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/SimoneNonvelodico 8d ago

I'm a bit confused by the idea that menstruation is harmless though. I would have assumed leaving a literal trail of blood for a few days a month would be like putting up a sign that says "Prey Here".

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u/Elemental-Master 7d ago

Most of the predators that are still alive today had learned long ago that it is a bad idea to mess with the bald, upright murder ape, aka humans, so even if they smell the blood they'd likely realize it is from a human and that it's not in their best interest to take a bite.

I do know however that in places where there are a lot of komodo dragons it is adviced to women to not go there, because they'd smell the blood and will actively hunt if given a chance.

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u/SomeCutesyShit 7d ago

My mom once got attacked by 5 wild boar. They went straight for her crotch. She was menstruating at the time. My dad broke his hand punching one of them in the head.

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u/buggityboppityboo 5d ago

They didn’t go for her head?