SciShow Tangents - Sweat

Episode Date: July 23, 2024

Woo boy! It's hot out there, why don't ya grab a nice glass of ice cold lemonade and listen in on everything you did and didn't want to learn about sweat. Are humans the sweatiest of them all? Do fish sweat? What lives in the ecosystem between two people holding hands for the first time? What is it all even for!??SciShow Tangents is on YouTube! Go to www.youtube.com/scishowtangents to check out this episode with the added bonus of seeing our faces! Head to 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! A big thank you to Patreon subscribers Garth Riley and Glenn Trewitt for helping to make the show possible!And go to https://store.dftba.com/collections/scishow-tangents to buy some great Tangents merch!Follow us on Twitter @SciShowTangents, where we’ll tweet out topics for upcoming episodes and you can ask the science couch questions! Sources: [Truth or Fail]Sweat sucking spiders supplementing salts Polar bears follow sweaty paw paths in search for loveA new bacteria-infecting cure for extra stinky sweaty feet [Trivia Question]NASA’s ECOSTRESS measures evapotranspiration aka plant sweatinghttps://www.jpl.nasa.gov/missions/ecosystem-spaceborne-thermal-radiometer-experiment-on-space-station-ecostresshttps://www.jpl.nasa.gov/news/watching-plants-water-use-is-no-sweat-for-ecostress[Fact Off]Charles Blagden experiments with “super-sauna” that cooked steak but made humans sweathttps://publicdomainreview.org/collection/experiments-and-observations-in-a-heated-room-1774/https://www.jstor.org/stable/106218?seq=1https://royalsociety.org/about-us/who-we-are/history/Antiperspirant made with propylene glycol that evaporates your sweat before it leaves the ducts [Ask the Science Couch]Non-water stuff in eccrine sweat (salt, urea, hormones, etc.)https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6773238/https://pubmed.ncbi.nlm.nih.gov/12817713/https://www.penn.museum/sites/bulletin/1733/https://ontarioarchaeology.org/wp-content/uploads/oa048-02_macdonald.pdfhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC5941775/Patreon bonus: Effects of stress/emotion on sweat composition and smellhttps://onlinelibrary.wiley.com/doi/10.1111/j.1467-2494.2007.00387.xhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC9518869/https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9246182/[Butt One More Thing]Treating hyperhidrosis in the perianal region with botoxhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC8436621/https://pubmed.ncbi.nlm.nih.gov/11172190/ 

You're listening to a Complexly Podcast. Hello and welcome to SciShow Tangents. It's the lightly competitive science knowledge showcase. I'm your host Hank Green. And joining me this week as always is science expert and Forbes under 30 education luminary, Sari Reilly. Hello. And more importantly, it's our resident everyman, the adorable Sam Schultz.

I think I'm more important too. Thanks. Hi. I think a really important question that everybody needs to know is, do you guys have a grocery store? I was told when I worked for Walmart that it was like 10 times harder to get somebody to come to a new grocery store than it was

to keep somebody coming to the Walmart. So if we ruin that relationship with that customer, that will be, it'll be 10 times harder to ever earn that trust back. And it's amazing that they were giving me that level of responsibility, but they really did. Have you had your trust earned by a grocery store? Does that mean you have to screw up 10 times worse

as a grocery store to mess up the relationship too though? And I don't think so. I think you can mess up very easy. This is in general, a phenomenon of trust. It's all about building the trust bank and it's very easy. This is in general a phenomenon of trust. It's all about building the trust bank and it's very easy to spoil it. I despise going to other grocery stores than the one that I go to.

You have like one that you love? Yeah, I go to food farm, of course. Like any normal person should go to a food farm. Even though it's a disgusting place. It's not disgusting. Has bad selection. There's the free, there's like the weird food shelf. Not free food shelf, but the weird food shelf in the back. There is a extremely inexpensive shelf

that is next to the weird food shelf. Yes. Where you don't get to choose what's on that shelf, but whatever it is, there's something wrong with it. And it's basically free. Nobody else wanted it for some reason. They also have a really cheap meat area. They're like, this stuff's about to go, you guys.

I like the plastic bags of basil that they just pin up next to the other herbs and vegetables. It's like, this came out of someone's backyard and I love it. Who knows where that stuff came from? They could do almost anything and I wouldn't stop going there. That place is so great. And currently they have the best chicken sandwiches I've ever had in my life.

I don't know if you ever. I do have those chicken sandwiches. Yeah, no, I try to not eat them because they're so good. I think they're dang good. They're so good. They're even good like at the end of the day when they've been sitting around for five hours. Totally.

But there's other objectively much better grocery stores in town, but when I go to them, I'm just like, I don't like to be here. I like to be at Food Farm. I like to be at Food Farm as well. Have you ever gone to the bathroom at the Food Farm? No, I'm scared to. I've looked back there and thought,

I know that I've seen people go back there. I've been like, what's gonna happen to you? I've done it. As you'd expect. Everywhere I've ever been, I've gone to go back there. I've been like, what's gonna happen to you? I've done it, as you'd expect. Everywhere I've ever been, I've gone to the bathroom. How is it? It's a lot, it feels intimidating. It's like, all right, you've welcomed me

into the inner sanctum, I must respect this space. You're in their house. It's clearly not meant to be for normals. I feel like I'm being trusted with a sacred space. It's just for all of the painfully cool, disaffected teens who work there. Yeah. Sari, do you have a grocery store in Boston?

