Kleptothermy Why Animals Steal Heat by RadioLab

Kleptothermy Why Animals Steal Heat by RadioLab

Intro 00:00:00.000
Wait. Wait. You're listening [laughs]




Alright. [clear throat]

You're listening to Radiolab [echoes] Radiolab from

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Yeah. [quiet laughter]

Molly Webster 00:00:17.860

Lulu Miller 00:00:17.870

Molly Webster 00:00:19.750
How are you feeling?

Lulu Miller 00:00:21.100
I mean, I feel fine, I think I still am like a dash [cross talk] [conversation fades out] Hi, there. It's Radiolab. I'm Lulu Miller here with senior correspondent Molly Webster. So can you humor me and close your eyes?

Molly Webster 00:00:33.160
Yes. Eyes closed in my closet.

Lulu Miller 00:00:36.100
Okay. So now [chuckles] journey with me, me and you are on a trip. We've got our backpacks [chuckles] that are hiking boots.

Molly Webster 00:00:42.940

Lulu Miller 00:00:43.510
And 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 a old globe. And then we come across this book that's like covered in dust and we blow the dust off, and the dust like it turns into like snowy, frosty, snowflakes and little tiny flames. It's like, oh, and then it says in silver letters, Kleptothermy. And we were like, Ooh, what? And we crack the book and it's like ,[inaudible] and we open it. And there's five chapters, and we turn the page in the first chapter. There's just a picture of a snake in a coil. So we're going to start and read that chapter.

Molly Webster 00:01:47.910

Lulu Miller 00:01:51.020
So once upon a time, there was a bright blue snake in New Caledonia. Its bright blue and black, so it's just like[cross talk]

Molly Webster 00:01:59.330
Is this real?

Lulu Miller 00:01:59.931
This is real.

Molly Webster 00:02:01.700

Lulu Miller 00:02:02.750
This whole book is stored in the Library of Congress as non fiction.

Molly Webster 00:02:08.450

Lulu Miller 00:02:09.630
So it's this blue and black snake. It looks kind of like Beetlejuice, and it's 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.

Hans Eisenman 00:02:22.520
They sneak into burrows, which are occupied by large tropical seabirds.

Lulu Miller 00:02:27.770
This is Hans Eisenman, a social scientist at the University 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.

Hans Eisenman 00:02:47.930
And they take advantage of the mass body heat in warming their own bodies.

Lulu Miller 00:02:52.430
And are they not even eating those birds? They're just kind of like curling around them and sucking up their heat.

Hans Eisenman 00:02:59.210
That's essentially what they're doing, yes.

Lulu Miller 00:03:00.830
Wow, [laughs] there's just something so primal about the heat being more important even than the meat. [laughs]

Hans Eisenman 00:03:07.520
Yeah. So this behavior is called kleptothermy.

Lulu Miller 00:03:09.750

Molly Webster 00:03:11.060
And what does that mean?

Hans Eisenman 00:03:12.050
Basically engaging in heat theft?

Lulu Miller 00:03:13.790
Okay. You see it all throughout the animal kingdom, kleptothermy.

Molly Webster 00:03:16.820

Lulu Miller 00:03:17.273

Molly Webster 00:03:18.030

Lulu Miller 00:03:18.860
Yeah. So like male garter snakes?

Hans Eisenman 00:03:21.071
They pretend to be female so that other males will try to mate with them.

Molly Webster 00:03:25.220
Like the friction of them trying to mate just warms them up?

Hans Eisenman 00:03:28.430

Lulu Miller 00:03:28.881
There's little dwarf Cayman's, which are kind of like crocodile licking things that steal from termite nests.

Molly Webster 00:03:34.929
How do you cuddle up to a termite?

Lulu Miller 00:03:36.833
You just - I don't know.

Molly Webster 00:03:38.960
[laughs] You just get in there.

Lulu Miller 00:03:38.961
I think you just like throw yourself upon the whole warm nastiness of all that bug heat.

Molly Webster 00:03:43.212

Hans Eisenman 00:03:43.730
And as humans also engage in kleptotherapy when we want to.

Lulu Miller 00:03:49.280
That also sweet act of cuddling or as the scientists call it:

Hans Eisenman 00:03:54.531

Lulu Miller 00:03:54.540
- is, for at least one person involved, a theft.

Hans Eisenman 00:03:58.910
I remember reading about it a couple of years ago, and I thought it was just fascinating. But if you think about it feeds into the same kind of equation.

