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0:00This BBC podcast is supported by ads outside the UK. This advertisement feature is paid and presented by Go Turkier. Istanbul takes food seriously, very seriously. And Mayhane restaurants are where it all comes to life. These traditional establishments are all about community, shared plates, loud conversations and Raka served as part of the ritual. But take a small detour and the food starts doing something different. As innovators in the kitchen, like Chef Deniz,

1:03continue to rewrite the menu. In Istanbul, new young chefs like me, they will opt to Turkish cuisine, but we don't replace tradition. We give it new life. Because in Istanbul, food never stands still. Old players, new ideas. It evolves. Slowly, confidently, one plate at a time. Plan your next detour at Go Turkier.com today. So this past weekend, I spent slightly too long trying to work out how to grow a shell in a kettle. Let me explain. I've been looking into how mollusks make their hard outer shells and it turns out it's pretty much calcium carbonate, which is the same stuff I regularly descale from my kitchen kettle. So I'm thinking that all I need is some sort of shell-shaped scaffolding, which I can pop into the bottom of my kettle and wait.

2:03And maybe I get something similar to what snails and scallops have perfected over millions of years of evolution. Now, I'm aware that human attempts to mimic nature's efforts usually end badly, but this is like early chemistry, right? Back before scientists were standing on the shoulders of other giant-brained scientists way back, there had to be someone with my basic skills, experimenting for the wonderment or the possible riches. Just call me Alchemist. I'm Moni Chastatin. From the BBC World Service, this is Unexpected Elements. This isn't an Alchemy show. This is a science discussion show. And for that, you need some excellent knowledgeable people to talk to. So let's introduce them in Berlin, Germany, contributing

3:06correspondent for Science Magazine, Kai Kuperschmitt. Hello, Mani, how are you doing? And from South Paolo, Brazil, Science Broadcaster Camilla Mota, welcome back. Thank you, Mani, you're being very good to be back. What we do on Unexpected Elements is look over to current affairs, find an event that we like the look of and jump off from that into a world of often-laterally connected science stories. But it all starts with one story. Take a listen to this. Well, let me introduce you now to the members of Queen. Freddie Mercury. Brony Me. Roger Taylor. John Deacon. After a couple of years of knowing each other, we just decided we'd form a band to get the really simplest band. One of the best showmen, one of the best frontmen I ever saw. There's no apology when Freddie's on stage. There's just swagger and there's confidence. And it's very attractive. And what else could I do? I mean, this is the thing that interests me most. Yes, the frontman with Queen, pop star Freddie Mercury,

4:09a man who loved throwing extravagant bashes for his birthdays would have turned 80 this week. Now, sadly, the singer died in his 40s, and so he's missing his 80th celebration, which is a shame because, one, this is a man who wants turned up to a, come as your favourite person, themed party as himself. Love that. Two, there's going to be more than just a single party. His fan club have four days of events lined up at the end of this week, culminating in a party in the Swiss town of Montreux with a dress code of fancy and formal. So, you know, Tuxedo, Black Tie, with extra snazzy bits, maybe crevaz or monocles. Well, I thought you can't really have an episode inspired by Freddie Mercury without talking about the element Mercury itself. That's kind of obvious. Something that's maybe less obvious is Freddie Mercury's connection to space. So, in case you didn't know his bandmate, the guitarist Brian May,

5:10is actually an astrophysicist. And he's worked with NASA. And if you look at the lyrics of Queen Songs, there's a lot of references to the cosmos. So, I want to talk about something that combines both of these things. And that's telescopes with a mirror that's made of Mercury. So, telescopes made of liquid mercury. How do you make a mirror out of a liquid? It has a lot to do with the physics of a rotating liquid. I vaguely remember that there were some experiments that I said Newton did with a spinning bucket filled with water. And that's really where the story starts. So, Newton showed that if you let a bucket filled with water hang from a rope and you twist the rope so that it then starts spinning, the water starts moving with the bucket after a while. And as it does, it pushes up the sides of the bucket. So, the liquid kind of goes up the sides. And the shape it settles into, that's the parabola. Okay, if you put a teaspoon into a cup of tea to stir it, it sort of does the same thing. It all kind of bunches up around the edge of the mug.

6:13So, how do we get from a spinning bucket of water to a telescope? As usual, it takes a lot of time and many people. So, Newton himself was actually more interested in why this would happen. And whether this meant that there had to be some absolute space relative to which the bucket is rotating. But there was another researcher in the middle of the 19th century called Ernesto Capocci. And he pointed out that this means you could actually use rotating mercury as the main mirror of a telescope. Now, that's because what you really need for a telescope is just a parabolic mirror that reflects the light it collects and focuses the light rays on one point. That's usually where you take the photo then. And not only is mercury a shiny reflective metal, but it's also the only metal that's liquid at room temperature and pressure. And so, thanks to Newton, we know that when it rotates, it forms a parabola. OK, I have seen some people doing the work that goes into grinding a telescope mirror.

