Something You Should Know - SYSK Choice: How Material Science Has Changed Your Life & The Joy of Sweat

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Starting point is 00:00:27 Download June's Journey now on Android or iOS. Today on Something You Should Know. Why does aluminum foil have a shiny side and a dull side? What's the difference? Then, the amazing ways certain technologies have changed how we live. The railroad, clocks, glass cookware, even the telegraph. The telegraph actually had a hand in shaping language because sentences became compressed. If you went to a telegraph

Starting point is 00:00:54 office they would tell you you had to keep your messages brief. If you look at books written before the telegraph and books written after the telegraph you'll see that sentences are shorter. Also, airplanes have oxygen masks. So where do they keep the oxygen? And the science of sweat. Why we do it and where does it come from? What sweat is, is the liquidy parts of blood. If you drink something, it takes about 15 minutes

Starting point is 00:01:19 before whatever it is that you're drinking ends up out on the surface of your skin as sweat. All this today on Something You Should Know. This is an ad for BetterHelp. Welcome to the world. Please, read your personal owner's manual thoroughly. In it, you'll find simple instructions for how to interact with your fellow human beings and how to find happiness and peace of mind.

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Starting point is 00:02:29 And if you have spent any time in the kitchen, you've noticed that aluminum foil has both a shiny side and a dull side. And in cookbooks, you'll find recipes that say, cover with aluminum foil, shiny side down. Some cooks believe that it makes a difference which side is up or which side is down when you line a pan. Does it? No, it doesn't. And here's how we know.

Starting point is 00:02:54 First of all, the folks at Reynolds Aluminum say that the reason there is a dull side and a shiny side is simply the result of the manufacturing process. It's not intentional. It just comes out that way. They claim there is no significant difference which side you use when you cook or freeze or refrigerate food. Secondly, the chefs at America's Test Kitchen

Starting point is 00:03:17 did three tests where they cooked baked potatoes in foil, cooked mashed potatoes in a pan covered with foil, and heated water in a container covered with foil, and heated water in a container covered with foil, all in a regular conventional oven. They did each test twice, once with the shiny side facing out and once with the shiny side facing in.

Starting point is 00:03:37 And there was no difference. There is no difference. And that is something you should know. There's something called, and you may have never heard of this, I hadn't really heard of this before either, it's called material science. It's a real science, and people who work in this field do a lot of really interesting things that affect how you live your life. You'll understand this in just a second. Anissa Ramirez is a material scientist. She's worked as a research scientist at Bell Labs and held academic positions at Yale and MIT.

Starting point is 00:04:12 She's author of a book called The Alchemy of Us, How Humans and Matter Transformed One Another. Hi, Anissa. Welcome to Something You Should Know. Thank you so much. Great to be here. So explain briefly what material science is, because I think this is really fascinating. Well, it's the science of stuff. I call myself an atom whisperer, and I'm interested in how atoms move in the world, and then I try and convince them to do new things so we can make new materials. So that's what material scientists do. And give me a real quick example of what you just said, of making moving atoms and making new stuff. For example, what? Your cell phone, that was made possible by material scientists.

Starting point is 00:04:54 The fact that that glass is almost indestructible. Glass is usually fragile. Well, material scientists figure out how to make it so that it's strong and so when you drop it, it doesn't break. That's kind of the things that we think about. Well, that's actually really cool. Sounds like a fun job. So one of the ways that material science has affected our lives and really changed our lives is how material science changed clocks, which is really interesting. So explain that.

Starting point is 00:05:29 Clocks weren't always precise. I remember going to my grandmother's house and she would have a grandfather clock and it was always off. But we got better at the materials that are inside. First, they were very sophisticated springs and then they became quartz gems. And quartz actually vibrates if you put it in an electrical signal, and it vibrates a certain amount of time. And you can use those vibrations as a way to mark off time precisely. So that's the material that's involved in making our clocks more accurate. And what's the story of how and who decided that instead of springs, we would use quartz to make clocks more accurate? Tell the story of that development. Oh, sure. Well, it ends up there was a Bell Lab scientist that most people don't know about. His name is Warren Marison. And he had a project where he was actually making a frequency generator.

