Kleptotherms

In this episode, we break the thermometer and watch the mercury spill out as we discover that temperature is far stranger than it seems. We first ran this episode in 2021: Five stories that run the gamut from snakes to stars. We start out underwater, with a species of snake that has evolved a devious trick for keeping warm. Then we hear the tale of a young man whose seemingly simple method of warming up might be the very thing making him cold. And Senior Correspondent Molly Webster blows the lid off the idea that 98.6 degrees Fahrenheit is a sound marker of health. Reported by - Lulu Miller and Molly WebsterProduced by - Becca Bressler, Lulu Miller and Molly Websterwith help from - Carin LeongFact-checking by - Emily Krieger Sign up for our newsletter!! It includes short essays, recommendations, and details about other ways to interact with the show. Signup (https://radiolab.org/newsletter)! Radiolab is supported by listeners like you. Support Radiolab by becoming a member of The Lab (https://members.radiolab.org/) today. Follow our show on Instagram, Twitter and Facebook @radiolab, and share your thoughts with us by emailing [email protected]. Leadership support for Radiolab’s science programming is provided by the Simons Foundation and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.

• 0:01Speaker 00

  Hey, this is Radiolab. I'm Latif Nasser. So at this point of the year, at least here in the northern hemisphere, it can start to feel like enough with the cold already. The newness of the season has worn off, the winter holidays are over, and most of us are just ready for it to be warm again. So today, we are defrosting an episode about people and creatures seeking warmth. Sometimes they do it in obvious ways, sometimes they do it in devious ways. We first aired this episode back in 2021, and you'll hear there are certain things about it that do feel very 2021.

• 0:44Speaker 00

  But there's also so much in here that feels timeless, stories that I feel confident will stay relevant until the thermal death of the universe.

• 0:54Speaker 01

  Yeah, you're like, wait, you're listening. Okay. All right.

• 0:58Speaker 02

  Okay.

• 0:59Speaker 01

  All right.

• 1:01Speaker 03

  You're listening to Radiolab.

• 1:04Speaker 01

  Radiolab.

• 1:04Speaker 03

  From?

• 1:05Speaker 01

  WNYC.

• 1:09Speaker 04

  Rewind.

• 1:13Speaker 05

  Lou.

• 1:14Speaker 04

  Hey.

• 1:15Speaker 05

  How are you feeling?

• 1:17Speaker 04

  I mean, I feel fine. I think I still am like a dash nasally. Hi there. It's Radiolab. I'm Lila Miller, here with senior correspondent Molly Webster. So can you humor me and close your eyes?

• 1:29Speaker 05

  Yes, eyes closed in my closet.

• 1:31Speaker 04

  Okay, so now journey with me. Me and you are on a trip. We've got our backpacks and our hiking boots.

• 1:38Speaker 05

  Okay.

• 1:39Speaker 04

  And we've, we come across this site, an archaeological dig, and they are, they're like unearthing this ancient library. And we're like looking all around, and you're over there, and I don't know, you find like an old globe, and then we come across this book that's like covered in dust, and we blow the dust off.

• 2:03Speaker 04

  And the dust, like, it turns into like snowy frosty snowflakes and little tiny flames.

• 2:10Speaker 05

  Oh.

• 2:10Speaker 04

  It's like.

• 2:13Speaker 04

  And then it says in silver letters, kleptotherms.

• 2:22Speaker 04

  And then we were like, ooh, what's what? What? And we cracked the book and it's like, and we open it. And there's five chapters and we turn the page and the first chapter, there's just a picture of a snake in a coil. So we're gonna start and read that chapter.

• 2:43Speaker 05

  Okay.

• 2:46Speaker 04

  So, once upon a time, there was a bright blue snake in New Caledonia. It's bright blue and black, so it's just like striped.

• 2:55Speaker 05

  Is this real?

• 2:56Speaker 04

  This is real. Oh, this is one.

• 2:57Speaker 05

  Okay, this is, okay, this is real.

• 2:59Speaker 04

  Oh, it turns out this whole book is stored in the Library of Congress as nonfiction.

• 3:04Speaker 05

  Okay.

• 3:05Speaker 04

  So it's this blue and black snake. It looks kind of like Betelgeuse and it is a horrible thing. It's an amphibious sea snake, so it can live in the ocean and on land. And scientists have observed that it does this thing.

• 3:18Speaker 06

  They sneak into burrows, which are occupied by large tropical seabirds.

• 3:23Speaker 04

  This is Hans Ismerman, a social scientist at the Université Grenoble Alpes, who explained that the snake will slither deeper and deeper into the burrow, toward the bird, sneaking up. And then it just kind of hugs it.

• 3:43Speaker 06

  And they take advantage of the mass body heat in warming their own bodies.

• 3:48Speaker 04

  And are they not even eating those birds? They're just kind of like curling around them and sucking up their heat?

• 3:55Speaker 06

  That's essentially what they're doing, yes.

• 3:56Speaker 04

  Wow. There's just something so primal about the heat being more important even than the meat.

• 4:03Speaker 06

  Yeah. So this behavior is called kleptothermy.

• 4:05Speaker 04

  Kleptothermy. And what does that mean?

• 4:07Speaker 06

  Basically engaging in heat theft.

• 4:09Speaker 04

  Okay. You see it all throughout the animal kingdom.

• 4:12Speaker 05

  Really?

• 4:13Speaker 04

  Yeah.

• 4:13Speaker 05

  Seriously?

• 4:14Speaker 04

  Yeah. So like male garter snakes?

• 4:17Speaker 06

  They pretend to be female so that other males will try to mate with them.

