EDIT: I probably should have said why does *menstruation* last so long
I know every women is different and this doesn’t apply to everyone, but many women experience 2 heavy days, 1 medium day and then 2 extremely light days. How come our bodies can’t rid it all in 3 days instead of dragging it out into 5 with 2 almost pointless days?
In: Biology
First of all, what you are talking about is not the menstrual cycle, but about the menstruation. When you talk about a menstrual cycle you are talking about the whole 28 ish day process for a female body to prepare for a possible pregnancy. With that out of the way, menstrual blood is not just bleed, its endometrial cells that are being “shed” from the uterine walls. This is actually a gradual process as hormone levels drop, and that is one of the reasons it lasts for some days, because the hormone drop is not really that uniform. Evolution could have developed a way to do it in one day quickly if it saw the need to, but if you think about it, that would cause you a great deal of pain as the muscle around your uterus contracts to expell the endometrial cells. So it rather does it slowly and delicately.
The main purpose of the menstrual cycle is make the woman ready to have a baby. The mood swings are just side effects as the hormones that regulate the menstrual cycle changes.
Mine were long when I was a teen and young adult but now they last about 3 days maybe with some spotting the fourth day. So I either don’t use as much blood as I use to or my body is more efficient.
Interestingly enough other than other primates there are only a few other species of mammals that have periods. Most other animals will absorb the blood. Humans have a thicker lining than other animals because our fetuses are greedier than others and burrow deeper into the lining. The extra blood helps the mother ration nutrients so the fetus doesn’t take everything. Also humans are more likely to spontaneously miscarry it’s estimated that more than 50% of pregnancies end in miscarriage most happen before you would get your first period so you might not even realize that your pregnant except perhaps a heavier flow. The miscarriages are likely caused because the embryo was abnormal some how and the mother’s body didn’t want to waste resources bring a non-visible offspring to term. So one or both of these reasons could be why humans have periods unlike other mammals.
If you have seen a dog bleed it is not a period that is a sign of ovulation.
Likely because it doesn’t matter that much that it’s so long. Evolution doesn’t select for the most convenient thing, it selects for the most advantageous thing and if something is annoying but not harmful, it’s not going to selected against by evolution. The reason it didn’t matter to have a 5 day period for most of human development is that periods used to be quite infrequent. With no birth control and with the greater exercise and less rich diet of Paleolithic times, a woman might menstruate 50 times in her entire life. A heavier period might even have meant a greater chance of pregnancy because it discouraged people from having sex when not fertile, meaning more sex during fertile days of the month and greater odds of pregnancy.
I think it is because the uterine lining doesn’t build or breakdown all at once.
I imagine the shedding of endometrium less like wiping off a table, more like peeling wallpaper-there’s layers to deal with.
Before my hysterectomy, I had an 84 day period. So as much as I hate being the it could be worse lady, it definetely could be worse.
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