Well, I'm kind of like by where I was raised, a Costco loyalist, which listeners of the pot know. Oh, of course. Kirkland Washington, Kirkland Brand, Costco. Wherever I go, I have a Costco membership. You are a Kirkland Brand, basically. Yeah, I am Kirkland Brand. As far as like local grocery shopping though, we have to drive a little ways to go to a Costco.

It's like 30 or 40 minutes away. Oh, wow. That's a lot. We used to be a Wegmans household because my partner's from upstate New York. And so land of Danny Wegman, we would go to Wegmans. But now we don't live by Wegmans anymore either. So now we're stop and shop. We've switched to loyalties based on convenience.

But I think the one in my heart is Costco, where we will drive a distance to go to Costco as opposed to other big box warehouses. Yeah. I'm kind of equidistant to a fancier grocery store that I would never, ever switch allegiances to. I met people who used to work at that grocery store and then opened a similar grocery store in Boston. Oh wow. Yeah, because they were missing the bulk food section.

There aren't a lot of like bulk places to buy in Boston. And so now. Bulk food always seems like a bit of a magical mystery to me because you like it doesn't come As I mean, I guess it arrives as bulk food in that it arrives outside of as much packaging But it still arrives in boxes and stuff like it still comes in packaging But I get to pick I get to pick exactly how much I want the problem with that is I actually always pick more than I want

exactly how much I want. The problem with that is I actually always pick more than I want to. What do you think the largest amount of like loose nut you can ship is legally? Like a big box. I don't know. Somebody listening, somebody listening has to know the largest amount of loose nut that you can ship.

You can join our Patreon, join our Discord, message us there, but we do need to know what is the max loose nut. Yeah, subject line, loose nut, all caps. I bet it's different for different nuts. Like a shelled cashew is probably very different from like unshelled walnuts. Tariffs are gonna get you for sure though.

I bet you could fill a shipping container with just loose nut. If you were brave enough. If you're made of stern enough stuff, you can. Yeah. When I say I wanna buy in bulk, I mean I wanna buy in bulk. If you're able to tell us how much a shipping container full of loose nut would cost.

Also, I'd be curious to have that information every week here on SciShow Tangents. We get together to try to one up a maze and delight each other with science facts while also trying to stay on topic. Our panelists are playing for glory and for Hank bucks, which I will be awarding as we play. And at the end of the episode, we're going to have a winner. One of these people is going to win a game. But first, as always, we're going to introduce this week's topic

with the traditional science poem this week. It's from Sari. I'm going to hide you guys, because I think for this to be funny, I'll have to do it really earnestly. And I can't look at your face. I love you, but I cannot look at your faces or my own. And Tuna, you know what to do. Why do we sweat? Why do we sweat? Why do we sweat? I would like to talk about skin All those glands there Excluding stuff from within

Why do we sweat? Why do we sweat? Pretty weird stuff to be honest Well some is oily Some is wet It is salty, it comes out when there's a threat Why are we sweet? Why are we sweet?

Super weird somebody uh Haha! That's the only word he didn't say I would like to someday understand And we will leak, we will, we will perspire, we will I would like to someday understand And we will see if we will, and we will ooze Why do people sweat?

Why do dogs sweat? Why do horses sweat? Why don't fish sweat? Why do people sweat? Why do you wear sweat? Why don't fish sweat? Why do you sweat? Why do you have sweat? Why don't snakes sweat? Snake... Wow! A sciency musical interlude!

You know, there are actually a couple different kinds of sweat glands in humans at least. We have Eccrine glands, which produce watery sweat, and apocrine glands, which secrete oils and other stuff in your hair falling. Well, starting around puberty. Oh, my time's almost up. Gotta go! I would like to talk about skin. When we get hot, we drain stuff from within. Pretty weird somebody else. Now it gets swept up

By the breeze I get cooler And my heat starts to ease Sweat, sweat, sweat, sweat Pretty weird somebody up Well I would like to Someday understand

And we will leave We will, we will perspire We will, I would like to someday understand And we will lead, we will, we will perspire, we will I would like to someday understand And we will see, we will, and we will ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo Why do monkeys sweat? Why do camels sweat? Why don't birds sweat? Why do people sweat? Why do hippos sweat? Why don't frogs sweat? We can do it

That's all you got That's all? That's all? That was the whole song This is a 4 and a half minute song It is a long song. It is a long song. Can I ask you, can I ask you real quick a couple of questions? What exactly were you saying in the, in the little parts?

Oh, I just was making that half that song is just made up words. And so I said pretty weird and then Zubba da da and then super weird zub-a-da-da. I kept with the same syllables so that I wouldn't mess it up too much. Yeah, pretty funny to change every single word of the song except that one word. That would be funnier. So the topic of the day is sweat,

but before we get into that, we're gotta do a quick ad break and then we'll be right back All right, Sari welcome welcome back. What is sweat? Though I feel like we're going to be- Sing the song again, Sari. Cue it up. We're going again. I'm done, right?