7:13And the big ones I know cost huge amounts of money. How do liquid mirrors compare? Yeah, so they are a lot cheaper and easier to make. And like you have always been fascinated by the kind of work that goes into shaping one of these mirrors. I remember when they were building Hubble and all of these telescopes, it's just you have to cast the mirror, grind it, polish it, and all of that to this extraordinary level of precision. Now, like you said, that makes the mirror quite expensive and difficult to make. If you use rotating mercury on the other hand, the shape you need basically forms by itself. And then the surface is incredibly smooth, so that part is much easier. But in order to have a smooth surface, you need to make it rotate incredibly smoothly. Because every little wobble or every little vibration would distort the optical surface. So that's actually something that's quite hard to do with these mirrors. And there's one big drawback. And that's obviously you cannot tilt the telescope. Oh, wait, so you can't just point to anything specific. It just has to go straight up.

8:14Exactly. So a telescope that points straight up at the sky is known as a zenith telescope. And it's still pretty useful for some things. So you can, for instance, make repeated surveys of the sky. And so it's great for finding things that change, like Asteroid, say, or supernovae. And are there currently any of these kinds of telescopes up and running? Yes, there are. And this is actually the thing that most fascinated me. So there is something called the International Liquid Mirror Telescope in Northern India. And it was built in the Himalayas as part of an international collaboration of astronomers, and saw its first light in 2022. And it's now in routine use. That's amazing. So given that these type of telescopes are cheaper to make, could we see them being used more widely for astronomical observations? So maybe, but there are a few issues, right? There are people trying to build a liquid mirror that can be tilted. That, of course, would expand the kind of use cases for liquid mirror telescope.

9:15But the more radical idea that I find fascinating is researchers are discussing putting liquid mirror telescopes into space. So the idea is that instead of launching this huge solid mirror, which is complicated and expensive, you could launch the raw liquid and form the mirror in orbit. So NASA is actually studying a concept for such a space telescope that would be 50 meters across. And it would have an amazing advantage because its liquid, the mirror could potentially heal itself if it is hit by space debris. That's fantastic. So thank you, Kai. Camilla, your turn. What have you got linked to Freddie Mercury's birthday? Well, I've got a story about Queens. Killer Queens, to be exact. Excellent. That's a reference to a Queen song. If any of our listeners didn't get that, I'm sure there will be more. Tell me more, Camilla. It's a story about killer ant queens that sneak into another Queen's colony and trick their workers into violently murdering their own mother.

10:16It's a fascinating study published November last year, which according to scientists described for the first time the use of workers by another Queen as their proxy assassins. That's great. That's straight out of Game of Thrones. Tell me more, who made this grisly discovery? So that's actually a really cool thing about this study. And it was done by two citizen scientists in Tokyo. They're both an enthusiasm raised their own colonies to do the experiment. One of them posted the discovery on their blog called the ant room, a professor from QShoe University picked up the post three years later and said, hey, this is valuable and deserves to be documented as academic knowledge. Oh, that's great. So citizens got there first. I love a citizen science store and it does show that if you've got the time and inclination, just remember science is a process. And if you try something, you might discover it before the professionals. I say that as a woman trying to make seashells in a kettle.

11:16So the ant fans, what did they notice? So they observed interactions among different species of the same ant genus called latias. And to understand these interactions, you need to know that a lot of ant communication is done through the power of smell. It's all pheromones. And pheromones are hormones that ants produce to send chemical messages from the ant that secrete the pheromone to the ant that receives it. Like when you see a line of ants all following the same path to a food source, that's because the first ant to walk that path dropped pheromones on their way. So smell is key here. In this case, the key to chemical warfare. Curious, what's the chemical message that starts the warfare? How does the smell cause the ants to turn on their own queen? What it works is the parasitic ant would use the scent of the colony she wanted to invade to disguise herself and mingle as she was marching into the colony that workers would smell her and her scent would be the same as the others, which meant for them, friend, not foe.

