SciShow Tangents - Hands & Feet

Episode Date: February 8, 2022

The Season 3 finale draws ever nearer, but before we get to that big beautiful Butt episode, we need to make a detour to those nifty tools on the ends of our limbs: hands and feet!Head to https://www.patreon.com/SciShowTangents to find out how you can help support SciShow Tangents, and see all the cool perks you’ll get in return, like bonus episodes and a monthly newsletter!And go to https://store.dftba.com/collections/scishow-tangents to buy your very own, genuine SciShow Tangents sticker!A big thank you to Patreon subscribers Garth Riley and Tom Mosner for helping to make the show possible!Follow us on Twitter @SciShowTangents, where we’ll tweet out topics for upcoming episodes and you can ask the science couch questions! While you're at it, check out the Tangents crew on Twitter: Ceri: @ceriley Sam: @im_sam_schultz Hank: @hankgreen[Trivia Question]Heel-toe or toe-heel runninghttps://pubmed.ncbi.nlm.nih.gov/31525171/[Fact Off]Trench foot and (possibly, tenuously) water balloonshttps://www.ncbi.nlm.nih.gov/books/NBK482364/https://www.wemjournal.org/article/S1080-6032(06)70334-9/fulltexthttps://apps.dtic.mil/sti/citations/AD0666752https://www.sciencedirect.com/science/article/pii/B978012821606400017Xhttp://content.time.com/time/specials/packages/article/0,28804,2049243_2048654_2049039,00.html[Ask the Science Couch]Nail care evolution/historyhttps://www.britannica.com/story/how-do-monkeys-and-apes-trim-their-fingernailshttps://theconversation.com/curious-kids-why-do-we-have-fingernails-and-toenails-110989https://www.floridamuseum.ufl.edu/science/ancient-primates-had-grooming-claws/https://www.sciencedirect.com/science/article/abs/pii/S0047248417305134https://tedium.co/2017/02/07/fingernail-trimming-history/[Butt One More Thing]Bidets and poopy handshttps://pubmed.ncbi.nlm.nih.gov/29709985/ 

Hello and welcome to SciShow Tangents, the lightly competitive science knowledge showcase. I'm your host, Hank Green, and joining me this week as always is science expert sari riley hello and playing the role of resident everyman this week in scishow tangents is our old alumni stephen chin oh yeah i'm an alumnus yeah the only one graduated from tangents university yeah is alumni or alumnus the the singular one alumnus okay in fact i ran into cloacas uh today on a script of scishow uh scishow script um i did not run i did not physically run into a giant cloud of right into a cloaca um and the plural of cloaca is like it's the a, cloaca. Oh. And I said, no, I'm going to say cloacas because this is how language changes. SciShow says it one way, especially before people are exposed to the plural of a thing. Like, nobody knows the plural of cloaca.

If I hadn't told you, I bet you couldn't have told me. And so we're doing it. We're deciding unilaterally that it's cloacas. It sounds better. That's like the same thing with supernova where I'm like, it's gotta be supernovas, but that's not technically correct. Yeah, supernova.

It just sounds better. Oh yeah. The language is malleable. Sari, do you have an opinion on this? You're staying awfully quiet. If there is a cloud of cloacas, what are you running into? A murder of cloacas, what are you running into? A murder of cloacas?

Yeah. Yeah, I would say, just because it's easier for me to say, I like to tack an S on things. Yeah. If I'm staring at a bunch of exploding stars, I'm looking at supernovas. If I'm looking at a bunch of Stephans, I'm looking at Stephans. I'm not looking at Stephan-y. It's the only sensible way. It's just a whole other person.

Yeah. Great. I'm glad we got it settled. So we here are on a podcast. It's called SciShow Tangents. And here on this podcast, we basically, we try to amaze each other and delight each other and also be better than each other at science facts. And we also try to stay on topic.

This episode is not about cloacas, so we're failing so far. But our panelists are playing for glory. They're also playing for Hank Bucks, which I will be awarding as we play it at the end of the episode. Either Sari or Stefan will be crowned the winner. We are right now counting down to our big butt-themed season three finale by first taking a look at some of the less butt-like parts of the body, last week we looked at heads, which are very not butt-like. Unless, you know, certain people may be. But what will we do this week? Well, let's find out with the traditional science poem from Sari.

