Graphene’s magic angle reveals a new twist

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In this episode:

If you sandwich two sheets of graphene together and twist one in just the right way, it can gain some superconducting properties. Now, physicists have added another material to this sandwich which stabilises that superconductivity, a result that may complicate physicists’ understanding of magic angles. Research Article: Arora et al.

With evidence mounting that SARS-CoV2 can spread in tiny aersolised droplets, researchers have called on the WHO to change their guidance for disease prevention. News: Mounting evidence suggests coronavirus is airborne — but health advice has not caught up; Research article: Morwaska et al.; WHO: Transmission of SARS-CoV-2: implications for infection prevention precautions

Repairing human lungs by hooking them up to pigs, and a new form of carbon. Research Highlight: How to use a live pig to revitalize a human lung; Research Highlight: This material is almost as hard as diamond — but as light as graphite

For decades it's been thought that microbes that use manganese as an energy source must exist. Now, for the first time, researchers have found evidence that they do. Research Article: Yu and Leadbetter

We take a look at some highlights from the Nature Briefing. This time we discuss DNA evidence of contact between ancient Native Americans and Polynesians, reintroduction of bison to the UK, and the first extinction of a modern marine fish. Nature News: Ancient voyage carried Native Americans’ DNA to remote Pacific islands; The Guardian: Wild bison to return to UK for first time in 6,000 years; Scientific American: Smooth Handfish Extinction Marks a Sad Milestone

Subscribe to Nature Briefing, an unmissable daily round-up of science news, opinion and analysis free in your inbox every weekday.

Never miss an episode: Subscribe to the Nature Podcast on Apple Podcasts, Google Podcasts, Spotify or your favourite podcast app. Head here for the Nature Podcast RSS feed.

doi: https://doi.org/10.1038/d41586-020-02125-7

Host: Shamini Bundell

Welcome back to the Nature Podcast. This week, a new twist in the physics of magic angles…

Host: Nick Howe

And the bacteria living off manganese. I’m Nick Howe.

Host: Shamini Bundell

And I’m Shamini Bundell.

[Jingle]

Host: Nick Howe

Before we get started, a quick announcement. Last week, we retired the previous incarnation of our pandemic spin-off podcast Coronapod. Moving forward, we’re going to include a condensed version of it in this show each week. So, if you just want to hear the latest coronavirus updates, skip ahead to 8:40, but I hope you’ll stick around for some other great stories from the world of science. Speaking of, what have we got coming up first this week, Shamini?

Host: Shamini Bundell

Well, first up, reporter Adam Levy has been investigating a material with a twist.

Interviewer: Adam Levy

A magician never reveals their secrets, but that won't stop a scientist from trying to peer beneath the curtain. And today, we’re looking at physicists’ efforts to investigate the riddles of a fascinating material – graphene.

Interviewee: Stevan Nadj-Perge

Graphene is a single sheet of carbon atoms where the atoms are arranged in a honeycomb lattice. So, if you think about like a wire fence, that's a good way of visualising.

Interviewer: Adam Levy

This is physicist Stevan Nadj-Perge of the California Institute of Technology. Graphene is an intriguing material with incredible mechanical and electric properties, but when you put one sheet on top of another and twist by about 1.1 degrees – the so-called ‘magic angle – strange things start happening. Under certain conditions, the graphene sandwich starts behaving as an electrical insulator. In other conditions, it becomes a superconductor, conducting electricity without resistance. Here's Nature's senior reporter, Lizzie Gibney, who's been following the twists and turns of this magic angle research.

Interviewee: Lizzie Gibney

When this research first showed up, it caused a massive stir. In fact, it was at a big meeting of the American Physical Society in 2018, and the lead author on the paper said he felt like a rock star, that was how much everybody was interested in this particular idea.

Interviewer: Adam Levy

Other groups have since replicated the results, but physicists are still grappling with what's behind these bizarre properties. What's clear, though, is that by putting two graphene sheets together and twisting, a new structure emerges.

