EP. 125 — The Joy of Sweat with Sarah Everts

FACT-125-20211004-Everts-RCv02-DYN.mp3

Speaker 1 [00:00:22] Hello and welcome to Factually, I’m Adam Conover. Thank you so much for joining me once again as I do my favorite thing: talk to some incredible experts about all the amazing things that they know, that I don’t know and that you probably don’t know either. My mind’s going to be blown, your mind is going to be blown. We’re all going to have a great time together. That has been my intro for the show over the last couple of weeks. Is it getting a little rote? Are you bored of the intro? Send me an email. By the way, if you ever want to every want to talk to me about the show, you can always send me an email at factually@adamconover.net. Give me your suggestions about what you’d like to hear in the future. I always love to hear from you. But look, let’s talk about this week’s show. I’ll be honest, as I’m recording this right now, I’m a little exhausted. I just got back from a whirlwind week of travel. I was shooting segments for my new show: The G Word, which is going to come out on Netflix next year. It’s all about how the federal government works. We interview some incredible people and go do some amazing things. I’m under NDA, so I can’t talk about any of it. But suffice it to say, I did not sleep a lot and we got some amazing footage and I cannot wait for you to see this show when it comes out, hopefully in early 2022. But look beyond that, there’s a lot of horrible stuff going on in the world right now. So let’s talk about a topic that is a little bit lighter, more effervescent, a little bit moister this week. This week we are going to talk about sweat. That’s right. The salty, wet stuff that you excrete from your entire body (if you’re me) at basically all times. I know it seems like an odd topic for a podcast episode but let me tell you something: at the end of this interview, I think you will be convinced that sweat is not just very fascinating; it is the very thing that makes us human. That’s right. Not only is sweat almost unique to humans in the animal kingdom, we’re one of the very few species that do it across our whole bodies, giving us an evolutionary advantage that other animals simply don’t have (which we’ll get into in the interview). It also conveys information about us on a staggering scale. That’s right, you’re worried about social media leaking your private data. Well, you might want to worry about your sweat doing the same thing, but look, instead of trying to explain it myself, why don’t we just get to this interview? My guest today is Sarah Everts. She’s an award winning science journalist, and she’s the author of a new book called ‘The Joy of Sweat: The Strange Science of Perspiration.’ I think you’re going to be completely fascinated by this interview. I know I was, so let’s get right to it. Please welcome Sarah Everts. Sarah, thank you so much for being on the show.

Speaker 2 [00:02:53] Hey, it’s great to be here.

Speaker 1 [00:02:55] So you’ve written an entire book on sweat. Are the pages of this book moist? That’s a gross place to start but it’s the first thing that comes to mind. It’s a book full of sweat.

Speaker 2 [00:03:10] We’re like 30 seconds in and you’re already TMI. Yeah, it’s full of sweat, but not literal, damp – It’s not moist. The book is not moist.

Speaker 1 [00:03:20] OK, well, tell me what brought you to write this book. What is so fascinating about sweat?

Speaker 2 [00:03:28] I think like a lot of people, I’m a little bit mortified by my own sweat. I went through life worrying that I might sweat too much. I’m the kind of person that when I’m doing a workout, I’m grabbing my towel during the warm up or like during hot yoga I’m looking around to see if anybody else is dripping on their mat when I should be focusing on my downward dog and being zen. And yet, as a science journalist, I always knew that evolutionary biologists count sweating as one of our superpowers. One of the things that make humans unique in the animal kingdom, along with big brains and nakedness. And so I thought, ‘OK, I need to find some serenity rather than shame in all the sweating that I certainly do.’

Speaker 1 [00:04:18] Wait so our superpowers are our big brains, nakedness and sweat? That we are smooth, we are wet and we overthink it. That sounds like a pretty good description of humanity to me, but also I don’t know if that’s a picture that is correct. All of these slippery beings sort of sliding around the plains or whatever doesn’t sound that evolutionarily advantageous. So why is it?

Speaker 2 [00:04:45] Well, that’s the funny thing is because being naked is actually part and parcel to why sweating is also our superpower. In the animal kingdom, we are actually inordinately good at cooling down. That’s because we have millions of sweat glands (between two and five). I got mine counted, I have three million, not three total.

Speaker 1 [00:05:10] You have 3 million sweat glands.

Speaker 2 [00:05:11] I have three million, yeah.

Speaker 1 [00:05:12] Someone went over your whole body and counted up your sweat glands one by one and they got to three million.

Speaker 2 [00:05:17] They did it in a weirder way that involves dental polymer, the stuff that they used to take impressions of teeth and mild electrocution. But we can get to that now or later.

Speaker 1 [00:05:30] OK, no, that’s all right. That’s fine. That’s enough of a description.

Speaker 2 [00:05:34] Okay. So we sweat primarily to cool down, and that’s because our body heat effectively evaporates the water that is coming out of our sweat glands and takes our heat and whisks it from our bodies into the atmosphere. We kind of need to do this because death by heat stroke is a terrible way to go, and we’re really efficient at it, in part because we’re naked. So if you think about a dog, the way that they cool down is by evaporating the water out of saliva off their tongue, which is literally the only naked part of their body. But it’s a tiny little bit of real estate to cool down their whole body. Yet we have all the parts: we are naked and so we can evaporate off of our entire body. This is super efficient, which gives us the sneaky trick where we can exercise and cool down simultaneously. We can run marathons because we don’t actually have to stop running. well, some of us do. But in the heady days of our evolution, you can imagine that most of our prey ran a lot faster than we do. They sprinted away. Ultimately, they would have to stop running in order to cool down so that they don’t die this horrible death by heatstroke. Whereas because we’ve got this great super sweating strategy and a lot of nakedness to cool off, we could keep running and catch up with them and force them to sprint again. And then again and again until they become so weakened by heat stroke that they were easy to kill or just died. This is the superpower part of it. We can run, exercise and stay cool all at the same time.

Speaker 1 [00:07:26] So I’ve heard this theory before, that was the original way that humans hunted or one of the very original ways in our very early history. I wish I can remember the name. I saw this on TikTok.