• 4:21Speaker 04

  Like the friction of them trying to mate.

• 4:22Speaker 05

  Trying to mate just warms them up?

• 4:24Speaker 06

  Yes.

• 4:25Speaker 04

  There's little dwarf caimans, which are kind of crocodile-y looking things that steal from termite nests.

• 4:30Speaker 05

  How do you cuddle up to a termite?

• 4:32Speaker 04

  I don't know. Just like, I think you like, you just like throw yourself upon the whole warm nestiness of all that buggy.

• 4:39Speaker 05

  Wow.

• 4:41Speaker 06

  And us humans also engage in kleptothermy when we want to.

• 4:45Speaker 04

  That oh, so sweet act of cuddling, or as the scientists call it.

• 4:49Speaker 06

  Huddling.

• 4:50Speaker 04

  Is, for at least one person involved, a theft.

• 4:54Speaker 06

  I remember reading about it a couple of years ago, and I thought it was just fascinating. But if you think about it, it feeds, it feeds into the same kind of equation.

• 5:03Speaker 04

  An equation biologists call the economy of action.

• 5:07Speaker 06

  It's very simple. Animals need to take in more energy than they exert. And one of the most expensive things that we do, particularly as mammals, is warming our bodies.

• 5:18Speaker 04

  And it turns out that of all the ways to keep our body warm, jumping up and down, finding a sunspot, eating something really fatty, getting our warmth from another creature is super efficient.

• 5:29Speaker 06

  It can decrease the cost of thermoregulation by up to about 60 or 70%.

• 5:36Speaker 04

  Wow.

• 5:37Speaker 06

  There are a lot of observational studies on this for many, many different animals.

• 5:41Speaker 04

  Rats, penguins, dagus.

• 5:43Speaker 06

  Not only is their peripheral temperature higher, but also their base metabolic rate is much lower, meaning that they exert much less energy.

• 5:52Speaker 04

  To stay warm.

• 5:53Speaker 05

  Huh.

• 5:55Speaker 04

  And so Hans's idea is that because for so long, humans relied on getting warmth from one another to survive.

• 6:03Speaker 06

  Even 200 years ago, people would sleep with nine people in one bed to keep warm.

• 6:07Speaker 04

  Our sense of how chilly or warm we feel isn't just about air particles. It is being influenced by the people around us, way more than we typically think.

• 6:23Speaker 06

  I think it's, it's for most people, it's hard to imagine until you see it and then you can't unsee it.

• 6:34Speaker 04

  Which brings us to.

• 6:39Speaker 04

  Chapter.

• 6:42Speaker 04

  Two.

• 6:51Speaker 04

  What's the picture?

• 6:52Speaker 07

  I'm wearing sweatpants, a long-sleeved shirt.

• 6:55Speaker 04

  It's a guy in a jacket.

• 6:57Speaker 07

  It's probably one of my nicer shirts. I wanted to look nice, even though it's only the radio.

• 7:03Speaker 04

  His name is John, and he's gonna lead us to a different idea about how to get warm. Okay.

• 7:09Speaker 07

  Okay.

• 7:10Speaker 04

  Can you tell me a little bit about where you grew up?

• 7:14Speaker 07

  I grew up in the woods, in a house in the woods in Connecticut.

• 7:20Speaker 04

  Do you remember how the world felt to you as a kid?

• 7:25Speaker 07

  Um, like, thinking back, me and my sister would make paths through the woods. There was a pond nearby, and we would go frogging. And I just remember playing with the hose, getting water all over us, and feeling free.

• 7:47Speaker 04

  But as he started to get a little bit older...

• 7:50Speaker 07

  When I was 13 or 14, things really started to change. I gained a lot of weight, and everyone was, like, making fun of me. And I became very uncomfortable in my skin.

• 8:06Speaker 04

  Which, you know, happens to a lot of middle schoolers, but for John, it hit him harder.

• 8:11Speaker 07

  I was scared of looking at my own reflection. I almost thought I, like, was seeing a ghost. I would keep the lights off and keep a distance from the mirror. I didn't look at the mirror for, like, two or three years.

• 8:32Speaker 04

  And then, once he hit college?

• 8:34Speaker 07

  I started hearing voices.

• 8:38Speaker 04

  And what were some of the, like, the kinds of things they might sort of be saying to you?

• 8:43Speaker 07

  Um, do this and do that. I gotta walk in a certain fashion, and they told me that I didn't deserve to eat. It was madness. And then I saw a doctor.

• 8:58Speaker 04

  Like, did you get a diagnosis then?

• 9:01Speaker 07

  Yeah, um, schizoaffective.

• 9:04Speaker 04

  Which is not exactly schizophrenia, but has some of its symptoms.

• 9:08Speaker 07

  He prescribed me a drug, an antidepressant, and I had a really bad reaction to it.

• 9:15Speaker 04

  What happened?

• 9:17Speaker 07

  It it really brought on those internal voices. Like, I remember driving in the car, thinking everyone on the road was targeting me.

• 9:27Speaker 04

  So.

• 9:28Speaker 07

  I went off my meds.

• 9:30Speaker 04

  But this sense that people were out to get him just kept getting worse.

• 9:35Speaker 07

  I just remember everyone giving me a hard time.

• 9:38Speaker 04

  What, how did they give you a hard time?

• 9:41Speaker 07

  They would, like, give me dirty looks. They would pull schemes on me and mock me at times, maybe even.

• 9:50Speaker 04

  Hmm.

• 9:51Speaker 07

  I remember my mom saying once, people aren't out to get you. And if you take your meds, then you'll realize that.