I can leave the podcast. I like exerted all my energy for today. Dogs and cats sweat? Yeah, dogs. I've heard that dogs just sweat from the bottom of their feet. Is that right? That is right.

Yeah, so humans are the sweatiest animals and some monkeys and apes in that we have sweat glands all over our bodies. Are you joking? We're the sweatiest animal. Does that surprise you at all? I'm constantly. No, I guess not. There's a lot of ways in which we're like there's going to be a sweatiest animal. Yeah. And there's like never seen an animal anywhere. One animal. No, I have never seen an animal as wet as a human playing basketball.

Yeah. Yeah. So we're, we're pretty sweaty. And yeah, sweating is found in a wide variety of mammals, but mostly in other monkeys, apes, cats, dogs, it's on your paws. And I think they have apocrine glands there. So those are the ones that are watery but also more oily. And there's like a scent component to that, right? Yeah. And those oils also have a scent component to them. And anal glands on cats and dogs, I was looking up, also have modified sweat glands in them.

So those secretions, those pheromone secretions are also sweat adjacent. Well, I mean, where does the line get crossed? Though like is like are spiders sweating out silk? I don't think so. I think there is a fuzzier one. Are people sweating out milk? We are not sweating out milk. We're sweating out mostly water. Other guys sweat out milk, though, don't they? But like milk is mostly water.

It's the act of... So like, I think milk... Milk is sweat. Milk is maybe African glands too, is milk sweat? Milk is sweat. Milk is sweat. Milk is sweat. This is gross. They're modified sweat glands. Oat milk isn't sweat.

That's why you have to drink oatmeal. You're drinking sweat otherwise. Are you kidding me? Yeah, I guess milk is modified sweat. I think you can say a cold milk. You're drinking sweat otherwise. Are you kidding me? Yeah. I guess milk is modified sweat. I think you can say a lot of secretions are modified sweat. And when you talk about hippo sweat, that mucousy stuff that is red and irony is from subcutaneous glands. So they're kind of like sweat glands, but they're not exactly the same as sweat glands. And it's not exactly the same composition.

So sweat, generically, is a term that means anything you kind of secrete on the surface of your skin. But then when you dial down to it, I think a lot of the ways that we define sweat is in relation to humans. Yeah, yeah, because like all this like apocrine, like oily, like excretions isn't, like what I think of sweat,

I think of like the stuff specifically designed to cool off my body. Yeah, and so that's the eccrine glands. That's the watery, I think of like the stuff specifically designed to cool off my body. Yeah, and so that's the Echring glands. That's the watery, salty majority of glands in humans. We have like two to four million sweat glands found all over our skin, our palms, our feet, the hairy skin, like on top of our head, whatnot. And then there are some more recently discovered

and by more recently, 1987, as opposed to like 1800s, apoechrine glands that kind of act like in between where there's some watery, some oily and we don't really know. But we're just seeping. We're seeping all the time. We're seeping from all over the place all the time and other animals seep less. Horses I know get sweaty. They get frothy or something, right? Horses get frothy. Yeah, they have a protein called latherin, which acts like a surfactant, like soap.

And that's why they get frothy on top. And I think it's specifically so that they can wet their fur. So they are pretty wet as far as animals go, but they wet their fur so that it can evaporate and cool them a little bit more. So they are all over sweaty in ways that many animals are not. Right.

I'm gonna go ahead and hold on to the potential reality that horses are sweatier than people. I don't wanna be the sweatiest animal. I think it's fun. All right. Superlatives are nice, but we already got a bunch. You know, we got so many things. There's some other stuff we don't have like,

like jumping and running and stuff like that. Like everybody else is so much better That's a most of that stuff than we are that I want to be wet. It's okay to be wet I like that, but yeah, well fish are wet, but they just don't sweat. They don't count You know what I mean wet on land wet on land. I'm wet on land, baby. Yeah And sweats an ancient word it must be an ancient word. It absolutely is. Yeah, it's been basically the same throughout English and Germanic languages,

as far as we know, from the Proto-Germanic language. It was Switas, basically sweat. And then it was just various versions of sweat, or sweat spelled with an O, like swat, throughout Old English, Middle English. Oh, I'm SWATty. Yeah.

And for some reason in Greek and Latin, there are two different forms that I think came from the Proto-Indo-European Swede or sweat, so it came from the word for sweat. But in Greek, it became hydros or hydros, which means sweat. And you see that in anhidrosis or hyperhydrosis, which are like, you can't produce very much sweat or you produce excess sweat. And then Latin, it's suitor, which is like Spanish suitor. And if you have a medicine that causes sweat, you call it suitorific or a suitori.

So we have, again, Greek and Latin words sprinkled throughout medicine. Those are the only ones, despite being everywhere, that don't kind of sound like sweat. But as far as we've been talking, sweat's been the word. Well, and then also the, I don't know, the country of Sweden comes from the word sweaty.