Speaker 2 [00:07:41] Persistence hunting?

Speaker 1 [00:07:41] Persistence hunting? Is that what it’s called?

Speaker 2 [00:07:44] Or persistence running, yeah.

Speaker 1 [00:07:44] I saw on TikTok (and of course I can’t remember the username), this guy describing it as: imagine how creepy that would be if you’re an animal (if you’re a gazelle or whatever is being hunted) and there’s this creature with a spear, that’s trying to get you. So you run away. You think I got away from it and you rest and then it’s like, ‘Okay wait, here it comes. Wait, there it is. It’s still coming for me. I gotta keep running.’

Speaker 2 [00:08:06] It’s like zombies. Zombies don’t run very fast (well in some movies) but they’re just constantly coming at you, right? That is us.

Speaker 1 [00:08:12] Yeah and it’s because we have this special superpower of being able to evaporate heat in a way that almost no other animal does, that’s really so cool. I run distance for exercise. I like to go on long runs. Normally I run three miles, but on a weekend I’ll run seven or eight miles or something like that. But I’m very slow. I take a lot of breaks, I walk a lot. It’s hot in Los Angeles, but you’re saying this when I’m doing that, I’m sort of partaking in humankind’s original advantage.

Speaker 2 [00:08:47] Yeah. You’re totally flexing to any animals that are watching.

Speaker 1 [00:08:51] That’s so cool. Well, and that’s so different than what we normally hear about humanity’s evolution. We normally about in terms of the brain, which you have mentioned, but more that we make tools and x y z. This is not part of the narrative that we use for ‘here is how humanity got a leg up and took over the world.’ Right?

Speaker 2 [00:09:12] Well, I think it’s part and parcel. Obviously, having big brains and, being able to construct things that help us along the way is important. But the fact that we could stay cool in really hot environments allowed us to hunt during the day when a lot of similarly sized mammals have to hide out in the shade. And it allowed us to live in almost any ecosystem. Because when it gets cold, we can wear the pelts of other animals, but we can handle the heat. We’ve been able to dominate the natural world, for better or for worse. It’s really kind of odd that as we face this coming climate apocalypse which is part and parcel to humans dominating the natural world, as climate heats things up, we are going to need our sweating capabilities to stay cool. So it’s kind of a little macabre or ironic that this biological function that has allowed us (in part) to dominate the world is ultimately going to help us survive the apocalypse that we created ourselves.

Speaker 1 [00:10:27] Yeah, I’ve actually read about – and I don’t know if we’re jumping ahead here at all, but I’ve read about the idea that there’s a particular temperature that we need to worry about in climate change. I think it’s called the ‘wet bulb’ temperature. Is this right? Where the danger zone is literally related to the temperature at which our sweat is able to effectively cool us or not, that some places are going to go over that temperature and our sweat will not be effective. Do I have that right?

Speaker 2 [00:10:54] Yeah. So I think if you’ve sweated in a variety of places you know that when you’re in a desert, you don’t feel as hot, even if it’s like super super hot outside. That’s because you’re sweating so fast that heat that all that water vapor close to your skin is being whisked out into the atmosphere, because the air in the desert is super dry. But if you are in a very humid place and there is a lot of water vapor; evaporating water around you. So when you are sweating, it’s actually hard for those water molecules. Even though your body’s really hot and they would normally evaporate up, there’s this back pressure because there’s already a lot of water molecules in the air pushing back and making it harder for you to evaporate away your heat. That’s why humans feel worse, often, in a human place, because it’s actually harder for us to get that heat away because of the physics of it. It’s hard for those water molecules to occupy space where it’s already very packed with water molecules.

Speaker 1 [00:12:07] Wow. I’m sorry, I have to have something very basic. I understand that we sweat so that the water will evaporate and that cools us. But I’m realizing, I don’t know, why does water evaporating cool us down?

Speaker 2 [00:12:22] Oh, great question. OK. Yay.

Speaker 1 [00:12:25] Extremely basic. I probably should know this from high school bio class or something.

Speaker 2 [00:12:29] You’re letting me nerd out on some physics and biochemistry. So if you’ve ever been in the kitchen, right and you have a sauce and you’re getting all fancy and you want to make a  reduction.

Speaker 1 [00:12:45] Like a balsamic glaze.

Speaker 2 [00:12:46] Yes, you need to heat that very slowly to get the water molecules out into the atmosphere and  effectively reduce that down to a kind of sludge, a delicious sludge. So the process of water evaporation is actually consuming heat. You need to turn on your stove to make those water molecules leave your sauce. So the process of evaporating the water in your sweat off your body is consuming heat to do that. You need to consume heat to evaporate water, and so it’s literally consuming the heat of your body in order to whisk that water up into the atmosphere.

Speaker 1 [00:13:36] Oh, I get it. OK, there’s heat coming in. I’m out in the sun, there’s heat coming in and hitting my body and the ambient temperature, and that’s going to heat me up to the point where I die. But instead, I’ve got all this water on my body, and that water is using that heat to be turned into gas. It’s like a chemical reaction using up all this heat before I end up internalizing it and taking it away. I got too much vinegar in my house, so I’ll buy a whole lot of baking soda and now I’m going to have less vinegar because I’ve used it. I think of every chemical reaction as baking soda and vinegar, which is very stupid of me, but I just go back to elementary school.

Speaker 2 [00:14:16] So I would say, that strategy of getting yourself wet with a bodily fluid is the best strategy for any animal to cool down. Humans happen to have millions of glands specifically for that purpose. Dogs use saliva, but other animals use all sorts of other bodily fluids.

Speaker 1 [00:14:39] You’re talking about pee.

Speaker 2 [00:14:40] Right! If you don’t have millions of sweat glands to dispatch sweat, you have to rely on something else: namely pee or watery poop. That’s what vultures do. They poop on their own legs. Seals urinate on themselves. Honeybees vomit on themselves in order to get their body wet to evaporate away their. Okay. If you know that, then sweat is so much less gross. Imagine you’re all on the subway, and instead of just sweating – We’ll just leave it there.