Molly Webster 00:04:07.850
An equation biologists call the [said at the same time] economy of action.

Hans Eisenman 00:04:11.810
It's very simple. Animals need to take in more energy that they exert. And one of the most expensive things that we do, particularly as mammals, is warming our bodies.

Lulu Miller 00:04:22.760
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.

Hans Eisenman 00:04:33.950
It can decrease the cost of thermal regulation by up to about 60 or 70 percent.

Lulu Miller 00:04:40.700

Hans Eisenman 00:04:41.300
There are a lot of observational studies on this for many different animals.

Lulu Miller 00:04:45.410
Rats, penguins, tigers.

Hans Eisenman 00:04:47.840
Not only is their peripheral temperature higher, but also their basic metabolic rate is much lower, meaning that they exert much less energy

Lulu Miller 00:04:57.021
To stay warm. And so Hans' idea is that because for so long, humans relied on getting warmth from one another to survive.

Hans Eisenman 00:05:07.190
Even 200 years ago, people would sleep with nine people in one bed to keep warm.

Lulu Miller 00:05:11.390
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.

Hans Eisenman 00:05:27.350
I think it's for most people, it's hard to imagine until you see it and then you can't unsee it.

Lulu Miller 00:05:38.910
Which brings us to [vocal creaking sound effect] chapter 2. [blows air sound and wind chimes] What's the picture?

John 00:05:56.510
I'm wearing sweat pants, a long sleeve shirt.

Molly Webster 00:05:59.450
The guy in a jacket,

John 00:06:01.010
It's probably one of my nicer shirts. I wanted to look nice, even though it's only the radio. [laughs]

Molly Webster 00:06:07.160
His name is John, and he's going to lead us to a different idea about how to get warm. Okay?

John 00:06:13.491

Lulu Miller 00:06:14.840
Can you tell me a little bit about where you grew up?

John 00:06:18.600
I grew up in the woods. In a house, in the woods, in Connecticut.

Lulu Miller 00:06:24.880
Do you remember how the world felt to you as a kid?

John 00:06:29.730
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.

Lulu Miller 00:06:51.560
But as he started to get a little bit older

John 00:06:54.710
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.

Lulu Miller 00:07:10.220
Which, you know, happens to a lot of middle schoolers. But for John, it hit him harder.

John 00:07:15.150
I was scared of looking at my own reflection. I almost thought I 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.

Lulu Miller 00:07:36.080
And then once he hit college,

John 00:07:38.300
I started hearing voices.

Lulu Miller 00:07:42.440
And what were some of the like the kinds of things they might sort of be saying to you?

John 00:07:48.800
Do this and do that. I got to 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

Lulu Miller 00:08:02.830
Did you get a diagnosis then?

John 00:08:05.560
Yeah, schizoaffective.

Lulu Miller 00:08:08.260
Which is not exactly schizophrenia, but has some of its symptoms.

John 00:08:12.340
He prescribed me a drug, an antidepressant, and I had a really bad reaction to

Lulu Miller 00:08:19.570
What happened?

John 00:08:20.341
It really brought on those internal voices. Like I remember driving in the car, thinking everyone on the road was targeting me. I went off my meds.

Lulu Miller 00:08:34.260
But the sense that people were out to get him just kept getting worse.

John 00:08:39.210
I just remember everyone giving me a hard time.

Lulu Miller 00:08:42.600
How did they give you a hard time?

John 00:08:45.630
They would like give me dirty looks. They would pull schemes on me and mock me [reserved laugh] at times and maybe even, I remember my mom saying once people aren't out to get you and if you take your meds, then you'll realize that.

Lulu Miller 00:09:06.790
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?

John 00:09:19.000
It could have been something inside me somewhat. But it's hard for me to believe that it was all me making it up.

Lulu Miller 00:09:29.860
So he keeps just trying to muddle through. And at a certain point, John does something seemingly trivial. [music] It's a nice, warm day out shorts and T-shirt kind of weather. And he puts on a winter hat.

John 00:09:45.490
I got for Christmas one year.

Lulu Miller 00:09:47.470
What color?

John 00:09:48.220
It was gray. It's a comfort.

Lulu Miller 00:09:51.490
And before he heads out the door, he rifled through his stuff and decides to also put on...

John 00:09:56.470
A hooded sweatshirt, hood up.

Lulu Miller 00:09:59.200
And then he grabs the third layer.