• 10:02Speaker 04

  Huh, it's like, how sure are you that you were actually being mocked and actually being given dirty looks? And how much do you think that could have been something inside you seeing it that way?

• 10:14Speaker 07

  It could, it could have been something inside me somewhat, but it's hard for me to believe that it was all me making it up.

• 10:25Speaker 04

  So he keeps just trying to muddle through. And at a certain point, John does something seemingly trivial. It's a nice, warm day out, shorts and t-shirt kind of weather. And he puts on a winter hat.

• 10:41Speaker 07

  I got for Christmas one year.

• 10:43Speaker 04

  What color?

• 10:44Speaker 07

  It was gray. It it's a comfort.

• 10:47Speaker 04

  And before he heads out the door, he rifles through his stuff and decides to also put on.

• 10:52Speaker 07

  A hooded sweatshirt, hood up.

• 10:55Speaker 04

  And then he grabs a third layer.

• 10:57Speaker 07

  It was a jacket.

• 10:59Speaker 04

  And a fourth.

• 11:00Speaker 07

  Sweatpants.

• 11:01Speaker 04

  Until eventually, he's all bundled up from head to toe. And he started going out in the muggy heat of a Connecticut summer, wearing this little getup all the time.

• 11:15Speaker 04

  And people would say things like,

• 11:17Speaker 07

  What are you preparing for a wrestling match? Like trying to lose weight for a wrestling match?

• 11:23Speaker 04

  Right, like training in trash bags kind of thing.

• 11:25Speaker 07

  Yeah.

• 11:28Speaker 04

  And John is the first person to say, like, as he was putting on all these layers, he was falling into this trope. Like, if you saw someone walking around in a ton of layers in the heat of summer, you're probably gonna think something's up, maybe keep a wide berth.

• 11:44Speaker 05

  Mm hmm.

• 11:46Speaker 04

  I mean, when you, when people see you wearing layers, what do you think they think about you?

• 11:52Speaker 07

  I think they're fearful, they're fear, they fear me.

• 11:57Speaker 04

  Hello. Hello. Hello. And the thing is, while most people might step away when they see someone wearing layers, there were a few people all over the globe who decided to look closer. Am I audible? There you are. Sorry about that. This is Dr. Tathagatamahin Tamani, a psychiatrist in India. Currently, I am in northwestern part of India. Who, back when he was starting out as a psychiatrist in Raji, started noticing that in the middle of summer, every now and then, people with schizophrenia would walk into the hospital wearing tons of layers. Ladies were wearing multiple layers of saris and male patients who are wearing multiple layers of shirts. And over in Melbourne, Australia.

• 12:42Speaker 01

  I was doing my first psychiatry rotation.

• 12:45Speaker 04

  Dr. Terence Chong was treating a patient with schizophrenia.

• 12:48Speaker 01

  I noticed at the time he was taking off layers and layers and layers of clothing. And this was in the heat of summer.

• 12:57Speaker 04

  There was a doctor in Memphis, Tennessee, who noticed the same thing.

• 13:00Speaker 05

  Wow.

• 13:01Speaker 04

  Yeah, and eventually it even got a fancy medical name. Redundant clothing. So the idea there is just it's it's redundant. You don't need it. It's it's multiple. It's redundant redundant clothing.

• 13:13Speaker 00

  Yes.

• 13:14Speaker 04

  So a bunch of doctors were seeing this, but nobody really knew why. And some of the explanations were like, look, people with schizophrenia, some of them end up not having homes. They're living on the street. You have to keep your belongings on your back. So like you have you wear them all.

• 13:30Speaker 00

  Another thing might be abolition.

• 13:33Speaker 04

  A lack of motivation. So basically, the person maybe forgot to take the last layer off.

• 13:38Speaker 00

  Yes, yes. Or.

• 13:39Speaker 04

  Another explanation is just this generalized erratic. I'm confused, so I have on all these clothes. I mean, there were all kinds of different explanations.

• 13:49Speaker 07

  Um.

• 13:50Speaker 04

  Can you just describe why you crave the the layers?

• 13:56Speaker 07

  I think it's a way of shielding myself from the world. Like, I feel the world is harsh. It's it's it's hard. It's hard for me to completely put a finger on it because I was just doing what felt natural.

• 14:12Speaker 04

  And Dr. Mahin Tamani, after seeing enough people walk through his door, wearing layers in the heat, seemingly comfortable, wanted to figure out if something else was going on. So he got a group of people with schizophrenia, some of whom wore layers and some of whom didn't. And he just ran all these tests. He did like cognitive tests and psych tests and physiological tests. And basically, long, long, long, long, long story short, what he found was that the people in layers had something different going on with their blood. First of all, their blood pressure was dropping way lower on certain tests. And when he analyzed blood samples, he found that their T3 and T4 levels were lower. And what does that really mean?

• 14:57Speaker 04

  Like, what does that mean?

• 14:59Speaker 00

  So free T3 and free T4s are. Very reliable markers of temperature regulation.

• 15:05Speaker 04

  Temperature regulation?

• 15:07Speaker 00

  Yes, with cold intolerance.

• 15:10Speaker 04

  Like you just get cold quicker?

• 15:12Speaker 00

  Yes.

• 15:12Speaker 04

  Okay.

• 15:13Speaker 00

  You feel cold quicker.

• 15:15Speaker 04

  Wait, so they're actually, they may have layers on because they are actually physically colder. I asked him almost exactly that. Is your idea that they are actually wearing the layers to feel warmer?

• 15:32Speaker 00

  It is our findings that not.

• 15:38Speaker 00

  And our ideas are based on our findings.

