Pod Insights Radiolab Kleptotherms About this episode 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
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Transcript 0:01 Speaker 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.
0:44 Speaker 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.
0:54 Speaker 01 Yeah, you're like, wait, you're listening. Okay. All right.
0:58 Speaker 02 Okay.
0:59 Speaker 01 All right.
1:01 Speaker 03 You're listening to Radiolab.
1:04 Speaker 01 Radiolab.
1:04 Speaker 03 From?
1:05 Speaker 01 WNYC.
1:09 Speaker 04 Rewind.
1:13 Speaker 05 Lou.
1:14 Speaker 04 Hey.
1:15 Speaker 05 How are you feeling?
1:17 Speaker 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?
1:29 Speaker 05 Yes, eyes closed in my closet.
1:31 Speaker 04 Okay, so now journey with me. Me and you are on a trip. We've got our backpacks and our hiking boots.
1:38 Speaker 05 Okay.
1:39 Speaker 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.
2:03 Speaker 04 And the dust, like, it turns into like snowy frosty snowflakes and little tiny flames.
2:10 Speaker 05 Oh.
2:10 Speaker 04 It's like.
2:13 Speaker 04 And then it says in silver letters, kleptotherms.
2:22 Speaker 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.
2:43 Speaker 05 Okay.
2:46 Speaker 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.
2:55 Speaker 05 Is this real?
2:56 Speaker 04 This is real. Oh, this is one.
2:57 Speaker 05 Okay, this is, okay, this is real.
2:59 Speaker 04 Oh, it turns out this whole book is stored in the Library of Congress as nonfiction.
3:04 Speaker 05 Okay.
3:05 Speaker 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.
3:18 Speaker 06 They sneak into burrows, which are occupied by large tropical seabirds.
3:23 Speaker 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.
3:43 Speaker 06 And they take advantage of the mass body heat in warming their own bodies.
3:48 Speaker 04 And are they not even eating those birds? They're just kind of like curling around them and sucking up their heat?
3:55 Speaker 06 That's essentially what they're doing, yes.
3:56 Speaker 04 Wow. There's just something so primal about the heat being more important even than the meat.
4:03 Speaker 06 Yeah. So this behavior is called kleptothermy.
4:05 Speaker 04 Kleptothermy. And what does that mean?
4:07 Speaker 06 Basically engaging in heat theft.
4:09 Speaker 04 Okay. You see it all throughout the animal kingdom.
4:12 Speaker 05 Really?
4:13 Speaker 04 Yeah.
4:13 Speaker 05 Seriously?
4:14 Speaker 04 Yeah. So like male garter snakes?
4:17 Speaker 06 They pretend to be female so that other males will try to mate with them.
4:21 Speaker 04 Like the friction of them trying to mate.
4:22 Speaker 05 Trying to mate just warms them up?
4:24 Speaker 06 Yes.
4:25 Speaker 04 There's little dwarf caimans, which are kind of crocodile-y looking things that steal from termite nests.
4:30 Speaker 05 How do you cuddle up to a termite?
4:32 Speaker 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.
4:39 Speaker 05 Wow.
4:41 Speaker 06 And us humans also engage in kleptothermy when we want to.
4:45 Speaker 04 That oh, so sweet act of cuddling, or as the scientists call it.
4:49 Speaker 06 Huddling.
4:50 Speaker 04 Is, for at least one person involved, a theft.
4:54 Speaker 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.
5:03 Speaker 04 An equation biologists call the economy of action.
5:07 Speaker 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.
5:18 Speaker 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.
5:29 Speaker 06 It can decrease the cost of thermoregulation by up to about 60 or 70%.
5:36 Speaker 04 Wow.
5:37 Speaker 06 There are a lot of observational studies on this for many, many different animals.
5:41 Speaker 04 Rats, penguins, dagus.
5:43 Speaker 06 Not only is their peripheral temperature higher, but also their base metabolic rate is much lower, meaning that they exert much less energy.
