A Brief (Scientific) History of Butts

Thanks to Morning Brew for supporting PBS Hello smart people, Joe here. Here is a word that no one would be ashamed to say. However, there are other words that are a little more taboo. Words that no one likes to talk about. Like ASS OR ANUS. Which is a shame. Because the endpoint of your digestive tract is much more than just a door, excrement outlet, or excrement portal. It could be the most important hole in your body. Well Joe, what's wrong with my eyes, my nose, my ears or my mouth? Well, they're okay, I guess? But the tramp has gotten a bad reputation!

It is such an important hole that it is the first part of the body that you grow. The story of the anus is actually the story of how all of Earth's complex animals came to be, from mole rats to the mantis shrimp. A hole to which we owe our existence? Maybe. It's time for us to shine a little light where the sun doesn't shine. "This video contains language such as butt, poop, and anus used in a largely

scientific

context. For our younger viewers and other viewers who still live with their parents, discretion may be advised, although literally everyone poops, so it shouldn't be like that.

It's a big deal, I'm just not trying to punish you or anything, so don't say I didn't warn you... Inside, you're huge, the lazy river of digestion, nutrient extraction, and excretion. waste that connects your body. The mouth to your butt extends about 12 meters. And if it were open, the accordion-shaped surface of that alimentary canal would cover a small apartment, although apparently we are taught not to end a sentence with a conjunction. no one told evolution, because this all ends in a but... t. So what is a butt? You know it when you see it, but can you define it "Butt", as we use it today, for? refer to the fleshy rubbish at the base of our collective trunks, it probably derives from the Middle English "bott", the hindquarters of an animal, and it did not.

It became a slang word for people's

butts

until the 19th century. But the stock is really defined by its most important feature. In Latin, the word anus means ring or circle. The same root that gives us words like annular eclipse, named for the halo of light visible during some solar eclipses. Life comes in all shapes and sizes, but almost all animals share the same basic needs. We have to eat, absorb nutrients and get rid of waste. Some things make it that way. No mouth, no anus. Imagine living life like a coffee filter, digesting everything that passes by.

Or you can level up and get a mouth. Now that you've turned your body into a sack, you can store some food inside, secrete some digestive enzymes, absorb as many nutrients as you can, and expel what's left through the same hole it came in. poop in the mouth. Imagine throwing some Cheetos in your mouth, letting them sit there for a few hours, and blah! This is what you would do if you were a jellyfish. Or anememnomeneme. Or a jellyfish. That's fine if your final position in life is sitting at the bottom of the ocean or floating like a limp mass of cheap spaghetti.

There are plenty of such creatures out there, so it's obviously pretty cool in the eyes of evolution. But if you add an anus, things get really interesting. Don't make memes of that. The origin of the anus was a monumental improvement in the body plan of animals and the way they could eat, digest, and get rid of waste. There is a reason why most animals alive today are basically built like a tube surrounded by flesh and skeleton. Having a through intestine, the anatomical term for a digestive tract with a front and back door, means you can eat again before your last meal comes out, allowing you to extract more energy and nutrients from more foods, giving you allows you to grow more and more. complex body.

Animals that poop outside the mouth sac? They can't do that. And many animals had their guts removed and accessories added! Like different chambers to allow digestion of a wider range of things. And many, from termites to wildebeest to humans, added mobile homes for billions of microbes. These microscopic digestive helpers do the hard work of breaking down wood or grass, or synthesizing critical vitamins and micronutrients. The pass-through intestine even allows you to store your waste until you have a nice, quiet place to leave it. And the longer your digestive tract is, the more nutrients you can extract from your food.

Some animals have developed longer intestines by making longer bodies. Others have kept their bodies small and circled their bellies backwards—yes, that means defecating right next to the mouth. It sounds complicated, but whatever floats your digestive boat. Or you could solve the problem like we did, by rolling up a long, multi-chambered intestine and tossing it into your stomach like last year's Christmas lights. None of these specialized animal forms would be possible without the anus. Because it takes two holes to make a tunnel. Otherwise, it's just a cave. Fortunately, unlike a tunnel, the anus is not open all the time.

It is one of the many sphincters in your body. These rings of muscles have important functions, keeping our digestive chambers separate and protecting them from the outside. While there are six sphincters in the digestive system, the anus is the shining star. Most muscles in the body spend most of their time relaxed. But the anal sphincter is rare among muscles and spends basically every moment of your life fully flexed. Fortunately for that. The anus is also among the parts of the body with the highest nerve density. And for good reason. You must be able to distinguish, by touch, between solid, liquid and gas, and be able to selectively release one, two or perhaps all.