What is a hand? It's not a gland or a strand. It can help you grip some sand or articulate as planned. But then what are feet? They're made of meat. That's neat. They help you walk on a street or be an athlete. So what is a toe?

Um, a hoof? Oh, no. Or those on a rhino that are dainty and slow. What I'm getting at here is anatomy is weird, and whether front or rear, hands and feet are mere, ends to limbs I fear, and the specifics are unclear. The topic for today's episode is hands and feet. Sari, what are hands and feet? And you're going to be like, I don't know. Yeah, I tried.

I looked at this first. I had such trouble looking at my fact. I had such trouble writing my poem. And it's because hands and feet are freaking weird. So the things we call hands and feet seem to be restricted to human hands and feet or primate hands and feet. Okay. Anything else, it's all feet, kind of. I don't know.

I think a raccoon has hands. Well, that's because they just look little hands, but they don't have opposable thumbs. People say koalas have hands also because they look kind of handy. Yeah, they do hand work. That's just because they look like it. I don't know. Are those really hands? There's no biological line. I think that if you don't walk on them, they're hands. And so T-Rex has hands and feet and humans have hands and feet and kangaroos have hands and feet.

But koalas are a little bit on the edge there because they can do it either way they can walk on their feet or on their hands and feet primates walk on their hands though too so then are those now feet not hands i'm not surprised that you can poke holes in my theories if they're closer to your head and you do hand-like things with them, then they're hands. If they do handiwork. Yeah, handiwork. That's why they call it that. So if we just say hands and feet as one thing, now do we have a rule?

I mean, kind of. It's like the end of a limb is what we call it. Well, and with vertebrates, you have... But this isn't... But then with wings, then you're like, no, no, no, no, no. Bats don't have hands. Or like snakes where everything is kind of vestigial. Then it's like, oh, there's no hand and feet there.

It's just bones. But even if like... I don't know. Because the bats, don't they have like there's little or is it whales that have like the full hand skeleton looking thing inside their flipper but if they broke those bones i guess you wouldn't say they broke their hand bones we'd probably we have you'd say they broke their flipper but you might still say they broke their hand bones like the it's still phalanges which is which but but non-vertebrates also have feet like ants have feet yeah so and that and if an ant can have feet then it's all bets are off yeah you could draw the line between like tetrapods

so tetrapod is like four feet and those are four limbed animals they're all within the phylum chordata so like you could say you have to be a chordate to have feet and that eliminates all arthropods so ants have legs but not feet well what the hell am i gonna call the end of the Legs. Leg ends. Leg ends? They're legends. Yeah. Look at those legends at the end of those legs. All right. Well, I guess I'm going to ask you if we know where the words for hand and feet come from. And I will also do a hand wavy answer.

Hand, uncertain origin. No idea where it came from, which I think is very funny. We just started, like European folks just started using it at some point. What does that look like? Looks like a hand. Yeah, hand. And maybe related to words for like power or control or possession. So in the same way of like the hand of the king or whatever. Not meaning the body part, but also uh a power a seat of power

based on like the actions that you do with a hand which is like taking or collecting or other uh steely things instead of couldn't be sharing but it's always taking and it's always controlling foot on the other hand is like a more logical connection to something that we would have heard of. It's from the root ped, P-E-D, which makes up words like tetrapod or arthropod. So even arthropods which don't maybe have feet in their names.

But how does head go to foot? That's a big leap. That's just how it happens just some lazy chiseling on those old tablets and they were like oh yeah that says foot clearly yeah the middle part of the p got eroded away or like filled in and they were like oh that's a weird one it must be a foot all right well i feel like we've vaguely waved our hands around enough. Yeah. At reality.

And that means that it's time to move on to the quiz portion of our show. This week, we're going to be playing a little game called, Whose Hands Are These Anyway? So this is very much a part of the short tradition of our body-focused month. So last week, we talked about, I described to you skulls. Now you're going to imagine you're on a walk and you're going to see a hand peeking out from behind a corner. The unsettling thing is that you might not be sure what animal that hand belongs to. Luckily, scientists have been doing all sorts of cool experiments to describe

hands and figure out the many variety of types of hands out there. So can you guess whose hand is it? And I'm just going to assign you success by how close you are compared to each other. I'm going to tell you about a hand. It's long. It's thin. It's got creepy looking fingers. It's got a particularly long middle finger that swivels around on a ball and socket joint. These fingers are great for digging insects out of wood,

but they make it hard for this animal to grab onto things. But researchers have found another structure in this animal's hands that help it grab onto things, a sixth digit called the pseudothumb located in the middle of this animal's palms. What animal is it? I don't like that idea. I know, it's terrible.

