How do we adapt to the cold?

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1:11It is cold.

1:13Caroline Steel:I am wearing lots of layers though. You're listening to CrowdScience from the BBC World Service. The show that answers your science questions. I'm Caroline Steele. And this is the sound of me and producer Hannah feeling a tad chilly. Your face is very red. I'm so cold. I'm in Svalbard, a remote group of islands far north of Norway in the Arctic Circle. It's winter here and the average temperature is around minus 15 degrees Celsius. So I'm wearing thermals, a snowsuit, three pairs of socks, boots, a woolly hat and gloves. But I'm still cold. I'm struggling to work out the right combination of layers, which is a common experience in Svalbard because 40 % of residents aren't originally from the islands or from its neighbour Norway.

2:05Caroline Steel:So getting used to life in the Arctic, including dressing for it, is a shared challenge. Here's Svalbard resident June. I live in the Philippines for the entire of my life. It's polar opposite. Because at first I find it hard to adjust, but then I just get tired of complaining. And Katie. I'm from the UK. I think when you first come, you dress so warm, you're actually too hot. So I think it took me about a year of experience to really figure that out. And this is Leila. Before I lived in Germany and in Finland, but I now feel when it's like minus 10, it's not that bad anymore. Because also when we have like minus 20 for a couple of days, and then you go back to minus 10, it feels really warm.

2:48Caroline Steel:So it's already in a couple of days you can adjust quite a bit. Fingers crossed I adjust soon. The reason I'm spending time on this interesting international island is thanks to a question from listener Anne in Wales in the UK. Do we all really respond to cold in the same way or is it cultural and habitual? OK, so you're wondering whether there's like a physical difference in how we respond to the cold, or if it's just informed by our previous experiences and like, this is much colder than where I grew up, therefore it feels really cold. Yeah, and what we're used to and attitudes to physical comfort and that sort of thing.

3:30Caroline Steel:And what made you think of this question? I spent my early years outside London, and then my parents moved to South Africa when I was seven. and although it doesn't get as cold as here, there's no central heating and people tolerate temperatures of, you know, 8, 9, 10, perhaps being a bit less concerned about the cold. But I find that all the houses I go into here in Wales, in winter people have the heating on to extraordinary temperatures and I find it very puzzling. I think it's cultural, but I could be wrong. So, do we all respond to cold in the same way? How much do the bodies we're born with and the environment we live in have an impact?

4:15Caroline Steel:I was born and spent my earliest years in Canada, where it can be as cold as minus 30 degrees Celsius. But now I live in the UK and I'm terrible at managing the cold. I'm the first to shiver and carry a jumper with me even in the height of summer. So what's going on when we feel chilly? is my body actually worse at keeping warm than listener Anne's? OK, after you. So what temperature is it when we get in there? So the temperature in there at the moment is zero degrees Celsius and 18 % humidity, so it's very dry in there and very cold at the moment. Great! To find out what happens to our bodies as we cool down, I'm walking into a very cold room in just a cotton t-shirt.

5:00Caroline Steel:It is cold. It's really cold. I reckon I'm minutes away from shivering. I am turning on this infrared camera so this will show you visually what your skin temperature is. I'm with Matt Mailey. He's a lecturer in environmental physiology at Loughborough University in the UK. Oh, there I am. Then you can see your neck skin temperature at the moment is around 29 degrees Celsius. That's quite cold. Yeah, but your skin should be around 33 degrees Celsius, so it's only a little bit cooler than what is firm and neutral. The cold room is basically a large glass box, cooled to a chilly zero degrees, and I'm literally watching my body temperature plummet.

5:43Caroline Steel:There's an infrared camera pointing at me, and it's projecting what it sees onto a TV screen. And if you used to spend longer in here, you would actually witness that skin temperature dropping. Although we keep our cores at a balmy 37 degrees Celsius, Our skin is usually a bit cooler at around 33 degrees. But my skin temperature has already dropped to about 29 degrees. And without thinking about it, I've crossed my arms. And then most people will come into the environment and actually fold their hands. If they're sitting, they will put their knees up. That is actually closing off your body surface area.

6:19So the amount that is being exposed to the environment. So in the heat, people stand a little bit wider. and then they have their hands open or they're on the hips or anything like that. In the cold, they're not happy. Their behaviour changes way before any physiology.

6:33Caroline Steel:Despite changing my behaviour to try and keep warmer, my hands are in my armpits and my legs are pressed together, I can still see my skin temperature decreasing on the screen in front of me. Look at my nose. I said my nose gets cold really fast. Like 17.9 on your end of your nose. Yeah, my nose is terrible.

6:55Caroline Steel:We'll check back in with me and my cold nose later on in the show. But for now, back to Svalbard, which makes Matt's cold room feel practically tropical. Hello. Good morning, how are you? To help residents deal with this harsh environment, the university centre runs safety courses, and I got the chance to get some tips from one of the people in charge. My name is Gunnil Birgitte Sætre. I live with my family here in Longebyen in Svalbard. and I work as a manager at the Arctic Safety Centre and as an associate professor of safety psychology. Part of Gunnhild's job is to teach people how to stay warm.