Speaker 1 [00:15:16] That’s also why they just getting wet, just immersing yourself in water, also works to a certain extent. Also the water’s water cooler than the ambient temperature, but also it evaporates in the same way. It’s why you feel chilly when you get out of the pool.

Speaker 2 [00:15:31] Right. There’s some people who have a genetic condition where their sweat glands didn’t form in utero and so they don’t actually have sweat glands and they are miserable, even in temperate climates. So they spritz themselves typically, I’ve heard, as a solution. You walk around with a spray bottle and spritz yourself with water in order to achieve the same end.

Speaker 1 [00:15:58] I want to hear more about this, it’s a genetic condition and it means you do not sweat at all. You don’t have sweat glands or you simply don’t sweat?

Speaker 2 [00:16:06] Yeah. So what happens is, in utero is when your sweat glands are formed and so you’re born with all the sweat glands that you’re going to have. Although they don’t get truly functional until your toddler years, but you’re born with what you got. Some folks have a genetic condition where that message to make the sweat glands doesn’t get heard. So they are born with skin, but their skin just doesn’t have sweat glands in it. So they don’t have this capacity to cool down. It’s actually a really tough life because we are actually constantly sweating. We mostly notice it when our body goes berserk, when our body temperature really rises; either because you’re running and thereby creating a lot of internal heat or if it’s really hot outside. But at any moment of the day – right now, you are sweating, right? Your body’s making incremental changes to your internal temperature.

Speaker 1 [00:17:04] I’m very nervous for this interview,

Speaker 2 [00:17:08] Right, and so you’re releasing tiny amounts of sweat and it’s evaporating before you even notice it.

Speaker 1 [00:17:13] Wow. That’s just part of homeostasis: of staying the same temperature all the time. I would imagine if you can’t sweat that, that would be very dangerous. You’d have to be very aware of the temperature of the place that you’re going. It would be hard. Here in L.A., we have a couple hundred degree days, more and more of them every year, and you’d have to be very careful about going outside. Wouldn’t you be more at risk of heat stroke and things like that?

Speaker 2 [00:17:42] Oh yeah, you’re constantly at risk of heat stroke. I would say probably there are very few people with that condition living in L.A.. I think you’d want to go to more northern climes.

Speaker 1 [00:17:53] Wow, that is wild. Well, let’s just talk a little bit about the shame factor that you brought up. Like, we shouldn’t be ashamed of sweat. It’s better than other things. It’s better than shitting on your legs to cool down. Although now that I know it’s a strategy, I might try it next time I’m on a run. Actually, a lot of marathon runners, I think, do use that strategy. Frankly, it is a thing that happens sometimes. Is people pee and poo on themselves. Well, not for that reason, but maybe that’s part of why. Sorry. But also I’ve always felt that with bodily fluids, there is something fundamentally unnerving about them because they remind us of our animal natures. I’ve always felt one of the reasons we don’t like poop, in addition to it being gross and smelling bad and having a revulsion to it, is that it reminds us that we’re just biological machines when we want to be so much more. So we want to get it away from us and not think about it. You know what I mean? It somehow reminds us of our animal nature and sweat is the same way, especially if it’s our fundamental human advantage. I don’t know, does that track for you at all?

Speaker 2 [00:19:05] Yeah, I think you’re onto something. What’s so interesting to me about sweat is that, unlike some of these other bodily fluids that you mentioned, like peeing or pooping or even burping. All of these things, you can control it just for a second. So you’re in a social situation, and you feel something happening and you can move out of that social situation and deal with it. But with sweat, you have absolutely zero control over your body’s decision to open the floodgates. And I think that that is partly why there’s so much discomfort and shame associated with it because it is utterly out of our control. Humanity really doesn’t like it when things are not in our control, we’re a little bit micromanagy as a species and particularly in this era of online curated personalities and having a an image: that your body goes rogue on you, I think, is why it’s very particularly kind of shameful.

Speaker 1 [00:20:12] For performers like myself, you’re literally on stage and if you’re perspiring in a way that is obvious to people, you have no control over it. You’re in a situation where you should be controlled, and it’s really unnerving whenever that’s happened. I’ve had experiences onstage where I had sudden dry mouth or where I had heart palpitations. I had a panic attack on stage at one point, I’ve experienced sweating as well. It’s really upsetting. I don’t know if you remember, this is very specific to me, but you remember when Marco Rubio had to grab the glass of water? Do you remember this, when he was giving the speech? He was doing the response to the State of the Union. He’s he got dry mouth and he stepped off camera really awkwardly to get a drink of water. It came out that he had like he had sort of a phobia of always needing water nearby because he got dry mouth all the time. A lot of people made fun of him, and I was like, ‘Oh, I get it. I understand. I have been there, man.’ Solidarity. You are not totally in control of yourself and you need that thing nearby. It’s really interesting that we don’t have any control over sweat specifically, though, because we have control over our breathing and that’s the most fundamental bodily process of all. That’s the most basic thing that our body is doing to maintain itself and we can hold on to that for at least a period of time. But sweat, we can’t hold it in until we get really overheated and then it floods out. We can’t hold it in whatsoever. Why? Is there something special about sweat that means it works that way?

Speaker 2 [00:21:49] I think it speaks to the fact that temperature control is utterly important for us. We were talking about what makes us hot and what makes us need to sweat. Even if you’re not in a really hot environment or running, your body’s constantly doing biochemical reactions. It’s dividing cells, it’s breaking down glucose, it’s making hormones. Many of those biochemical reactions produce heat. So you, just sitting on your couch, eating a bag of chips and watching Netflix, you are actually creating a lot of body heat. That happens also while you’re sleeping. So your body needs to be constantly on top of your temperature. I think that just speaks to why it’s so essential and why it’s so amazing that humans have such a sensitive control mechanism for doing that, for controlling our temperature.

Speaker 1 [00:22:48] Yeah. We’re just constantly adjusting the thermostat all of the time.

Speaker 2 [00:22:54] All the time.

