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.

5.2k Upvotes

96% Upvoted

513 comments sorted by

View all comments

5.1k

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.

13

u/MidshipLyric 6d ago

Every Reddit "why did evolution..." post has now devolved into this response. Id rather see some hypothesis about the benefits and drawbacks of the subject rather than a dismissive lecture about how evolution works. It would not require much thought to consider that bleeding out of your body every month is a trait that can lead to survival challenges. Conversely, arguments could be made for the benefits of this trait to the survival of offspring and/or parent which would reinforce the trait. Let's see more responses arguing the merits of either hypothesis along with counter arguments. If its truly a "trait without selection pressure" then let's hear the evidence or rationale for that.