The gift of science

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0:41So, this week I ended up in hospital. I got into a bike accident at 3am. It was my fault. I hit a pothole, flipped over my handlebars, and knocked myself unconscious. Leaving my bike on the pavement, I made my way to hospital and was patched up and sent on my way, courtesy of the gift that is the NHS here in the UK. Colour me surprised when I went back and my bike was still sat on the pavement. It was so terrible that nobody stole it, which I feel is rather insulting. Really, I should be at home right now, resting and recuperating. So for you listeners, my presence is a present. What does that mean?

1:21I'm Alex Lathbridge from the BBC World Service. this is Unexpected Elements.

1:40And I've got the lovely gift of spending today's show with some brilliant science journalists. Joining us from Sao Paulo, Brazil, we have Camila Mota. Hi Alex, feel better. I'm glad you're with us. You know what? So am I. And so are the millions of people listening right now. And dialing in from Nunavut, Canada, we have Marelle Jamal. Hey, Alex. Hey, Kamala. So have either of you ever got into a cycling accident that was completely your fault? You know, yeah, when I was a kid, but I'm very uncoordinated. So yeah, 100 % my fault. Marelle, this is the point where you're going to say entirely, yes, I do it all the time and you shouldn't feel bad, Alex.

2:21Not at all. While I am also very accident prone, so the only vehicle I'm trusting is my feet. Like, nothing else whatsoever. Not cycles, nothing else. Oh yeah, I broke my arm rollerblading, so we're all on the same team. Yep. I respect it and I love it. This is Unexpected Elements, the show where we take a headline and use it as a jumping-off point to discover unexpected science stories found underneath. One story leads to another and another and another, and eventually we all go away far more knowledgeable, if very confused as to how we got here. And today is a very special show. This season from 8 November through January also means celebration season, which means that people around the world will be splashing their cash on the gift giving frenzy.

3:14We give gifts to others because you see the happiness and the smile when the person is opening the gift.

3:30In many parts of the world, we're in the middle of the holiday season. Here in the UK and many other Commonwealth countries, it's Boxing Day. But most importantly, I'm surrounded by lots of holiday time gifts. which got us thinking about the science of gifts. Yeah, and one of the things that sprung to mind when we settled for the gift giving theme was blood donation. You know, the act of gifting your blood to people you don't know, but who really need it. Are any of you blood donors, by the way? Yes, I am. I love giving blood. How about you? Me too. When I give blood, I do it primarily because I'm there to help other people, of course, but they give us free snacks afterwards because you know after they give blood you're like you've got to stick around for like 15 minutes to make sure you get your fluids up and everything and it's fantastic the unexpected elements team love when i give blood because i come back with a bag full of snacks and i always feel bad because i'm like am i just taking all this this food this free food and they're like you are saving lives and i'm like i make this blood for free mate.

4:38You know, I love the whole ritual of giving blood. You know, I try to look at the needle when they're sticking inside of you. I mean, I love it. I try to do it every four months. But you know, one thing I've always asked myself was, is it good for you? You know, the fact that we're making our body work to replace the blood we gave away got me thinking if that could be, you know, beneficial in any way. I went searching and the answer is yes. So besides doing some good to others, you can actually benefit yourself from donating blood. For example, there are a few studies that link regular blood donation to lower blood pressure and a lower risk for heart attacks.

5:16Somehow I feel I'm balancing that out with all the chocolates and snacks I'm eating afterwards. Fair. And you know, the rationale for this is that taking a controlled amount of blood from your body helps to lower the viscosity of the blood. And blood viscosity, as we know, has been associated with the formation of blood clots, heart attacks, strokes. Interestingly, women sort of do this naturally with the menstrual cycle. So these benefits appear to be more significant to men, but there's something to everyone. I will just quickly say, Camilla, that's so interesting that there is an unexpected benefit for women for one time without us actually doing anything and dealing with all the bad parts of menstrual cycles.