Speaker 1 [00:22:55] But then if that’s the case, people are still very sensitive to temperature. Right? My partner and I just had an argument the other day about the thermostat in the middle of the night because she wanted a little bit colder and I’m like, ‘We’re asleep. You put a fan on. You don’t need the thermostat to be at the same temperature when you’re asleep as when you’re awake. You bump it up a couple of degrees to save power.’ That’s how I was raised. I’ve become a thermostat dad, unfortunately. So this is still something that people feel really, really strongly about. It’s like we have a limited degree to adjust our temperature. It’s interesting. You said we’re comfortable at many different climates, but also we have this desire to fine tune it. I don’t know.

Speaker 2 [00:23:40] Well, yeah. We are each our own unique biological selves, right? We put on the pelts of other animals, right? Maybe you need two pelts and maybe your partner needs one. But I think I’m going to step away from this particular conversation because I do not get in between couples.

Speaker 1 [00:24:04] ‘Honey just put on another pelt. Come on.’ Ok, I’m surprised were 22 minutes into this interview and we haven’t said this yet. What exactly is sweat? What is in it?

Speaker 2 [00:24:16] Yeah, it’s actually really interesting. It’s so much more complicated than salt and water. So all your sweat glands – When your body gets the temperature directive to cool down, it sources sweat from your blood. So sweat is actually the watery parts of blood, minus the big things like blood cells and immune cells.

Speaker 1 [00:24:36] What?! Sweat is blood?

Speaker 2 [00:24:38] Yeah, well, it’s the watery parts of blood. So what happens is, OK, you get hot, right? Immediately your body’s like, ‘Oh crap, we’ve got to get the core cool.’ So all your blood vessels push up against your skin, which is why people with lighter skin tones turn red, because all of your vasculature (you’ve got those veins) pushing up against your skin. That’s for two reasons: one, because your sweat glands need to source sweat from somewhere and so they’re pulling out the watery parts of blood and two, because effectively you’re cooling the hot blood in your core. It’s swooshing out to the surface of your skin, passing by your skin where the evaporating water cools it, and then it swoops back into your core to cool you down. But the sweat, the reason it’s salty is because we’re salty oceans inside. Our blood is very salty, and so is our sweat. But anything that’s circulating in your sweat; whether it’s hormones or vitamins or the drugs we consume, that also comes out in your sweat. So I went to a forensic chemist who effectively took a fingerprint of mine (because fingerprints are just sweat prints, they’re inked in sweat) and so just with the tiny little bit of sweat that I left with my index finger, she could tell me that I had my morning coffee because she found evidence of caffeine metabolites like caffeine in my sweat. Now, had I topped up my coffee with a little vodka or snorted a line of cocaine as part of my morning routine that also would come out in my sweat and be left in the trace amounts of a fingerprint. So when you’re dripping on your yoga mat or onto whatever it is that you do, you are actually dripping out secrets. It’s not just secrets that you’re overheated or maybe nervous talking to your special crush, but you’re actually literally leaving chemicals behind that can also say whether you have certain diseases. This kind of forensic analysis is super young. It’s just being developed. But yeah, the next generation of iPhones and smartwatches will (or may) include these adhesive patch add ons where (you imagine a Band-Aid with some electronics) they are measuring your sweat. Then it sends you a little push alert on your smartphone or your smartwatch, saying, ‘Dude, you’ve had one too many at the bar. Best to take a cab home tonight instead of driving.’ Or for athletes, you can imagine a sports team: there’s a coach on the sidelines watching the players in a really important game. They are all wearing these sweat patches which are sending information about the contents of their sweat. The coach sees that one of the players is really releasing stress hormones and thinks to themselves, ‘OK, best to switch out that player.’ So this is kind of what’s on the horizon. So really exciting if personal measurement is your jam. If you have a Fitbit, this is the next generation of that. So that’s cool. But it’s also terrifying because you can imagine that just with a fingerprint, which we leave literally everywhere, can be used by an employer.

Speaker 1 [00:28:20] Yeah, give this to Amazon to put on warehouse workers and it’s a much different story.

Speaker 2 [00:28:26] Right, or are you in your cubicle at work showing up intoxicated? And your boss is able to lift a print and make decisions like that or health insurers could use it because certain diseases leave biomarkers in your blood, which come out in your sweat. They could also surreptitiously sample that and make decisions about you or your coverage that may not be in cahoots with justice.

Speaker 1 [00:28:58] Wow. OK, because look, this is wild to me because we did a whole segment on our show, ‘Adam Ruins Everything,’ a couple of years ago about how the idea of sweating out toxins is kind of bullshit, and we’re going to get to that in a second. I want to ask you for your take on this. You’re mouthing, ‘thank you’ at me. We’re going to get into it. But I still, I go to yoga classes and the yoga teachers still go ‘Sweat out all those toxins.’ And it bugs me. I’m like, ‘Fine, I’m just doing the pose. I’m not thinking about the pseudoscience.’ I wish, instead, they would say, ‘Let’s sweat out all those secrets, sweat out the secrets.’ That is so much more evocative: to think that you are releasing secrets onto your yoga mat. That feels spiritual to me, in a way.

Speaker 2 [00:29:39] Purging those negative things that you bottle up inside, right? Like the emotions and such. But yeah, no. Oh my gosh. Sweating is not a detox strategy.

Speaker 2 [00:29:49] Let’s go to break on that note because once we get into that, we’re going to spend the next half hour really unpacking that. So if you want to find out about why sweating out toxins is bullshit, come on right back with us after the break. We’ll be right back with more Sarah Everts. OK, we’re back with Sarah Everts, and we were just getting into it. You said that sweating is not a detox strategy. Tell me what is so wrongheaded about this idea that you hear all the time; that you sweat out toxins. What’s the problem with that?