Interviewee: Lizzie Gibney

You get that, almost, it looks like an interference pattern. In fact, it's called a moiré pattern and you get it sometimes on butterfly wings. So, instead of them just having those tiny repeating units, instead what you have is this massive repeating unit, a kind of big diamond over the top instead, and that actually changes how the kind of behaviours of the electrons within it and how they are able to move, so you can really radically change the material's properties.

Interviewer: Adam Levy

One of the things that physicists are so excited about is how tuneable these funky properties are. They emerge when the sheets are cooled and exposed to an electric field – things that can be easily varied along with the angle.

Interviewee: Lizzie Gibney

That ability to be able to control it is really something that's quite novel. But even beyond that, there were hints that the kind of superconductivity that we were seeing in graphene might be this kind of unusual kind that we’ve seen in relatively high-temperature superconductors, and so that got people very excited because graphene is so simple. It's so much easier to understand than the other materials that we’ve seen with that property. So, there was the idea that it might be this kind of Rosetta Stone, this was of cracking the secret to unconventional superconductivity.

Interviewer: Adam Levy

Understanding if graphene twisted at the magic angle had unconventional superconducting properties could help develop superconductors at room temperature, as opposed to conventional superconductors that require super-cold conditions. But this is no easy task. These materials have baffled physicists for decades. Stevan, who you heard from earlier, has been fascinated by what can be learnt from the magic angle, and this week in Nature, to try and uncover some of its secrets, he decided to add to the graphene sandwich.

Interviewee: Stevan Nadj-Perge

So, we kind of decided to investigate what will happen when you put twisted bi-layer graphene sandwiched with another material called tungsten diselenide.

Interviewer: Adam Levy

And simply including this other material alongside the graphene added even more magic to the magic angle.

Interviewee: Stevan Nadj-Perge

It stabilised superconductivity for the angles that are really far away from the magic angle, mainly much smaller than the magic angle. It was very surprising and kind of fascinating, so the first thing I was asking my students to do was to repeat the experiment and try to make sure that everything is okay.

Interviewer: Adam Levy

Seeing superconductivity extended to different angles could give insights into what's behind the magic angle in the first place. One of the reasons this is so interesting is it gives physicists a way to check their theories, since if they can't explain this new experiment, they might not be the right description of the underlying physics.

Interviewee: Stevan Nadj-Perge

So, if you’re making some theory and your theory is only valid at one specific angle, that might not be the most correct theory to explain the phenomena.

Interviewer: Adam Levy

This experiment seems to have suppressed the insulating state that was seen with the simpler set up of the magic angle. This might be tricky to explain with theories of unconventional superconductivity, though it's too early to be throwing out theories just yet. But if anything, these results will only give physicists even more reasons to investigate magic angle twisted bilayer graphene. Here's Lizzie again.

Interviewee: Lizzie Gibney

It's also the case that it still looks really unusual. So, even if it's not exactly the same mechanism that's going on in those other materials that we’ve been trying to crack for decades, it's still something that looks quite exotic and maybe a different kind of superconductivity that we’re not familiar with. And on top of that, it's just exciting because this is another way now that physicists have found that they can use to tune graphene to change its properties just by making these relatively small changes, so I think that proves that actually these kinds of systems in graphene are even more versatile than we thought.

Interviewer: Adam Levy

Stevan is interested in whether the ideas of his paper could be applied to systems outside bilayer graphene, potentially revealing new properties of old materials.

Interviewee: Stevan Nadj-Perge

Can similar ideas stabilise superconductivity in different classes of superconductors? So, it would be kind of very interesting trying to put the substrate or similar sandwiches and explore how they affect superconductivity or other interesting states in similar structures.

Interviewer: Adam Levy

So, it seems like the magic angle isn't revealing its secrets anytime soon, but given what a complex trick it seems to be, Stevan is far from the only one asking questions.