12:18And here's another TV reference. If you've seen the zombie show Walking Dead, one of the researchers compared it to characters smearing themselves with walker blood to pass through a horde of zombies. Once inside the colony, the parasitic queen would then wondering side the nest searching for the other queen. And when she found her, she would spray her multiple times with a fluid that would shift her smell to then trick the workers into perceiving her as a menace rather than their mother. No, and what happens to the poor real mother? I'm sensing bad things. Yeah, disclaimer, bad things are going to happen. Yeah, in a video done of one of the experiments, you can see the parasitic ant bending her abdomen forward than a bunch of workers done on their queen and start attacking her. Then the parasitic queen comes back and sprays the other queen again and keeps doing that for 20 hours. Workers her own daughters end up killing their own mother brutally severing her apart.

13:22And when the parasitic ant finally takes over, she starts laying her own eggs, which are tended by the other species workers up until the time they eventually die. And the colony is completely replaced with a species of the parasitic killer queen, taken advantage of all the resources gathered and stored by the previous colony. You know, matricide in an ant colony is not unheard of. It typically happens when a colony produces multiple queens or when a solo queen reaches the end of her fertility, but this particular scenario, you know, in which an outsider queen turns workers into her proxy assassins isn't heard of in any species, you know, not just ants. This is the first time this has been documented at all in biology. So yay, citizen science. That's fascinating. There's a whole emerging field called semiochemistry, which is about species intercepting hormonal messages for other species, but I've never heard such a tale of family drama

14:22that would, you know, make Shakespeare proud. Still to come on the show, the secret history locked up in teeth all inspired by Freddie Mercury's four extra ones. Hello, Lucy here with this week's Unexpected Elements Quiz. This week we're inspired by the legendary frontman of Queen Freddie Mercury. One of the band's biggest hits was under pressure, a song all about the mental pressures of modern life. And we've all felt it when external life pressures have so great that it feels like your brain is being physically compressed. But what about when that actually happened? Just how squishy is your brain? So here's the question. When put under pressure, which of the following is the brain as squishy as? A. Polystyrene. B. Jello. Or C. Rubber. That's when put under pressure, which of the following is the brain as squishy as? A. Polystyrene. B. Jello.

15:22Or C. Rubber. Have a think and I'll be back soon with the answer. No pressure though. You're listening to Unexpected Elements from the BBC World Service. This week we've been inspired by the late rock legend Freddie Mercury on what would have been his 80th birthday and the thousands heading to Switzerland to celebrate with a party. Now, Freddie Mercury was unusual, a voice in a million, an iconic flamboyance, but did you know about his hyperdontia? It's a rare condition, meaning that he had four extra teeth in his upper jaw. Mercury refused to have them taken out for fear that it would affect his incredible four octave vocal range. Now, while I couldn't find any science linking extra teeth to vocal range, there is so much more out there. Science fact that teeth can reveal about us and our lives.

16:25And it's information that's preserved long after we're gone, just waiting to be discovered by an archaeologist who knows what she's looking for. And what a coincidence we're joined by such an archaeologist. Carolyn Frywold from the University of Mississippi, welcome to Unexpected Elements. Thank you for having me. And we've got you live from Belize on a dig, right? Yes, I'm actually doing some research. I'm actually on an archaeological site that might look like a resort because people live in and around the runes across the river is ancient city center from a thousand years ago. And to my left, the little housemounds where people were living, farming, kind of like people are doing today. So tell me about why archaeologists get so excited about teeth. I don't think it's because we're strange. It's more because teeth are one of the parts of the archaeological record of the human history that preserves better than anything else, even in a place that it's tropical, even if something's been buried in the ground for tens, hundreds or thousands of years,

17:28teeth tend to preserve pretty well. So how far back can you go and still have a tooth and extract a story? Oh, it can be, well, most archaeologists are working and say the past 10,000 years or so, but we can go back to human ancestors that lived long before us, for example, Neanderthals. But if I were back, you go the more difficult it is to get information, but we can still find out pieces of culture from ancient humans, pre-human species like Neanderthals that you can't get any other way. And a lot of that is because we have their teeth. Okay, so we've got different layers of the tooth. Can you tell me about the different layers and the different types of information that you can get from each one? Yeah, so you can look at the exterior of the tooth, your mammal. And cultures around the world, people have used this to maybe decorate their teeth or people, file them, they ship them, maybe embedded jewels in them.

