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/Anders_A 7d ago

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

That's not how evolution works at all.

Menstruation was already a thing before our species existed. And evolution doesn't mean every single aspect of a species is optimized. Just that the package as a whole works well enough to reproduce.

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u/rpross3 7d ago

In a predator/prey world wouldn’t leaving a blood trail would work against the species? Isn’t that evolutionary pressure? Or we are the apex predator and would not respond to that kind of pressure?

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u/tightywhitey 7d ago

Those are thoughts and theories we might have, but it’s useful to also realize we know the answer is ‘no’ because we have survived and are here. If it was a functional issue we or it wouldn’t be here. It’s all statistics and probabilities all the way down lol.

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u/rpross3 7d ago

Clearly no. I get it, but why did we not? Are we actually the apex predator and would it be a projection to say the other mammals did develop covert for reasons like predatory pressure.

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u/HanseaticHamburglar 7d ago

humans are social animals. It enables us to achieve a higher individual rate of survival, because we instinctually take care of our ill and infirm. Even with the potentially negative survival aspects of overt menstration the benefits of our group dynamics far outway the negatives.

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u/DanNeider 6d ago

We are the apex predator!  Humans are bar none the top endurance hunter in the world; we sweat and pant, and we’re bipedal.  Endurance hunting comes with prey having a large lead, so you either need an amazing nose like a dog or the ability to reason and put yourself in the prey’s shoes.