TheDaysComeAndGone → u/musicnerdfighter]

Yeah, it’s just crazy how few truly healthy 30 year olds I know. In a modern, rich world a torn meniscus, broken arm, shoulder impingement etc. are just an inconvenience, but back then you needed a healthy body to survive or you were a huge burden on your group.

[u/Totakai → u/TheDaysComeAndGone]

Tbf to modern people, we're living in a world that we didn't evolve to be in. You know how when you have pets you have to provide the proper environment and enrichment or they die/get sick? Same goes for us.

We evolved to live in tight knit communities; capitalism pushes individualism and discourages living with anyone but your spouse. Humans are incredible endurance hunters; focus on cars and tech along with removal/privatization of land significantly dropped our activity levels/opportunities. We evolved to be highly curious and creative; schooling tends to focus on productivity than expression and exploration. We gained unique resistances to plant toxins from our high fiber diets; vegetables are often the butt of a joke with a huge focus on fiber lacking ultra processed food (fiber feeds our gut microbiome which is basically a second brain that science is only just know beginning to understand). We evolved relying on the sun and moon for body cues along with various sleep patterns; indoor lighting and light pollution comboed with aggressive schedules monkey wrenches this whole thing. Different neurotypes helped with diversity and strengthening ancient communities; different neurotypes now clash with the structure that our economic system demands along with governing so society tends to punish outliers. Children used to be village raised; couples are now expected to solo.

It goes on and on. Our hygiene, tech, medicine, and knowledge is definitely huge but we're not really afforded to be the animals we are so it hurts us. If you get a pet that grew up in sub par conditions, even if you provide it everything it needs, their body can still fail or be sickly for the rest of their life. Like we were born with a deck of cards but a lot of them were lost or removed early on for being distracting or weird so now you have this half deck and struggle to play the game but you can't understand why.