18:28You can also tell what someone was eating, but if you go inside that an mammal, you can start to look at the chemical composition of the food groups they were eating. So if you like surf or turf, if you ate a lot of meat or a little bit meat of seafood, you can start to get the types of foods that people were eating. And because your tooth and animal forms starting actually before you're born, we have a record of as the baby teeth formed all the way into infancy, all the way till the teeth stop forming right about the time that people are entering adolescence. So you've got this record of the food, but also where that food was grown. So you have to be a little bit of a geologist too, not only a dentist, to understand that people living in some areas, their food, we can track to the geology it was grown on, and then see if they moved during life, if they were living in a city where the geology was a complete mismatch for their teeth, we can actually identify ancient migrants and mobility across time and across cultures. But if we go inside the teeth into the pulp cavity where the DNA is,

19:28that is the genetic history, not just of that person, but else of their deep family history. I remember reading something about grains that hadn't been properly picked out of the teeth and finding things that were not the tooth itself, but the secrets trapped between the teeth. Oh yes, that's plaque or dental calculus. So now think about what you were eating for breakfast and whether you cleaned your teeth afterward, but as archaeologists, we love it when people's plaque remains on their teeth, because we can tell what was your dental health, did people have dentistry in ancient times in different parts of the world, but also the types of foods they ate, or maybe if they were cleaning their teeth with the toothpick, maybe if they were sowing and running those cotton threads through their teeth, those little grains can be trapped there, and they are like little time capsules that can tell us not about who you were, what you had for dinner, but what you were doing throughout the day. I've mostly heard about this work in terms of infectious diseases and finding in the dental plaque, finding, for instance, the genetic evidence for plague and other things.

20:30I'm kind of curious, there must be so many researchers with different interests who kind of hope to find something, and I mean, there's not that much dental plaque, I imagine. So is it a little bit of a fight about who gets to analyze this plaque and for what, or how does it work? That's a great question. There's generally an order, because DNA is harder to get, the DNA analyst or the geneticists get to go first, and then maybe we can do some isotope workers and bone work after that, but it all has to come after the excavations, after we get permissions to export and to do the sample, as you know, respectfully with the governments and the communities here. So that order dictates it a little bit, but we try and have a culture of sharing information and at the end of the day going out and maybe having a bellicain beer together here. I love the mental picture of a bunch of scientists fighting over fossilized dental plaque. Can I ask a silly question? Have you analyzed your own teeth, baby teeth? Yes. I have a piece of tooth and amuletip off,

21:30so I try to use that as the baseline to make sure that an amulet is still good enough to study. So yeah, I have sampled my own tooth. I think a lot of researchers will try and do that. I hope I met the only one. Caroline, can I ask about migration and how much you can tell about how people moved around from finding teeth? Yeah, that's a really good question, because we find out a lot, but there's always more we want to know, because it's going to be based on geologic differences. So if you have somebody who lives on volcanic soils, like the Highlands and Guatemala, their chemical signatures and their teeth will look really different than someone who lives where I am now, that's by these older mountains with igneous rock. And so we can gauge long distance migration quite easily, but I think most people moved over shorter distances based on what information we have now. What we found where I work in the Maya regions, up to 20% of the people in any given city weren't born there. So that people like today were highly mobile.

22:32They were moving around and it was men, women, children, if you look around at all the households, probably each of those households had somebody move in who wasn't born there. And then they must have assimilated because they were then buried with all the local people in the same household. So it gives you a different idea of what, you know, maybe ancient cities were a little bit like ours in that way. So I was just wondering how you work on the migration of ancient people is being used in the modern day. All the data that we're collecting and archaeology is now also being used in forensics. And that's really important because if you think about the big migrations that people are making today that are in the news every day, crossing the Mediterranean people coming across the southern US border, crossing the desert, sometimes forensic anthropologists when they don't make it have trouble figuring out who the people were and how to get them back home to their families. And so making big databases with a lot of these piecemeal studies that we've collected might be able to help analysts, forensic anthropologists and others identify missing persons and use this in modern forensic cases.

23:36Wow, that's useful work. Well, thank you for coming on to unexpected elements and sharing the hidden secrets of teeth. Thank you for having me. So the late Freddie Mercury's 80th birthday celebrations have us celebrating Mercury and how it forms a perfectly smooth telescope mirror. We've had a look at killer queens and Freddie's overbites just inspired a long look back at the secrets hidden in our ancestors teeth. Don't stop me now, cause still to come on the show, the Mercury is rising as I share the tale of a killer. How the search for the elixir of life had the opposite effect. Stay with us. The September's always busy. Whole Foods Market can help.

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25:43That's GoodRanchers.com. American Meat Delivered. This is Unexpected Elements from the BBC World Service. The science show inspired by the news. I'm Marnie Chesterton in London in the UK and I'm here with... Kaikopflashmuth in Berlin, Germany. And Camila Mardin's Songpaldu, Brazil. So this week, when I say news, we've picked what would have been the birthday of the great Freddie Mercury. And in honour of him, we started off hearing about telescopes with mirrors made of liquid mercury and parasitic killer queen ants before taking a bite out of the science of ancient teeth. Next up, we've asked our panelists to scour their local news stories and bring us something that they think ought to be brought out from under the radar. Sean in the light of global news in only the way the BBC can.