Sweatin'. Because they're just very sweaty people. They're sweatin' over there. They are the sweatiest humans. The sweatiest humans. I don't actually know where Sweden is. One's own, referring to one's own, referring to one's own tribe from the tribal period,

says Wikipedia. Thank you for correcting the record, Sari. It is now time to move on to the quiz portion of our show. Would you guys like to play Truth or Fail? Okay. You have no choice. Along with the wonderful cooling effects of sweat, often comes some strong smells.

And while sweat is initially odorless, it does not stay that way for long. And what is a place that produces quite a bit of sweat? You know it, it's our feet. So today we're playing truth or fail sweat edition where I present to you three stories about stinky feet, but only one of them is true. You ready?

Okay. All right, story number one. If you ever found spiders in your long unused running shoes, they may have gotten there because of the sweat. There is a jumping spider in East Africa that supplements its sodium and moisture intake by consuming human sweat. There is a jumping spider in East Africa that supplements its sodium and moisture intake by consuming human sweat. In order to test this, scientists set up two separate clusters of these spiders. One was regularly

provided with freshly collected samples of human sweat. The scientists found that the spiders that were deprived of the sweat became tired and unable to reproduce, which they attributed to a lack of sodium. Oh, that's good Ian. But that might be fake. It might be story number two. Polar bears traverse a vast amount of sea ice within the span of a year, around 200,000 square miles of it.

They also spend most of their time traveling alone. So how is it in a space that big that they happen to come across another bear to potentially mate with? Well, polar bears have a relatively high concentration of sweat glands in their feet that leave behind unique secretions on the sea ice, so scientists have hypothesized that male polar bears rely on these sweaty paw paths to track down possible mates. That's cute. That might also be fake. They're into feet. So maybe it's number three.

They're into feet. They're not the only ones. I don't know. Oh, God. Yeah, that didn't sound like it's one of us. Okay. Okay. Another mammal with a sweat gland covered feet is people.

But have you ever noticed that some human feet are out there just being extra specially stinky? Our sweat from gland secretions is initially odorless, but undergoes a transformation into that body odor stank from bacteria metabolizing the sweat product. So the research team from the Osaka Metropolitan University Graduate School of Medicine

sought to discover what it was in specific people's sweaty feet that made it such a powerful odor by sampling the skin microflora in body fluid samples from men's feet. Among other odor-causing precursors was the bacteria Staphylococcus hominis, which they were able to eliminate with a serum containing onion and peach extracts. So is it story number one, the sweat sucking spiders supplementing their salts? Story number two, polar bears following sweaty paw paths in the search for love? Or story number three, a new bacteria infecting cure for extra stinky sweaty feet

The spider one sounds so familiar to me. I think there are a lot of insects that supplement their diets with other stuff Yeah, for sure. They're always hanging out in mineral rich pools We think that like oh mosquitoes bite but like every you got to get your sodium from somewhere You got to slope up whether it's from like poop on any scale animals crave that mineral Polar bears we just talked about paw pads and how they got a little sweat I think I don't know about bears, but I think a lot of mammals do it's like their paw pads are the sweaty parts I don't know how long things would stick around on the ice though that that is what's giving me pause

To how any animal find each other, how animals find each other, there's not a lot of them. Well, they do. I think they do a lot of things. Like koalas rub themselves on trees. Like trees feel more like a stable place to rub your odor. It could seem like, does Leeloo rub herself on the edge of a corner or something?

She's trying to tell her friends where she's hanging. Yeah. Yeah. The pee, poop, yelling. They yell to each other a lot of the times to be like, I'm here. It's a mess. I mean, it's not easy. It's ridiculous that we have made it so complicated.

But it's just like genomic mixing is so useful that you got to do it. And the last one I bet is like, onions make your pit stinkier. You know, something like that. I don't know, that one was just too much. I couldn't, I couldn't. It was really specific. Yeah, maybe too specific or maybe exactly as specific as an actual thing would be.

I don't know. That's what I don't know. It could be a different body part. It could be the same, but it makes sense. Like onions are kind of sulfury maybe. Oh sure. I don't know about peach though Maybe there's like a sweetness this makes it sound like I'm the guy who likes Each feet yeah, peach is nice, but also a little stinky sometimes

Yeah, get it like I feel like it is can be I don't know if I can hang with you on that one I think the polar bear one seems wrong, but I'm going to go with it anyway. I don't know. There's just something about it that's so simple. I'm going to go with the onion feet one just because I feel like... That's a great one. Bacteria eating oils is what makes it stinky. And we just found out what the stink is maybe.

Well, fact number three was indeed inspired by the movie holes. No. Boo. What? They had a foot stink curing product called Sploosh. And the movie is made from a mixture of onions and peaches.

Oh, wow. Oh, I was just talking about holes too, damn. I was just talking about holes. Should have been watching holes, not talking about holes. Yeah, I was talking about how I had seen it and a friend had and I was like, it's so good, you gotta see it, I better watch it again. You're a fake holes fan was like, it's so good. You got to see it. I better watch it again. You're a fake holes fan.

Yeah, so good. Story number two is true. The polar bears might also purposely tread on their urine in order to include it in their scent paths. Other kinds of bears tend to use things like biting or scratching trees to mark their territory, as we talked about. But the lack of such things in the Arctic sea ice led polar bears to other sweatier methods.