Starting point is 00:06:17 Radio was very popular back then. And sometimes radio stations were on the wrong station. And so they wanted to have a precise frequency generator so they knew where to broadcast their station. So he figured that out and he used quartz to do that because you can get quartz to vibrate a certain number of times per second. And when he figured that out, he's like, well, look, if quartz can vibrate a certain number of times per second, maybe I can use this as a yardstick, if you will, for time. If I know it, if I know this material will vibrate 10,000 times per second, I can count off those 10,000 vibrations and say, okay, that's one second. And so with that invention, he was able to create

Starting point is 00:06:57 the first quartz watch. And so he was the inventor behind the quartz watch. And the weird effect that's going on with quartz is that it has a strange material property where that if you apply electrical signal to it, it wiggles. It's called piezoelectricity. And that was found a long time ago by the Curie brothers. We know the name Curie with Madame Curie. But her husband and his brother, they actually found this effect long before she was married to him.

Starting point is 00:07:26 And so quartz clocks replaced spring clocks. Is that a fair statement? Yeah, that's correct. So before quartz clocks, there were these springs. Crucible steel is the material that needed to figure out how to make steel springs that vibrated and were flexible precisely and uniformly. Before that, it was really hard to make uniform metals. See, if you think about old movies, you would see blacksmiths and they would be folding over materials and they would make things like shoe horns and the like. And those were fine, but if

Starting point is 00:08:04 you wanted to make something uniform, folding it over and heating and beading it really wasn't the best way to do that. So there was a gentleman whose name was Benjamin Huntsman. He figured out how to make very, very well-controlled, in terms of the composition of the steel, he figured out how to do that. And once he was able to do that, then we had very, very well made uniform metals and we can make springs that worked accurately. And so that's what was the heart of an early clock. And then later on, that was replaced by quartz. Because as accurate as those springs were, quartz is more accurate. So that's why they replaced springs with quartz and and another area where material

Starting point is 00:08:47 science really changed everything is the railroads so explain that well the railroads we don't think about the railroads but the railroads actually changed a lot of of our experiences first of all long ago before the railroads we used to travel by stagecoach and it would take a long time to get from a distance like from new york to b. People wouldn't really do it. In fact, people wouldn't really travel more than 50 miles. If a son moved away from his family more than 50 miles, his mother might not see him again. So the railroads really made the country smaller because we were able to travel those distances to greater extents. The other thing that the railroad did is it actually changed a holiday that we don't even think about,

Starting point is 00:09:29 and that's Christmas. Now, Christmas used to be this holiday which was about meeting with the family and eating food. But around the Industrial Revolution, there were so many products that were available that the industrialists had to figure out a way to get these products and convince people to buy them. And so what happened is that Christmas was transformed into a gift giving occasion. And the way to get those gifts to people was through the railroad. So the railroad had a hand in commercializing Christmas. And it was because of the steel, right? The steel tracks that the railroad ran on is what changed everything. Yeah, it's the rails. It's the rails. It's the steel. Why?

Starting point is 00:10:11 We knew how to make steel. Steel is a fantastic material because it's very hard. It's very tough. And usually you don't have materials that have both of those properties at the same time. And we had to figure out how to make it abundantly. Because at one point, you could make a small amount of it, enough to fill like a pot. But when Henry Bessemer figured out how to make tons of it, then we were able to make lots and lots of steel rails and have them go across the country. Now, before steel rails, there were iron rails. And iron is a good material, but it had to be replaced every two years. But with steel, it could be replaced in 18 years. And so that means that you don't have to worry about the infrastructure. You can just build and build and build. If it's every two years,

Starting point is 00:11:01 you have to replace these iron rails all the time. And so steel allowed us to forget about that for a while and build and build and build this infrastructure. So it was certainly the material that allowed us to build this huge network that connected the entire country. Were rails for trains built out of iron first and then converted to steel or we waited until steel? No, no. First, early rails were made out of wood. Now that's not going to last long at all. A couple of rainstorms and you've got to replace that. So it was wood and then iron. And that was fantastic because it was better than wood. But again, it couldn't last very long. But then when steel came along, then you didn't have to worry about it for nearly two

Starting point is 00:11:45 decades. So it was really, the railroads had been around for some time, but they really took off when we had better rails. When you think about the telegraph today, I mean, it's virtually a forgotten technology. And yet, at the time, it was such a big deal. And you think about the materials that went into creating this network of poles with wires going across all over the nation where you could send messages get information used to be by letter. And it would take maybe two weeks. So let's say you send a letter to your aunt, tell her about things that are going on. It would take two weeks before you hear back. But the telegraph changed all that. In minutes, you can hear from a relative. And that was amazing.

