carnie-vorex:

bettsplendens:

zoologicallyobsessed:

Menstration cycles are different to estrous cycles. During estrous cycles dogs may have some blood discharge. This is not a period or menstruating. 

Estrous = eggs are being released, it is now time for babies. 

Menstruation = inner lining of uterus is being shed to remove improperly attached eggs, it is time for NOT BABIES. 

We’re a very unlucky species T_T Though maybe sentience comes with a curse, which doesn’t have to be logical bc it’s a fucking curse.

Humans menstruate because human pregnancies are very hard on the body. Humans have one, rarely two or three, comparatively massive babies, which take a long time and a great deal of energy to bring into the world. Menstruation happens because, since pregnancy is so hard, it’s vital to start out with a healthy fetus. Therefore, the wall of the uterus is difficult to attach to, to make sure that only strong embryos can latch on. If an embryo takes hold, menstruation stops. If no embryos take hold, menstruation occurs to remove any unfertilized eggs and dead (too weak) embryos from the wall of the uterus. I’d imagine it’s the same deal for the other mammals that do the same. By contrast, dogs and cats have many small, relatively easy babies, so it’s less of a problem if a weaker embryo attaches and then fails to gr ow to term, so there’s no need.

Or it’s a curse.