Speaker 2 [00:30:32] Oh my gosh. This myth kills me because if you know anything about how the body functions, you know that this cannot be true. So remember how I said that sweat comes from the watery parts of blood? So if we sweat out toxins, you would literally have to sweat out all the water in your blood in order to get all the nasty stuff out. You would literally have to sweat out every last drop of your blood to get the toxins out, onto your skin and away. That would leave you completely dehydrated and likely dead. Instead, our body has kidneys which filter the blood of the nasty stuff and dispatch that out in pee. So anything that’s coming out in your sweat is incidental. Certainly some nasty stuff comes out, right? Anything that’s circulating in your blood that hasn’t perhaps passed through your kidneys yet can come out: things like urea or or heavy metals. But at the same time, really important things are coming out like glucose. This is your body’s energy molecule, or vitamins or hormones. Everything that is coming out in your sweat is just what happens to be coursing through your blood. But it is not the way that your body actively gets those toxins out and you can’t do that. Like, if that was the way, then you would have to dehydrate yourself to death, which is really not an optimal life strategy.

Speaker 2 [00:32:11] Because you’re only sweating out a little bit of the water. So even if the toxin that you’re worried about was able to pass through the skin and leave in that particular way, rather than just a marker of it, you’re only sweating out some small percentage of your blood because otherwise you’d be dead. All it does is indicate that there’s more of it in you, at its very best.

Speaker 2 [00:32:34] Exactly. And so what’s interesting about that, is that sweat could be used in the future as a strategy for identifying things. Like, ‘Oh hey, you have maybe this contaminant in you.’ It could be a diagnostic to say, ‘This is circulating in your blood,’ in the same way that you can figure out that someone has been drinking alcohol because it’s coming out in their sweat. But that’s not how your body’s purging those things.

Speaker 1 [00:33:01] Your body is very clearly purging stuff that you don’t want to have in your body via pee and poop. That’s why pee and poop are gross.

Speaker 2 [00:33:08] Exactly, right.

Speaker 1 [00:33:09] That’s why I assume (you’re the you’re the science writer) there’s an evolutionary connection with the fact that I am revolted by my poop, to the fact that there’s stuff in it that I don’t want in my body. If I want it back on my body, it would be delicious to me and I would want to eat it but I don’t want to eat it, so therefore my body must be trying to reject that stuff. We do that already. You’re giving me such a look, like this guy is really going into detail.

Speaker 2 [00:33:38] I’m really enjoying your explanations very, very much.

Speaker 2 [00:33:43] Instead of saying ‘Sweat out all your toxins,’ the guru should go with you to the bathroom and say ‘Pee and poop out all your toxins’ and do some therapeutic peeing and pooping classes. That’s what we should have to get the toxins out, right?

Speaker 2 [00:34:01] I love this. So an interesting segue about this is that when you do go to, say, a yoga class and sweat a lot or a workout, you do feel good. What those yoga instructors and literally every spa on Earth and spin instructors and all these people who kind of promote this thing, they’re referring often to this very lived experience of ‘Wow, I feel euphoric after a workout.’ What’s actually happening, is that when you sweat a lot, your heart starts to beat really quickly. And so (whether you’re sweating and actually exercising or just sweating in a sauna) because your heart is pumping blood so quickly through your body in order to cool down, you’re getting the release of all these happy chemicals. Things like epinephrine and endorphins. These happy hormones that come when you exercise do make you feel so happy that you are having a catharsis.You feel like you’re getting out toxic emotions, and that’s certainly true. But you’re not actually literally getting out toxic chemicals.

Speaker 2 [00:35:21] Yeah. There’s nothing that feels better than my favorite part of going on a run. Obviously running often is pain and you just wait for it to be over. It’s specifically an endurance exercise. You’re enduring it, but then you come home and you’re all sweaty and then you take a shower and then you feel so refreshed and there’s something so good about it. This is going to be my next question; (even though the toxin thing isn’t real) having a centralized way to sweat a lot: a steam room or a sauna (pronounced sow-na). I know people say sauna (pronounced saw-na). My grandparents were Norwegian. They taught me to say sauna (sow-na). You gave me a fist in the air. So you think that’s right. I got made fun of by kids in my high school for saying ‘sauna’ like that because they were all long islanders. They all went ‘saw-na,’ and I was like ‘No, it’s a sow-na!’ Anyway. This is an age old practice, right? People specifically going in a small, hot room to sweat? There must be a purpose for it? Is that the purpose?

Speaker 2 [00:36:26] Yeah, maybe. I mean, if you look at human history: from indigenous people of the Americas to the Humams in the Middle East to the Jjimjillbangs in Korea, to the Banias in Russia, to the Saunas in Finland and most of Western Europe, there is this catharsis and a desire to sweat in vast quantities. I do think it’s because you get this release of happy chemicals that also give you a sense of purpose and a sense of calm. It’s a very ancient practice and I think we see the modern incarnations in spin classes and hot yoga.

Speaker 2 [00:37:08] Is it actually good for you though? In addition to feeling good and just, ‘Oh, I feel refreshed and maybe my brain is a little clearer because I’ve got some new chemicals coursing through my brain that I like.’ Is there a health benefit to going in and intensively sweating for half an hour to an hour – Forget exercise, if you’re just going in the sauna on a cold day, is there a health benefit to that?

Speaker 2 [00:37:33] Yeah, there is. The health benefit is to your heart. There has been a lot of pseudoscience claims and oh my god, it kills me. I love to go to a sauna or a spa. But most of the things that they claim just kill me, it does not cure cancer to go to sauna. OK? But what actually has been done in terms of really good science is that Finnish researchers did this enormous cohort studying people over many, many years. They found that if you went to the sauna very regularly, you had a lower incidence of heart attack, heart disease, deaths by something related to heart health. So it is good for your heart, because your heart is getting exercise. When you are sweating in vast quantities, you have to be pushing the hot blood from your interior out to the surface of your skin, getting all that liquid to the surface of your skin. Your heart is booting it; your heart is a muscle and it’s getting exercise. The downstream effects of this are plaque clearing enzymes being expressed and other good things for your cardiovascular system. There are some actual health benefits just to sitting in a very hot place and forcing your body to cool down. It’s not time to quit your gym membership yet, because of course you’re not burning that many calories and you’re not building muscle, but you are working out your heart. But the one tiny caveat, is this research was done in Finnish men. I don’t know if you’ve been to Finland, but there are more saunas in Finland than there are humans. When they’re doing this very long term study, they struggled to find anybody who didn’t go to the sauna at least one time a week. So these health benefits that I just told you about, that’s if you go like four to five times a week. So you really need to up your game to get your heart healthy. But the point is, is that there are health benefits and you know, maybe you’re getting microbenefits if you just go to the sauna now and again.