Hmm. Good job, you guys. I over thought it. You've been made a fool of, Sari. It was based on a movie. I know. It does feel mean, now that I said it out loud. You lost all, whatever. The spiders do not feed or eat the human sweat,

but they are attracted to it. They are the only known predator that specifically targets blood carrying mosquitoes as its preferred prey. And since those mosquitoes are attracted to our sweat, the scientists went on to see if these spiders were attracted to that human odor. So they indeed are, They sniff out our sweat.

They're also sweat bees. They're a different little bug. And they actually do eat human sweat for the moisture and the salts. So it's a thing that can happen. You guys sweaty? I'm sweaty. I'm always sweaty.

I guess. I guess we're among the sweatiest animals on earth. I bet I'm in the top percentile of sweatiness too. I think I'm above average also, sweaty wise. As a person who grew up in Florida and moved to Montana, I feel like I'm never sweaty because I used to be wet all of the time. So now I'm like, it's like 80 percent humidity in Missoula. I'm like, oh, hey, big, wet.

That's like four days of the year. Yeah, I I get really I get sweaty when I get nervous. Unfortunately, good things just sweats. Are you nervous right now? I'm always nervous. It's us. It's around. Not the yeah. Yeah, I have sweaty hands and which did not help my self-esteem.

And then I did not date in high school, but when people touch my hands, but you're so sweaty and I did not help with my self-esteem, my self-confidence. Now I've just accepted. I've reached acceptance that I'm sweaty. But yeah, there's that there's that like holding hands time where it's like, you both really wanna let go, but like, you feel like you can't and it's just like, become a whole ecosystem in there. Yeah, I don't hate you.

I'm just so wet. My hands are just so wet. I don't hate you, I'm just so. We have to stop. So Sam, you got a point. Next, we're gonna take another short break, then the fact off. ["Fact Off Theme Song"] All right, everybody, it's my favorite part of the show.

Get ready for the fact off. Our panelists have brought in science facts present to me in an attempt to blow my mind. And after they have presented those facts, I'm going to pick which one I like the best. And then that person is going to feel exceptional and special. And the other one's going to feel just awful. It's terrible for the whole rest of the week. But to decide who goes first, I have a trivia question. So we were talking earlier about how plants can't sweat,

but they kind of can, because there's evapotranspiration, which moves water through the plant and converts it into water vapor. And in that process, both the plant and the land they are on gets cooled. And NASA has on multiple missions studied that evapotranspiration gets cooled. And NASA has on multiple missions studied

that evapotranspiration as a gauge of surface temperatures in agricultural areas. One mission that ran on the ISS from 2018 to 2023 was called the Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station or EcoStress. An EcoStress used a high resolution thermal radiometer to track evapotranspiration to measure both the surface temperature and water vapor emissivity of various areas

in primary temperate agricultural zones on Earth. The goal was to get increasingly precise measurements of how water availability impacts surface temperature and plant health. How precise an area could eco stress measure with its radiometer? Let's do it in square meters. Twenty. 200. Good job everybody for guessing quickly. The no idea. Uh, 200. Good job, everybody, for guessing quickly. The answer was about 2,500, sorry. Oh, God.

Good job. Um, the actual size is 130 by 230 feet. It's about 2,500 square meters. It's about half the size of a regulation soccer pitch. Also, plants can regulate how much they sweat through their stomates. So if the soil is too hot and dry, they can close those down to prevent evapotranspiration

and ultimately conserve that water. Good job, you little guys. They're so smart. Good job, plants. I would love to be able to do that. Be like, I'm anxious, but I gotta conserve. I gotta suck up my hands really quick. Like, give me 10 minutes.

I got to hold hands with a babe. Are you kidding me? I can't be sweaty right now. I got to hold hands with this hot tamale. So suck it in. Terry, what you got me? What you got me? So a couple men, a dog and some raw steak and eggs sat in a room

heated anywhere from 110 to 260 degrees Fahrenheit. The proof of point. And this is not a locked room mystery anywhere from 110 to 260 degrees Fahrenheit to prove a point. I did it. This is not a locked room mystery or the setup to a very weird joke. It was a series of experiments on heat transfer and thermoregulation that showed how humans are very good at keeping ourselves cool, in part because of sweat. This was in 1774 and 1775 when the word scientists didn't really exist. And instead, lots of wealthy white male natural philosophers

who were fellows of the Royal Society of London would do experiments because they could and then talk about them. So many of those scientists don't grace our textbooks, but they were there doing science all the same. Like Dr. George Fordyce, who quote, procured a suite of rooms. And those rooms were heated by fiery ovens in the floor. And he invited some other mence who quote, procured a suite of rooms and those rooms were heated by fiery

ovens in the floor and he invited some other men over to quote, observe the effects of air heated to a much higher degree than it was formerly thought any living creature could bear. And this, I'm not a guy, so this is like a normal hangout with guys being dudes, right? That's pretty much what we always are doing. Yeah, we're cranking up the electric heaters and we're sitting in the room until we can't sit in there anymore. Cool, good to know it's been happening

since at least the 1700s. And the main documenter of these experiments was Dr. Charles Blagdon, a British physician who also participated in the room sitting. Their first few trials started at lower temperatures like 110 to 120 degrees Fahrenheit where they would stand in a hot room and just measure how hot they got