Starting point is 00:12:37 But the telegraph along the way actually started to have a hand in shaping language. Because it had a limitation of how much information could be sent. And so if you went to a telegraph office, they would tell you that you're welcome to use it, but you had to keep your messages brief so that other customers could use it. And what I discovered is that the telegraph actually had a hand in shaping language because sentences became compressed. If you look at books written before the telegraph and books written after the telegraph, you'll see that sentences are shorter. Now, there's many reasons for that, one of them being that America wanted to change the way it spoke English relative to the UK. But another was

Starting point is 00:13:16 a technology of the telegraph. It actually had a hand in shaping language. Well, I have a question about why things had to be kept so brief. But first, I'm speaking with Anissa Ramirez. She's a material scientist, and the name of her book is The Alchemy of Us, How Humans and Matter Transformed One Another. Bumble knows it's hard to start conversations. Hey. No, too basic. Hi there. Still no. What about hello, handsome?

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Starting point is 00:14:17 All Porter fares include beer, wine, and snacks, and free fast-streaming Wi-Fi on planes with no middle seats. And your Tampa Bay vacation includes good times, relaxation, and great Gulf Coast weather. Visit FlyPorter.com and actually enjoy economy. So, Anissa, what difference would it make if the sentences were longer or shorter, the messages were longer or shorter? Why was it necessary to keep things brief? Well, they wanted to keep the lines free for future customers. And also the telegraph, as wonderful as it was, sometimes it was unreliable and the lines could go down.

Starting point is 00:14:56 So you wanted to make sure that your message, your dispatch, made it to its destination. So they would say, keep it brief because if the lines go down, at least they got some of the message, as opposed to if you keep a long sentence, you know, you can hear part of the sentence and not know what the full meaning was. So that was one of the reasons why people were encouraged to keep their messages brief. And so what about the technology and the materials used that made the telegraph feasible? Well, the wires of the telegraph wires were initially made out of iron, but later made out of copper. And it relies on electricity going through that. And if you have electricity, how do you send a message? I liken it to water going through a pipe. If you're at one end of

Starting point is 00:15:37 the pipe and I'm at the other end of the pipe and there's no way for me to communicate with you, how can I do that? Well, I can turn on and off the water to tell you, hey, Michael, there's something's going on. And if I get a little bit more sophisticated, I can turn it on for a short amount of time or turn it off and on for a long amount of time. And this could alert you of what's that something is necessary on my end. And so that's what's going on with the telegraph by using short and long pulses of electricity and creating a code that equals each letter of the alphabet, this is how information was able to get shuttled across those copper wires. And so that was the basis for the telegraph.

Starting point is 00:16:15 The carbon filament is one of those materials that really changed everything. So explain that story. Sure. A filament is a word that Thomas Edison came up with. And a filament just means a very, very thin wire. And he was very much focused on figuring out the best wire for his incandescent bulbs, his light bulbs. And he tried thousands of different materials. And he eventually focused on carbon because carbon was able to glow very brightly.

Starting point is 00:16:46 And that was the birth of the incandescent bulb. Now, what I also discovered is as light bulbs became abundant, it ends up that the type of light that surrounds us is not exactly the best light that we should have. Now, in Edison's day, people lived by the sun and then at night they lived by his incandescent bulb. The sun generates a lot of blue light and incandescent bulb. The sun generates a lot of blue light, and incandescent bulbs are a redder light. But today, you and I are surrounded by lights that generate a lot of bluer light. And this is not necessarily good for our health because our bodies have two modes, a growth mode and a repair mode. Our growth mode is where we have more growth hormones going through our bodies. And how our body knows to generate that is when it detects blue light.

Starting point is 00:17:28 So we're in growth mode most of the time. And as a result, there's a range of different health ailments that are bubbling up because of lights. So the carbon filament is something that we really don't think about. Light bulbs are things that we really don't think about. But now we're starting to see that they're impacting our health. The development and improvements in glassware. I mean, nobody really talks about that. You never hear about that.

