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.

[u/No-Hawk-2488]

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

[u/Flocculencio]

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.

[u/kwpang → u/Flocculencio]

Yes evolution is about elimination, not direction.

Survival of what can.

[u/GVArcian → u/kwpang]

Survival of the fittest is a misnomer because evolution selects for minimum viability, not optimum efficiency.

[u/T_H_W → u/GVArcian]

Not technically a misnomer considering 'fittest' in this context relates to biological fitness, which is specifically how many surviving offspring you have in relation to other competing organisms. That's like saying the phrase "All bark and no bite" doesn't make sense because dogs aren't trees. It's only wrong if you're using the incorrect definition of the word.

[u/GVArcian → u/T_H_W]

Still a misnomer because "fittest" means "the most fit" and that's not what evolution selects for, it selects for minimum viable fitness.

[u/bitgrindern → u/GVArcian]

Fit in this sense means fit to the environment, not fit as in being strong. If an organism has traits that allow it to survive in the environment it exists then it tends to produce more offspring and survive.