5:52 Speaker 04 To stay warm.
5:53 Speaker 05 Huh.
5:55 Speaker 04 And so Hans's idea is that because for so long, humans relied on getting warmth from one another to survive.
6:03 Speaker 06 Even 200 years ago, people would sleep with nine people in one bed to keep warm.
6:07 Speaker 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.
6:23 Speaker 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.
6:34 Speaker 04 Which brings us to.
6:39 Speaker 04 Chapter.
6:42 Speaker 04 Two.
6:51 Speaker 04 What's the picture?
6:52 Speaker 07 I'm wearing sweatpants, a long-sleeved shirt.
6:55 Speaker 04 It's a guy in a jacket.
6:57 Speaker 07 It's probably one of my nicer shirts. I wanted to look nice, even though it's only the radio.
7:03 Speaker 04 His name is John, and he's gonna lead us to a different idea about how to get warm. Okay.
7:09 Speaker 07 Okay.
7:10 Speaker 04 Can you tell me a little bit about where you grew up?
7:14 Speaker 07 I grew up in the woods, in a house in the woods in Connecticut.
7:20 Speaker 04 Do you remember how the world felt to you as a kid?
7:25 Speaker 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.
7:47 Speaker 04 But as he started to get a little bit older...
7:50 Speaker 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.
8:06 Speaker 04 Which, you know, happens to a lot of middle schoolers, but for John, it hit him harder.
8:11 Speaker 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.
8:32 Speaker 04 And then, once he hit college?
8:34 Speaker 07 I started hearing voices.
8:38 Speaker 04 And what were some of the, like, the kinds of things they might sort of be saying to you?
8:43 Speaker 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.
8:58 Speaker 04 Like, did you get a diagnosis then?
9:01 Speaker 07 Yeah, um, schizoaffective.
9:04 Speaker 04 Which is not exactly schizophrenia, but has some of its symptoms.
9:08 Speaker 07 He prescribed me a drug, an antidepressant, and I had a really bad reaction to it.
9:15 Speaker 04 What happened?
9:17 Speaker 07 It it really brought on those internal voices. Like, I remember driving in the car, thinking everyone on the road was targeting me.
9:27 Speaker 04 So.
9:28 Speaker 07 I went off my meds.
9:30 Speaker 04 But this sense that people were out to get him just kept getting worse.
9:35 Speaker 07 I just remember everyone giving me a hard time.
9:38 Speaker 04 What, how did they give you a hard time?
9:41 Speaker 07 They would, like, give me dirty looks. They would pull schemes on me and mock me at times, maybe even.
9:50 Speaker 04 Hmm.
9:51 Speaker 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.
10:02 Speaker 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?
10:14 Speaker 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.
10:25 Speaker 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.
10:41 Speaker 07 I got for Christmas one year.
10:43 Speaker 04 What color?
10:44 Speaker 07 It was gray. It it's a comfort.
10:47 Speaker 04 And before he heads out the door, he rifles through his stuff and decides to also put on.
10:52 Speaker 07 A hooded sweatshirt, hood up.
10:55 Speaker 04 And then he grabs a third layer.
10:57 Speaker 07 It was a jacket.
10:59 Speaker 04 And a fourth.
11:00 Speaker 07 Sweatpants.
11:01 Speaker 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.
11:15 Speaker 04 And people would say things like,
11:17 Speaker 07 What are you preparing for a wrestling match? Like trying to lose weight for a wrestling match?
11:23 Speaker 04 Right, like training in trash bags kind of thing.
11:25 Speaker 07 Yeah.
11:28 Speaker 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.
11:44 Speaker 05 Mm hmm.
11:46 Speaker 04 I mean, when you, when people see you wearing layers, what do you think they think about you?
11:52 Speaker 07 I think they're fearful, they're fear, they fear me.
11:57 Speaker 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.
12:42 Speaker 01 I was doing my first psychiatry rotation.