Starting point is 00:17:54 But really, glassware, the ability to have containers you can see through, I mean, it was a big deal. Well, glassware is so important, particularly in science, because science is based on seeing and observation. And so it was very important to have a way to do that. And glass has been tremendous for that. We use that with glassware such as beakers and Erlenmeyer flasks, but we also use it for lenses and microscopes and telescopes. But for a long time, we couldn't get very good glass. You would look in a microscope or you would look in a telescope and it kind of looked like 3D glasses, whereas the red side,

Starting point is 00:18:32 there was a red side and there was a blue side. Now, there's no way that you can discover anything if you really can't see through the glass. So for a long time, people were trying to make better and better glass. Now, glass was also necessary for glassware that goes in scientific laboratories. And that had some problems too, because if you poured an acid into older glassware, it would actually be eaten up by the acid. Well, that's no good. You're going to have new problems if you do that. So it was really necessary for us to figure out how to make better glass. And it ends up that there was a woman, her name was Bessie Littleton. She came up with this idea that she needed a better way to cook in a casserole dish. But she was complaining about

Starting point is 00:19:19 this to her husband who actually worked for Corning. And he was working on a new type of glass. He brought one of his samples home. She tried it out. She made a wonderful pie and different types of foods with it. This was actually the birth of Pyrex, so it became initially a way to cook better foods, but then later Pyrex was used for scientific glassware, such as I mentioned with Erlenmeyer flasks and test tubes and the like. So this idea of finding better bakeware is actually what gave rise to better science equipment. So with glass cookware, why doesn't it break? I mean, if you took just a regular glass, drinking glass, and put it in the oven and turned it up to 500 degrees,

Starting point is 00:20:00 it would shatter. So why doesn't cookware break? The secret element is boron. Boron is an element of the periodic table, again, that we don't usually think about, but it creates really, really strong bonds. So depending on how much boron you put in the glass, it's able to do different things. Some, if you have a certain amount of boron in the glass, the glass will be very, very strong so that it won't expand when you put it into the oven. And so you don't have to worry about it breaking.

Starting point is 00:20:30 If you put less boron in it, it will be able to survive. If you include other materials as well, it will be able to survive having acids in there. So the secret ingredient is boron. And these types of glasses are called borosilicate glasses. So like Pyrex measuring cups that you could put boiling water in, they have boron in them? They have boron. They're borosilicate glasses, and that's the reason why they're doing it, because of this element boron. One of the interesting examples of material science through the ages is sound, music, and how it has changed as the materials have changed.

Starting point is 00:21:07 Well, what's so fantastic about sound is that it's very much linked to technology, and particularly music. Early music was actually molded by early phonograph. The phonograph kind of looked like a huge horn that was connected to this cylinder, but it couldn't pick up very, very soft sounds like guitars. And so if you listen to early music, you won't hear too many guitars. You'll hear loud music like horns and tubas and things like that. So the technology actually shaped music that we listen to. And the creator of the telegraph, sorry, the creator of the phonograph was actually Thomas Edison and he made this wonderful device

Starting point is 00:21:47 that was able to capture sound. In fact, people had thought this was a dream that you could actually capture sound and this ability to store information besides words on a page, but actually little pricks that are in tin foil, which is how the phonograph is made, actually put us on the path for other ways of storing things.

Starting point is 00:22:09 And that put us on the path for the hard disk. So music was actually part of the origination story for the hard disk. And the ability to store music really changed over the years because the materials changed over the years. You know, we had those big, very brittle, scratchy 78s. And then we had, you know, 33 RPM records and 45 RPM records and eight track tapes and cassette tapes. And then the CD. And the CD was really, I think, a big deal in the sense that it was a digital way to store music. The CD was amazing because you can get to the specific song that you wanted right away.

Starting point is 00:22:53 That was revolutionary because before that was the cassette tape. And if you wanted to get to a specific song, you would have to fast forward and stop, fast forward and stop. The CD was also kind of based on a similar way of thinking, meaning that it's made out of short and long dashes or short and long holes. And so it was a digital form of storing information. The phonograph was analog. The way that you spoke, like if I put my hand in front of my mouth and I can feel the pressure wave, that is sort of what you would see on a phonograph. You would see big things when you say something like the letter P and you would say, you would see smaller things when you saw, when you said something like the letter S. So every bit of the space of sound was

Starting point is 00:23:36 captured with the phonograph, but with the compact disc with CDs, it was digital. So there was a threshold for when a big dish, a big dash would occur and when a smaller dash would occur. So it was a big deal, but it was part of the evolution of sound. Well, it is amazing to realize how some of these early technologies and early materials were not only a big deal at the time, but were so profound that they continue to reverberate and help shape our lives today. Anissa Ramirez has been my guest. She's a material scientist, and the name of her book is The Alchemy of Us, How Humans

Starting point is 00:24:16 and Matter Transformed One Another. And you'll find a link to that book in the show notes. Thanks, Anissa. This has been kind of a real fun romp through history. So thank you for being here. Thank you so much. Metrolinks and Crosslinks are reminding everyone to be careful as Eglinton Crosstown LRT train testing is in progress. Please be alert as trains can pass at any time on the tracks. Remember to follow all traffic signals, be careful along our tracks,

