Alright, let’s get into it. We all have them, we all use them everyday (if not, some more fiber in your diet may be necessary). We’re talking about the butthole, sphincter, the back door, if you wanna be crass: the asshole. When you really think about it, it’s amazing. It’s the end of the line for a system of tubes that break down and process everything we put into our mouths. It dates back to our ancestors to 550 million years ago, and we’ve been spittin’ and shittin’ ever since.
So what came first, the anus or the mouth? According to a recent Atlantic article, nailing this down has been tricky for experts of The Behind. Some scientists believe development happened in perfect synchronicity: just two ends of a tube, stretching out and becoming two distinctly different but useful orifices. Another theory follows the pattern that worms have repeated many times throughout history; the gut develops first and then “punches” an anus-shaped tunnel right through our bodies.
Thinking about this too long gives way to the idea of other possible places for our anuses to be located. Also, there’s potential for many, many more anuses than the one humans have now, similar to the root-like systems of the Syllis ramosa and Ramisyllis multicaudata—which have up to thousands of anuses just bursting through their skin. Jinkies. There is evidence to suggest that our digestive tract followed the example of the reproductive system, which already positioned itself near the posterior. But ultimately, the jury’s still out on exactly how we got them.
While many organisms have an anus in some form, what makes us truly special is not our sentience but the cushiony muscles that surround our anus that we have an innate desire to shake. Our buttocks— that’s the true evolutionary beauty here. The way we developed butts is much more clear cut—they resultied from our bipedalism (thanks for the butt, no thanks for the back pain). Any old worm can develop an anus, but we have something that’s not only useful but plentiful in social constructs.