12:45 Speaker 04 Dr. Terence Chong was treating a patient with schizophrenia.
12:48 Speaker 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.
12:57 Speaker 04 There was a doctor in Memphis, Tennessee, who noticed the same thing.
13:00 Speaker 05 Wow.
13:01 Speaker 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.
13:13 Speaker 00 Yes.
13:14 Speaker 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.
13:30 Speaker 00 Another thing might be abolition.
13:33 Speaker 04 A lack of motivation. So basically, the person maybe forgot to take the last layer off.
13:38 Speaker 00 Yes, yes. Or.
13:39 Speaker 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.
13:49 Speaker 07 Um.
13:50 Speaker 04 Can you just describe why you crave the the layers?
13:56 Speaker 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.
14:12 Speaker 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?
14:57 Speaker 04 Like, what does that mean?
14:59 Speaker 00 So free T3 and free T4s are. Very reliable markers of temperature regulation.
15:05 Speaker 04 Temperature regulation?
15:07 Speaker 00 Yes, with cold intolerance.
15:10 Speaker 04 Like you just get cold quicker?
15:12 Speaker 00 Yes.
15:12 Speaker 04 Okay.
15:13 Speaker 00 You feel cold quicker.
15:15 Speaker 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?
15:32 Speaker 00 It is our findings that not.
15:38 Speaker 00 And our ideas are based on our findings.
15:40 Speaker 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.
15:51 Speaker 07 Wow.
15:52 Speaker 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.
16:03 Speaker 07 It was a really, it was a really difficult time for me.
16:06 Speaker 04 And things finally got so bad that he goes back to the doctor and this time is in fact diagnosed with.
16:12 Speaker 07 Paranoid schizophrenia.
16:14 Speaker 04 And he's prescribed a different medication.
16:17 Speaker 07 I immediately noticed less up and down, less craziness. I noticed myself getting better by the day.
16:27 Speaker 04 And the world seemed to be getting a little better too, a little gentler.
16:32 Speaker 07 And I felt people liked me.
16:35 Speaker 04 And he started loosening up, literally taking off his hat.
16:39 Speaker 07 Yeah.
16:40 Speaker 04 His jacket.
16:41 Speaker 07 Um, well.
16:43 Speaker 04 Or one of them.
16:44 Speaker 07 It was winter and I was, I would wear like a tank top under a winter jacket and that was it.
16:52 Speaker 04 And he started to embrace his diagnosis.
16:55 Speaker 07 I read about how people with schizophrenic disorders oftentimes think divergently and a link to creativity.
17:05 Speaker 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.
17:12 Speaker 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.
17:28 Speaker 04 She thinks there's someone shooting in the building. And then, one day, about thirty miles away from where he lived.
17:34 Speaker 01 Shooting at an elementary school in Newtown, Connecticut.
17:39 Speaker 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...
17:50 Speaker 07 Like, when they first heard about the news that there was a shooting in Connecticut, they thought of me.
17:57 Speaker 04 For an instant, they worried the shooter had been John.
18:01 Speaker 07 It was really hurtful. It was like, I would never do anything like that. I definitely stopped having that pride towards my diagnosis.
18:12 Speaker 04 He stopped taking his medication.
18:14 Speaker 07 I felt a lot more gloom and doom, and I started to slip real quickly.
18:21 Speaker 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.
18:39 Speaker 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.
18:55 Speaker 04 So as John was drifting, the world started seeming even colder.
18:59 Speaker 07 Thinking everyone was targeting me.
19:02 Speaker 04 So he'd layer up, which itself would make the world, oftentimes, be colder.
19:09 Speaker 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.
19:29 Speaker 04 And then it's like one more layer.
19:30 Speaker 05 Another layer.
19:31 Speaker 04 Wow.
19:33 Speaker 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.
19:51 Speaker 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.
20:11 Speaker 00 Yeah.
20:12 Speaker 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.
