Normally, a person looses around 40ml of blood per period with people having 450 periods on average in their life. This means that on average a person would loose 18l of blood from menstruation alone. With the average human having between 4.5l and 5.7l, you'd only need to sacrifice 4 people to the menstruation gods to never have to shed blood for that ever again. ~~In my experience, it works best when sacrificing transphobes or terfs.~~
As a quick side note: I hate it when someone refers to it as a "pseudo-period". The hormonal cycle is very very real, I can assure you that.
I believe humanity is still very naive about our own brain, hormones and pheromones affect wildly understudied.
I am convinced every person regardless of sex have cycles running all the time, its just usually a lot more subtle and blended in with everything else affecting us.
There might even be an argument that female menstruation is only so pronounced because there was an evolutionary benefit to having a basic understanding of reproductive patterns.