A palm thumb. Do you have an idea terrible a palm thumb do you have an idea sari i do have an idea i think i've heard of this animal before but i'm i might be going too specific okay i'll go first then i also have an idea but i might i don't know what it sounds like to me is the eye i think that's the animal with the really creepy long fingers. I don't know if it has a ball and socket and it wiggles around in wood and has a six thumb. I don't know. But it has creepy hands, I think. I think I'm remembering the right animal. So I'll go with the aye-aye.

Ooh. All right. Cool. That was the other one that I was thinking, but I couldn't remember which of these two it was. So one of us is going to be right. Oh, good. I'm going to guess a kinkajou uh which i think is very similar in that it has long weird digits and roots around in trees and i think they're both related which

makes sense that they both have gnarly hands but i don't remember which one it is remarkably stefan got it on the nose the ii lem is so rare, it is very hard to study. But researchers were able to study several specimens that had died of natural causes. And one of the things they looked at is a muscle called the abductor pollicis. In humans, that muscle goes from our forearm to the base of our thumb. But in eye eilemers, the muscle doesn't just go to the thumb. It also branches off to the middle of the palm, connecting to a small bone nub called the radial sesamoid.

It's a pseudothumb that moves in three directions and has its own fingerprint. That just seems like one of those mistakes that wasn't bad enough to get removed. It just kept going. I would pay for a second thumb. Could you imagine just like grabbing onto like a set, like holding something and then having your whole hand free to do stuff while still holding onto something? Okay.

All right. I see. Yeah, yeah, yeah. Carrying groceries? No problem. Yeah. Oh, my God. Yeah, like taking all the dishes to the table.

Oh, beautiful. Yeah. Yeah. All right. I'm sold. Okay. All right. Now we're going to go on to round number two.

To understand the evolution of this extinct animal's hands, researchers studied modern-day birds. I'm sold. Okay. All right. Now we're going to go on to round number two. To understand the evolution of this extinct animal's hands, researchers studied modern-day birds. Specifically, they looked into birds' flexible wrist joints, which allowed them to fold their wings while at rest. The researchers looked into this extinct animal's wrist bones and found a wedge-like shape similar to birds, a trait that would allow it to flap its wrists sideways and to quickly sink its claws into prey. I'm going to guess, and this is popular media absolutely influencing me, a velociraptor, like a little small chicken, got little chicken wings, but to sink claws into prey instead of flap around and fly.

Huh. That's a pretty good answer uh the only other thing that's occurring to me which i'm pretty sure is wrong but i'm gonna go with it is the terror bird which like i'm pretty sure it's wrong because i feel like i i don't think the terror bird has wrists by our definition uh more of a bird but but it's got giant claws and it's i think it's an honorable mention so okay well you've taken the brave way out the answer is velociraptor okay they are theropods a predatory dinosaur likely to be ancestors of birds early theropods had straight and inflexible wrists so scientists have been curious how those wrists eventually led to the very flexible wrists that birds have today so birds wrists are flexible, the equivalent of having a wrist that

you can bend your hand so far that your pinky touches your arm. The wrist can't bend in the opposite direction, nor can it fully straighten, and that helps birds fold their wings when they're resting. It also improves their flying efficiency. And when scientists studied the wrist bones of theropods, dozens of species, they found that this wedge-shaped wrist showed up in those theropods more related to birds, including the velociraptor. Do you want round number three? Yes, please. Sure, we gotta break the tie. We gotta break the tie. This animal has dramatic hands, if you call them hands. It has five digits,

including a thumb that extends as a small claw. Scientists compared the development of hands in this animal when it's an embryo to hand development in a mouse embryo and found that while their hand growth looks similar early on, around halfway through gestation, three of the animal's digits begin to grow very quickly, forming the elongated structure we see in its final form. What the heck?