20:27 Speaker 05 Hmm, that's, I, that's pretty.
20:29 Speaker 04 I mean, I put the idea to Dr. Mahin Tavani and he was like,
20:32 Speaker 00 Uh, I am not in a position to answer this, but this is a wonderful and intriguing question.
20:38 Speaker 04 Yeah, but I also put it to John.
20:41 Speaker 07 Um.
20:42 Speaker 04 Is there anything to that or am I like overly projecting an idea?
20:48 Speaker 07 No, I think you're, you could be on to something. I think there could be like a cry for help through layers.
20:57 Speaker 04 And he told me a story about one time when someone seemed to read it that way.
21:03 Speaker 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.
21:32 Speaker 04 Jorts, the old lady jorts?
21:34 Speaker 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.
21:48 Speaker 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.
22:16 Speaker 04 Yeah. Did you feel a little bit better after that?
22:19 Speaker 07 Yeah, I did feel better.
22:22 Speaker 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.
22:35 Speaker 07 Yeah.
22:52 Speaker 04 Okay, so, turning the page.
22:56 Speaker 04 Chapter three. Picture two people playing a game sort of like catch.
23:00 Speaker 06 Uh, the Cyberball experiment.
23:02 Speaker 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.
23:18 Speaker 05 Boop, boop, boop, boop.
23:20 Speaker 04 Okay. And then at a certain point, they just suddenly start rejecting you.
23:24 Speaker 06 You're not part, part of this ballgame anymore.
23:27 Speaker 04 They just suddenly start excluding you and won't throw you, pass you the ball. And in-
23:31 Speaker 05 That's terrible.
23:31 Speaker 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.
23:41 Speaker 06 With Velcro on it, was just a bunch of sensors, uh, with a wire sticking out of it.
23:45 Speaker 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.
23:57 Speaker 05 Huh, wow.
23:58 Speaker 04 I mean, to see it reflected on the skin felt like such a leap from emotion or feeling or thought to physical reality.
24:12 Speaker 04 What was it like for you to find that result?
24:15 Speaker 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.
24:32 Speaker 04 What else was there? After the break.
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25:09 Speaker 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.
25:42 Speaker 04 This is Lulu. Radiolab back here with senior correspondent Molly Webster.
25:46 Speaker 05 Should we go back to the book?
25:47 Speaker 04 Yeah.
25:49 Speaker 05 Nice. Chapter four here, right? Chapter four. Picture's pretty groovy. It's like a thermometer.
25:57 Speaker 05 And it's broken. And mercury is spilling out of it like blood. Mmm.
26:06 Speaker 05 And I want to take chapter four. Hell, yeah.
26:10 Speaker 04 Welcome, welcome.
26:12 Speaker 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.
26:29 Speaker 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.
26:39 Speaker 04 The temperature gun.
26:40 Speaker 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.
26:46 Speaker 04 Oh, like the new bouncer of temperature.
26:49 Speaker 05 Exactly. We got a 96.1. And this is happening.
26:54 Speaker 03 Before I go to work every morning.
26:56 Speaker 05 Basically everywhere.
26:57 Speaker 03 I have to take my temperature and text it to the school nurse. So here we go.
27:02 Speaker 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.
27:10 Speaker 02 Arriving at Masked Sound in East Rutherford, New Jersey.
27:13 Speaker 05 Or to the grocery store.
27:14 Speaker 01 I'm at my supermarket. I'm about to go take the temperature.
27:17 Speaker 05 Dropping their kids off at school.
27:19 Speaker 01 Okay, Joey, let's take your temperature so you can go into school.
27:21 Speaker 02 Stop if your temp reads above 99.4.
27:26 Speaker 05 This is how we decide now whether or not it's okay to be around other people.
27:31 Speaker 04 Normal temperature. You are free to pass. Thank you. Good to go.
27:35 Speaker 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.
27:42 Speaker 02 97.5.
27:43 Speaker 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.
27:54 Speaker 04 98.5.