7:36Caroline Steel:So at the moment, is it about minus 15 outside? Might be, yeah. Didn't feel that cold. So a bit very cold for me, not super cold for here. So I put on wool, thermal trousers, wool thermal top, then I've got jeans on top of my thermals, then a fleece, then a big snowsuit, snow boots, gloves and a hat and two layers of woolly socks. Would you say that is appropriate clothing for the weather? Did I get it right? Absolutely, depending on the activity you're about to do. Interesting. OK, so I'm not underdressed. That's enough, I'd say. I don't think you're underdressed, but it depends. It's individual.

8:15So what should we consider when choosing our clothes? First and foremost, I would say that perhaps the gender differs. So male often are more tolerant perhaps than females. Then it's of course what you're used to. Are you used to dealing with the cold? Are you not? Another thing is your weight. So if you're really light and you don't have much fat on your body, you could freeze much faster than if you have like isolation layers. And of course, how you dress, age. If you're elderly, you freeze quicker.

8:54Caroline Steel:How important is your frame of mind when dealing with the cold? Is being positive about it helpful or maybe that's actually even more risky because you might not take the necessary precautions? I think the psychological robustness regarding cold is really important in that you have a mindset of this will be cold. It might be a bit uncomfortable and not be afraid of that. Have you ever got it really wrong and misjudged the cold yourself? No. Well done. I haven't. I always overdress. So, yeah, my kids have, but I haven't. Good, well done.

9:32Caroline Steel:So from Gunhill's experience, your mindset, body fat, age and sex all affect how well you handle the cold. And based on all those things, you need to pick the right clothes to wear. Unlike me, forced to wear a t-shirt in a freezing cold room. Here's physiologist Matt again, talking me through the changes happening in my body. What will happen over time is as skin temperature starts to lower, then that will affect your internal body temperature. As that internal body temperature starts to go closer to 36 degrees Celsius, so starting up at 37, the body will start to shiver. I'm already starting to shiver.

10:10You start to see your hands become quite blanched, which is like a white appearance. maybe on your palms, on your fingers. My heart kind of blue.

10:17Caroline Steel:What's going on with my veins? So you're seeing a vasoconstriction in what we call the cutaneous circulation, so that's your skin blood flow. So it's starting to reduce quite dramatically. And what that does, again, is protecting the internal core body temperature because it doesn't want to provide the warm blood to the skin because you'll just lose it. So what it's doing is protecting the internal organs, so it wants to maintain that heat. You can see this quite clearly in white skin, a little bit harder to see in individuals of black African descent, though you can see it a little bit paler.

10:50You start to see shivering of the hands as well because that's your agonist and antagonist muscles in your arms, start to contract and relax against each other.

10:59Caroline Steel:Although I'm not visibly shivering, I can tell my core is shivering, like these muscles are contracting. Well, maybe I am visibly shivering. I probably get this cold in England in the winter, but then I get into my nice warm house. It's really uncomfortable. So we have vasoconstriction and we have shivering response. And that's really our two mechanisms. And that's all we rely on, physiologically speaking. Contracting and relaxing muscles generate heat. So my body is trying to warm up by essentially doing involuntary exercise. And my hands have gone white as my body stopped worrying about blood flow to my skin, as it's instead prioritising the vital organs in my core, which is clear from my ever-decreasing skin temperature being picked up by the infrared camera.

11:47So within 10 minutes or so, it's gone down quite a bit. So you can see that's reduced by 4 degrees Celsius already.

11:54Caroline Steel:And I'm not just feeling it in my body. It's starting to get harder to talk and even think properly. Cognitive performance actually declines quite quickly as well. To measure somebody's cognitive or satisfaction with the environment, you find that when you ask somebody to tell a joke, if their humour starts to disappear, that's where their cognition starts to disappear as well. We used to do simple mathematics questions. We'd put people in cold water up to the clavicle and say, for every wrong answer you get, we lowered the water temperature by one degree Celsius. So it's like a torture experiment.

12:28And after 20 minutes of being in quite cool environments, people stopped laughing and joking with us as much. So even though they were getting the answers wrong beforehand, their humour started to disappear quite quickly.

12:40Caroline Steel:But Matt's experiment has a twist. Interestingly, we never lowered the water temperature, but they perceived the water temperature to become colder. Actually, it wasn't. But you can see their mental arithmetic is actually diminished completely. They can't compute, and then if it goes out the window, cognition's gone. So if you put people in cold water and make them do mental maths, Eventually, their sense of humor starts to fail. I'm not surprised. Next, we make things even more unpleasant in the cold room. This is summer at its peak. Whole Foods Market Summer Fruit Fest is your invitation to eat the season.

