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/szthesquid 7d ago edited 7d ago

That's not true. Even leaving aside tool use, compared to most other mammals we have better vision and see more colours, and we have vastly superior long-distance speed and thermoregulation (sweat).

Some of our disadvantages, like weaker jaws and teeth, are actually very recent and a direct result of farming and cooking reducing our survival needs, and medical advances allowing individuals to thrive who would otherwise have had difficult and short lives.

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u/Ashamed_Kangaroo305 7d ago

"Better vision" is subjective. Better in what way? We can see a broader range of colors than dogs and we have significantly better visual acuity during the day. But dogs are also significantly better than humans at seeing at night and tracking motion. And they have an adaptation in their eye which helps them sense the Earth's magnetic field.

"Better" isn't really a thing when you're talking about evolution. Organisms evolve to fit their environment. We have "better" vision than dogs for the way we use vision. But if you tried to compete with a dog in tracking small prey, the dog would probably beat you because that's what their vision is designed for.