26:46So Camila, you are up this week. What have you got for us? And I will give you entirely useless bonus points if you can relate it in any kind of way to Freddie Mercury. Okay, challenge accepted. So, you know, there are few queen songs that talk about mythical civilizations, living in nature, that kind of stuff. You know, like the fairy-fellarist masterstroke, which is actually based on a painting. So anyway, I'm going to talk about a real lost civilization in a real big forest. Yeah. Talked to us, but I love it. Thank you. Okay. So you're going to talk to us about a lost civilization. Tell me more. Okay. So Carolin's research about the Maya's reminded me that there's some exciting archaeological work being done here in South America in the Amazon, more specifically. And as you can imagine, doing archaeological work in a dense forest is not easy. And that kept scientists away from the region to do that kind of work for a long time.

27:49The logistics are challenging. You need hours on a boat to reach some parts of the forest. The weather is extremely humid and decomposition happens really fast. So very few artifacts are left behind. Before the past year, scientists have been using any technology to track ancient civilizations in the region. Okay. So traditionally, this is something that hasn't been a job for anyone except basically the hardiest of hikers. How do you track a civilization that's been lost in time? They've been laser scanning the forest from above with something called LIDAR, light detection and ranging. It uses pulsed laser light to measure distances by timing how long it takes for each pulse to reflect off the surface and come back. We know the speed of light so we can use that to create detailed 3D maps of surfaces and objects. So from an airplane, they scan the ground through the gaps in the canopies looking for signs of lost cities, you know, bumps and slopes that don't fit in the forest natural landscape.

28:51And what have they found? So scientists from Finland and Brazil joined forces and made a super interesting discovery using LIDAR published last July in a true magazine. They found what is thought to be the remains of a law civilization that could have had a population of something around 1.5 million up to 3 million people when they peaked, which was between the years 100 and 300 of the common error. So more than a thousand years before the Portuguese invaded Brazil. Wow, 3 million people is a lot. So how do they even estimate that? Right. So they reached that conclusion by analyzing the images they collected back in 2024 when they flew over two Brazilian states covering almost 5,000 square kilometers. So this huge area in what the lasers can show it was 432 structures known as earthworks. These are manmade changes in the land level. They can be made from piles of artificially placed rocks or soil. And these earthworks were huge geometric drawings in the ground called geoglyphs made by this civilization called ackery.

29:57And the pictures in the city show, you know, big squares and circles, some overlap, some connected with each other by pathways. And scientists believe they were builds and maintained for centuries by the ackery for various reasons from administrative to cultural and even cosmological. And this is a proper big civilization. Those numbers that you're talking about. This is millions. So it's not just, you know, a small village with the equivalent of one shop and a post office. Exactly. And, you know, they also point out that in order to build these monumental structures in the rainforest, the ackery had to have a large workforce, division of labor and understanding, of course, of math and geometry. Which is something really interesting to me, you know, a Brazilian who grew up hearing that in Gisinaus communities in the Amazon didn't form complex civilizations in the past because the environment was quote unquote too friendly to them. The idea was that they were hunters and gatherers basically because they had an abundance of food and water. So it's fascinating to see that being challenged now.

30:59Kai, had you come across this before? I actually never heard of them. I'm kind of curious how we know that it wasn't aliens. I mean, it sounds very suspicious to me. We can't roll that out yet. I remember reading about this and finding it astonishing. Also hugely comforting as well because if ever you wished for a time machine to go back, it would be for this because I've always thought of the Amazon rainforest as this, you know, permanent structure. Of course, it was always trees. It was always trees. But if you had a civilization with millions of people there, what did it look like and what happened to it so that a forest grew over the top of it? I find it quite comforting given that we were told about deforestation all the time that maybe there was a civilization and then you got the Amazon growing over the top of it. They were inside the forest maybe? I don't know. You know, just like indigenous communities today, when we still have some in Brazil that haven't really been contacted and they live inside the forest.