6:02So I'm glad there's a silver lining to what we have no say in. I'm sorry. Yeah. Whenever we're in fetal position in pain, we can just think, look, we're lowering our blood viscosity and it's good for us. Yay. But moving on, because there's more. I found a recent study published earlier this year, which points out that frequent blood donation can also produce genetic benefits. German and British researchers looked into the genetics of more than 200 frequent blood donors, people in their 60s who had donated blood more than 100 times. And they wanted to see whether their genetic material changed over time as a result of blood donation.

6:46In other words, they were looking for genetic mutations in their blood cells. And they compared the results with a group with around 200 occasional donors, which is people who had given blood less than 10 times over their lifetime. And so did they find any difference between the groups? Yes, they did. What they found was that frequent donors often developed a mutation in a particular gene that interferes in blood cell production. Is this a bad mutation? So there are mutations that are bad for you, right, that can cause cancer, for example. Not this one, though. This one pushed stem cells to produce more blood cells, meaning blood cells regenerate faster in frequent donors.

7:27The authors argue blood donation can put a positive stress on the body, like jogging or weightlifting, you know, and that can produce long-term benefits on a genetic level. That's so cool. Right? I feel like there's so many benefits to the community that we know, but it's just interesting that the scientific benefits to ourselves is ever expanding. Camilla, thank you so much. I can tell people now that in addition to saving lives, I'm actually giving my blood a bit of a boost. Of course, I'm not there to get free snacks to bring to the Unexpected Elements HQ, where this week the producers prove that their gift-giving abilities are sorely lacking.

8:11Season's greetings, Hannah. Are you okay, Aman? Yeah, I've just got a bit of the flu. No biggie. You've got the influenza virus? Then what are you doing here? Are you trying to give your infection to me? Tis the season for giving? Public health is no joke. Sorry. But don't worry. I know that the flu can spread through droplets, so the virus is sent into the air when I sneeze or cough, and then infects the mucus of someone else's mouth, nodes, or eyes. but that's why I'm coughing into my elbow, not in your face. Yeah, thanks. But that's not the only way the flu is transmitted. The flu virus can also live for short periods of time on different surfaces and so if your hands have the virus after blowing your nose, for example, and then you touch a surface like a table, the virus can actually linger and then be picked up by someone else who comes into contact with that table.

9:05Well, I'm washing my hands and using hand sanitiser so I'm not touching things with potentially drummy hands. That's all great, but even just breathing can spread the flu. Teeny tiny droplets with the virus can hang around in the air after you breathe out. So I should wear a mask? Yes, but also go home. I'm just glad to have had my flu vaccination a few weeks ago. Hopefully my immune system is prepared to fight off any disease coming my way. Ah, ah, achoo! uh-oh i think it's too late you know our hard-working producers they care about this program they aren't taking care of themselves hannah iman please go home and if you won't listen to me the unexpected elements listeners will email in at unexpected the bbc.co.uk and tell you to do so while i'm safely in another room from them morale what sort of science gift are you sharing with us today?

10:03Yeah, so this conversation about gifts got me thinking about the gift givers of the Arctic. And so I'm wondering, do either of you know who the gift givers are in the Arctic food web? Reindeer. I'll say krill. You know, the teeny tiny crustacean? Well, I love those because they're both cute, But in the Arctic, it is none other than the polar bear. So researchers at the University of Manitoba, the San Diego Wildlife Alliance, Environment and Climate Change Canada, as well as the University of Alberta, have found that polar bears are far more than apex predators. They are vital providers for a sprawling community of Arctic scavengers, and they help to keep an array of the polar regions wildlife fed.

10:58OK, so who are they actually feeding? They're feeding at least 11 vertebrate species, and this includes Arctic foxes, ravens, gulls and wolves. And the research, which was published in October, estimates that polar bears leave behind as much as 7.6 million kilograms of prey each year across the region. And these remains, which are mostly seal carcasses, form a crucial energy bridge between the ocean and life in the Arctic. 7.6 million kilograms. Why do polar bears leave so much prey behind? Yeah, are they intentionally being altruistic? So the way that this happens is thanks to the polar bear's unique hunting methods.