John 00:10:01.870
It was a jacket.

Lulu Miller 00:10:03.430
And a fourth.

Lulu Miller 00:10:04.540
Sweat pants 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. And people would say things like:

John 00:10:21.450
What are you, preparing for a wrestling match? Like trying to lose weight for wrestling?

Lulu Miller 00:10:27.180
That's right, like training in trash bags, kind of thing.

John 00:10:30.030

Lulu Miller 00:10:32.800
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 going to think something's up. Maybe keep a wide berth.

Molly Webster 00:10:50.230
hmm hmm.

Lulu Miller 00:10:50.230
I mean, when people see you wearing layers, what do you think they think about you?

John 00:10:56.930
I think they're fearful. They fear me.

Molly Webster 00:11:01.780

Dr. Tathagata Mahinda Mani 00:11:02.530
[phone speaker] Hello.

Lulu Miller 00:11:03.070
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.

Dr. Tathagata Mahinda Mani 00:11:13.750
Am I audible?

Lulu Miller 00:11:14.620
There you are. Sorry about that. This is Dr. Tathagata Mahinda Mani, a psychiatrist in India.

Dr. Tathagata Mahinda Mani 00:11:21.520
Currently, I'm in northwestern part of India,

Lulu Miller 00:11:24.040
Who back when he was starting out as a psychiatrist in Rachi, started noticing that in the middle of summer, every now and then, people with schizophrenia would walk into the hospital wearing tons of layers.

Dr. Tathagata Mahinda Mani 00:11:36.820
Ladies were wearing multiple layers of Soris, and male patients were wearing multiple layers of shirts.

Lulu Miller 00:11:44.140
And over in Melbourne, Australia.

Dr. Terence Chong 00:11:46.390
I was doing my first psychiatry rotation.

Lulu Miller 00:11:49.330
Dr. Terence Chong was treating a patient with schizophrenia.

Dr. Terence Chong 00:11:52.810
I noticed at the time he was taking off layers and layers and layers of clothing, and this was in the heat of summer.

Lulu Miller 00:12:01.180
There was a doctor in Memphis, Tennessee, who noticed the same thing.

Molly Webster 00:12:04.330

Lulu Miller 00:12:05.080
Yeah. And eventually it even got a fancy medical name.

Dr. Tathagata Mahinda Mani 00:12:08.110
Redundant clothing.

Lulu Miller 00:12:10.060
So the idea there is just it's you don't need it. It's multiple. It's redundant clothing.

Dr. Tathagata Mahinda Mani 00:12:17.620

Lulu Miller 00:12:18.430
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, like you wear them all.

Dr. Tathagata Mahinda Mani 00:12:34.480
Another thing might be abolition,

Lulu Miller 00:12:37.180
A lack of motivation. So basically, the person maybe forgot to take the last layer off.

Dr. Tathagata Mahinda Mani 00:12:42.190

Lulu Miller 00:12:42.531
Another explanation is just this generalized, erratic, I'm confused, so I have on all these clothes. I mean, there are all kinds of different explanations. Can you just describe why you crave the layers?

John 00:13:00.430
I think it's a way of shielding myself from the world like I feel the world is harsh. It's it's hard for me to completely put a finger on it because I was just doing what felt natural.

Lulu Miller 00:13:16.960
And Dr. Mahin Timoney, 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 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? Like, what does that mean?

Dr. Mahin Timoney 00:14:03.220
So free T3 and free T4 are very reliable markers of temperature regulation.

Lulu Miller 00:14:09.640
Temperature regulation?

Dr. Mahin Timoney 00:14:11.380
Yes, with cold intolerance.

Lulu Miller 00:14:14.650
Like you just get cold quicker.

Dr. Mahin Timoney 00:14:16.480

Lulu Miller 00:14:16.900

Dr. Mahin Timoney 00:14:17.500
You feel cold quicker.

Molly Webster 00:14:18.490
Wait. So actually they may have layers on because they're actually physically colder.

Lulu Miller 00:14:25.450
I asked him almost exactly that. Is your idea that they are actually wearing the layers to feel warmer?

Dr. Mahin Timoney 00:14:36.170
It is our findings, and our ideas are based on our findings.

Lulu Miller 00:14:44.790
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. 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.

John 00:15:07.480
It was a really difficult time for me.