27:55 Speaker 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.
28:09 Speaker 04 Okay, so what are these guns? They don't work. Was that, I mean, if.
28:14 Speaker 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.
28:36 Speaker 04 Yes, the golden number of like what a human body should be.
28:43 Speaker 05 Except it's kind of a con.
28:48 Speaker 04 A con?
28:50 Speaker 05 Sort of. Let me just explain first where it comes from.
28:53 Speaker 04 Okay.
28:54 Speaker 05 So, the story of 98.6 starts in the 1800s, as all good science stories do.
29:01 Speaker 04 Yep.
29:03 Speaker 03 So, in the late 19th century, you get the introduction of thermometers into medical practice.
29:08 Speaker 05 So, for this section, I'm going to get a little help from Deanna Day.
29:11 Speaker 03 I'm a writer and historian.
29:15 Speaker 03 Sorry, I got some-
29:16 Speaker 05 Great, great.
29:19 Speaker 03 I always have this moment because I am doing like 50,000 things.
29:22 Speaker 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.
29:39 Speaker 03 The fever was just the disease.
29:41 Speaker 05 They thought fevers were the actual illness.
29:44 Speaker 03 The thing you had that was causing all of your symptoms.
29:49 Speaker 04 Like you catch a heat and then it like gives you all this bad vomit, a tiredness.
29:55 Speaker 05 Yeah. But then along came a guy named Carl Wunderlich.
30:00 Speaker 04 Cool name.
30:01 Speaker 03 So, Wunderlich was a physician in Germany.
30:05 Speaker 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.
30:30 Speaker 04 There were lots of pencils.
30:31 Speaker 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-
30:48 Speaker 03 At his hospital, they took temperature readings repeatedly, over and over, from about 25,000 patients.
30:56 Speaker 05 25,000 patients, a million and a half temperature recordings.
31:01 Speaker 04 Did he have a fleet of temperature collectors?
31:04 Speaker 05 No, it was basically him and whoever worked in his clinic. He just had a really busy clinic in Germany.
31:10 Speaker 04 Wow, that's like, that feels, but I guess over like decades, right?
31:14 Speaker 05 Yeah, like 20 years. So Wunderlich collects all this data and
31:20 Speaker 03 did the 19th century version of crunching the numbers and created all of these charts.
31:27 Speaker 05 Fever charts.
31:27 Speaker 03 He found different diseases had different fever progressions in patients.
31:34 Speaker 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.
31:46 Speaker 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.
31:54 Speaker 04 Cool. I've never thought of that, like that, that each illness has a little curly Q signature that you're like,
32:00 Speaker 05 I know.
32:01 Speaker 04 Oh, that's cool.
32:02 Speaker 05 If I'm honest, like, I don't know if that actually still holds up today.
32:05 Speaker 04 Yeah.
32:06 Speaker 05 But
32:06 Speaker 03 His idea was that you could track someone's temperature and diagnose them that way. And that was a big change.
32:14 Speaker 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.
32:35 Speaker 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.
32:47 Speaker 05 Which is the conversion to Fahrenheit is 98.6.
32:51 Speaker 04 Interesting. So he was just like, oops, I was studying this other thing I accidentally have a cache million data points.
32:57 Speaker 05 Yeah, it was essentially a footnote.
32:59 Speaker 04 98.6, that thing we all sort of bow before was just a little footnote from the 1800s?
33:05 Speaker 05 Well, yes, until this guy came along named Edward Seguin.
33:09 Speaker 03 Edward Seguin is the person who actually translated Wunderlich's work and introduced it to the United States.
33:16 Speaker 05 And he's really into thermometry.
33:19 Speaker 04 Which is a word.
33:20 Speaker 05 It was just a word. I know.
33:21 Speaker 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.
33:30 Speaker 05 And so Seguin, along with thermometer companies, kind of went on this big push through like-
33:38 Speaker 03 Articles in Good Housekeeping and Ladies' Home Journal and Scientific American.