11:47So they hunt seals from sea ice platforms and drag their prey onto the surface. And they leave the carcass behind when they're done feeding themselves and share their bounty with the other animals. So this is important because each carcass represents a pulse of marine-derived nutrients the seal had. And it helps the animals on the land in a region that is so harsh and so sparsely populated with any kind of food for them. But polar bears, they're facing population decline, aren't they? So how is this affecting the ecosystem? Yeah, it's interesting because on the one hand, polar bears are leaving behind the carcasses that is feeding so much of the other life or wildlife in the region.

12:36but there is documented decline in two subpopulations of polar bears, and this has already led to a loss of more than 300 tons of food for scavenging animals each year. But of course, climate change is making sea ice thinner and affecting polar bear populations, which in turn is affecting this food cycle. Of course, the climate change domino effect. Wow. Thanks, Meral, for showing us that polar bears are really important in the ecosystem and we need to take much better care of them. Listeners, are there parts of your holiday meals that you'd like to leave behind for another part of the ecosystem to gobble up?

13:18Let us know. You can email us at unexpected at bbc.co.uk or send a message on WhatsApp. plus 44 330 678 3080. Next, we'll hear about the scientific wonders of a cosy wintertime handicraft after this. Hello, and welcome to this week's Unexpected Elements quiz. Atoms are the chemical building blocks of the world around us, and they're made of particles called protons, neutrons, and electrons. When atoms interact with each other to build larger chemical compounds. They oftentimes make chemical bonds with each other using their electrons. Can you tell me what kind of bonds involve atoms giving or transferring electrons to other atoms?

14:07Are they A. Metallic bonds, B. Ionic bonds, or C. Covalent bonds? Again, what kind of chemical bonds involve atoms giving or transferring electrons from one atom to another? Are they A. Metallic bonds, B. Ionic bonds or C. Covalent bonds Give this some thought and we'll be back shortly with an answer.

14:38You're listening to Unexpected Elements from the BBC World Service. Now, when it comes to gifts, lots of my friends have been receiving my hand-knitted scarves. Here's the thing, it's the perfect idea because they have to like them and they can't complain about the quality because I made them myself. And that's great because I only know how to knit scarves. Now, knitting is a practice that's centuries old and is incredibly complex. You know what else is very, very old and incredibly complex? Physics. Here to speak to us about the science of knitting is Dr. Krishma Singhal, a postdoctoral physicist at Rice University in the US.

15:18Hello, how are you? uh good how about you you know what it's chilly here i'm cold and i have vitamin d deficiency but that's that's for another program now we've got you here you're an expert i need to know what is knitting how is it different from other ways of making things i i love that question so there's lots of fiber art techniques out there like weaving crocheting knitting what makes knitting so interesting and so different from the rest is that when you have weaving you have a lot of separate perpendicular like fibers and threads kind of like interlocking with each other and with knitting though you can get a continuous piece of yarn and you essentially can form in simple terms loops on loops on loops and you can form a lattice of loops that really become a whole fabric and it's just by manipulating yarn and pulling it through itself and you can create some really complicated structures through it.

16:19Krishma, what makes knitting textiles so interesting physics-wise? What's so fascinating about knitting is that it's made of yarn. Traditionally speaking, a lot of yarns are inextensible. They're not very stretchy. Like when you get a piece of string or rope and you pull on it, you don't really expect it to bounce back unless it has some elastic material in it. Right here, I have like a little bit of thread here. But what's fascinating is that if I take this yarn and I form these different loops and I pull the loops through each other and you get a fabric, you have something that has what we say emergent elasticity.

