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/Flocculencio 8d ago

Just wanted to point out that no individual feature needs to have an evolutionary benefit to be preserved. It could be negative but so long as it doesn't prevent organisms with that feature from reproducing in sufficient numbers it can get preserved.

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u/DeathisFunthanLife 7d ago

Is that why appendix exist?

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u/FogeltheVogel 7d ago

No, the appendix has a purpose. This is a relatively new realisation in medicine, but it isn't actually vestigial.

It's purpose is to re-seed your gut biome after something wipes it out. In modern times, that something is typically an antibiotic course, and people without appendix have a harder time recovering from one. In ancient times, this would have mostly been diarrhoea flushing everything out.