Ladies and gentlemen, I'm talking about menstruation.
Fellas, I know a lot of us complain about this, and may or may not (but definitely do) yell at you for being so lucky as to have a penis. For us humans of the female gender, we do tend to overdramatize some stuff, but things are really not that easy.
First of all, ever notice how we all get so freaking cold? All the time? It's because our bodies perceive our uteruses (and other internal organs) as being the most important pieces to our bodies. That means when it's cold out, the blood flow keeping our extremities warm is suddenly diverted to our baby makers.
Humans are basically the only animal that truly has a menstrual cycle too. Most other mammals simply reabsorb the lining of the uterus, the endometrium. Chimpanzees, one of our closest relatives, can sometimes shed the endometrium, but it is often absorbed as well, and even more often, they don't have their cycle. Think about it. There's no birth control or marriage in the wild. As soon as a female ovulates, males take notice, and a baby is soon born. Then she must breast feed, which further prevents menstruation, until the baby is weaned and she is impregnated again. Thank goodness for our cultural norms, because nobody should a mom at 13, but it means we get to experience more periods.
But why do we shed the endometrium? I'm in Animal Sciences, and my Reproduction professor explained this phenomenon using words like "placental teeth".
Is that creepy or what!?
Humans have one of the most aggressive placentas in the animal kingdom. There are three main types of placental implantation based off of how many layers of the maternal tissue are invaded. Horses, pigs, and ruminants have it easy; their placentas lay on the surface of the womb digging into no layers. Dogs and cats lose their first two layers, the endometrial epithelium and connective tissue, to help anchor the placenta.
Humans and rodents have placentas known as "hemochorial". You might recognize "hemo" in words like hemoglobin and hemophilia. These words all involve blood. Our placentas invade three maternal layers, and actually tap into the mother's blood vessels. It is theorized that because our placenta rummages through so many layers, we have too much to reabsorb and thus it must be shed, including blood vessels that grow in response to estrogen (hence the bleeding).
I know that's a lot to absorb right now (pun intended). So here's a brilliant thing I found to help explain:
When I was just beginning the wonderful journey of becoming a woman, I remember having menstrual cramps so intense I literally was forced to the fetal position on the floor crying. This is what the medical worlds calls dysmenorrhea. These cramps are caused by your uterus losing its sh*t and contracting too hard, cutting off blood flow and basically suffocating itself. It turns out that birth control is a good method for reducing this pain, along with Advil, heat pads, exercise, and avoiding salty and caffeinated foods.
I won't even get into the crazy roller-coaster ride that is hormones during the cycle. But obviously they cause a lot of unusual behavioral changes.
However, on a brighter note, I can honestly say our species has the most friendly looking penis. I have taken an animal reproduction course. You will not believe the morphology of some of the penes other species have. Specifically the pig, the sheep, and the cat.
- The pig, or boar, is known for having a "corkscrew" penis. It actually locks into a female pig, or sow's, cervix during copulation.
- The sheep, or ram, is unique in that it has an appendage on its appendage, known as the filliform appendage. It's still not quite understood what this thing does. Are sheep aliens? Perhaps.
- The cat, or tom, in response to testosterone, grows keratinized BARBS on his penis. They rake the lady bits to induce ovulation. All I can say is that I finally know why my female cat is so angry all the time...