Starting point is 00:24:46 and only make left turns where it's safe to do so. Be alert, be aware, and stay safe. This episode is brought to you by Melissa and Doug. Wooden puzzles and building toys for problem solving and arts and crafts for creative thinking, Melissa and Doug makes toys that help kids take on the world because the way they play today shapes who they become tomorrow. Melissa and Doug, the play is pretend, the skills are real. Look for Melissa and Doug wherever you shop for toys. Sweating or perspiring is something we all do. And so do horses, and monkeys, and hippos, and probably a few other animals. You've likely heard that the reason we sweat is to help us stay cool.

Starting point is 00:25:35 Which is true, but it's so much more involved and interesting than that. As you're about to hear from science journalist Sarah Everts, who has thoroughly researched this topic for her book, The Joy of Sweat, The Strange Science of Perspiration. Hi, Sarah. Hi, Michael. Nice to be here. So why is sweat and sweating so interesting and important to understand? So sweat is actually humanity's evolutionary superpower or one of them. The fact that we can cool off while in motion is something that we can do better than most other animals on this planet. So if you think about it, like one of

Starting point is 00:26:20 the things that makes humans unique is that we're a naked ape. We're pretty much hairless, or mostly so. And because we're hairless, we have a lot of surface area on our body that can sorts of things in really hot temperatures. We can go foraging in the middle of the day. We can run marathons. And this has actually been this huge evolutionary advantage. So if you think about our predecessors, if you're hunting, right, most of the prey that we would be seeking runs faster than us. They can sprint way faster. But they have to stop to cool down because dying of heat stroke is a really terrible way to die. But because we can cool down while we're running, we can catch up with that prey and effectively force them to run again and run again and run again until they are so weakened by heat stroke that it's easy to kill them or they actually just die of that. And, you know, if you consider a

Starting point is 00:27:32 dog, dogs cool down by panting, right? And they're doing the same thing. They are evaporating a liquid but only off the surface of their tongue because that's the like only hairless area of their body, whereas we have our whole bodies. And also just to go back to dogs, they're evaporating saliva. We are evaporating sweat. And if you like look at other animals, this sweating evaporation is one of the most efficient ways to cool down. But if you don't have sweat glands to do that, you have to rely on other bodily fluids. And I'd argue that saliva is one of the least gross other bodily fluids you could rely on. Some animals like seals urinate on themselves to get wet enough to evaporate that heat away. Vultures poop on their own legs. Honeybees vomit on themselves. So it's kind of amazing that we have a heat control sort of mechanism embedded in our own skin, like millions of little machines that are devoted to keeping us cool.

Starting point is 00:28:38 Interestingly, though, we don't all sweat the same. Some people seem to get real sweaty and other people don't seem to break a sweat. So what's the difference there? Certainly your genetics play an important part. Some people have more sweat glands. So your average person has between two and 5 million. I actually got my sweat glands counted and we've only known each other a few minutes, but I feel comfortable to say that I have 3 million. Congratulations. Thank you. So there's like the number of sweat glands that you have. There is another genetic component, like how fast that sweat comes out of your glands, like the rate, the flux of sweat. And then there's also, you know, the triggering, you know, how quickly does your body react to, you know, a hotter core. But then there's also nurture. So you are born with

Starting point is 00:29:34 all the sweat glands that you're ever going to have on your body, but it's in your toddler years that they actually all become either fully activated or not. And so some researchers are looking into the impact of environment. So where did you spend your toddler years? Was it in a cold climate? Was it in a hot climate? And based on that, that may affect how many sweat glands got activated and how efficient they are. Because pretty much everybody is sweating all the time. Even if you're not boiling hot, your sweat glands are making tiny, minute adjustments to your core temperature by releasing tiny amounts of sweat. And then, of course, you know, if you go for a run or you're out in the sun, you get really hot and they start releasing more. But, you know, people who have

Starting point is 00:30:26 grown up in very hot climates often have more sort of efficient sweating. So they may not look like they're sweating, but certainly they are because otherwise they would be totally miserable. So the sweat that I sweat probably, I'm guessing, started out as something I drank. It's the water in my system that somehow gets to my sweat glands and then comes out as sweat. Is that a fair assessment? Yeah. So effectively what sweat is, is the liquidy parts of blood. So anything that is circulating around and yeah, yeah. Because the way that your sweat glands find something to put out on the skin is they effectively recruit what's called interstitial fluid. So you got blood, right? And then if you were to open up your body, your body's wet inside,