Lulu Miller 00:15:10.440
And things finally got so bad that he goes back to the doctor, and this time is in fact diagnosed with

John 00:15:16.351
Paranoid schizophrenia,

Lulu Miller 00:15:18.720
And he's prescribed a different medication.

John 00:15:21.660
I immediately noticed less up and down less craziness. I notice myself getting better by the day.

Lulu Miller 00:15:31.231
And the world seemed to be getting a little better, too. A little gentler,

John 00:15:36.810
And I felt people liked me.

Lulu Miller 00:15:39.600
And he started loosening up, literally taking off his hat.

John 00:15:43.920

Lulu Miller 00:15:44.431
His jacket, or one of them.

John 00:15:48.570
It was winter and I would wear like a tank top under a winter jacket, and that was it.

Lulu Miller 00:15:56.250
And he started to embrace his diagnosis.

John 00:15:59.190
I read about how people with schizophrenic disorders oftentimes think divergently and a link to creativity.

Lulu Miller 00:16:09.330
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.

John 00:16:16.440
And 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 wasn't very proud, but I had some pride.

Speaker 4 00:16:32.420
All is indicating she thinks there's someone shooting in the villa.

Lulu Miller 00:16:34.970
And then one day, about 30 miles away from where he lives.

Speaker 5 00:16:39.531
Shooting at an elementary school in Newtown, Connecticut.

Lulu Miller 00:16:43.220
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,

John 00:16:54.503
Like when they first heard about the news that there was a shooting in Connecticut. They thought of me.

Lulu Miller 00:17:01.350
For an instant, they worried the shooter had been John.

John 00:17:05.610
It was really hurtful. It was like I would never do anything like that. I definitely stopped having that pride towards my diagnosis.

Lulu Miller 00:17:16.650
He stopped taking his medication.

John 00:17:18.960
It felt a lot more gloom and doom, and I started to slip really quickly.

Lulu Miller 00:17:25.020
Into this chilly spiral [sad piano plays] where without his meds, the world started to seem colder, which Dr. Mahin Timoney 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

Dr. Mahin Timoney 00:17:43.590
Neurotoxic effect on the brain. Loss of brain function. And also there is structural brain damage also there. As the day progresses, the patients with schizophrenia often, you know, drifts.

Lulu Miller 00:17:59.190
So as John was drifting, the world started seeming even colder.

John 00:18:03.750
Thinking everyone was targeting me.

Lulu Miller 00:18:06.480
So he'd layer up which itself would make the world oftentimes be colder.

John 00:18:13.170
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.

Molly Webster 00:18:33.270
And then it's like one more layer.

Lulu Miller 00:18:34.891
Another layer.

Dr. Mahin Timoney 00:18:38.980
At the end of our study, we also thought that this might be a window. You know, this is kind of redundant clothing might be a window through which we can peep towards something really really broken down.

Molly Webster 00:18:55.940
Dr. Mahin Timoney 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 see that from the outside.

Dr. Mahin Timoney 00:19:16.890

Molly Webster 00:19:16.900
Which made me start to wonder, is it almost like humans have within them this visual signal for like, I'm really lost. I might not even know how to ask for help, but here is a signal.

Lulu Miller 00:19:32.210
I was pretty. I mean, I put the idea to Dr. Mahin Timoney and he was like,

Dr. Mahin Timoney 00:19:37.910
I'm not in a position to answer this, but this is a wonderful and intriguing question.

Lulu Miller 00:19:43.100
Yeah. But I also put it to John. Is there anything to that or am I like overly projecting an idea?

John 00:19:52.440
No, I think you could be on to something. I think there could be like a cry for help through layers,

Lulu Miller 00:20:01.320
And he told me a story about one time when someone seemed to read it that way.

John 00:20:07.710
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 '70s white hair. I think she was wearing a T-shirt and short Jean, the Lady Georges. I said, Hey, how are you? Now it 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. I took a bite or two from my grilled cheese sandwich. I almost felt I didn't deserve that food, and I said to her, I think I'm going to feed the rest of the birds. And she said to me, Don't feed the birds, just eat your food. And then I ultimately fed the birds. She went, Oh, I like feeling empathy towards me.

Lulu Miller 00:21:20.230
Yeah. Did you feel a little bit better after that?

John 00:21:23.910
Yeah, I did feel better.

Lulu Miller 00:21:26.590
He eventually felt so relaxed, he slipped off his sandals. And he put his feet on the sand and he just walked home barefoot.