• 15:40Speaker 04

  He says the evidence suggests that like they are wearing layers for the same reason you or I wear layers when we go out into the winter, like their body is telling them they feel colder.

• 15:51Speaker 07

  Wow.

• 15:52Speaker 04

  Now, back in Connecticut, John didn't know any of this. He just knew that the more he tried to stay warm by bundling, the more it pushed people away.

• 16:03Speaker 07

  It was a really, it was a really difficult time for me.

• 16:06Speaker 04

  And things finally got so bad that he goes back to the doctor and this time is in fact diagnosed with.

• 16:12Speaker 07

  Paranoid schizophrenia.

• 16:14Speaker 04

  And he's prescribed a different medication.

• 16:17Speaker 07

  I immediately noticed less up and down, less craziness. I noticed myself getting better by the day.

• 16:27Speaker 04

  And the world seemed to be getting a little better too, a little gentler.

• 16:32Speaker 07

  And I felt people liked me.

• 16:35Speaker 04

  And he started loosening up, literally taking off his hat.

• 16:39Speaker 07

  Yeah.

• 16:40Speaker 04

  His jacket.

• 16:41Speaker 07

  Um, well.

• 16:43Speaker 04

  Or one of them.

• 16:44Speaker 07

  It was winter and I was, I would wear like a tank top under a winter jacket and that was it.

• 16:52Speaker 04

  And he started to embrace his diagnosis.

• 16:55Speaker 07

  I read about how people with schizophrenic disorders oftentimes think divergently and a link to creativity.

• 17:05Speaker 04

  And he would tell people about it. Like one time he went to go buy cigarettes and the guy behind the counter thought he looked a little young.

• 17:12Speaker 07

  And I, I said something like schizophrenic people tend to look young, which I don't know if it's even true, but I was very proud. I was, I wasn't very proud, but I was, I was like, I had some pride.

• 17:28Speaker 04

  She thinks there's someone shooting in the building. And then, one day, about thirty miles away from where he lived.

• 17:34Speaker 01

  Shooting at an elementary school in Newtown, Connecticut.

• 17:39Speaker 04

  A young man walked into Sandy Hook Elementary School, and we all know what happened. And the day it happened, one of John's online friends sent him an instant message, saying...

• 17:50Speaker 07

  Like, when they first heard about the news that there was a shooting in Connecticut, they thought of me.

• 17:57Speaker 04

  For an instant, they worried the shooter had been John.

• 18:01Speaker 07

  It was really hurtful. It was like, I would never do anything like that. I definitely stopped having that pride towards my diagnosis.

• 18:12Speaker 04

  He stopped taking his medication.

• 18:14Speaker 07

  I felt a lot more gloom and doom, and I started to slip real quickly.

• 18:21Speaker 04

  Into this chilly spiral. Where, without his meds, the world started to seem colder. Which Dr. Mahin Tumani explained can be this unfortunate part of the disease, that the longer you go it alone, it can have what's called a neurotoxic effect.

• 18:39Speaker 00

  A neurotoxic effect on the brain. Loss of brain function, and also there is structural brain damage also there. As the time progresses, the patients with schizophrenia often, you know, drifts.

• 18:55Speaker 04

  So as John was drifting, the world started seeming even colder.

• 18:59Speaker 07

  Thinking everyone was targeting me.

• 19:02Speaker 04

  So he'd layer up, which itself would make the world, oftentimes, be colder.

• 19:09Speaker 07

  There was a woman walking, and she just gave me the dirtiest look I've ever seen in my life. And I said to her, "What is it, the winter clothes that I'm wearing, that makes you dislike me?" And she immediately called the police.

• 19:29Speaker 04

  And then it's like one more layer.

• 19:30Speaker 05

  Another layer.

• 19:31Speaker 04

  Wow.

• 19:33Speaker 00

  At the end of our study, we also thought that this is, this might be a window. You know, this kind of... Uh, redundant clothing might be a window through which we can, we can pip towards uh, something really, really broken down.

• 19:51Speaker 04

  Dr. Mahin Tavani found that the thing that the people who were wearing layers all had in common was that compared to the controls, they were the ones who had been going it alone without treatment for longer. That's really wild that you could just look out and like see that from the outside.

• 20:11Speaker 00

  Yeah.

• 20:12Speaker 04

  Um, which made me start to wonder, is it almost like humans have within them like this, this visual signal for like, I'm really lost. I might not even know how to ask for help, but here is a signal.

• 20:27Speaker 05

  Hmm, that's, I, that's pretty.

• 20:29Speaker 04

  I mean, I put the idea to Dr. Mahin Tavani and he was like,

• 20:32Speaker 00

  Uh, I am not in a position to answer this, but this is a wonderful and intriguing question.

• 20:38Speaker 04

  Yeah, but I also put it to John.

• 20:41Speaker 07

  Um.

• 20:42Speaker 04

  Is there anything to that or am I like overly projecting an idea?

• 20:48Speaker 07

  No, I think you're, you could be on to something. I think there could be like a cry for help through layers.

• 20:57Speaker 04

  And he told me a story about one time when someone seemed to read it that way.

• 21:03Speaker 07

  Well, there was one time I was at the beach and I was having a tough day. I was wearing a sweatshirt, a beanie, sweatpants, sandals. And I went and ordered a grilled cheese and french fries from this stand at the beach. And I talked to this old woman. She was probably in her late seventies, white hair. I think she was wearing a T-shirt and short jean jorts.

• 21:32Speaker 04

  Jorts, the old lady jorts?