Speaker 1 [00:39:47] Does the humidity matter? A lot of times the sauna, you go in and there’s dry heat, there’s a wet steam room. I guess I don’t know. Variation is good. Now I’m just asking you for advice on how to take a good sauna. Sorry. Is it good when you jump in a frozen lake? That’s what we used to do at my grandparents cabin. You go in the sauna and you jump in the frozen lake afterwards.

Speaker 2 [00:40:06] It’s glorious.

Speaker 1 [00:40:09] And then you go back in the sauna. It was great fun when I was 13 years old. Maybe I would enjoy it less now.

Speaker 2 [00:40:16] I enjoy it enormously. Yeah, it’s called the heat cycle, and it’s just incredible to have the contrast. It really just makes you feel glorious. It definitely ups those happy chemicals.

Speaker 1 [00:40:34] This actually makes me feel a little bit better, because (especially in L.A.) there’s people are always coming up with a new treatment that is claimed to do something. A couple of years ago, the big thing in L.A. was cryotherapy, where you go get in a cold chamber and it’s supposed to do x y z your body. And my take was I was like, ‘Ah, it probably just feels good. It’s just an extreme feeling.’ You go into a really cold room. You withstand it, you come out, then you feel warmer and you feel like something has happened to you. I always assumed that a sauna was the same way. But there actually can be a health benefit to this, even if it’s not going to cure cancer or toxins or things like that, it can be good in a subtler way.

Speaker 2 [00:41:11] Yeah, but I think like exercise, you have to do it regularly. So if you decide to get all super healthy and get the benefits of exercise and just go hardcore for two weeks and then never exercise again in the course of your life, it’s not going to have an ultimately great impact. But if you regularly go to the sauna and regularly give your heart this workout, I do think that is going to benefit you.

Speaker 1 [00:41:37] For all the people who are doing a lot of coke and getting really drunk and going on a bender and then saying, ‘Now I got to go to the steam room to sweat the toxins out.’ That’s not the healthiest set of behaviors. That’s not really going to work in the way that you think it is. We got a little bit of time left, and I just want to know what other amazing shit did you learn about sweat that I don’t even know to ask about, that you can blow my mind with in the time that we have left. What’s the coolest story in your book about sweat?

Speaker 2 [00:42:06] Oh lord. We haven’t even talked about stink, right?

Speaker 1 [00:42:08] Oh my God. We haven’t even talked about the fact that sweat is stinky? Holy shit. I really didn’t think we would fill this whole interview with sweat facts, and we’re not even all the way through it. So, yeah, tell me about about stinky, stinky sweat.

Speaker 2 [00:42:22] Up until this point, we’ve been talking about this one gland that releases the salty floods to cool you down. But there is another and it appears that puberty, mostly anywhere where you grow hair. This other sweat gland, it’s called the apocrine gland. It’s what’s responsible for morphing armpits into stink zones from the teenage years onwards. That sweat is not salt watery at all. It’s actually more like earwax, and it actually comes out not smelling bad at all. But you’re covered in bacteria, right? We are a hybrid organism of human and bacteria doing stuff. The bacteria living in your armpit eat that other kind of sweat and it’s their metabolic products (which is a euphemism for poop in the scientific jargon) that is the stink that gives you your body odor print and me a slightly different body odor print. But that definitely gives us some body odor. So, yeah, it’s interesting because we have top notes. Like, there are top notes to our human B.O. that scientists have figured out are the things in human B.O. where you go into an elevator and it’s super stinky and you know that it was a human in there before and not a dog. Those two top notes, one is kind of smells like a raunchy goat.

Speaker 1 [00:43:57] You’re talking about this like you’re a wine connoisseur.

Speaker 2 [00:43:59] It’s the same science, dude. Then the other one is overripe passion fruit with onions. Those are  the two human top notes.

Speaker 1 [00:44:10] {snooty voice} ‘Mmmmm yes with hints of overripe passion fruit. {sniff sniff sniff} Yes, I’m getting human. I’m getting human. Yeah, yeah, yeah.’

Speaker 2 [00:44:17] Those are the things that you and I probably share in common about our B.O.. But then there’s hundreds of other molecules that make it possible for a dog to track me versus track you based on a t shirt that we’ve worn. There’s so many interesting things that humans learn from one another from our B.O.. We learn the odors of the people we love; siblings can identify each other even if they haven’t seen each other for years based on that B.O.. We can identify anxiety, I have just met you and I could tell if you’re anxious or not, most likely from the sweat on your T-shirt because we sweat differently when we’re anxious.

Speaker 1 [00:45:04] But you wouldn’t do this consciously. I’ve never been around a person and been like ‘Sniff sniff, yeah they smell anxious.’ I’ve been around a person and and felt anxiety coming off of them. Are you saying I am sort of subconsciously or unconsciously detecting anxiety based on their smell? Really?

Speaker 2 [00:45:22] Yeah. So this was an observation that first came from a law enforcement who observed that when people come in to be interrogated, they smell like themselves. Whatever that is. But when they leave, they all smell the same, anxious. And when scientists –

Speaker 1 [00:45:37] Wait, cops were like, ‘Yeah, all the perps smell the same, you been in this business long enough, you know that all the perps smell the same.’ That’s wild. What a weirdo, who is making this observation.