32:03I mean, it's not complex cities or anything, but still, I mean, makes me wonder if only we had time machines, right? You know the one bites the dust? Oh dear. Bleak, bleak show, but yes. Well, thank you Camilla for sharing that with us. Listeners, if you have any thoughts on anything you've heard so far today, you can contact the show. The email is unexpected at bbc.co.uk or you can send us a message or voice note on WhatsApp. The WhatsApp number is plus 444-330-678-3080. But my favourite way for you to get in touch is postcard. And Dominic has done just that. He's sent us a postcard from Jersey in the Channel Islands. Thank you so much Dominic. Now, after hearing our recent episode on an Australian library book that was finally returned 150 years over due,

33:08we got on to the subject of reading and how so many of us are reading less as we spend more time on screens. But as Dominic points out, maybe we shouldn't feel so bad after all. Camilla, do you want to read his message? Sure. Dominic wrote, I thought you might take some comfort from following quotation from Boswell's Life of Samuel Johnson. The year of the conversation is 1763 and Johnson is reflecting on his own reading. Sir, in my early years, I read very hard. It is a sad reflection, but a true one, that I knew almost as much at 18 as I do now. My judgment to be sure was not so good, but I had all the facts. I remember very well when I was at Oxford. An old gentleman said to me, young men, plie your book diligently now and acquire a stock of knowledge for when years come upon you, you will find that pouring up on books will be but an irksome task. If a towering literary genius like Dr. Johnson could feel as he did, then perhaps we don't need to beat ourselves up too much.

34:13There we go. Dr. Johnson being the polymath literary critic, poet, essayist. And writer of the dictionary. Dr. Johnson says, basically, don't worry. Read the books when you're 18 because when you're older, it'll be irksome to read any thoughts. No, I feel like when you're 18, go dance. When you're in your 40s, it becomes increasing your awkward to be on the dance floor. I read more than I ever did. Question, is it technically reading if it's audiobooks? Because I've discovered the app for my local library and they have all of these audiobooks. And so I've been just for the last few months. I've been listening to so many books and I really, really love it. I find that when I read, I have to stop myself from skipping ahead. I think it comes from reading science papers where you're basically skimming the paragraph, looking for the key sentence. But you don't want to do that with maybe a beautiful work of fiction that someone has poured their life into. You know, my mom used to do this with crime novels and it drove me insane.

35:15And I always asked her, like, why would you do that? And she's like, well, I have to check whether the ending is worth the read. I can't really. I do like spoilers. I'm one of those people. I don't know if there are many of us out there. You like a spoiler and then you still want to know who done it, even though you know who done it. Yeah, I mean, how was it done? You know, what happened? Yeah, you need a why done it, not a who done it. To be fair, I just watched the Odyssey and I mean, I knew the story and it was still a good watch though. Apparently it has a twist, so I've heard. Anyway, I think Dominic was sending us words of comfort. And so thank you Dominic for your postcards. And I'm going to chuck in a quote from Charles Darwin, which always makes me feel better about myself. He wrote, I'm very poorly today and very stupid and I hate everybody and everything. And I don't know. I find that oddly inspiring that someone that wrote the paradigm work within a field

36:18could have what was clearly a down day. Yeah, very relatable. Moving on. Now, last week, my panel and I were pondering why there aren't any insects in the sea and we asked our listeners if they had any theories. John Cadell has emailed us with this. Current thinking is that insects evolved as a lineage from within a large group of animals we call crustaceans. So crabs, lobsters, shrimp, etc. The majority of crustaceans are marine. Insects are the numerically dominant form of arthropods known as hexapods, six-legged creatures. The closest relatives of hexapods are a poorly known group of crustaceans called the Remapidia, which are known from marine caves in the Caribbean Sea. So insects are merely crustaceans that made it to land. Kai, any thoughts? I have this discussion a lot when I talk about eating insects because people find it very normal to eat shrimp

37:18and then they find it so weird to eat grasshopper and I've always felt antagest insects in the sea, like what's the difference? So I find this very reassuring. Someone tried to rebrand crickets as land prawns. This was in the Netherlands. I went to this day on the science of eating insects. And when they said that, I just thought, now I don't want to eat prawns or crickets. So it's expanded the wrong category. Moving things along, just a reminder listeners that you can add your wisdom to this show in a number of different ways. So email is Unexpected at bbc.co.uk And that number for sending us WhatsApp messages plus 4433067830 postcards to unexpected elements, BBC World Service Cardiff CF104GA in the UK. Still to come on the show, more on Mercury and its life or death power over us after this.