• 21:34Speaker 07

  Yeah. I said, hey, how are you? I was probably not talking that clearly and making much sense either. And she asked me if I would sit down and have lunch with her.

• 21:48Speaker 07

  I took a bite or two from my grilled cheese sandwich. I almost felt I didn't deserve that food. And I said, I said to her, I think I'm gonna feed the, the rest of the birds. And she said to me, don't feed the birds, just eat your food. But then I ultimately fed the birds. She went off, like, like feeling empathy towards me.

• 22:16Speaker 04

  Yeah. Did you feel a little bit better after that?

• 22:19Speaker 07

  Yeah, I did feel better.

• 22:22Speaker 04

  He eventually felt so relaxed. He slipped off his sandals. And he put his feet on the sand. And he just walked home barefoot.

• 22:35Speaker 07

  Yeah.

• 22:52Speaker 04

  Okay, so, turning the page.

• 22:56Speaker 04

  Chapter three. Picture two people playing a game sort of like catch.

• 23:00Speaker 06

  Uh, the Cyberball experiment.

• 23:02Speaker 04

  Okay. So Hans, our researcher from earlier, told me about this study he did where he had people playing this game called Cyberball. And the way it works is that you enter the game and two other computer players invite you to start tossing a ball around with them.

• 23:18Speaker 05

  Boop, boop, boop, boop.

• 23:20Speaker 04

  Okay. And then at a certain point, they just suddenly start rejecting you.

• 23:24Speaker 06

  You're not part, part of this ballgame anymore.

• 23:27Speaker 04

  They just suddenly start excluding you and won't throw you, pass you the ball. And in-

• 23:31Speaker 05

  That's terrible.

• 23:31Speaker 04

  Yeah, and so like in that, people rate the room temperature as colder. But then what he did was he snuck onto their fingers a little, uh, digital thermometer.

• 23:41Speaker 06

  With Velcro on it, was just a bunch of sensors, uh, with a wire sticking out of it.

• 23:45Speaker 04

  And he found that their peripheral skin temperature, their skin temperature dropped in that condition when they were excluded. Yeah, and so it's like you perceive it as colder and your skin actually gets a little colder.

• 23:57Speaker 05

  Huh, wow.

• 23:58Speaker 04

  I mean, to see it reflected on the skin felt like such a leap from emotion or feeling or thought to physical reality.

• 24:12Speaker 04

  What was it like for you to find that result?

• 24:15Speaker 06

  I think in the beginning, it was stunning to find it. I mean, I think that's also why we repeated the experiment. But it also opened up the door for kind of trying to figure out what else was there.

• 24:32Speaker 04

  What else was there? After the break.

• 24:43Speaker 04

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• 25:09Speaker 01

  This week on the New Yorker Radio Hour, will House Democrats try once again for impeachment? Let's not make a fetish out of impeachment. Let's not make a taboo out of impeachment. We understand it's not a panacea, but it is an essential tool in the constitutional toolbox that's always there. Congressman Jamie Raskin joins us next time on the New Yorker Radio Hour from WNYC. Listen wherever you get your podcasts.

• 25:42Speaker 04

  This is Lulu. Radiolab back here with senior correspondent Molly Webster.

• 25:46Speaker 05

  Should we go back to the book?

• 25:47Speaker 04

  Yeah.

• 25:49Speaker 05

  Nice. Chapter four here, right? Chapter four. Picture's pretty groovy. It's like a thermometer.

• 25:57Speaker 05

  And it's broken. And mercury is spilling out of it like blood. Mmm.

• 26:06Speaker 05

  And I want to take chapter four. Hell, yeah.

• 26:10Speaker 04

  Welcome, welcome.

• 26:12Speaker 05

  Thank you for letting us in. Because I've been thinking about this a lot lately. Like, for all of us right now, our core body temperature is that basic temperature that our body is working at has become a literal passport back into society.

• 26:29Speaker 05

  So it might be a little bit light. So I went to a bar in Brooklyn, where like any other bar in the city right now, there are people at the front of the bar with the gun. Temperature gun.

• 26:39Speaker 04

  The temperature gun.

• 26:40Speaker 05

  Zapping everybody who shows up. Bonnie and Scott have got it under control. Deciding if people can come in and out of the door.

• 26:46Speaker 04

  Oh, like the new bouncer of temperature.

• 26:49Speaker 05

  Exactly. We got a 96.1. And this is happening.

• 26:54Speaker 03

  Before I go to work every morning.

• 26:56Speaker 05

  Basically everywhere.

• 26:57Speaker 03

  I have to take my temperature and text it to the school nurse. So here we go.

• 27:02Speaker 05

  We actually put a call out to our listeners, had people send us little recordings. I'm walking up to get my temperature tested. I'm a tutor. As they head it to work.

• 27:10Speaker 02

  Arriving at Masked Sound in East Rutherford, New Jersey.

• 27:13Speaker 05

  Or to the grocery store.

• 27:14Speaker 01

  I'm at my supermarket. I'm about to go take the temperature.

• 27:17Speaker 05

  Dropping their kids off at school.

• 27:19Speaker 01

  Okay, Joey, let's take your temperature so you can go into school.

• 27:21Speaker 02

  Stop if your temp reads above 99.4.

• 27:26Speaker 05

  This is how we decide now whether or not it's okay to be around other people.

• 27:31Speaker 04

  Normal temperature. You are free to pass. Thank you. Good to go.

• 27:35Speaker 05

  See you, buddy. Now, we did not get anybody who was in the sort of uh-oh range, but what you do hear in the tape.

• 27:42Speaker 02

  97.5.