John 00:21:40.090
Yeah. [pensive violin music]

Lulu Miller 00:21:56.460
Okay, so turning the page, Chapter 3. Picture 2 people playing a game sort of like catch.

Hans Eisenman 00:22:05.160
The Cyber Ball experiment.

Lulu Miller 00:22:06.690
Okay, so Hans, our researcher from earlier told me about this study he did where he had people playing this game called Cyber Ball, 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. ["foop" sound effects from voice]

Molly Webster 00:22:25.020

Lulu Miller 00:22:25.770
And then at a certain point, they just suddenly start rejecting you.

Hans Eisenman 00:22:29.070
You're not part of this ball game anymore.

Lulu Miller 00:22:31.410
They just suddenly start excluding you and won't throw you past you the ball.

Molly Webster 00:22:34.440
That's terrible.

Lulu Miller 00:22:35.970
Yeah. And so like in that, the room temperature is colder, but then what he did was he snuck under their fingers, a little digital thermometer

Hans Eisenman 00:22:45.121
With velcro on it, was just a bunch of sensors with a wire sticking out of it.

Lulu Miller 00:22:49.680
And he found that their peripheral skin temperature, their skin temperature dropped in that condition when they were excluded, and so it's like you perceive it as colder and your skin actually gets a little colder. Huh?

Molly Webster 00:23:01.930

Lulu Miller 00:23:02.700
I mean, to see it reflected on the skin felt like such a leap from emotion or feeling or thought to physical reality. What was it like for you to find that result?

Hans Eisenman 00:23:19.540
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. [pensive music]

Lulu Miller 00:23:36.950
What else was there? After the break. [music continues]

Laurel 00:23:46.330
[answering machine speaker] Hey, my name's Laurel. I'm calling from London. Radiolab is supported in part by the Alfred P. Sloan Foundation, enhancing public understanding of science and technology in the modern world. More information about Sloan www.Sloan.org.

Jed Abumrad 00:24:01.810
Science reporting on Radiolab is supported in part by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science.

Lulu Miller 00:24:19.140
This is Leila Radiolab back here with senior correspondent Molly Webster.

Molly Webster 00:24:22.860
Should we go back to the book?

Lulu Miller 00:24:24.330
Yeah. [breath blows into wind chimes]

Molly Webster 00:24:24.721
Nice. [fantasy orchestral music] Chapter 4 here, right?

Lulu Miller 00:24:28.080
Chapter 4. Pictures pretty groovy. It's like a thermometer and it's broken and mercury is spilling out of it like blood.

Molly Webster 00:24:42.930
And I want to take Chapter 4.

Lulu Miller 00:24:46.740
Hell, yeah.

Speaker 6 00:24:47.461
[record speeds up] Welcome.

Molly Webster 00:24:48.753
[background chatter]

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.

Speaker 6 00:25:05.190
[background chatter]

It's kind of a rainy day, so it might be a little bit light.

John 00:25:07.771
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.

Bouncer 00:25:15.930
Temperature gun.

Molly Webster 00:25:16.591
The temperature gun zapping, everybody who shows up.

Bouncer 00:25:19.350
Scott have got it under control.

Molly Webster 00:25:20.881
Deciding if people can come in and out of the door.

Lulu Miller 00:25:23.580
Oh, like the new bouncer of temperature.

Molly Webster 00:25:26.640
Exactly. We got a 96.1. And this is happening -

Listener 00:25:31.421
before I go to work every morning, basically everywhere. I have to take my temperature and text it to the school nurse. So here we go. We actually put a call out to our listeners, had people send us a little recording

Listener 2 00:25:43.380
I'm walking up to get my temperature tested.

Molly Webster 00:25:45.270
As they headed to work,

Listener 3 00:25:47.523
Arriving at Mask Sound in East Rutherford, New Jersey,

Molly Webster 00:25:50.463
Or to the grocery store.

Listener 4 00:25:51.870
I'm at the supermarket, I'm about to go take the temperature.

Molly Webster 00:25:54.691
Dropping their kids off at school.

Listener 5 00:25:56.670
Let's take your temperature so you can go in the school.

Listener 6 00:25:58.531
And stop if your temperature reads 99.4.

Molly Webster 00:26:02.990
This is how we decide now whether or not it's okay to be around other people.

Automated Voice 00:26:08.060
Normal temperature, you are free to pass.

Lulu Miller 00:26:10.970
Thank you.