Interviewee: Lizzie Gibney

Everybody has been putting together different numbers of layers of graphene. We’ve seen trilayers as well as these bilayers, different methods to twist, imaging, so looking really, really, close up to see what's actually going on within the material and yeah, twisting with whole new materials. People have just been taking their favourite thing and shoving it in and seeing what happens. So, at the moment, there are so many open questions, but it's a really, really exciting field.

Host: Shamini Bundell

That was Lizzie Gibney, and before her, Stevan Nadj-Perge. You can find Stevan's paper along with a News and Views in the show notes. We’ll also put a link to the feature Lizzie wrote last year all about how magic angle graphene is stirring up physics.

Host: Nick Howe

Next up, Benjamin Thompson, Noah Baker and Amy Maxmen are here to give us the latest coronavirus updates in this week's Coronapod. In the past, we’ve kept the podcast a coronavirus-free zone, so if you’d rather not hear this segment, you can skip ahead to 19:16.

Host: Benjamin Thompson

So, yeah, as Nick said, it's time for Coronapod. I’m Benjamin Thompson, and if you haven't heard Coronapod before, it used to be its own podcast, but we’re going to sort of fold a condensed version each week into the regular Nature Podcast that you’re listening to right now and try and give you some of the updates on the COVID-19 pandemic as we get them. Of course, I’m not alone in this endeavour and I’m joined on the line by Nature's Noah Baker and Amy Maxmen. Hi, both. How are you doing today?

Interviewee: Amy Maxmen

I’m pretty good.

Interviewee: Noah Baker

Yeah, I’m very well. It's a different time of recording today because the Nature Podcast is a different time to when Coronapod was going out and we can see Amy Maxmen's video call, so everything is different but we’re going to try to bring you something that makes some sense still.

Host: Benjamin Thompson

Yeah, we managed to go for like three months without seeing Amy's face in a video call and she has joined us today which is an absolute treat, so, Amy, thank you so much.

Interviewee: Amy Maxmen

You’re welcome.

Host: Benjamin Thompson

Today we’re going to be chatting about a big question that remains in the outbreak, but there's been some debate on it really, and it is how the coronavirus spreads between people. Now, it's widely agreed that the main driver for that spread is droplet transmission, but there's been a lot of talk recently about the importance of aerosols. But I thought maybe before we start, maybe if we can try and work on a definition of what that means. What's the difference between a droplet and an aerosol? Who’d like to take that one?

Interviewee: Noah Baker

I reckon I can do that one, actually. So, an aerosol is a particle that's smaller than 5 microns across, so these are these really tiny particles that are released during speech or singing or breathing that can transport the virus or a viral load potentially further distances than a droplet might be able to travel in the air, maybe be able to get it into ventilation systems, and it kind of changes the dynamic of how this virus could spread. But as you said, there's a lot of questions about how important aerosolised particles are in transmission for the coronavirus.

Host: Benjamin Thompson

Well, I think you’ve got to the nub of it there straight away. Maybe these aerosols can linger in the air. So, a lot of the advice that we’ve heard over the past few months is that by putting a distance between you and somebody else, and obviously by wearing a mask as well – we might talk about that in a bit – you’re sort of lowering the risk of these droplets, these sort of bigger particles because they tend to be a bit heavier and fall to the ground and what have you. But things changed this week when a group of researchers wrote a letter saying, well, actually, ‘I think we need to seriously consider that the aerosols could be a big driver as well.’

Interviewee: Amy Maxmen

Yeah, exactly. So, their letter was sort of pointed directly to the World Health Organization saying that as the global body of public health guidance, they should be saying something about airborne transmission and the potential for airborne transmission.