So it sounds like it has three big toes and then two kind of like dinky toes. Three big toes, correct. Or fingers. Fingers. It depends. Yeah, I want it three digits. Yeah. Like the obvious answer, this is not my answer, I don't think,

is like a three-toed sloth. Because it's right there in the freaking name. I feel like I got to go with something more rodent-y. I don't think is like a three-toed sloth because it's right there. It's a freaking name. I feel like I got to go with something more rodent-y. I don't know. Those are my thoughts so far. Well, I'm kind of waiting for you so I can piggyback off your answer and go with something similar because I have no idea. A classic Sam strategy. Okay, I'll go with

an armadillo. Armadillo. Oh, that's a good answer. They're kind of like rodent-y, but like large. And I feel like they, I don't even know how many digits they have.

So they could be hiding any number under that little shell. I've even tickled an armadillo, but I didn't count the fingers. Oh, no. Okay, I'll go with three-toed sloth because I really don't have a better answer. This is terrible news for me because I don't know how to judge it. Because the answer is a kind of bat.

Those are the extra long fingers that you were missing. Their fingers grow very long because they turn into wings. I see. The problem is that sloths and armadillos are really actually quite closely related, which you might not think. Weird. Yeah, armadillos are some of sloths' closest relatives, along with anteaters. So who, but who is more?

It's a tie. Yeah, it's very much a tie. But I have determined that armadillos are more closely related to bats, but not very, very close. But armadillos come out on top. So as for how bats work, they have five forelimb digits,

three of which are elongated and connected with that thin membrane that turns into the bat wing. And over the evolutionary history of bats, the ratio of the size of those digits compared to the body size of bats hasn't changed much, which means that the evolution of the bat wing probably happened quite suddenly. And they sort of like hit the optimum bat wing size. And they're like, we did it. We're bats now. Congratulations. All right. Well, congratulations to all of you. I can't believe you got two of those on the nose.

Next up, we're going to take a short break. Then it'll be time for the Fact Off. Welcome back, everybody. Time for the Fact Off. Our panelists have brought science facts to present in an attempt to blow my mind. And after they have presented their facts, I will judge them and award Hank Bucks to the one I think will be easiest to turn into the best TikTok. And to decide who goes first, though, I have a trivia question. When running, the part of your foot that you land on makes a significant difference in how your body absorbs the impact.

A 2019 study found that when you land on the heel or middle of your foot, your tibia absorbs more of the shock than when you land on the balls of your feet. And that amount of shock increases with speed unless you land on the balls of your feet, then there is no change. So when you land on the balls of your feet and that amount of shock increases with speed unless you land on the balls of your feet then there is no change so when you land on the balls of your feet how much lower is your tibial shock compared to landing on your heels what units are the answer are we looking for oh it's a percentage okay this is the part where sam and i are like we have no clue yeah that's it this is really an excuse for me to tell you a fact and then to know who goes first. Yes.

Give me a number between one and a hundred. Twelve and a half. Twelve and a half. I'm going to go 50. It is 19 point something. I was pretty dang close. Well done. Fitness buff,

Stefan Shin. You know all about tibial impact. And balls of your feet. It is a thing that runners think about, like where you impact on your foot because there's different amounts of stress on the body. So I feel like I had somewhere buried in the recesses of my mind,

some sense of the scale. I was like about one eighth, I bet. Wow. So that's why i went with 12 and a half look at you well that's wild who do you who do you want to go first stefan well i'll go first i guess okay so in the early 1900s a man by the name of dr jacob lowe invented a machine that used the recently discovered x-rays to help him see through people's shoes and see all their foot bones inside and this was intended why didn't he just take their shoes off i'm about to tell you so he was involved in some way with like soldiers coming from world war one and so he invented this to help him process the soldiers faster without having to take off

the boots oh wow because it took too long it's taking so long to get these guys boots off yeah so they had stinky feet i bet too that's also true he hated the stink yeah yeah that was the real reason um but then after the war he's like where else could we use these devices? Shoe stores, eh? So there ended up being a few different companies that made these devices for shoe stores. And they had different names like Footoscope and Pedoscope. They were really common in the 1930s through the 1950s in a few different countries, including the US. And the idea was, and they were sort of marketed as like, get, if you get your shoes scientifically fitted, then your feet will be like way better. Your health will be way better or whatever.