• 27:43Speaker 05

  And what I saw in the bar. 95.5. 96. 96.3. Is a pretty surprising range of numbers. 97.5. 7.2 degrees. 96.4.

• 27:54Speaker 04

  98.5.

• 27:55Speaker 05

  95.2, that's not right. 94.6. Little chilly, but low is better than high. I mean, there were temperatures from maybe 92 all the way up to 98. That's six whole degrees.

• 28:09Speaker 04

  Okay, so what are these guns? They don't work. Was that, I mean, if.

• 28:14Speaker 05

  There was just a study out that says the temperature guns read like two to three degrees cooler than you actually are. Which is troubling in its own right. But the thing that really hit me is that the spread of supposedly healthy people sort of flies in the face of that that bedrock of human health, that golden number, 98.6.

• 28:36Speaker 04

  Yes, the golden number of like what a human body should be.

• 28:43Speaker 05

  Except it's kind of a con.

• 28:48Speaker 04

  A con?

• 28:50Speaker 05

  Sort of. Let me just explain first where it comes from.

• 28:53Speaker 04

  Okay.

• 28:54Speaker 05

  So, the story of 98.6 starts in the 1800s, as all good science stories do.

• 29:01Speaker 04

  Yep.

• 29:03Speaker 03

  So, in the late 19th century, you get the introduction of thermometers into medical practice.

• 29:08Speaker 05

  So, for this section, I'm going to get a little help from Deanna Day.

• 29:11Speaker 03

  I'm a writer and historian.

• 29:15Speaker 03

  Sorry, I got some-

• 29:16Speaker 05

  Great, great.

• 29:19Speaker 03

  I always have this moment because I am doing like 50,000 things.

• 29:22Speaker 05

  She is the master of many things. But anyway, Deanna told me, there's a couple of things to know about the 1800s, for the purposes of our story. One is that fevers back then weren't seen as some sort of like signal or sign of a disease.

• 29:39Speaker 03

  The fever was just the disease.

• 29:41Speaker 05

  They thought fevers were the actual illness.

• 29:44Speaker 03

  The thing you had that was causing all of your symptoms.

• 29:49Speaker 04

  Like you catch a heat and then it like gives you all this bad vomit, a tiredness.

• 29:55Speaker 05

  Yeah. But then along came a guy named Carl Wunderlich.

• 30:00Speaker 04

  Cool name.

• 30:01Speaker 03

  So, Wunderlich was a physician in Germany.

• 30:05Speaker 05

  He was the chair of medicine at the University of Leipzig, and he was one of the first people, one of the first doctors to use thermometers in his clinic. At the time, they were like two feet long and took 20 minutes to take a temperature. And in the 1850s, when Wunderlich was doing his thing, it was like an era when big data was becoming king, which is funny because you wouldn't actually think about that because there were no computers.

• 30:30Speaker 04

  There were lots of pencils.

• 30:31Speaker 05

  Yeah, lots of pencils, lots of paper. And, and so, his thing that he was like, okay, the data that I'm going to collect is I want to understand how temperature of a human body changes throughout the progression of an illness. And so-

• 30:48Speaker 03

  At his hospital, they took temperature readings repeatedly, over and over, from about 25,000 patients.

• 30:56Speaker 05

  25,000 patients, a million and a half temperature recordings.

• 31:01Speaker 04

  Did he have a fleet of temperature collectors?

• 31:04Speaker 05

  No, it was basically him and whoever worked in his clinic. He just had a really busy clinic in Germany.

• 31:10Speaker 04

  Wow, that's like, that feels, but I guess over like decades, right?

• 31:14Speaker 05

  Yeah, like 20 years. So Wunderlich collects all this data and

• 31:20Speaker 03

  did the 19th century version of crunching the numbers and created all of these charts.

• 31:27Speaker 05

  Fever charts.

• 31:27Speaker 03

  He found different diseases had different fever progressions in patients.

• 31:34Speaker 05

  He would have like a patient that had syphilis, say. And he could map their temperature change throughout syphilis and he would get like a really pretty pattern on an X Y graph.

• 31:46Speaker 03

  Some diseases would have a fever that would spike and drop and spike and drop. And other diseases had a fever course that would kind of like ramp up gradually or ramp down slowly.

• 31:54Speaker 04

  Cool. I've never thought of that, like that, that each illness has a little curly Q signature that you're like,

• 32:00Speaker 05

  I know.

• 32:01Speaker 04

  Oh, that's cool.

• 32:02Speaker 05

  If I'm honest, like, I don't know if that actually still holds up today.

• 32:05Speaker 04

  Yeah.

• 32:06Speaker 05

  But

• 32:06Speaker 03

  His idea was that you could track someone's temperature and diagnose them that way. And that was a big change.

• 32:14Speaker 05

  All of a sudden, we start seeing fever, um, not as something that comes at you from the outside, but something that your body does on the inside when it's reacting to a disease. And this is how we get to a place where we can gun someone and say, oh, you're sick. Stay away. Anyways, he publishes it all in this big book.

• 32:35Speaker 03

  And kind of incidentally, he was like, and in healthy people, when they are no longer sick, we have found that body temperature is 37 degrees Celsius.

• 32:47Speaker 05

  Which is the conversion to Fahrenheit is 98.6.

• 32:51Speaker 04

  Interesting. So he was just like, oops, I was studying this other thing I accidentally have a cache million data points.

• 32:57Speaker 05

  Yeah, it was essentially a footnote.

• 32:59Speaker 04

  98.6, that thing we all sort of bow before was just a little footnote from the 1800s?

• 33:05Speaker 05

  Well, yes, until this guy came along named Edward Seguin.