33:42 Speaker 05 To talk about thermometers and make them like a new tool for the home.
33:46 Speaker 03 And there are advertisements in all kinds of publications.
33:50 Speaker 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.
34:18 Speaker 03 Well, it turns out that there's a lot of variation across all these different parameters.
34:24 Speaker 05 So this is Catherine Lay.
34:25 Speaker 03 Infectious disease epidemiologist at Stanford University.
34:29 Speaker 05 And as Kat explained it to me, there is no one healthy human temperature.
34:34 Speaker 03 Women have higher temperatures than men. Bigger people have higher temperatures.
34:40 Speaker 05 Fatter and skinnier people have different temperatures.
34:43 Speaker 03 Taller people have lower temperatures.
34:45 Speaker 05 Whoa. They're just so thinned out that they got surface area for days.
34:50 Speaker 03 I don't know.
34:51 Speaker 05 Hormones can change your temperatures. Morning and night can change your temperatures.
34:55 Speaker 03 Younger people have higher temperatures than older people.
34:58 Speaker 04 I'm already thinking about the sweatsuits I want to rock again.
35:02 Speaker 05 And even in the same person, temperature taken in the ear, in your armpit, and your butt can vary by like two degrees.
35:09 Speaker 04 Wow.
35:10 Speaker 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.
35:28 Speaker 04 What?
35:29 Speaker 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.
35:52 Speaker 04 Wow.
35:53 Speaker 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?
36:04 Speaker 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.
36:12 Speaker 05 It was just slipped in there, you know?
36:14 Speaker 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.
36:28 Speaker 05 Yeah, so much so that for some people, because you're a man, you're old, and it's early in the morning.
36:37 Speaker 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.
36:54 Speaker 04 But even when you know that, it's so hard to let go of that number.
37:00 Speaker 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?
37:36 Speaker 04 A big faker?
37:37 Speaker 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.
37:55 Speaker 04 While you're in the midst of this reporting.
37:56 Speaker 05 I'm in the midst of this reporting.
37:58 Speaker 04 You were still like measuring yourself up against that number.
38:02 Speaker 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.
38:18 Speaker 04 Mm hmm.
38:19 Speaker 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.
38:30 Speaker 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.
38:54 Speaker 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.
39:19 Speaker 04 Can I add one more kind of eerie one?
39:21 Speaker 05 Of course.
39:22 Speaker 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,
39:41 Speaker 05 Ooh.
39:41 Speaker 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?
40:06 Speaker 05 It's not number, it's groups or something.
40:10 Speaker 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.
40:25 Speaker 05 The more, how do you, does he have any explanation for that?
40:29 Speaker 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.
40:43 Speaker 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.
41:09 Speaker 04 Yeah.
41:09 Speaker 05 Which makes me think back on that temperature check tape a little differently.
41:16 Speaker 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.
41:31 Speaker 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?
41:50 Speaker 05 Or maybe you're off it?
41:54 Speaker 05 Do you live alone? Who do you love?
41:59 Speaker 05 Have you seen them?
42:21 Speaker 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.
43:08 Speaker 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.
43:25 Speaker 05 We're stealing something.
43:26 Speaker 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?
43:42 Speaker 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.
43:50 Speaker 04 Yeah. Do you know what that's called? You know what the physicists call that?
43:54 Speaker 05 No.
43:56 Speaker 04 The thermal death
43:58 Speaker 05 Wait.
43:58 Speaker 04 of the universe.
44:05 Speaker 05 Wait, equilibrium is thermal death?
44:07 Speaker 04 Yeah, like there will be a time when everything becomes the same temperature. And that is the end.
44:15 Speaker 04 I don't know.
44:16 Speaker 05 I'll be grateful for the give and take.
44:18 Speaker 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.
44:31 Speaker 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,
45:16 Speaker 02 and Sophie Semeyi.
45:24 Speaker 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.
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