Is there any advantage to penises and vaginas being so close to the end of the digestive tract? Why does the penis double up to extract waste and make babies?
In: 41
Limited space inside our body. With more than 20 feet of intestines in our gastric tract, which requires the length of the throat as well to enter that, there isn’t much room left at the bottom of the torso to allow waste to leave. As for the penis doubling up, efficiency and hygiene. The vagina is self cleaning and therefore doesn’t require the users intervention in cleaning. The penis does not. When a penis wielder ejaculates, not all of the semen exits, and some remains in the urethra. The bladder is closed off by muscles contracting during arousal, and does not open up until arousal ends. After ejaculation, the bladder opens back up and signals the body to pee so it can remove any semen that was left in the urethra through urination.
Edit: I realize I am only referring to humans in the case of a “torso” but it is generally true throughout the animal kingdom due to the amount of internal organs.
[gastropods](https://en.wikipedia.org/wiki/Gastropoda) have their gonads near their heads. Most vertebrates give birth to either large eggs or live offspring. They have to carry the fetus or egg inside them until they are developed enough to not die which means they need to be relatively large compared to the size of the adults and somewhere that’s protected. That pretty much limits the location to inside the lower abdomen. If it was in the chest cavity breathing would be an issue, especially during birth.
we evolved from animals that only had ONE hole for all purposes except eating. Many animals still use a combined opening for some or all excretory & reproductive purposes.
“why” is not always a good question when it comes to evolution. the answer is “it was good enough for some ancestor (like a precambrian worm, i dunno), it wasn’t bad enough that they all died, so and it stuck around”
Many animals do not have the reproductive system at the end, as they have just one opening for everything, including eating. Sponges dont even have specialised organs, some of their cells just differentiate into gametes
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