Yeah. Um, and so it's basically just a wooden cabinet with an x-ray tube inside, uh, and a slot where you slide your feet in. And then there's like three different viewing ports on top so that different people can be looking at it. But then by like the late 1940s, they started to like have enough data around like x-rays and stuff to be like, maybe this should be banned. Maybe we shouldn't have these unshielded x-ray devices in shoe stores. And so I think the FDA banned them. More and more states were banning them. But in, and in the States that they didn't ban them,

they were, there were increasing restrictions. So like in some places you had to be, you had to have a medical doctor operating them, which is kind of prohibitive for a shoe store probably. And so they ended up getting phased out over time. And I think the last ones stopped being used in the late 70s uh which they it made it longer than i was expecting a long time yeah to have a doctor

on staff at your shoe store at that point is it a shoe store or is it just a doctor's office maybe it was like a doctor who retired and was like yeah i'll sell shoes on the weekend yeah that makes sense could you bend over and see your own foot bones? Could you like really crouch? I mean, the machine was designed so one of the viewing ports was for the person whose feet were in the machine. Oh, great. So yeah, they thought about everything.

Yeah, because if the doctor looks in there and is like, ah, look, you're metacarpal. And then you're like, well, I guess I just got to trust you. And then no, you look and you see it. And it's like, oh, I'm all messed up. And they're like, you're all messed up. i just gotta trust you and then no you look and you see it and it's like oh i'm all messed up and they're like you're all messed up pay me lots of money that's how you get them or you could be like what's that in my foot and then the doctor is like that's literally how everyone else's bones look you just don't know there's actually a piece in the instruction manual though for these that says it's like we recommend that you don't use these to like diagnose people's feet that if people come in and try to ask you about their foot health you

should send them you should refer them to a specialist for that or something uh so like the manufacturers were like don't use these for medical use this is for this is a sales gimmick guys uh so as the the uh regulations and stuff were increasing the shoe industries was like guys the health risks of radiation is nothing compared to the health risks of having poorly fitted shoes that was their like response to all who have you heard who's gotten foot cancer? That's not a thing. Don't worry. Who has complained about their too tight boots? Everyone. Your dad, your neighbor.

You all the time. Your child, your dog. How does your foot feel? It hurts. Owie. It turns out that the health effects weren't too bad overall. Because most people, you're just going in to buy shoes every once in a while so you're not going to be exposed too much but it was more a problem with the

sales people who are around this all the time and then apparently like children just like after school they're like ah what do you want to do and then they're like let's go to the shoe store and take a look at our feet yeah and so like there was a report of a girl who kept breaking her feet bones doing other things because they had become more brittle from doing this foot things so much um and there was a shoe model who had to have a leg amputated because she got a severe radiation burn and there was like another report of a salesperson that had like x-ray dermatitis detached toenails and ulcers under the nails that's legit i was i wasn't thinking the exposure would be that significant but i guess it makes

sense that it would be yeah well because you could turn them up to like to stay on for like 45 seconds and so i assume if you like these people were like we're going all out we're gonna look at this for as long as possible max power and then i don't know it ended poorly yeah so there were a few incidents but overall the health issues didn't seem to be too widespread but the other thing is they didn't really seem to help people get better fitting shoes either which was the whole point of the device in the first place yeah it turns out that like with the x-ray you can see your bone but there's a lot of flesh around the bone that needs to fit in the shoe also and like the x-rays kind

of don't show you that very well so you know how you see that actually a special scientific device called your fucking eyes it's free 99. Perfect. Perfect. All right. Stefan, that was a great fact. I feel very good about it. Sarah, what do you got for me? I don't feel so confident.

Stefan is coming strong. Okay. In my opinion, one of the most annoyingly uncomfortable bodily sensations is wet socks. I hate them. Your feet feel damp and there's that weird squishy sound and sometimes they chafe.

Some water is fine and you just get pruney, but if you keep your skin too moist for too long, whether from water or sweat or anything, it starts turning kind of a translucent,

kind of mushy color and texture, which is medically called skin maceration. Basically, your skin cells are kind of liquefying, which can lead to more physical damage or infection from pathogens.