That's not a decision you want to ruin. You're not fully aware of this, but six to eight times a day, a muscle contraction occurs in your body called a mass movement, squeezing out the contents of your colon, like a half-used tube of toothpaste. This contraction can be triggered by eating. And the more you eat, the bigger the squeeze. And eventually, some of those things are pushed into the rectum, the exit hatch of the body. Here, special nerve receptors measure the pressure, and when enough waste pushes against the walls of the rectum, the defecation reflex is triggered.

When you poop, you are not technically “pushing” it. You increase the pressure in the rectum, the walls tighten, the sphincter muscles relax, and... Throughout the animal kingdom, buttocks come in many different shapes, sizes, and even numbers. So what is the BEST butt? Some years serve double duty. When they are not defecating, sea cucumbers use their

butts

to absorb oxygen. One species also uses its anus as a second mouth. True bottom feeders. Reptiles, amphibians, most birds, and monotremes like the platypus have a cloaca, a multipurpose Swiss army knife full of holes, linking the urinary, waste, and reproductive systems...

I guess you could say: a ring to rule them all. But nature is full of exceptions and, curiously, some animals have lost their anus. Brittle stars and many parasites had ancestors with anuses, but they no longer have them. Even the microscopic mites that live on our faces, hiding in our pores and eyelashes, don't have an anus either. When they die, all the poop they have accumulated throughout their lives bursts out, and this microscopic faecal faeces have even been linked to skin inflammation. Does everyone defecate? I do not think. Lies. I'm fine, I'll calm down. Lies! Some animals even lose their anus during their life.

A rare group of scorpions sometimes break their tails to escape predators. They may escape quickly, but in the process they say goodbye to their anus and never poop again. There are even years that come and go. The warty comb jelly looks like a jellyfish but it's not a jellyfish. It has an anus that only appears when it's time to poop, and then disappears, like a ghost's butt. This ocean-dwelling flatworm went anus crazy and sprouted multiple anuses all over its back. And although they don't use bathrooms, I can't help but wonder what theirs would be like. As varied as the anuses of the animal kingdom are, none of them have bones.

So they don't fossilize well. That makes it difficult to trace the beginning from the end. And scientists are still not sure when and how the anus originated. But the origin of your anus is a little more certain. It was the first body part you built. We belong to a class of organisms called deuterostomes. In Greek it means “second mouth” (or really “second mouth”) when you were very young. No, younger. Basically just a small ball of cells, you looked more like a hollow raspberry than a person. Then your cells started folding in on themselves, from right here.

That fold worked its way to the other side, creating a donut-like tripe in the process. And the end of the tunnel that formed first? That became your anus, while the second opening became your mouth. Now you know why they call us “second mouth”. In other kinds of animals, this process is reversed and the part that folds first becomes the mouth. They are called protostomes, which in Greek means "first mouth." But you and I came into the world after the first baby. During the more than three billion year journey of life on Earth, anal evolution occurred independently many times in different branches of life.

They are so old that the butts are more than the holes they contain, and today they do much more than just dispose of waste. Wombats have steel buns that they use as defense, capable of crushing the skulls of their attackers. Manatees fart to maintain proper buoyancy in the water. And dragonfly larvae use their butts as aquatic jet packs. But our butts are also very special. The human butt is the largest in the animal kingdom. Its built-in cushion is made of fat on top of some pretty strong gluteal muscles. And that's thanks to our unique (and very useful) habit of walking on two legs.

Compared to our chimpanzee cousins ​​and prehistoric human relatives, we have a shorter and wider pelvis, with muscles oriented and enlarged to support the weight of our entire upper body when walking and running. Your oversized glutes are the reason you can get up from a chair or stand on one leg. Seriously, ask a chimpanzee to do that sometime. I bet they won't even listen to you. The fat reserves that increase the volume of our buttocks are a little more mysterious. They may have helped our ancestors store energy when food was scarce. But many researchers think it's pretty obvious that they also serve as a sexual signal, since bigger, fuller buns unconsciously signal to potential partners that you're healthy and have a lot of... assets.

A look at our culture's musical, artistic, and fashion tastes makes it clear that butts are something everyone thinks about, but considering how many euphemisms we've invented to avoid talking about butts and anuses, we're pretty uncomfortable talking about them. . Which is a shame. Because now, I hope you realize, from black holes to back holes, the universe is full of wonder. Lastly, remember to subscribe and don't forget to click the button. “What is a but for” you ask? For pooping, you fool. Stay curious. Hey guys, I want to quickly thank Morning Brew for supporting PBS. From Wall Street to Silicon Valley, and everywhere in between, Morning Brew is an aggregated and curated source of news from major media outlets so you can get up to speed in just minutes.

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