Interviewee: Noah Baker

Yeah, I think as time has gone on, there has been a growing body of evidence that suggested that this might occur, and there have been some relatively well documented case studies of things like this happening. So, there was, for example, a choir in Washington State that gathered, they sang, there was distancing that was encouraged, sort of hugging and things were discouraged, there was hand sanitiser there, and yet through this sort of two-hour choir rehearsal, there was something like 30 or maybe more choristers that were infected and a few of those died as well. And the kind of suggestion is that there really wouldn't have been a way to transmit the virus to that many people if those other kind of distancing measures were in place unless it was through aerosols that are released through singing. And there are some researchers that have modelled this in that particular hall as well and come up with a kind of similar conclusion there. I mean there are other examples of this sort of around the world, of similar sort of case studies that seem to point towards some significance of aerosol transmission.

Host: Benjamin Thompson

And it's not just case studies, right? There have been some experiments as well that are kind of adding to this evidence base that aerosolised particles may be involved in spreading the virus.

Interviewee: Amy Maxmen

And I think that's why a lot of this always rides on that. There is no one perfect study that proves this beyond a doubt. However, like you said, there's a number of various lines of converging evidence saying that aerosolised spread is something that we should think about and we should think about in recommendations. In the story that Nature published, there's kind of a nice list of some of the main studies that are pointed to at this point. There's one from May where researchers used laser light scattering to detect droplets that healthy people emit just when they’re speaking. So, this is sort of a biophysics sort of study, and what they calculated is that in one minute of loud speaking, you could have 1,000 virus-laden aerosols generated, and these aerosols are just 4 micrometres in diameter and they could remain airborne for 8 minutes, and then they added in a confined environment. So, that's an important detail when you think about what to do with this information. The idea is if you’re outside and it's a breezy day then maybe this isn't such a concern, but if the air isn't moving around and if it's not clean air coming in then you’re going to be in trouble. Another one of the studies talks about people who were infected with the coronavirus. They exhaled 1,000-100,000 copies of the virus per minute, and this is the RNA, so that's just a marker of the pathogen being there. I should say, we don't know if it's infectious at that stage. So, there still is kind of a lot of questions in this space, but I think a point that public health researchers and a bunch of other people, physicists, have pointed out is that there still is enough evidence to say that we should really be thinking about ventilation and the recirculation of air indoors and an emphasis on masks, even more strongly than we have in the past, for recommendations by the World Health Organization but also recommendations from the bodies giving public health advice within governments.

Host: Benjamin Thompson

And you mentioned ventilation there, and the letter from the researchers does talk about ventilation and suggests that opening windows and what have you could be a potential way to mitigate this sort of transmission and, Amy, you talked last week about the prison and the lack of ventilation there, so it seems like this is something that does need to be considered.

Interviewee: Amy Maxmen

It's funny, with the whole attention around this letter that came out, I think there was a part of me that was like, ‘Wait, but people are already advising about ventilation,’ but I realised that what these researchers are saying is right, that if public health guidelines aren't really taking this on, even though I personally was thinking, ‘Of course you need ventilation,’ it has to be brought up at a higher level. And to think through the situation you just mentioned and maybe once we decide that ventilation is necessary, maybe people will start thinking about, ‘Are there air filters that will help? Is there something to this UV thing? Can you actually use UV indoors to do something?’ Right now, I wouldn't trust anybody that says they definitely have found the way, but it's something to certainly look into.

Interviewee: Noah Baker

This is totally anecdotal here, but my Dad is currently in the process of trying to work out if he can get married to his partner at some time in the next couple of months, and they’re looking into the rules around that, and one of the rules at the moment in the UK is that you can only have one person singing a distance away if you’re going to get married, and this sort of limitation on singing is something that is in quite a few of the UK event management recommendations. And again, my assumption is that that's aerosol related because again, I don't see why people singing would be a problem apart from if it was for aerosolising. I do sort of have this image now of a wedding where there's someone standing in a corner looking at a wall singing and that is the sort of entertainment in a wedding, and I think that would be quite amusing.

Host: Benjamin Thompson

So, I mean although it seems like the droplet transmission is still the main driver then, people are thinking about these aerosols and putting things in place to try and stop that kind of drifting across the air to the other side of the room where you might be sitting, for example.