And this was and is especially a problem for people who are stuck in wet socks for a long time, such as military folks standing in muddy, wet trenches. And in World War I, so same time, so many people suffered from macerated feet that then got infected that it got a horrible gross name that matched the horrible gross feeling trench foot so people then and now because wet feet remain a problem in many situations have been trying to fight against trench foot a lot of the strategies are behavioral like trying to change into dry socks as often as possible or rubbing water-repelling oils and fats onto your skin. But another bucket of strategies are technology-based, basically making more waterproof socks and boots to protect against cold and damp, but also making them breathable for sweat and whatnot in hot desert climates.

It's a really tricky challenge and is an ongoing discussion for textile scientists today. And here is where I want to add a caveat and where I think I'm going to lose to Stefan because this is going to be the nugget of my fact. But after researching for literal hours across several days, I can't find if this is freaking true. And that's just how it is sometimes. And now I'm sharing the research process so i'm not called a liar okay but according to a time magazine article from 2011 that everyone else in the world cites but frustratingly doesn't include any sources a british inventor named edgar ellington was trying to create a waterproof sock using latex and cotton to help people protect their feet from trench foot he saw a bunch of like thousands upon thousands of soldiers died from trench foot that were

british and he was like gotta create a waterproof sock and when he filled it with water to test it so the story goes it had a leak so he got mad and threw it on the table and it exploded and thus the water balloon was invented and ellington's water grenades were supposedly the first commercial version of these toys and i wish i could say this is my fact because it's so freaking weird but i haven't been able to find a patent any sort of historical magazine or newspaper any evidence that a british inventor that named edgar ellington even existed he might be a ghost someone might have made him up like hank made up joshua everly anthony tripe so i guess my fact is let me know if you find anything about this freaking guy

he used all his water balloon riches to erase himself that the world. That's right. Yeah. Yes. He must have. He's a vampire and he erased himself. Once you invent something, this is a little known scientific fact, if you invent something

as good as a water balloon, you live forever. Whoa. Yeah. You just get the secret key to immortality. You live forever, but no one can remember you.

Mm-hmm. Yeah. Yeah. Yeah. So really what my fact is, is I know that Trenchfoot exists. It's very bad. It's up there on my worst nightmare list.

Water balloons also exist. Uh-huh. And the funniest possible story for the invention of water balloons is that they were a failed sock. Not necessarily true, but the funniest possible i to me it sounds real it sounds real but it is frustrating that you can't even find the guy it seems like something you could find i looked at every possible freaking website even all the ones that looked like garbage

like just reposting old articles from other places, plagiarizing, all that. Does anyone have even a single source? I looked in Google Books. I looked in Google Scholar. I looked like everywhere. And there's really no documented history of latex balloons in general, which I thought was interesting. They just like occurred.

There's one mention of them in 1825 in the Glasgow Mechanics Magazine and Annals of Philosophy, volume two of some guy named Mr. T. Hancock, who glued two pieces of rubber together and then inflated it with air. And that's the earliest latex balloon that I could find. There has to be a person on earth who's obsessed with the history of balloons and there must be or not it's a wide open field well siri i'd like to reward you for your intellectual honesty and journalistic integrity but stephan's fact was really good and i really want to make a tiktok about it also you were very close in the first game. So I think that Stefan is going to come out on top for the episode.

This is why I had to leave the show because I was too dominant. It's true. We were in a race to the top of season whatever, too. Season two. And you won. So I kicked you out. Yeah, yeah. So I could show off my big old brain.

Speaking of, it's time to ask the science couch where we ask listener questions to our virtual couch of finely honed scientific minds. This is from N2OSFORATU on Discord discord who asks how did we take care of our nails before tools i feel like i got an answer yeah go for it that's probably right it's got to be teeth right yeah and also like tools yeah we've been using tools for an awful long time like a stick just doing doing things probably keeps them in check to some extent. We did a lot more working with our hands in dirt and stuff, probably kept our nails a little bit more at bay. But also, as we have proven as modern humans,

you can nibble those things if they get too long. Would you really want to nibble them back in the day? Look, compared to trench foot, it's no big deal. I googled Trenchfoot and looked at pictures of it. I would eat a caveman's fingernail any day. Yeah, you did pretty good. I can just retire if you and Stefan take over. Sam and I can go take a nap.