Molly Webster 00:26:11.720
Good to go.

Speaker 12 00:26:12.350
See you, buddy.

Molly Webster 00:26:13.820
Now we did not get anybody who is in the sort of a range, but you do hear in the tape.

Bouncer 00:26:19.311

Molly Webster 00:26:20.211
And what I saw in the bar.

Listener 00:26:21.801

Listener 00:26:22.640

Molly Webster 00:26:25.640
It's a pretty surprising range of numbers.

Listener 00:26:28.010
97.5 97.2 96.4 98.5 95.2 94.6. A little bit 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.

Lulu Miller 00:26:46.630
Okay, these guns they don't work. 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 bedrock of human health, that golden number, 98.6.

Molly Webster 00:27:13.550
Yes, the golden number of like what a human body should be. Except i t's kind of a con.

Lulu Miller 00:27:25.440
A con?

Molly Webster 00:27:26.850
[chuckles] Sort of. let me just explain first where it comes from.

Lulu Miller 00:27:30.390

Molly Webster 00:27:30.781
So the story of 98.6 starts in the 1800s as all good science stories do.

Deanna De 00:27:40.140
So in the late 19th century, you get the introduction of thermometers into medical practice.

Molly Webster 00:27:45.000
So for this section, I'm going to get a little help from Deanna De.

Deanna De 00:27:47.940
I'm a writer and historian .[laughs] I always have this moment because I'm doing like 50,000 things.

Molly Webster 00:27:59.840
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 Fever's back then weren't seen as some sort of like signal or sign of a disease.

Deanna De 00:28:16.670
The fever was just the disease.

Molly Webster 00:28:18.620
They thought fevers were the actual illness.

Deanna De 00:28:21.470
The thing you had that was causing all of your symptoms.

Molly Webster 00:28:26.273
Like you catch a heat and then it gives you all this bad vomiting, tiredness.

Deanna De 00:28:32.450

Molly Webster 00:28:32.460
then along came a guy named Carl Wunderlich, cool name.

Deanna De 00:28:38.060
So Wunderlich was a physician in Germany.

Molly Webster 00:28:41.930
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, there 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 he wouldn't actually think about that because there were no computers, lots of pencils, lots of paper. 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.

Deanna De 00:29:23.870
At his hospital, they took temperature readings repeatedly over and over from about 25,000 patients.

Molly Webster 00:29:33.230
Twenty five thousand patients, a million and a half temperature record.

Lulu Miller 00:29:37.970
Do we have a fleet of temperature collectors?

Molly Webster 00:29:41.450
No, it was basically him and whoever worked in his clinic. He just had a really busy clinic in Germany.

Lulu Miller 00:29:47.740
Wow, that feels b ut I guess over like decades, right?

Molly Webster 00:29:51.650
Yeah, like 20 years. So Wunderlich collects all this data and

Deanna De 00:29:57.650
The 19th century version of crunching the numbers and created all of these charts

Molly Webster 00:30:03.800
Fever charts.

Deanna De 00:30:04.820
He found different diseases, had different fever progressions in patients.

Molly Webster 00:30:11.630
He would have like a patient that had syphilis, say. And he could map their temperature change throughout syphilis, a nd he would get like a really pretty pattern on an x y graph.

Deanna De 00:30:23.210
Some diseases would have a fever that would spike and drop and spike and drop, and other diseases had a fever course that were kind of like ramp up gradually or ramp down slowl y.

Lulu Miller 00:30:31.610
Really. Cool. I've never thought of that like that each illness has a little curlicue signature, oh, that's cool.

Molly Webster 00:30:39.170
If I'm honest, like, I don't know if that actually still holds up today, but...

Deanna De 00:30:43.850
His idea was that you could track someone's temperature and diagnose them that way. And that was a big change.

Molly Webster 00:30:51.770
All of a sudden we start seeing fever, 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.

Deanna De 00:31:12.740
And kind of incidentally, he was like, a nd in healthy people, when they are no longer sick, we have found that body temperature is 37 degrees Celsius,

Molly Webster 00:31:24.590
Which the conversion to Fahrenheit is 98.6.

Lulu Miller 00:31:28.760
Interesting. So he was just like, Oops, I was studying this other thing. I accidentally have cash million data points.

Molly Webster 00:31:34.553
Yeah, it was essentially a footnote.

Lulu Miller 00:31:36.290
Ninety eight point six, t hat thing we all sort of bow before was just a little footnote from the 1800s.