38:22Hello again, Lucy here back with the answer to this week's quiz. Earlier I asked you when put under pressure which of the following is the brain as squishy as? A. Polostyrene, B. Jello or C. Rubber. The answer is B. Jello or jelly to those in the UK. Researchers at the University of Cardiff did MRI scans of people lying face down and then face up to see how their brains shifted in their skulls. And they were able to work out different material characteristics of the brain, like how much the brain collapses when pressed. And it turns out the brain is much softer than you'd think. It's ten times more easily compressed than Polostyrene, and it has a similar squishiness to a slab of jello. While done if you got that correct, and if not, better luck next week. In the meantime, I'm off to buy a helmet. When not writing about reading or whatever we've been discussing on the show,

39:22you still find time to puzzle about life and how it all works. And sometimes when a quick Google can't help solve your query, you know to call in the science unit at the BBC World Service and ask the unexpected. Yes, each week you challenge us to search through our worldwide database of scientific experts for exactly the right person to answer your burning question. This week we're answering a question from Janet, who asked, why do we get earworms? And how do we get rid of them? Now, if you don't know, earworms are... I think we've discussed them before on this show. Earworms are those pesky tunes that get stuck in our heads, going round and round and driving us to distraction and to bring it back to Freddie Mercury, he was really good at writing them.

40:23I currently have fat-bottomed girls going round in my head, which is just going to be there for weeks if we can't do something about it. I'm actually surprised that it's an English word earworm, because in German, or worm, it's a very colloquial thing, but if you'd asked me before the show, I would have said, I use that in English, I'm just transiting German in a way that doesn't make sense to ear speakers. Camilla, is it the same in Portuguese? Not really. I mean, we have songs get stuck in our heads, but we don't have an aim for it. To answer Janet's question, we asked Kelly Jakobowski, who's a professor of music psychology at Durham University, to explain how songs get into our heads in the first place. The most common reason is just simply that you've heard a catchy song playing, you know, on the radio or in a shop or whatever, and then it sticks with you later on. But actually, a lot of the times we can get earworms even not from hearing music, right? So we call these memory associations.

41:23So there's lots of different, what we call cues in our environment, and these can actually trigger spontaneous experiences of music. So imagine you're walking through a shop by Christmas cards, and you see the words Felice Navidad. That might just trigger that song laying back in your head for the next hour or so. I've actually had that experience myself once. I was walking and just started putting up an umbrella, and a man was walking by me and just started singing Rihanna's umbrella song. So there's lots and lots of things that can cause us to have music in our minds, which is beyond the actual listening experience. Okay, at this point, I just want to share that I used to work at the World Service back in the days when it was on one end of Waterloo Bridge. And so I used to have to walk over Waterloo Bridge, and my brain made a connection to the song Waterloo Sunset by the kinks and sang it to me twice a day for 18 months. And that's fine. Any earworms from either of you?

42:24Well, my husband says I have a whole playlist. Yeah. It's funny that you mentioned umbrella because literally every time my husband says, oh, do we need an umbrella? I swear it's involuntary. I go, Ella, Ella. Ella, Ella. It's there. I'm so pleased that we're all on the same page with this. The thing is, if they do go on and on and on, they can be a real pain in the neck. So how can we get rid of them? One of the big survey studies that we did, one of the most common strategies that came up was to distract yourself with other music that you like better, right? So it's really hard to have two earworms at once. So listen to a catchy song that you like a bit better, or try and just imagine a different song and try and push out that earworm with other music. Another strategy that people use is that they actually engage with the earworm song itself. So if that song is looping over and over, that's one of the really annoying elements is hearing that same section over and over. So sometimes people find if they listen to the whole song all the way through,

43:25or even a couple times all the way through, they can get some kind of closure and move on from the experience. The last thing that I would recommend, so this is out of a study from researchers at the University of Reading, they found that if you chew gum vigorously, this can actually block out your earworms. This sounds a bit silly, but actually to have music in our heads requires what we call sub-vocalization. And that means essentially you're making quite small movements with, for instance, your vocal cords and your tongue and so on. So actually if you chew gum, this can potentially interfere with that experience. Thanks Janet for a great question, and thank you Professor Kelly Jakobowski for helping us get to the bottom of it. If you have a burning science question, why not let us answer it with the help of our bolging contacts book of experts. The email address is unexpected at bbc.co.uk. Now each week I take our subject

44:29and I connect it to a recent story I want to tell with the help of the extensive, the cavernous, bbc archives. And wouldn't you know in a week where we're talking about Freddie Mercury, a different Mercury, the very dangerous version of Mercury, hit the news in the US. So the Massachusetts Institute of Technology closed its chemistry building last week. Kai, have you noticed this? Did this come across your radar? I didn't actually. Oh, it's fascinating. So they called in a hazardous waste management cleanup team because a student checked in to a nearby hospital worried they'd made a compound called Dymethyl Mercury. Have either of you Kai or Camilla, have you come across this stuff? Kai? I've heard of methyl mercury. I hope this isn't twice as bad. And I've heard of them separately. You know, dimethyl in our organic chemistry lessons and then mercury but not together. We all know that mercury, the metal isn't good for us. Here's our friend of the show and University College London chemist,