You can just do the show. But yeah, I did look some stuff up. But that is the gist of what I found. Both biting or picking at it, like any human still bite their nails, and then naturally wearing it down because of doing things with hands, whether it's like fighting or climbing or I don't know, you break a nail doing things with your hands. But what is interesting about this is kind of the evolutionary transition between claws to nails. And I know this isn't the question, but I think it ties into nail care because we think of like dogs and cats of claws they actively um like a cat and a scratching post like actively pick at them and actively like rub them down on other surfaces

to to hone them down but with primates like primates eventually evolved to have flat nails on fingers and toes rather than claws. And there's like a group of like lemurs and lorises and tarsiers. I don't know how to say that one. Have nails on most digits and then grooming claws on their second or third toes, which are like one leftover claw as opposed to all flat nails that they can use to like pick at themselves and whatnot and that is probably happened multiple times in the history of primates but first before we got to all flat nails we had like a grooming claw like a particular claw to do the purposes like

picking at bugs or picking at burrs or other things. But as social grooming evolved, like helping each other out, you don't need a really long gnarly claw to reach around your own back. You just ask someone else for help and then they can use their fingernails, which are good for like picking things, picking up small things, or like prying things off and holding tightly onto things to help you groom yourself which i think is nice there's things i like about having all flat nails and being like look i've i've evolved they're all doing the same job but now that i know that there was a time when we had like some nails and like one extra one that was different. Did we miss out on the universe where we had like a Swiss army knife of hand?

We had like a spoon and we had like a saw. We had a knife. We had to write you our nail. It'd be dangerous. I agree. Easy product. I guess I could strap them on now. Yeah.

A little fingertip prosthetics with like whatever you need on the end. Edward scissorhands. Yeah. And that could be the future of nail care. So the past was we just kind of scraped them on things. Now we have nail trimmers or whatever. And then the future is you just put a cap over your natural nails and don't think about them as you use your spoon finger to do whatever you want.

Spoon finger. If you want to ask the science couch or questions you can follow us on twitter at scishow tangents where we will tweet out topics for upcoming episodes every week or you can join the scishow tangents patreon and ask us on discord thank you to at jerek gora at 42 clocks and everybody else who asked us your questions for this episode if you like this show and you want to help us out it's easy to do that you can sign up at patreon.com slash scishow tangents where you can this show and you want to help us out, it's easy to do that. You can sign up at patreon.com slash scishowtangents

where you can be a patron, get access to all a bunch of cool things. We got bonus episodes where we really sort of completely lose it. We've got a newsletter that Sari writes

a weekly column for. We got our Cars 2 commentary and our Discord. Second, you can leave us a review wherever you listen. That helps us know what you like about the show and helps other people find us.

And finally, if you want to show your love for SciShow Tangents, just tell people about us. Next week, be ready for SciShow Tangents, the butt-stravaganza. Tell your friends. It's all been leading up to this moment. Just widespread. Be like, it's going to be a big butt episode. You cannot miss it. Thank you for joining us.

I've been Hank Green. I've been Sari Reilly. I've been Hank Green. I've been Sari Reilly. I've been Stephen Shun. SciShow Tangents is created by all of us and produced by Sam Schultz, who edits a lot of these with Hiroko Matsushima. Our story editor is Alex Bello. Our social media organizer is Paola Garcia Prieto. Our editorial assistants are Deboki Chakravarti and Emma Dallister.

Our sound design is by Joseph Tuna-Medish. Our executive producers are Caitlin Hoffmeister and me, Hank Green. And we couldn't make any of this, of course, without our patrons on Patreon. Thank you. And remember, the mind is not a vessel to be filled, but a fire to be lighted. But one more thing. As you might know, everybody's a pooper.

And after you do the pooping, we have a few different options for dealing with the dirty butt. So there was one 2018 study that had participants put gloves on and they wiped artificial diarrhea off of a fake butt with four layers of toilet paper to see how much of the poop bacteria was left on the gloves. Then they added a bidet into the mix so they could compare results. And they found that on the bidet gloves, there was almost 64,000 times less bacteria. On the bidet gloves, there was almost 64,000 times less bacteria. So we here at SciShow Tangents cannot tell you what to do, but, you know, a nice spray might be the way. Oh, classic episode, everybody.