Molly Webster 00:31:42.830
Well, yes, until this guy came along named Edward Cygwin Edward

Deanna De 00:31:46.971
Cygwin is the person who actually translated Wunderlich work and introduced it to the Aztecs,

Molly Webster 00:31:53.660
And he is really into thermometery.

Lulu Miller 00:31:55.140
Which is the word.

Molly Webster 00:31:57.200
It was just a word I know.

Deanna De 00:31:58.760
He writes this manual called family thermometer, which is supposed to teach moms how to take your kids temperature and why it's important and how to do it.

Molly Webster 00:32:07.580
And so Cygwin, along with thermometer companies, kind of went on this big push through like

Deanna De 00:32:15.111
Articles in Good Housekeeping and Ladies Home Journal and Scientific American

Molly Webster 00:32:19.521
To talk about thermometers and make them like a new tool for the home.

Deanna De 00:32:23.300
And there are advertisements in all kinds of publications,

Molly Webster 00:32:27.140
And over and over again, they'd hammer on this number. Ninety eight point six. That's what you should be. That's what your kids should be. And I feel like this like marketing campaign that happened at the end of the 1800s in 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 human body, which is bullshit.

Katherine Ley 00:32:54.860
Well, it turns out that there's a lot of variation across all these different parameters.

Molly Webster 00:33:01.040
So this is Katherine Ley,

Katherine Ley 00:33:02.543
Infectious disease epidemiologist at Stanford University.

Molly Webster 00:33:05.933
And as Kat explained it to me, there is no one healthy human temperature.

Katherine Ley 00:33:11.330
Women have higher temperatures than men. Bigger people have higher temperatures,

Molly Webster 00:33:17.170
Fatter and skinnier people have different temperatures.

Katherine Ley 00:33:19.960
Taller people have lower temperatures.

Molly Webster 00:33:22.090
They're just so thinned out that they got surface area for days. I don't know.

Lulu Miller 00:33:28.090
Hormones can change your temperatures. Morning and night can change your temperatures.

Katherine Ley 00:33:32.170
Younger people have higher temperatures than older people.

Lulu Miller 00:33:35.830
I'm already thinking about the sweat since I want to rock again.

Molly Webster 00:33:37.571
Even in the same person, temperature taken in the ear, in your armpit and your butt can vary by like two degrees. Now all of 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, r esearchers don't even think 98.6 is our average anymore.

Lulu Miller 00:34:05.530
Like, there is 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, a nd she said that it looks like our temperature has been dropping 0.05 degrees Fahrenheit every decade since the 1850s. 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,

Molly Webster 00:34:41.443
I mean, I remember that episode I was so focused on the scary fungus that I feel like I missed it.

Lulu Miller 00:34:48.631
It was just lifting there. You know,

Deanna De 00:34:51.160
It's like, you're saying, so not only is there all this individuality on person and time of day and part of body, and also the average isn't the average either.

Molly Webster 00:35:05.230
Yeah, so much so that. For some people, because you're a man, you're old, and it's early in the morning. Coming up to 98.6 might actually be a fever for you.

Deanna De 00:35:19.630
This is exactly why it's important to not believe that a number like your temperature can tell you everything.

Molly Webster 00:35:31.090
But even when you know that it's so hard to let go of that number. 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 second one and it like laid me low. 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, you know, turned on my voice memo and it's so bad and my voice is ridiculous. And I think my fever must be like 102. And I take my temperature and it just 98.1, comes out as 98.1. Oh, and I was just like, Oh, am I..

Lulu Miller 00:36:13.690
A big faker?

Molly Webster 00:36:14.563
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 Radiolab is going to believe me. The thermometer can't be right because it doesn't encapsulate, terrible. Despite knowing everything [cross talk] I'm in the midst of this reporting.

Lulu Miller 00:36:35.293
You were still like measuring yourself up against that number

Molly Webster 00:36:39.641
Ninety eight point six, and so it's like all of that against me. And then in the middle of sort of like the fever haze, the non fever haze, the neon fever fever haze. I'm like kind of hanging off the side of my bed, like very bad. And I was just like, This is just like what Deanna said.

Deanna De 00:37:07.040
I think that acting as if fever as a quantitative measure can give you objective truth. Just makes it impossible for anyone to see t he full scope of what is happening inside a person.