Starting point is 00:31:19 right? All your organs are moist. And that moist stuff is called interstitial fluid. And it's, yeah, it's blood minus the big red blood cells, the platelets, the immune cells. And your sweat glands just source sweat from that interstitial fluid. Ew. Sorry. But you're totally right. If you drink something, it takes about 15 minutes before whatever it is that you're drinking ends up out on the surface of your skin as sweat. Well, that kind of implies that we need to drink a lot because if we drink something and 15 minutes later, it's coming out as sweat. It means we need to replenish that. I mean, what mom said about drink lots of water seems like pretty good advice. Yeah, exactly. But I'd say, you know, drink to your thirst,

Starting point is 00:32:13 right? We don't need to overhydrate. And if you drink too much, you could have this like horrible condition called hyponatremia, which is when you drink too much and you swell your body up and you can actually die from swelling your spinal cord off. It seems like you'd have to drink an awful lot of water for that to happen. Isn't the bigger problem that we're not drinking enough water, not that we're drinking too much water? You're wrong about that. So if you look at marathons and people have done this research, more people have died of hyponatrenia than they have of heat stroke. Really? And that's because there's this constant push to drink, drink, drink, drink, drink,

Starting point is 00:33:00 which is good. But we have evolved over many, many, many years to have our thirst tell us when to drink. We also sweat when we're nervous. It has nothing to do with, or maybe it has something to do with being hot, but that isn't the root cause of it. We're just nervous. Why is that? Good question. So we're activated to sweat from two ways. One is obviously temperature, but another one is sort of hormones like adrenaline. So if you're nervous, that can also open the floodgate. So your sweating glands can be triggered to open two different ways. Well, I know I've heard that there's, you know, two kinds of sweating and that there's two kinds of sweat. There's the sweat, the perspiration that you give off to cool down. And then the nervous sweat is a

Starting point is 00:33:51 whole different kind of sweat, is it? Oh, so there are two different kinds of sweat glands. And I'm really glad you asked about that because one is the liquidy water stuff, right? The stuff that we've been talking about, it's called like an eccrine sweat gland and its job is to cool you down. And that sweat is the liquidy parts of blood. Whereas there's another sweat gland that appears anywhere where you grow hair during adolescence and its sweat is actually pretty waxy. And wherever hair grows during adolescence, including, of course, your armpits, that sweat starts getting released during the teenage years. And it's responsible for morphing the armpits into stink zones. And that sweat is waxy.

Starting point is 00:34:37 It's quite a lot more similar to earwax than to the salty, wet stuff that we're, you know, producing to cool down. And it turns into stinky stuff because the bacteria that live all over your body, they love to eat it. And when they eat it, they metabolize it. And what they release is really stinky. And so, you know, the good news is, you're not stinky because your sweat actually stinks. You're sorry, you're stinky because bacteria living in your armpits are eating your sweat and turning it into stinky stuff. So good news, bad news, don't know. Why is sweat salty? That's because our blood is salty, right? And so the salt is actually kind of an incidental tag along. We don't need the salt to cool down. We just need water to evaporate away the heat. But because our bodies are salty

Starting point is 00:35:34 oceans, the salt comes along for the ride. And so we've often heard that you, the commercials tell you that you need to drink not just water, but you need to replace your minerals, your salts and things because you sweat that out. Is that a valid claim? I totally agree with the claim that we need to replenish our electrolytes. I typically don't buy the products though. So think about the amount of salt that you lose. Oh, and by the way, your sweat glands are desperately trying to retrieve salt. So they really try to keep the salt in your body. And actually, the amount of salt that comes out in sweat is lower than the saltiness of the water inside your body because your body is trying so desperately hard to, you know, keep those electrolytes on the inside. But I think we probably can all admit that we have tasted sweat at some point in some capacity, and it's still pretty salty. And you can't imagine, or I couldn't imagine drinking a whole cup of that. And so if you need to replenish your electrolytes, you need to do that by eating salty foods or foods with salt in it, not by drinking it.

Starting point is 00:36:50 Because you can't actually get all those electrolytes back into your body that way. It's unpalatable. And so if you want to drink a sports drink, go right ahead. But the amount of sugar that's added is high. And the amount of electrolytes that you actually replace is low compared to what you've actually lost in your sweat. So let's talk about the connection between sweat and human attraction. Because I've heard there's a connection. I don't really understand it.