with a thermometer under their tongues or in their hands or in their pee. Also normal things you do with your bros. This is important. Honestly, this is important stuff to do. We don't know how bodies work. Let's get them hot and see how hot the pee gets. See how hot the pee gets with your buddies,

the other doctors. Oh yeah, pee is the pee important. Okay, anyway. And then you compare how hot the pee gets with your buddies, the other doctors. Oh yeah, pee is the pee important. Yeah. Okay, anyway. And then you compare how hot your pee gets, like does my pee get hotter than yours? Who's pee gets hottest? Who's pee gets hot? Get embarrassed because your pee is the coldest pee. Oh boy. I don't know, maybe that's winning. I don't know. Yeah, you got really powerful thermoregulation. So they repeated trials with increasing temperatures to 140, 210, or 260 degrees Fahrenheit, where they got really sweaty,

but their body temperature stayed around 100 degrees max. The heat felt worse when they moved around than when they stood still, and the heat felt better with clothes on than when they took their coats and shirts and whatnot off. So you just get half naked with your bras and then see who gets hottest or not. Half. We should bet it's half.

Yeah. And then you pee. But even in that trial where they took off their coats and shirts, Blagdon wrote, quote, after five or six minutes, a profuse sweat broke out, which gave me instant relief. So they basically concluded from these experiments that they phrased it like the body has a power to destroy heat, and that sweat played a considerable role, though it wasn't the only thing keeping them cool.

They also tested, as I said in the setup, a dog by putting it in a 220 degree room in a basket to protect its little paws for about 30 minutes, checking on the basket every so often. And they noticed that it didn't sweat on its body. They like put a thermometer there and they were like, there's no sweat, but it did pant a whole bunch and a lot of saliva pooled around it.

So they were like, this is the equivalent. And to prove they weren't cheating and the room was actually hot, they stuck some eggs and beef steaks in there. The eggs cooked in 20 minutes and the different beefs were dry after 47 and 33 minutes. They were grilling they invented Yeah, the dead stuff cooked the live stuff stayed cool it'd be interesting if They're like they put the steak in there and like and also steaks apparently can keep themselves cool

First doing the science, you gotta test it. You gotta test it. And so basically they did a lot of weird sweat experiments to learn things, which I'm sure, like different people knew intuitively from saunas and whatnot, but these guys wrote it down

and their papers are really funny. So they get some credit. I have several questions. I have maybe some answers. There are a lot of weird quotes. Yes. So did they have some thought about what was causing them to cool off? I think they thought it had to do with sweat.

Well, yeah, yeah. And I think they maybe had some ideas about evaporation. There was another experiment that was less funny where they put in water and then water with wax over the top to see how the water evaporated. And so I don't know if they knew exactly about heat transfer out of that because they were also saying that their breath was cold

when they blew on their finger. But they were getting somewhere in the, there is a transfer of heat going on and something to do with like sweat out of our bodies is affecting how cold we feel. My second question is, so like there's there's that like, age old question of like, who would you most want to have dinner within the world? But I think a better question is, who would

you most want to have a hot sauna sweat pee within the world? Like if you could have a person be a part of your pee, naked pee sweat experience. If you had to compare the temperature of your pee with one other person after spending 20 to 40 minutes in a hot room with them. This is the new hot ones. Jesus, of course. Obviously.

I mean, I would do, is this weird? I would do it with you guys for the content. We could say like, we got some pee. I'm not peeing with you guys, I'm sorry. I won't be. I will be peeing with you guys. Wow. Yeah. Wow. Sarah and I are ready to going with you guys. Wow. Yeah.

Wow. Sarah and I are ready to be with each other. Yeah. Sam, we've only been podcasting together for four years, five years, whatever. We've only known each other for like a decade. You can go into the corner. Okay. Okay.

If I can go into the corner, there's nobody I'd rather do it with What I will say is there's not anybody above you If I have to do it I might as well do it with my good friends and then we can eat some eggs off the Floor when we're done. Yeah, we can have steak and eggs hot Hot for ouchies hot for ouch, dry steaks. All right, Sam, can you beat that? If I had to guess, I would say that sweating is for the most part a good thing to do. It cools you down. It probably does a bunch of other good things too.

I thought we'd have talked more about them at this point, but does it do other good stuff, but cool you down? Oh, is that a real question? It mostly cools you down. And like- That's plenty of that. I don't know, smells can be good. But when a lot of people think of sweat, they don't think of it as a positive thing. They picture a wet stinky armpit bleeding through their dress shirt when

they're giving a presentation in front of a big new client. How embarrassing. You'll never land that contract with sweaty pits. Luckily, antiperspirant was invented to help people sweat less. Put super, antiperspirant was invented to help people sweat less. Put super simply, antiperspirant is deodorant that has aluminum-based compounds in it. These compounds stop sweating in a couple of ways. They react with water to make some kind of gel plug that clogs sweat ducts, and also the compounds,

the aluminum just kind of gets stuck in the ducts, clogging them up, and now you're dry. But antiperspirants are pretty controversial in some circles. The idea of putting aluminum salts directly in your sweat gland is pretty visceral if you think about it. So it makes sense that maybe people will be worried

about it and the safety of antiperspirants is a constant topic of debate, scientific study and scary myths. I don't have any business weighing in on the antipperspirant debate, so I will just leave it at, some people don't want to use anti-perspirants. But maybe some of those people

who don't want to use aluminum-based antiperspirants still don't want to be sweaty. So what are they supposed to do? In 2020, a team of researchers at Virginia Tech were thinking about just that problem and they had a thought. Your sweat is already full of all kinds of crap like urea and calcium, and even a salt that isn't aluminum salt.