Speaker 2 [00:45:50] It’s not just the perps, we all do. It’s kind of super stressful to be interrogated by a cop. I imagine a lot of innocent people smell anxious too. When scientists try to suss out ‘What the heck are they talking about?’ They gave people T-shirts to wear and then they put them in front of movies. One was a nature documentary and the other one was a really scary film, and they collected the different kinds of sweat. Then they gave it to a panel of sniffers; of people whose job it is to sniff things. That’s a great job, by the way. They could tell, these perfect strangers, just from the stink. Who was anxious and who wasn’t. The organization probably most interested in doing research on this and that funds a lot of research is the American military, because you can imagine in a tank situation, if you’ve got a bunch of people working close together and one person gets super anxious and they start making this odor, it could spread the fear among the other people in a combat situation. That could end up compromising that mission. So lots of chemists are trying to find a way to identify that top anxiety note, which they haven’t been able to yet of the hundreds of molecules percolating out of our armpits, that they haven’t managed to pluck. But once they do, the idea is to find a way to capture it like you would capture a poison gas with a gas mask or CO2, like carbon capture techniques. That’s just one of the little tidbits of information coming out of our body odor and moving from me to you.

Speaker 1 [00:47:29] That’s wild. I used to hear about pheromones as being a thing. I think we’re moving that way. But it was always like ‘Buy this vial of pheromones and put them on and you’ll attract women and whatnot.’ Even Axe body spray, they had a whole ad campaign basically about scent is going to attract women to you and stuff like that. It always seemed like bullshit, but that sounds to me like what you’re describing. If I’m able to sense something subtly, if someone’s smell that is not even consciously detectable to me is causing is influencing my opinion of them, it sounds like we’re halfway to pheromones being real. Are pheromones real? You have a sneaky expression on your face.

Speaker 2 [00:48:14] Well, I am a person who does buy pheromones cologne on the internet for funsies.

Speaker 1 [00:48:22] Because you think it works or because you’re like, ‘What the hell is this?’

Speaker 2 [00:48:25] I can tell you, because I was doing an experiment in the outskirts of Berlin with some horny boars, like wild pigs. I guess we can talk about that later. But anyway, because our body odor appears at puberty and because puberty is also when we become sexually mature, it is a logical progression that perhaps there’s something in our B.O. that is helping us find a mate. Probably the best evidence found to this effect in humans, was done by a guy named Klaus Vatican. He took a bunch of t shirts and gave them to men to wear. Most of these kinds of studies have been done in heterosexual men to heterosexual women, a lot of science has ignored the greater diversity that’s out there in humans, sadly. So in this case, these men had their stink on different T-shirts and the women were told to rank them for attractiveness. Meanwhile, everybody’s giving blood samples. What the scientists found, was that women found men to be most attractive when any combined progeny would have immune systems that were really strong. This makes sense if you think about humans in an evolutionary context. For most of our history, it’s been microbial pathogens that have been our greatest foe, whether it’s a plague or a pandemic or just an infection. So it behooves us to pick a partner to mate with that will produce progeny that can survive. But that’s not very sexy. It kind of comes into contrast with our pop culture notion that ‘I put on this pheromone cologne and you become my sex automaton.’ That is not true, thank the lord. The dating scene, already, is pretty dystopian. But that kind of chemical does exist in the animal kingdom. Silkworm moths make this molecule called ‘bombykol’ and a female will release it, and literally every male within sniffing distance makes a beeline towards her. It is the ultimate definition of a booty call. Or wild pigs (wild hogs) make a pheromones, the males make a pheromones in their saliva, and when they breathe heavily on a female in heat then she will swing around and lift her rump to present it to the male for mounting. There is nothing like that that scientists have found in human body odor and they have been looking for literally decades. It’s been a pretty impotent search (for lack of a better word) but that doesn’t mean that there aren’t cues in our B.O.. For even that T-shirt study where women were finding men attractive if they had a complementary immune system; scientists have done that study but they haven’t figured out what’s the component of body odor? Like, what’s the actual chemical that’s causing that reaction? All of these online entrepreneurs that sell pheromone cologne, what they’re actually putting in is that boar pheromones. That one which will make the female boar lift her rear and spin. They put that in because those molecules are called ‘androstenedione’ and ‘androstenol’ and they have been found in human sweat. But they’ve been found in both biological sexes. The strict definition of a sex pheromone is that one sex makes it to attract the other. So it’s not a human pheromones, but it is a bore pheromone. So all the dude bros out there who are buying these colognes on the internet and spritzing them on their bodies, they will attract a female, but it will not be a human female. It will be a wild pig female. I am not a person who’s judging you. So like, go for it.

Speaker 1 [00:53:00] That was such a wonderful explanation. So what you’re saying is, that we do communicate with each other with our sweat to some extent. We are passing information back and forth. But (and maybe some of that is related to sex in as much as sex is part of who we are and there’s probably something going on) it’s very complex and it’s not something you can buy in a bottle. Also, we clearly don’t have a sexual behavior with each other where men just go ‘I want a woman to present herself, somehow chemically’ and then women do it because that just doesn’t fucking happen. That’s not how it works at all. It might work in hogs that way, but we just simply don’t have that set of behaviors. But we may be communicating with each other. We are communicating with each other, somehow, using chemicals excreted through our skin.

Speaker 2 [00:53:55] Yeah. We’re also sniffing each other constantly, right?

Speaker 1 [00:54:01] (trying to control his laughter) Yeah, okay.

Speaker 2 [00:54:02] Until COVID 19, most common greetings involved a moment of proximity. Whether you do a cheek kiss, or a hug, or you bow. A handshake is a literal hands on collection of somebody else’s B.O.. Actually, this really great study was done where these scientists surreptitiously filmed people meeting for the first time and shaking each other’s hand. They found that within moments of that handshake, the people sniff their hands afterwards. They lift up their hand, in an unconscious sniffing of the handshake hand. It was so shocking to the participants that many of them accused the scientists of deep faking the videos. Like, ‘I didn’t do that’ because it is so unconscious, and so we are sniffing each other and we are certainly gathering information and smell is important to us. We have so much nostalgia associated with odor. When you go to the house of a loved one or, every time I land in Berlin it has a certain smell, the air. It smells like my adult home.

Speaker 1 [00:55:15] Smells like war chemicals, in Berlin to you?