Molly Webster 00:37:30.860
I definitely felt that in that moment taking my own temperature. But I think I also realized that you can 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, you know, whether you live in a place with adequate medical care.

Lulu Miller 00:37:56.390
Can I add one more kind of eerie one?

Molly Webster 00:37:58.580
Of course.

Lulu Miller 00:37:58.770
Of what your temperature might be able to tell you. So Huns 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, perceive 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?

Molly Webster 00:38:43.790
It's not number, it's groups,[cross talk].

Lulu Miller 00:38:44.070
Yeah, it's like your work 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. the

Molly Webster 00:39:02.301
Does he have any explanation for that?

Lulu Miller 00:39:06.260
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.

Molly Webster 00:39:20.470
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 w hat's happening mentally and emotionally in your brain, like emotions tuning your body temperature to what it is?

Lulu Miller 00:39:46.650
Yeah. Which makes me think back on that temperature check tape a little differently.

Molly Webster 00:39:52.960
Like, can I take your temperature?

Speaker 17 00:39:55.150

Speaker 18 00:39:55.160

Speaker 19 00:39:56.101
, ninety six point one 96.1.

Lulu Miller 00:39:58.340
Did you gain weight?

Speaker 20 00:40:00.370
Ninety seven point five

Speaker 21 00:40:02.770
96. 4.

Molly Webster 00:40:02.790
What time of day is this? Maybe you're pregnant.

Speaker 22 00:40:09.850
Ninety seven point two degrees, 97.7. 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 three. Normal Temperature. Did you talk to your sister? Ninety seven point five. Are you on medicine? Ninety five point five. Do you live alone?

Molly Webster 00:40:33.730
Who do you love ?[music] Have you seen them? Molly Webster, this episode was produced by Becca Bressler, Molly Webster and me with production help from Karen DeYoung and fact checking by Emily Krieger. Hans Eisenman 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 Bartolome, Julie Pasternak, Philip McAvoy, Carla Hoch, Lisa Alexander, Anna Stanwitzs, Brendan and all the folks over at the Commissioner in Park Slope. Our listeners for their voice memos. Thank you. 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. And while I have your ears, Invisibilia has a new season out with new hosts Joe Asia and Kiana Teeth. It is so good, and if you listen really close, you can hear the sounds of a show melting into something bigger, more beautiful and braver than anything we ever could have imagined when we first started out. I really recommend you go check it out. Thanks for listening.

Jonathan Chan 00:42:06.030
Hi, this is Jonathan Chan calling in from Singapore. Radiolab was created by Jad Abumrad and edited by Sean Wheeler, Lulu Miller and Latif Nasr. Our co-hosts, Susie Lichtenberg is our executive producer. Dylan Keefe is our director of Sound Design. Our staff includes Simon Adler, Jeremy Bloom, Becca Bressler, Rachel Cusick, David Gable, Matt Kilty, Andy McEwen, Sara Cari, Erin Wack, Pat Walters and Mollie Webster. With help from Shima, AI, Sarah Sandbank and Karim Leone, or fact checkers are Diane Kelly and Emily Krieger.

Lulu Miller 00:42:45.930
Okay, so remember, I said this book does have a fifth chapter.

Molly Webster 00:42:49.430
The pictures, just the scale in perfect balance.

Lulu Miller 00:42:53.130
So you know how there's a kind of gnarly ness to the concept of death like kleptotherm? This is all about how like we are concealing

Molly Webster 00:43:02.290

Lulu Miller 00:43:04.150
Yeah, it's like that acquisition you got to take in more than you give. And if you don't get enough, you feel wounded and at risk, a nd if you are getting enough, you're stealing it from someone or something else. If we got to equilibrium, wouldn't that be so nice?

Molly Webster 00:43:19.860
Yes, equilibrium would be. So we're all giving and taking and like coexisting. And it's a balance.

Lulu Miller 00:43:28.260
Okay, do you know what that's called? You know what the physicists call that?

Molly Webster 00:43:32.280

Lulu Miller 00:43:33.880
The thermal death of the universe .[music]

Molly Webster 00:43:42.500
Wait, equilibrium is thermal death?

Lulu Miller 00:43:44.990
Yeah, like there will be a time when everything becomes the same temperature. And that is the end.

Lulu Miller 00:43:53.290
I'll be grateful for the give and take

Lulu Miller 00:43:55.870
Wait for the give and take. We'll give you away to your life. That's the end. See you next time. Thanks for listening. Bye

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