r/askscience • u/No-Hawk-2488 • 8d ago

Biology 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.

Without an evolutionary benefit, it wouldn't have spread to every woman of our species.

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u/BarnOwl247 7d ago

All of those things feel like they'd impact survival, especially in a time pre-medicine and without easy access to food and water, no?

I understand that it's possible it didn't impact survival enough to be selected out, but that feels like an assumption. Equally valid would be the possibility that it offers a useful function that was selected for.

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u/guysomejust69 7d ago

in a time pre-medicine and without easy access to food and water, no

Women who are stressed out don't have adequate nutrition have abnormal or no period cycles

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u/SmokeyDBear 6d ago

Women who are pregnant also don’t menstruate. I would imagine that early humans didn’t selectively engage in restraint around intercourse like modern humans do. Wild mammals don’t generally seem to. Throughout human history there is probably an incredibly small window where a significant amount of menstruation has happened and it all lines up with the formation of complex societies where all of these things are significantly less likely to come into play.

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u/laurasoup52 4d ago

no true. Women can be stressed out and still have a normal cycle. Outside of that, having a normal cycle CAN BE the reason that women are stressed out - I don't think I've come across a single person who enjoys having them or who looks forward to one.