Bleeding, I mean
In: Biology
There are a few other mammal species that menstruate. certain shrews, and some bats. Many other species have similar reproductive cycles, with their endometrium growing with each ovulation cycle, but most just reabsorb the endometrium, rather than shedding it and bleeding like we do.
As for why? Because we evolved that way. so why did we evolve that way? is it a beneficial adaptation? Or is it just a trait who’s cost is low enough that natural selection never eliminated it?
There have been lots of hypotheses over the years, most of which have not been well supported by evidence. They used to think it was to remove toxins, but that was disproven. then they thought it was to protect against STD’s, but that doesn’t seem to be true. The current theory is that it has to do with the fact that in menstruating species, the endometrium thickens before pregnancy occurs. in most other species it doesn’t fully thicken until an embryo has already implanted. so most species just don’t have as much endometrium as us.
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