Salt! And all of this stuff could, in theory, plug your ducts just as well as any other solid. But wouldn't you know it, it's all dissolved up in your sweat, so useless for that purpose. So what this team decided to do was devise a way to evaporate sweat before it left your sweat ducts, thus leaving behind all of the minerals and junk in your sweat, clogging up the ducts with all the natural stuff. So in order to do this, the team created what they call sweat rigs, which were just really like thin glass tubes that emulate sweat ducts by having fake sweat pushed through them by pressurized gas. Isn't it crazy what we have to do to make like the body, like what the body does, we got to be

like, so right outside of the exit of the glass sweat ducts, they put down a layer of propylene glycol, which is I think the stuff that fog machine fog and vape juice is made out of, but it's also super attractive to water. So as the fake sweat seeped out of the tubes, the propylene glycol sucked the water out of the sweat, effectively drying up the sweat and leaving behind all of the crusty gross stuff which clogged up the sweat duct. So they did it. Now on to human trials, they said in 2020, but I couldn't find anything after that. So it worked on a bunch of tubes. Yeah

Of course aluminum salts might not really be that bad for you in the first place and also in researching this I started to Go down a rabbit hole of people who said that Propylene glycol is really bad for you, too So I guess the great what to put under your armpits debate will continue to rage on forever. When I was in high school, I got a giant clogged sweat gland in my armpit. I've never used antiperspirant since then. Really? Was it because of that or was it? I have no idea. It might not have been, but it was uncomfortable and I thought I had cancer, which is funny because it turned out at one point in my future,

a giant lump in my armpit would be cancer I mean, this is this is such a like I hear about this for some reason all the time I don't know if I just randomly run into people who talk about it, but yeah, I've heard like urban legends about it I've heard like there's like I was in medical school and I cut open a guy's armpit of a cadaver and it was just Just full of deodorant and I was like no of deodorant. And I was like, no, that's not the thing. It couldn't be, could it? No. I also, I feel like it was in my health class.

They were like, don't use antiperspirant with aluminum in it. And so I was scared. I was scared straight from that, you know? It's scared straight from the stuff that they sell at the grocery store. Yeah. That's what I needed to be scared straight from, you know, me in high school.

Yeah. As long as you can get like if you if it's rebellious to use antiperspirants, then maybe maybe they won't go on to the harder stuff like cigarettes. So I I have to choose between a couple of minute dog and some raw steak and eggs that got in the room, they got naked, peed a little bit and stayed pretty cool. Or Sam's of clogging your sweat ducts with your own sweat crusties solving a potential antiperspirant problem, but only potentially because no research seems to have been done since 2020.

It's good, Sam. It's good. But ultimately, what is twice as good is a butt-to-toot in a sweaty room with a steak and eggs, torturing a dog and peeing. Yeah. I know. I love early science so much. People just like figuring stuff out in all the weirdest possible ways.

You went into it and with the lead, Sam, but ultimately, I think Sarri pulled this one out. She sang a whole damn song. She also sang a song which we don't give points for the poems anymore, but it was very good. Really wanted to make my friends laugh this time. I don't know. I feel like we've all been going through it a little bit. The funniest part was when you started the second verse.

So. Ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha We've got a listener question for our couch of finally owned scientific minds Tannerbot 2k on discord and Koniko kagi on Twitter asked how much waste do we release with sweat? Ie I was told there is some urea in sweat. What else is in it? Which other electrolytes or less expected things? That's an interesting question. I always hear And I I always am kind, maybe due to my own bias, discount this, that you can sweat out toxins. And I'm just sort of like, my brain says, okay, I know roughly how sweat glands work.

You pump ions across a channel, and then it draws whatever is in the cells down the concentration gradient into the space of the sweat gland that is outside of your body. And in that world, what I am imagining being drawn across the membrane is a hundred percent water. But maybe that's not the case. Maybe there's some stuff in those cells that isn't just water getting drawn across that gradient. I have no idea.

Yeah, there's like some stuff in sweat, but I think from most of the literature and I also am coming in with the bias of I'm skeptical of miracle cures or other things like that. Like the idea of like this is how you get rid of the toxins in your body when it's like no like you have a whole bunch of mechanisms for that and we're that are very good at doing that. And also the idea of our bodies being full of toxins is definitely a scare tactic that people use to make you be afraid that something is wrong with you and nothing is.