• 33:09Speaker 03

  Edward Seguin is the person who actually translated Wunderlich's work and introduced it to the United States.

• 33:16Speaker 05

  And he's really into thermometry.

• 33:19Speaker 04

  Which is a word.

• 33:20Speaker 05

  It was just a word. I know.

• 33:21Speaker 03

  He writes this manual called Family Thermometry, which is supposed to teach moms how to take their kid's temperature and why it's important and how to do it.

• 33:30Speaker 05

  And so Seguin, along with thermometer companies, kind of went on this big push through like-

• 33:38Speaker 03

  Articles in Good Housekeeping and Ladies' Home Journal and Scientific American.

• 33:42Speaker 05

  To talk about thermometers and make them like a new tool for the home.

• 33:46Speaker 03

  And there are advertisements in all kinds of publications.

• 33:50Speaker 05

  And over and over again, they'd hammer on this number, 98.6, 98.6. That's what you should be. That's what your kid should be. And I feel like this like marketing campaign that happened at the end of the 1800s and the early 1900s is essentially been handed down to us through the century and made us think that 98.6 is the normal or ideal temperature for a human body, which is bullshit.

• 34:18Speaker 03

  Well, it turns out that there's a lot of variation across all these different parameters.

• 34:24Speaker 05

  So this is Catherine Lay.

• 34:25Speaker 03

  Infectious disease epidemiologist at Stanford University.

• 34:29Speaker 05

  And as Kat explained it to me, there is no one healthy human temperature.

• 34:34Speaker 03

  Women have higher temperatures than men. Bigger people have higher temperatures.

• 34:40Speaker 05

  Fatter and skinnier people have different temperatures.

• 34:43Speaker 03

  Taller people have lower temperatures.

• 34:45Speaker 05

  Whoa. They're just so thinned out that they got surface area for days.

• 34:50Speaker 03

  I don't know.

• 34:51Speaker 05

  Hormones can change your temperatures. Morning and night can change your temperatures.

• 34:55Speaker 03

  Younger people have higher temperatures than older people.

• 34:58Speaker 04

  I'm already thinking about the sweatsuits I want to rock again.

• 35:02Speaker 05

  And even in the same person, temperature taken in the ear, in your armpit, and your butt can vary by like two degrees.

• 35:09Speaker 04

  Wow.

• 35:10Speaker 05

  Now, all this variation piles up to an average of 98.6. But just to really crack this thermometer wide open, and you might remember this from the episode I did last summer fungus among us, researchers don't even think 98.6 is our average anymore.

• 35:28Speaker 04

  What?

• 35:29Speaker 05

  Like, there was just a new paper a year ago that said it looks like the sort of average of a healthy kind of Western population is 97.5. And Kat was actually involved in that research. And she said that it looks like our temperature has been dropping 0.05 degrees Fahrenheit every decade since the 1850s.

• 35:52Speaker 04

  Wow.

• 35:53Speaker 05

  There's a number of reasons they think that might be the case. Like, maybe we have better medicines, so we're not fighting infections as much. You know, maybe it's just the fact that we are older and taller, you know?

• 36:04Speaker 04

  Even the average is, I mean, I remember that episode. I was so focused on the scary fungus that I feel like I missed the temperature drop.

• 36:12Speaker 05

  It was just slipped in there, you know?

• 36:14Speaker 04

  But it's like you're saying, so not only is there all this individuality on person and time of day and part of body, but then also, oh, and also the average isn't the average either.

• 36:28Speaker 05

  Yeah, so much so that for some people, because you're a man, you're old, and it's early in the morning.

• 36:37Speaker 03

  Coming up to 98.6 might actually be a fever for you. This is exactly why it's important to not believe that a number like your temperature can tell you everything.

• 36:54Speaker 04

  But even when you know that, it's so hard to let go of that number.

• 37:00Speaker 05

  I just got the COVID vaccine. Yesterday and I feel so rough. So I had this moment where like I got my COVID vaccination, my, my second one and it like laid me low. So, so, so achy. And in the middle of that, I thought I should take my temperature. I was super achy and I really hurt. And so I, you know, turned on my voice memo and And it's so bad. And my voice is ridiculous and I think my, my fever must be like a hundred and two. And I take my temperature and it just Ninety eight point one. Comes out as ninety eight point one. Oh. And I was just like, oh, am I?

• 37:36Speaker 04

  A big faker?

• 37:37Speaker 05

  Yeah. Am I making this worse than it is? Like the thermometer just said I wasn't sick. And then I like, no one at Radio Lab is gonna believe me. I'm, the thermometer can't be right because it doesn't encapsulate how terrible I feel. Despite knowing everything I just told you.

• 37:55Speaker 04

  While you're in the midst of this reporting.

• 37:56Speaker 05

  I'm in the midst of this reporting.

• 37:58Speaker 04

  You were still like measuring yourself up against that number.

• 38:02Speaker 05

  Point six and, and, and so it's like all of that against, against me. And then in the middle of sort of like the fever haze, the non fever haze, the non fever fever haze.

• 38:18Speaker 04

  Mm hmm.

• 38:19Speaker 05

  Um, I'm like kind of hanging off the side of my bed, like very pathetic. And I was just like, this is just like what Deanna said.

• 38:30Speaker 03

  I think that acting as if fever as a quantitative measure can give you objective truth. Just makes it impossible for you, not you, makes it impossible for anyone to see the full scope of what is happening inside a person.

• 38:54Speaker 05

  I definitely felt that in that moment, taking my own temperature. But I think I also realized that you can actually throw out the 98.6 thing. And then your temperature, whatever it is, can be a window into so much more about a person. Like how old you are, what your hormones are, or whether you live in a place with adequate medical care.