Starting point is 00:37:19 I don't get how somebody's smells could really turn you on or off that much. But why don't you go? So you're not a candidate for the sweat dating events that sometimes happen around the world? Seemingly not. Okay. The funny thing about how we smell is that, you know, whether we like it or not, we do have an odor. And we recognize the odor of those around us. So for example, you know, parents can identify their newborns based on smell just, you know, hours after birth for the mother and a little bit later for the other non-birthing parent. And siblings

Starting point is 00:37:58 who haven't seen each other for years can identify their siblings' odor. And so we have an odor print, whether we like it or not. And law enforcement has long relied on dogs, for example, to sniff out individuals based on our odor print. So we do have an odor. And in that odor, there's all sorts of interesting pieces of social information that we share with one another. So if you're anxious, as you had mentioned a little bit earlier, you know, people sweat a stinky kind of odor when they're stressed out. Law enforcement have long said that people come into interrogations smelling like themselves and leave all smelling super anxious. Like there's this dominant thing that comes out and, you know, t-shirt experiments done by scientists, you can identify whether somebody has sweat just, you know, due to exercise versus whether they've been stressed out. But in terms of romance, I think that there's like a couple of things at play.

Starting point is 00:38:58 Clearly, you're going to smell the body odor of your romantic partner at some point or another, and it's going to be a make or break moment, right? So, you know, just, you know, on the surface, you're going to have to, you know, be comfortable with that odor. But of course, everybody loves to think about pheromones, right? You know, is there something in our sweat that is making somebody attracted to me? Is there a way to do that? And, you know, in the animal kingdom, pheromones certainly exist. So, for example, pigs are my favorite. The male pig will breathe heavily on the female, and there's a pheromone called androstenol and androstenone, which if she sniffs that, and if she's in heat, she will immediately spin around and raise her rump sort of in a universal physical sign that it's time to start a family. Moths do

Starting point is 00:39:54 the same thing. The female will release a pheromone called bombacol. If a male nearby smells it, he will immediately zoom to her to mate. It's like the perfect definition of a booty call. When you know that, it's kind of hard to imagine that that exists in humans. And it'd be kind of alarming if it did, because can you imagine actually being able to, you know, spritz something out and, you know, ultimately immediately get a booty call. But researchers have found that we are attracted to those of others who have immune systems that are slightly different enough that any progeny that we have will have a really robust immune system. And if you think about it, that, you know, is really beneficial to the human species. You know, for most of human history, it's been pathogens that,

Starting point is 00:40:50 you know, kill us. And so if you can be attracted to somebody who's got a different enough immune system so that, you know, the combination of immune systems, you know, is really strong, then great. Your child is going to probably survive to adulthood and maybe pass on your genes. For as long as humans have been human, we've been sweating. And so theoretically, we've also been stinking from our sweat. And I guess forever, it never really bothered anybody to the last hundred years or so. And now there's this whole industry, the antiperspirant industry and the deodorant industry that's convinced us that we shouldn't sweat and that if we do sweat, we don't smell. So where did that all come from? Around the turn of the 20th century is when

Starting point is 00:41:40 deodorants and antiperspirants are first being invented and brought to market. And at the time, it's the Victorian era. And people don't want to be talking about sweat. And also, quite frankly, they don't think they need to control their body odor. They think that washing with soap and water and maybe applying some perfume is, you know, good enough for me. Thank you very much. And so it actually took a very clever marketer called James Webb Young to figure out a way to put the fear of stink, particularly in his case, in America. And in the 1919s, he works with this woman named Edna Murphy, or she hires him to market her product, a product called Odor Oh No.

Starting point is 00:42:30 And he effectively discovers that, you know, everybody has heard of these sorts of products, but they don't think they need it. And so his strategy is to tell women that not only do they stink, but they stink a lot and people are talking about them behind their backs. The strategy is called whisper copy, by the way. And that not only are people gossiping about them, but this ultimately is going to mean they're not going to find themselves a husband. So, you know, it's 1919. And it's amazing because one of his advertisements, which appeared in Ladies Home Journal and effectively said, you know, within the curve of a woman's arm, you know, secrets too dark to, you know, to be uncovered, something like that. People canceled their subscription to Ladies Home Journal because they were so offended that he was saying this to women. Yet simultaneously, sales of odor oh no skyrocketed. And, you know, soon many other companies who are also trying to market deodorant-synonyming purse prints were