16:56All of a sudden I have a full textile that is much more stretchy than the yarn used to fabricate it. And that's one aspect of it that's very fascinating from a science perspective, as well as the fact that just by altering small things of how I loop the yarn and how these loops sort of communicate with one another, you can get fabrics that look different from one another, that feel different, but they also behave differently. You can code in elasticity into your fabrics and get very, very unique behavior. So this programmability, this like fine tunability is what makes it so fascinating for like a lot of scientists and engineers.

17:38And so you've been studying the physics of knitting. Now, what does that actually mean? You know, are you making tiny little hats and putting them under the microscope to see what's happening? A lot of what I was doing was just like constructing fabrics made of the simplest knit stitches, like the simplest loops you can form. And a lot of it was understanding how did these loops interact with one another. So throughout my PhD, I was the experimentalist of my lab working at Georgia Tech. And I would be fabricating lots and lots of knit samples from different types of yarns. And then I would do stretching experiments on the fabric.

18:13So like it sounds very simple, but we can use fancier words like uniaxial testing or mechanical response testing and getting the stress versus strain relationship. A lot of it was just like, how do I map out this connection between yarn topology? So the shape the yarn makes in the fabric, how do I map that to how the fabric is now stretchy in different ways? what's so complicated about these fabrics and why I'm just doing stretching experiments is because like when I stretch it enough it gets these different shapes to it depending on how I stretch it and different knit fabrics stretch differently and it sounds so simple but that's where a lot of the complexity was and again knitting is so so complicated all these things stack on each other they're called hierarchical materials because like there's so many points where you control what the fabric looks like and thus how the fabric behaves.

19:04Speaking about the variables, if I may ask, these physical properties like elasticity you were speaking about, they are more so pattern-based than material-based? A little bit of both. We found in our studies and for the samples we looked at, the topology, the patterning of the loops, like what structures we chose seemed to impact what we call like the low strain rigidity or basically like at low forces, when I put a little bit of stress on them, that has a dominant effect. So one example is, let's say if you're wearing a sweater, you'll notice on usually your cuffs and your collars of your sweaters, you'll have a knit rib structure.

19:45So it's designed to be very stretchy in one direction and stiffer in the other. So if you, when you put on like a sweatshirt or sweater, it like usually morphs around your hand and then kind of snuggles and sits nicely at your wrist. And that's because the structure of rib makes it such that it's stretchier in one direction than the other. Whereas something like garter, it's designed to just lay flat and like sit on your body. But then we find that once you stretch these fabrics significantly, you have more yarn on yarn tension. So I like to think of at low strains, at low forces, your yarn is kind of settling in.

20:21The loops are arranging around each other. There's maybe maybe some sliding maybe some friction depending on the type of yarn but it's sort of like moving against each other settling into a new position but at some point it's not going to move anywhere else and the yarn is pulling against itself and that's where you have more material properties coming into effect. When it comes to doing all these different experiments you know you're looking at knitting from a very scientific perspective you know is there like an underlying model of like what knitting is. A knit fabric is not just like a rubber sheet.

20:54It's made of so many interconnected parts and we say they're an isotropic materials that have non-affined deformation. If you take like your sock right now and you like stretch it you'll notice different parts of the sock look different depending on how you stretch it and it makes it so complicated to model and to predict its behavior. So a lot of like the work I've done and I'm doing now and And like a lot of the community is interested in how do we actually build a accurate knit model that predicts not only the geometry or like the shape your final knitted fabric will take, but like how it'll stretch.

21:29And I think it'll have a lot of implications for wearable electronics or like more body conforming things because everybody is different too. And you need a lot of custom things. So what's great about knitting is that you can customize it to yourself, but on a larger scale, it's very difficult. Oh, I was just going to say, Krishna, it's so fascinating. Like I'm based in Nunavut, which is in the Arctic. And of course, like there's this huge conversation about the clothing that we wear because Inuit rely so much on fur and have historically relied on that. But when you're in the time of climate change, where harvesting natural furs is going to be in decline, how do you find other material that can perform in the way that you need it to in harsh environments?