45:32Professor Andrea Seller, from the archives and a show called Business Daily, talking about mercury as a poison. And the point is that over the years we have realised that mercury is a profound, systemic and long-term poison for humans, but also for organisms. And so getting mercury into the environment is a very serious issue. Okay, mercury bad. Back to the scare over Dymethyl Mercury. Even hardened chemists feared this form of mercury because back in 1996, American chemist Professor Karen Vetterhan was working with it to calibrate some equipment. And she was doing everything right. She used a fume cupboard, she wore latex gloves. And yet she spilt a couple of drops onto the gloves, which she then took off and put in the bin and she washed her hands and everything, but that didn't stop her death months later. Fast forward to today and chemists work with much greater safety standards.

46:33MIT is currently offering mercury testing to students who worked near the student who took themselves to hospital, even though they now think that maybe they might not have synthesised Dymethyl Mercury in the first place. So the thing is, this metal in all its forms has the potential to poison. Do we know who got mercury poisoning in the past? Hatton makers, I remember from Alice in Wonderland. Yeah, the mad hattors. I mean, the thing is, even though there are records of plenty calling mercury a poison that acts on everything, there are still cases of mercury being used to treat pox or syphilis. Andrew Cunningham, former historian of medicine, say, if you've got scapes or pubic lice, if you cover yourself with an ointment with mercury in it, they disappear with this ointment. But then it came to big use with the pox.

47:33People were so desperate when they got the pox that they would try anything and the traditional physicians had nothing in their arsenal. But mercury they would use, which would make you salivate and if you're in absolute agony, we have first-hand test me with this. You would warm to mercury, pure alimepamurkery in a bowl, put your head over it, put a towel over your head, and breathe in. And so you would actually inhale very concentrated mercury vapor. Exactly. And the thing about this mercury treatment, it has effects, very, very visible effects. So it looks as though whatever the poison is, it's coming out. Because you salivate, salivate enormous quantities. In a short time, your teeth fall out, you shake all the time, and then you recover from that episode. So it looks as though it was a cure. And after a few weeks in general, you feel better anyway. Because we now know that syphilis has three stages.

48:33So whatever treatment you use, it's going to, unless you die, it's going to look as though it's successful. That was a program from a series called Discovery, hosted by Andrea Seller, again there. Now, maybe a health warning, don't inhale mercury. It's not a good cure for the pox, don't do it. I've been reading about mercury in a great new book called The Age of Alchemy. And I've just really wanted to share a story about the Chinese tang dynasty. So in some cultures, Alchemy was about the quest to make gold. And yes, that's one of mercury's great qualities, is that you can use it to dissolve gold, to purify gold. Back to the tang dynasty. For them, Alchemy wasn't about the quest for gold. It was the quest for the elixir of life. And yes, turns out that those elixirs that they were coming up with contained mercury.

49:35And at least five tang dynasty emperors are thought to have died from mercury poisoning ironically because of the promise that a mercury-based elixir could grant them extra life, isn't that terrible? So five people died, why did they drink it? I think that's a good question, because they did know they had incidences of people dying and going mad from the mercury. But there was also this curious element to things that mercury is also toxic to bacteria. And so what happens is that often it preserved corpses after the person had died. And that was interpreted as a sign that the former owner was now a mortal because the body was still there. So what was happening with the emperors was one was dying and then the person that had given them the elixir was being executed. And then more people were coming up going,

50:35don't worry, they just had a bad elixir. Try my elixir, which is a really good elixir and that kind of kept happening. And in fact, people got so suspicious about this that Claudia's were writing, I feel that anyone who is selling an elixir should be forced to drink it first. And then we wait a year and see what happens. Which is an idea. I know, right? I think that's very reasonable. So there we go. Another show bites the dust. And I hope that we've shown that we are the champions of science-based chat content. As the late Freddie Mercury's 80th birthday celebrations has us marvelling at mercury as a killer, as a really bad, don't do this cure, and as a perfect surface for a telescope mirror, maybe in space. We've looked at killer queens and Freddie's overbite as inspiration for a rummage through the mouths of long dead ancestors for teeth that reveal some of their secrets.

51:37It just remains for me to thank this week's panelists. He's cool under pressure in Berlin, it's Kai Kuperschmitt. Thank you very much. Thanks, Marnie. And she's more than somebody to love. She's someone to listen to in matters of science. In São Paulo, Brazil, it's Camila Mota. Thank you, Ma'am Hanqueen, over together. I'm Marnie Chesterton. The producer was Lucy Davis with Alice Lipscomb, Southwell, Imi Harper and Debbie Killbride. Join us next week for more unexpected elements.

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