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14:13Caroline Steel:You're listening to CrowdScience from the BBC World Service, the show that answers your science questions, even if it means doing an interview in essentially a big fridge. I'm Caroline Steele, and we're answering a question from listener Anne, who wants to know, do we all respond to cold in the same way? When we're cold, our bodies automatically do a specific dance. We change our behaviour, shiver and alter our blood flow as we try to stop our core temperature from dropping. And interestingly, the temperature of the air isn't the only thing that affects how cold our environment feels. Tucked away in the corner of physiologist Matt's cauldron is a giant fan.

14:53You have a small layer above your skin. We're talking millimetres here, but I can actually blow that away by increasing the air velocity.

15:00Caroline Steel:Ah, OK, so there is a warm layer of air around my skin? Yes. That you can get rid of, yeah? And you just increase your heat loss. Great! Fun, fun, fun. Matt is turning on the industrial-sized fan and I'm in its blast zone. Oh, this is horrible. OK, it's much colder when it's bluey. Oh,

15:31Caroline Steel:my neck's dropped down to 23. A couple of minutes in front of the fan, I couldn't stand the cold any longer. So, mercifully, Matt turned it off. I'm shivering. I'm grumpy. I want to get out of this cold room. Can I put my coat on now? You may. I've even got a jumper to put on underneath.

15:57Caroline Steel:Oh, that feels good already. I'm definitely zipping this up. So you would see a much more beneficial effect of the... You can see the dexterity. that's actually trying to zip. Struggling with the zip. So if you was in a windy environment, you would definitely feel more benefit by putting a coat on. So this coat would protect the sort of little warm layer above my skin from getting blown off. Exactly, yeah. Oh, this is so much better. I feel smug now. I think I could do a fair while in here in this coat. Yes. You guys are not looking good. Yeah, I mean, I'm struggling. We're all cold and struggling to concentrate, which doesn't make for a good interview.

16:37Caroline Steel:It's time to leave the cold room. Oh, it's so warm out here. Oh, it feels tropical. Yeah. How long will it take us to warm back up? So it really depends on how quickly your blood flow comes back around. So within about half an hour, you should be back to normal. I don't feel like I need this coat anymore. Nice. Stepping outside has quickly warmed us up. I've stopped shivering, feel less irritable, and I've found my sense of humour again. Oh, Hannah's glasses steamed up. I've learnt through bitter experience what happens to our bodies when we get cold and we know a huge range of factors play into that our clothes, mindset, age and sex but what about our ethnicity?

17:19So rice specifically we did a series of study probably about 10 years ago maybe a little bit longer now and we put people's hands and feet into cold water and we studied the difference between individuals of white European descent, those of black African descent and those of South Asian descent. And what we found is if you are of white European descent and you put your hands or feet into cold water, then your blood flow is greater than those of black African descent. And what we took home from that is that is a protective mechanism for people who are going into a cold environment and it's protecting you against something called non-freezing cold injury.

18:02Caroline Steel:Non-freezing cold injury is when your nerves and blood vessels in your hands and feet suffer long-term damage because of prolonged exposure to the cold. And Matt found that people of white European descent are more able to avoid it. So if your blood flow is higher in the fingers, that means that your tissue is more viable, which means it's alive. Whereas the individuals of black African descent, their blood flow went down in terms of reduced almost down to zero and stayed there. So their blood flow and their skin temperature actually reduced down and stayed at a dangerously low level compared to white Europeans.

18:40Caroline Steel:And will that be because it's an evolutionary advantage for people who have lived in colder climates to not completely reduce the blood flow to their limbs? We think, but to answer that question definitively, you would have to get an extra group in my study. My groups were a bit of a mix between those born in Africa and those born in the UK, but a minimum of two years in the UK. Matt's research shows that there are differences in how people respond to the cold. But without repeating his experiment with individuals of Black African descent in Africa, we don't know if this is down to longer term differences or shorter term acclimatisation.

19:23Caroline Steel:Because we don't know for sure how our personal experiences change our response to the cold. So your lived experience will influence your perception of the cold for sure. Whether it will change your physiology, there's still question marks about that. Ultimately, there is limited data to show that being exposed to cold environments makes you more able to better tolerate the cold. I think when you talk about culture, you talk about ethnicity, what you was raised with, what your early childhood looked like, what your parents' and friends' perception, that influences your cognition, your psychology, but also your diet, your socioeconomic status, all plays a part.

20:07And being able to study that within a laboratory with a small probe sometimes doesn't give you all of the answers. But in short, it's really difficult to acclimatise somebody to the cold. You can change their perception a little bit, but not their physiological responses.

20:23Caroline Steel:So there's not much evidence that our experiences of cold, like listener Anne getting chilly in South African winters, affects our physiology. But as Anne suspected, it does change our perception of cold and might alter how we manage the cold mentally. Plus, there is some evidence that our ethnicity affects our cold responses. But more research is needed before we can draw any big conclusions. There's a limit to what Matt can work out from inside a lab in the UK. So, I think we should speak to someone who studies people on the ground. People who live in cold temperatures every day and have done for centuries.

21:02So, I work with the reindeer herders in northern Finland. And these are people who are a combination of the indigenous Sami population of Finno-Scandinavia, as well as native Finns.