Starting point is 00:43:33 borrowing from this. So, you know, you'd see headlines, beautiful but dumb. She has never learned the first thing about body odor control. And finally, in the 30s, when they've exhausted all the advertising to women, they're like, oh, we need to make more money. Let's target men. But because they've spent, you know, over a decade presenting deodorant-cannabinoid perspirants as a female product, they have to go out of their way to make deodorants and antiperspirants very masculine. And so some of the early entrepreneurs are doing things like marketing them in whiskey jugs. They're getting sports people to advertise them. And the thing that they're kind of preying on is men's fear of having a job, right? It was the Great Depression at the time. Men are worried

Starting point is 00:44:23 about losing work. And so instead of saying they're not going to find a mate for life, they're like, you're going to lose your job if you're stinky in the workplace. I sometimes wear these products, but I'm always really cognizant that this is something that marketers have really instilled in my culture over the past hundred years. work? Because if perspiring, if sweating is such a natural and necessary thing, why would you want to stop it? But I can understand why you would want to stop some of it, but how do they work? What's the mechanism that they are effective? Great question. I'll start with deodorants. Deodorants work by being effectively an antiseptic. So they kill the armpit bacteria that would eat the waxy secretions, the sweat from your apocrine glands, and turn it into stinky stuff. Whereas antiperspirants actually physically plug the pores of your sweat glands in your armpits so that they effectively block that sweat from coming out at all and block the buffet for all those armpit bacteria. So what did you find doing the research for this? What did you find that was really surprising

Starting point is 00:45:52 about sweat? I'd say there's two quick things that I'll, you know, try and be short about it. The first is that fingerprints are actually just sweat prints. So anything that's circulating around in your blood gets left behind in a fingerprint. And law enforcement has typically picked up a fingerprint to try and see how it looks. But now chemists are figuring out how to analyze the microscopic amounts of chemicals left behind in that sweat print, right? And they can tell, I went and had my fingerprints analyzed and, you know, you could tell that I'd had a cup of coffee, there's caffeine coming out. And the researcher who did this, Simona Francesi at Sheffield, she's been working with law enforcement. And, you know, you can also tell if somebody has snorted cocaine, whether they have been drinking alcohol, just from the chemicals left behind in a fingerprint. So, you know, this is just in the early stages of research. But I do think a lot about, you know, the future of surveillance, because, you know, we worry about,

Starting point is 00:46:59 you know, the DNA that we leave behind in, you know, our hairs or, you know, on our spit on a coffee cup or whatever. And I think this is going to be another issue along the same lines. And I think the other super interesting thing is that there's an artificial sweat industry. So even though, like, we arguably produce enough sweat, thank you very much. There are many researchers who need to have synthetic sweat in their labs to do their work. And so everything from textile companies who want to make sure that the dye in their T-shirts doesn't leach out into somebody's armpit, or smartphone manufacturers want to make sure that the electronics on the surface of the phone can deal with sweaty fingers or watch manufacturers are worried about nickel leaching out. So people use synthetic sweat to do all sorts of funny experiments. And it just makes me laugh to think that around the world, little bottles of synthetic sweat are being shipped about all while I'm sweating up a storm out in the sun. Well, I never knew there was so much to know about sweating, but since it's something we

Starting point is 00:48:11 all do, it's kind of interesting to hear what it is that's going on and why it's going on. Sarah Everts has been my guest. She's a science journalist, and the name of her book is The Joy of Sweat, The Strange Science of Perspiration. And you'll find a link to that book in the show notes. Thanks for being here, Sarah. Appreciate you coming on. Thank you so much. You know, when you fly, the flight attendants do that little demonstration that includes what to do if the oxygen masks come down in an emergency. Well, have you ever wondered where on the plane they keep all

Starting point is 00:48:47 that oxygen? Well, they don't. There are no big tanks of oxygen. That would be dangerous, would weigh a lot, and take up a lot of room. Instead, what really happens is there is a chemical reaction that creates oxygen. The chemicals are barium peroxide, sodium chlorate, and potassium chlorate. And you know that part in the demonstration when the flight attendant says you need to pull down on the mask to release the flow of oxygen? Well, what really happens is that tug on the mask triggers a firing pin that initiates that chemical reaction. The byproduct of that reaction is oxygen. There's enough for about 20 minutes, which is enough time for the pilot to bring the plane lower so you can breathe again. And that is something you should know. I always appreciate when people take the time to leave a

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Something You Should Know - SYSK Choice: How Material Science Has Changed Your Life & The Joy of Sweat

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