Speaker 2 [00:55:18] (laughter) Anyway, we are influenced and emotionally impacted by odors. Certainly we we smell our partner. Actually, that’s the premise of smell dating. I went to a smell dating event in Moscow where you pick a partner or you’re matched based on B.O.: the premise being that in this digital era where we’re swiping right and left, at some point you’re going to smell the body odor of your partner and it will be a make or break moment. So why not skip to the chase (or actually entirely skip the chase) and just do that first level triage on B.O. instead of, say, looks or a shared love of taxidermy or whatever hobbies you have?

Speaker 1 [00:56:03] Did you try this? You smelled some B.O.s?

Speaker 2 [00:56:04] I did.

Speaker 1 [00:56:05] Was somebody there presenting you with vials or dirty T-shirts, or what?

Speaker 2 [00:56:09] No, what happens is you get a group of people together, and the first thing that you do is you get a wet wipe and you wipe off any products that you’ve been wearing. Then they take you through some high intensity intervals, some exercise, to work up a sweat. Then you’re given a cotton pad where you dab in all the places and then that pad is put into a glass jar and the jar has a number. You know the number of yourself and the organizers know your number. Then there is a table in all the glass jars are put on the table and you sniff through them and your job is to pick your top five. At the end, you submit your top five and if I picked your B.O. and you picked my B.O. (this being Moscow) we would get a VIP bracelet to an all you can drink vodka cocktail lounge. In order to find out whether the optics and hobbies also match.

Speaker 1 [00:57:08] (Russian accent) ‘You’re going to go to a house rave in a warehouse by the docks.’ That wasn’t an accent. Sorry, I guess I couldn’t summon it that quickly, but OK. When you smelled these B.O.s: first of all, was it stinky? And B, was it something that you had a conscious – Because so much of your talking about is unconscious. I would imagine myself going and sitting there going like, ‘I don’t know, do I like one or two better?’

Speaker 2 [00:57:40] I remember, some of the B.O.s you’re just like, ‘Holy hell, no.’ I remember this one, it smelt like adolescent boy. I didn’t ever want to smell that again. I also smelled a whole bunch that were familiar, I can’t even explain it. It just was like, ‘Oh, that smells like human and a likable human. Maybe somebody that I maybe liked.’ It was more of that nostalgic feeling, and then (I remember the number) number 15 comes along and I sniff it and I’m just like, ‘Yes, yes, yes. Oh yes.’ It didn’t send me into like some insane, spinning feeling of needing to bed somebody immediately. But it reminded me that, ‘Oh my god, there’s this very enjoyable thing called sex. And I certainly would be interested in finding out if I could do that very enjoyable activity with this number 15.’ But number 15 didn’t pick me. So it just goes to show that even in smell dating, your heart is freakin broken, depending.

Speaker 1 [00:59:01] I just want to end on this question, why is it? Do you have any thought on why so much of this is unconscious? That the thing that is coming back for me, because we could talk about food and the other half of food, which is pooping. Both those things I do consciously, I know when I’m eating. I know when I’m pooping. I can decide not to do it, to do a point. But sweat, we tend to think about it less. We have no control over it. We are releasing all these things without realizing it. We’re picking up on what other people release without realizing it until you make the decision, as you did, to pay conscious attention to it. It’s a much more invisible layer, but it also seems really powerful. Why? Why is that, and what effect does that have over our understanding of it?

Speaker 2 [00:59:50] I think it kind of speaks to our evolutionary history, right? If you look at other mammals, they are very driven by olfaction, by their noses. They make all sorts of decisions, take the laboratory mouse. Mice will literally smell each other’s pee, like dip their noses in it to learn the virginity status other animals, like whether they’ve had babies – All sorts of identifying features they are learning through pee. Now, we’ve evolved. We still, do smell each other. I think that there’s this  primordial, vestigial thing happen there. But we developed language, which is very useful for communicating subtle ideas. I think it’s still there and I think it’s influencing. But we also have free will and we do have control over our bodies, whether it’s motivated by a sense of decency or laws. I think it kind of speaks to our evolutionary history. What’s interesting to me is that for the last 100 years, we’ve been really masking our body odors by using deodorants and perspirants. We are constantly putting these products on. How is that affecting the background information that you get from me and I get from you when we need each other that goes along with these other subtle things: bodily cues or looks or turns of phrases, that give me an idea of who you are and you an idea of who I am.

Speaker 1 [01:01:44] We have this constant tension between our understanding of ourselves as biological and as social organisms. That we’ve built this thing on top of our biology, with our big ass brains, using language. We’ve built this whole other layer of existence: of sociality, of culture, of language, of all the things that we mainly dwell on that make us human. Then there’s this other biological layer that we only sometimes interact with – some as we interact with it too much. The idea that you know all human behavior can be reduced to evolutionary explanations is clearly not true, but also some can be; in a really complex, weird way, and that seems to really be what is a part of this.

Speaker 2 [01:02:27] Yeah, I think it’s inordinately complicated and it’s very hubristic for humans to think that we’re above all this; above our biological history. No, I think that stays with us. I kind of want to lean into it. It’s partly why I wrote the book.

Speaker 1 [01:02:46] Yeah, well, I hope folks check out the book. It’s called ‘The Joy of Sweat’. You can get it (just as a reminder to everybody) at our special book shop at factuallypod.com/books if you want to support the show and your local bookshop. Or walk down to your local bookshop or local library and get a copy. Sarah, this conversation been so fascinating. Thank you so much, and I hope you’ll come back on next time you’re exploring another weird and disgusting and mind blowing part of the human body or human experience.

Speaker 2 [01:03:13] It’d be a pleasure. It was great talking to you.

Speaker 1 [01:03:20] Well, thank you once again to Sarah Everts for coming on the show. If you want to buy her book ‘The Joy of Sweat.’ Please go to factuallypod.com/books. That’s factuallypod.com/books, to buy at our special bookshop. That is it for us this week here on Factually, I want to thank our producers, Chelsea Jacobson and Sam Roudman. Our engineer, Ryan Connor. Andrew W.K. for our theme song. The fine folks at Falcon Northwest for building me the incredible custom gaming PC that I am recording this very episode for you on. You can find me online at AdamConover.net or @AdamConover, wherever you get your podcasts. And hey, thank you so much for listening. We’ll see you next week on Factually.