And that's what I mostly found in the literature of the papers that I read, which I don't know, peer reviewed seem trustworthy, is that sweat does contain a lot of things. Like there are measurements of uric acid, of urea in sweat, in addition to the water, the salts. There are probably some hormones in there, there are probably some, like whatever is in

your blood plasma has a chance of making it into your sweat because it gets excreted from the pores and then some stuff gets pulled out before it reaches the surface of your skin. That's the whole point of glands is that you secrete some stuff and some glands squeeze extra stuff in, some glands, cells pull stuff out. There is some urea and whatnot, but compared to the systems in our body that are meant to get rid of waste and toxins.

So in the case of pee, like your kidneys, in the case of poop, your gastrointestinal track, your liver does a lot of filtering and whatnot. Sweating excretes so few junk molecules relative to everything else. And in fact, if you are excreting a lot of urea through your sweat for some reason, something's probably wrong with your kidneys, like go to your doctor if you think there's something wrong with your kidneys. But that's the only situation that it would be coming out of your body a different way,

because you already have a way to get it out. You already have your way to get like the waste products out of your body. And so in these studies where they measure sweat and they measure the concentrations of molecules and whatnot, the evidence of selective toxin excreting is pretty lacking. And even though there are studies that are like arsenic,

cadmium, lead, and mercury in sweat, a systematic review that review a bunch of studies, a lot of them recommend at the end of like, we need to research using appropriately sized human trials. And so there's like some evidence that in some people you find an equivalent amount of heavy metals in sweat as their pee or poop, but it's not, I don't know, not like significant enough.

That being said, the whole idea of like sweating out toxins, it's obviously been around for a really long time. Like sweat baths have had a presence historically in lots of indigenous cultures, like North American, Central American, South American groups. We found like Maya and sweat baths and whatnot. And it appears to be some combination of like hygiene practices and social practices, sitting in a hot room with your bros, like goes back a really long time, but also like spiritual practices, right?

So I think that it is a little bit reductive and a little bit new agey to say the only reason to sit in a hot room with your friends is to release toxins, especially when there's not a lot of scientific evidence, but that's not to negate, maybe you just like it, and you feel less stressed sitting in a sauna and sweating it out. And that can be good for your health in other ways that don't have to do with what is specifically being excreted out of your body. You can just feel relaxed with your pals

as you pee together, half and half. For clarity, usually in saunas, you don't pee. Yeah, I've never actually been in a sauna, so who knows? I might one report. I've been in like one and I didn't pee. I saw so. You did. In case you missed our announcement from last episode,

we're doing a new thing for our listeners on Patreon. We're going to answer a bonus science couch question. Sam, what is the second question? At orbitingwombat on Twitter and at ChloeLily8833 on YouTube and Sky on Discord and many others asked what is it that makes sweat from stress smell different than sweat from exercise? When I'm done playing Fortnite, I stink. I'm telling you what. That's like gamer sweat.

Those Fortnite sweats. That's why Fortnite stink, yes. If you want to hear the answer to that question, as well as enjoy all new episodes, totally ad free, you can head over to Patreon. That's patreon.com slash SciShow Tangents. At our $8 a month tier, You get new episodes ad free and extended shenanigans as we answer a bonus Science Couch question every episode. Also, you get a link to our private Discord server and maybe some more goodies in the future. Who knows? Also, we can keep making the podcast, which I love. Our patrons are amazing, and we are so grateful for you for supporting the show. If you want to ask the Science Couch your question you can follow us on Twitter at SciShowTangents

or check out our YouTube community tab where we will send out topics for upcoming episodes every week or you can join us on the SciShow Tangents Patreon and ask us on our Discord. Thank you to everybody who asked your questions for this episode. If you like this show and you want to help us out super easy to do that first again patreon.com slash SciShow Tangents. You can become a patron, get all that stuff that we just talked about. Shout out to our patron, Les Aker, for their support. Second, you can leave us a review wherever you listen. That's super helpful, and it helps us know what you like about the show. And finally, if you want to show your love for SciShow Tangents,

just tell people about us. Thank you for joining us. I've been Hank Green. I've been Sari Reilly. And I've been Sam Schultz. SciShow Tangents is created by all of us and produced by Jess Stembert. Our associate producer is Eve Schmidt. Our editor is Seth Glicksman. Our social media organizer is Julia Buzz Buzio. Our editorial assistant is Debukhi Chakravarti.

Our sound design is by Joseph Tuna-Menish. Our executive producers are Nicole Sweeney and me, Hank Green. And of course, we could not make any of this 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! Botulinum toxin A is produced by a bacterium and can be dangerous because it blocks the neurotransmitter acetylcholine from being released, which is a key part of how nerves signal other things like muscles. But in carefully applied doses, it's used cosmetically for medical treatments, and you might know it better as Botox.

In addition to de-wrinkling faces by paralyzing muscles, Botox can prevent signaling to sweat glands to help treat patients with hyperhidrosis, or excessive sweating that is impacting their quality of life. And there have been studies testing Botox ingestions for overly sweaty armpits, hands, feet, and also, I assume that you know what I'm about to say, butt cracks. Oh, have a beautiful butt crack as well when you're done. A nice smooth, wrinkle-free crack. The smoothest crack in the land. Don't put too much in or your crack will go away if you put too much in though.

Be careful. Yeah, careful. You wouldn't want to have a uni-butt. No, just a hole. Just a hole.