• 39:19Speaker 04

  Can I add one more kind of eerie one?

• 39:21Speaker 05

  Of course.

• 39:22Speaker 04

  Of what your temperature might be able to tell you. So Hans, our researcher from before, he actually did a study where he wanted to see what predicted core body temperature. So he plugged in all these variables, age, height, weight, location, distance from equator, cigarette consumption, sugary drink consumption,

• 39:41Speaker 05

  Ooh.

• 39:41Speaker 04

  perceived level of stress, any medications, access to your cellphone, like tons and tons of, tons of things. And this thing that was right up near the top, more important than body weight or height, was diversity of your social network. And so what that means is like, not how many friends you have, but how many different kinds. So like, do you have your work?

• 40:06Speaker 05

  It's not number, it's groups or something.

• 40:10Speaker 04

  Friends and your soccer friends and your knitting friends and your extended family and the Webster sisters. And so like, the more kinds of groups you had, the higher your core body temperature was.

• 40:25Speaker 05

  The more, how do you, does he have any explanation for that?

• 40:29Speaker 04

  I think the, I mean, he doesn't know, like, he doesn't know exactly what that means. But I think there's some idea of like, if one type bails on you, the more types of backups you have, the safer your body, the less at risk your body feels.

• 40:43Speaker 05

  It's just, there's this very porous border between what I thought of as a very physiological thing, which is your body temperature, to what's happening mentally and emotionally in your brain. Like, like emotions tuning your body temperature to what it is.

• 41:09Speaker 04

  Yeah.

• 41:09Speaker 05

  Which makes me think back on that temperature check tape a little differently.

• 41:16Speaker 05

  Like. Can I take your temperature? Yeah, that's fine. Ninety-six point one. Did you gain weight? Ninety-seven point five. Ninety-six point four. What time of day is it? Temperature is normal.

• 41:31Speaker 05

  Maybe you're pregnant. Ninety-seven point two degrees. Ninety-seven point seven. Have you seen a doctor? Ninety-seven point seven. Did a stranger wave at you on the street? Ninety-five point four. Ninety-six point ten. Did you talk to your sister? Ninety-seven point five. Are you on medicine?

• 41:50Speaker 05

  Or maybe you're off it?

• 41:54Speaker 05

  Do you live alone? Who do you love?

• 41:59Speaker 05

  Have you seen them?

• 42:21Speaker 04

  Molly Webster. This episode was produced by Becca Bressler, Molly Webster and me with production help from Karen Leong and fact checking by Emily Krieger. Hans Eizerman has a new book about a lot of the science we covered in this hour called Heartwarming: How Our Inner Thermostat Made Us Human. Special thanks to Tony Bartlamay, Julie Parsonette, Philip Makoviac, Carla Hock, Lacey Alexander, Anna Stanowitz, Brendan and all the folks over at The Commissioner in Park Slope, our listeners for their voice memos. Thank you, thank you, thank you, temperature, temperature, temperature. And last big one to invisibilia. I first started talking to John back when I was working with them and they let me use some of that audio. I really recommend you go check it out. Thanks for listening.

• 43:08Speaker 04

  Okay, so remember I said this book does have a fifth chapter? Ooh. The picture is just a scale. A perfect balance. Okay. So you know how like there's a kind of... Gnarliness to the concept of theft, like kleptothermia. This is all about how like we are constant.

• 43:25Speaker 05

  We're stealing something.

• 43:26Speaker 04

  Yeah, it's like that equation. You gotta take in more than you give. And if you don't get enough, you feel wounded and at risk. And if you are getting enough, you're stealing it from someone or something else. And like, if we got to an equilibrium, wouldn't that be so nice?

• 43:42Speaker 05

  Yes, equilibrium would be. So we're just, we're all giving and taking and like coexisting. And it's, it's a balance.

• 43:50Speaker 04

  Yeah. Do you know what that's called? You know what the physicists call that?

• 43:54Speaker 05

  No.

• 43:56Speaker 04

  The thermal death

• 43:58Speaker 05

  Wait.

• 43:58Speaker 04

  of the universe.

• 44:05Speaker 05

  Wait, equilibrium is thermal death?

• 44:07Speaker 04

  Yeah, like there will be a time when everything becomes the same temperature. And that is the end.

• 44:15Speaker 04

  I don't know.

• 44:16Speaker 05

  I'll be grateful for the give and take.

• 44:18Speaker 04

  Be grateful for the give and take. Uh, we'll, we'll give you away to your life. That's the end. See you next time. Thanks for listening. Bye.

• 44:31Speaker 02

  Hi, I'm Eric Baum, and I'm from Minneapolis, Minnesota. And here are the staff credits. Radiolab is hosted by Lulu Miller and Latif Nasser. Soren Wheeler is our executive editor. Sarah Sandback is our executive director. Our managing editor is Pat Walters. Dylan Keefe is our director of sound design. Our staff includes Jeremy Bloom, W. Harry Fortuna, David Gable, Maria Paz Gutierrez, Sindhu Niyasambadhan, Matt Keelty, Mona Madgawker, Annie McEwen, Alex Neeson, Sarah Kari, Rebecca Rand, Anissa Vitza, Ariane Whack, Molly Webster, and Jessica Young. Our fact checkers are Diane Kelly, Emily Krieger, Natalie Middleton, Angelie Mercado,

• 45:16Speaker 02

  and Sophie Semeyi.

• 45:24Speaker 07

  Leadership support for Radiolab's science programming is provided by the Simons Foundation and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.