22:15I really love that you point that out because I'm very interested in pushing knit fabrics to like their full, full potential. And I'm also very passionate about the sustainability aspect of knit garments and knitted fabrics because it can be made from a continuous piece of yarn in theory. oh you don't like it you just unravel it I have definitely unraveled pieces of hand knit if I can't stand it but I think that's important to consider also with like how the climate is changing and thinking about like what will be reusable what is something that can be customized what is something that can really be tailored to your needs where you're at for that thank you Dr.

22:52Krishma Singhal I'm gonna knit like crazy now

23:00So far, we've discovered how donating blood is the gift that keeps on giving, and how polar bears are the ultimate Arctic present providers. Plus, how every stitch and pearl on your hand-knitted jumper has some very interesting physics behind it. Even more unexpected gifts coming your way. Are piranhas really as violent as people think? Are your sneezes unique? Why do we salt icy roads? Plus, how can you get better at jigsaw puzzles when you're stuck indoors?

23:57and experts about how markets really work. And join me for a separate episode where I answer listener questions on how to make those markets work for you. Follow Merrin Talks Money on Apple Podcasts, Spotify or wherever you listen.

24:17This is Unexpected Elements from the BBC World Service. Now this is the part of the programme we call Under the Radar, where one of our panellists takes a story that needs a bit more attention and brings it here. Camilla, what is the unexpected story that you've brought us? Well, keeping this under the radar in the theme, in our very own unexpected elements way, I want to sort of give a Christmas gift to piranhas, or piranhas as we say here in Brazil, you know, the South American fish with sharp teeth. You know that for decades they have been portrayed in movies as these ferocious animals that gather in schools to attack humans, right?

24:54Yeah, yeah. They're like, you know, piranhas and quicksand. When I was a kid, I assumed that those would be the two biggest risks in my life. Yeah, but their bat reputation actually predates cinema. You know, in 1913-14, Theodore Roosevelt, former American president, published a book called Through the Brazilian Wilderness, with tales about his scientific expedition to explore rivers in the Amazon forest. He had quite a lot to say about piranhas, including that they had a jaw-dropping ability to devour dead or injured animals in a matter of minutes. Some really freaky stuff. You know what, I'm going to go out on a limb and I'm going to guess that Mr.

25:34Roosevelt didn't give us the full picture. You're guessing right, Alex. You know, a group of Brazilian researchers is arguing that piranha's bad reputation is a classic case of bad PR. Let's put it this way. In an article published in October in the Journal of the Brazilian Society of Tropical Medicine, they analyzed 711 cases of piranha bites in Brazil, reported in media outlets in the decade from 2012 to 2022. And they point out that the vast majority, 82%, were mild with single punch-out shaped injuries on the hands and feet with only skin loss. Look, I've seen some of the pictures. they're not pretty but the bites were quite small superficial and contained do we get to see these photos let's see if you want to click on the link there's a link in the chat okay oh oh okay okay taking a look at these pictures um i feel like it sounds worse than it actually is yeah yeah you know what this looks like this looks like if you imagine getting your skin punched out with a hole puncher that you might use for paper or you know things they use for taking out um like potato cores it's they're on the feet so there's one with the sort of one toe one on the heel one on someone's big toe they look worse than they are you know there's a lot of blood but actually it's quite a small wound so they're not exactly the monstrous speed chomping that the movies promise us, these photos give us a different picture.

27:13Right? Yeah. So no school of fishes cornering a human prey and fisting on it. In many cases, actually, the attacks were associated with the behavior of males to protect nests and baby piranhas in dams and lakes. The scientists' conclusion was that the media coverage of piranha attacks here in Brazil tends to negatively reinforce the perception that many people have that these species deliberately target humans, You know, that they're villains. So they're doing it for the safety, while some of them to protect their nests in dams and lakes. But I imagine like this bad PR must have some consequences for these fish.