Interviewee: Amy Maxmen

And on 9 July, the WHO did update their guidelines on transmission, so now they include a layout of the evidence and some recommendations to avoid indoor crowded gatherings, in particular when physical distancing isn't feasible, and ensuring good environmental ventilation. So, they did update their guidelines in that way and, of course, all of this is contingent on how bad transmission is in your area. Surely, in some countries or cities where there's no coronavirus, you don't have to be quite as worried.

Interviewee: Noah Baker

Amy, I kind of wanted to ask you as well as someone that's reported on the WHO for quite a while, the WHO has come under quite a lot of fire from various people for being too slow to make recommendations or to support wearing masks soon enough or not have recommendations related to aerosolised particles soon enough. To what extent, in your judgement, are they being slow, and to what extent is it a case of they have to have a commensurate level of research to work with? I’m kind of interested in your take?

Interviewee: Amy Maxmen

Yeah, it's a tricky one. I think maybe in this regard, yeah, maybe they were a little bit slow here, which wouldn't be totally novel too. They’ve been slow to pick up recommendations that people have pushed for for a long time. I read about malaria a lot. They were very slow to recommend artemisinin as the gold standard drug after many trials had shown it. On their side, I also see the complication there is it's easy for scientists who might be doing the experiments to write a paper and say, ‘You must do this.’ It's harder to speak for the entire globe, make sure all of the evidence is in and figure out what people should do with that data. That's kind of tricker, so I understand the position they’re in. But it did seem that they have been paying attention to this.

Interviewee: Noah Baker

And I suppose it is worth mentioning here, it's probably important to mention, that although there has been this letter from a group of experts that's been written sort of aimed at the WHO to try to make more of this and to say more, this isn't a case of like scientists say one thing and the WHO doesn't agree. Even within the ranks of scientists and specialists in this area, this still isn't a done deal. There's still a lot of debate about how significant might be, and so the WHO's job, I suppose, is to try to listen to all of those scientists and reflect a global picture, which makes things a lot fuzzier for them.

Interviewee: Amy Maxmen

It is that tricky thing, when there's an absence evidence, it's not evidence of absence, and you’re jugging all of those tangly issues. Tangly issues. Tangled issues.

Interviewee: Noah Baker

I like tangly.

Host: Benjamin Thompson

Well, this may be a new incarnation of Coronpod, but it seems like yet again, there are still many, many questions for us to answer. But let's call it there for the time being, both, and I’ll hope you’ll join me again next week and we’ll continue to bring everyone the latest coronavirus news. Amy and Noah, thank you so much.

Interviewee: Amy Maxmen

Thank you.

Interviewee: Noah Baker

Thanks, Ben.

Host: Shamini Bundell

And we’ll hear more from the Coronapod team next week. Coming up on the main show, we’ll be finding out about some bacteria that are able to use an unusual metal as an energy source. Right now, though, it's time for the Research Highlights, read by Dan Fox.

[Jingle]

Dan Fox

Human lungs deemed too damaged for transplantation could be revitalised by hooking them up to the circulatory system of a living pig. A team of researchers collected five human lungs that had been judged unsuitable for transplantation because of acute damage. Then after dosing five pigs with immunosuppressant drugs and a component of cobra venom used to stop the pigs’ immune system from attacking the lungs, they connected the organs to the jugular veins of the animals. Twenty-four hours later, they examined the lungs and found that their structure and function had improved enough to make them suitable for transplantation, although they are yet to begin human trials. The team hopes that this method could be used to make more healthy lungs available for transplant and cut the time people spend waiting for an organ. Read that research in full at Nature Medicine.

[Jingle]

Dan Fox

Pentadiamond – a new form of carbon – is predicted to be as light as graphite, as hard as diamond, and semiconducting like silicon. Carbon is an extremely versatile element with many observed varieties, like diamond and graphite. In diamond, each atom of carbon connects to four others in a 3D cubic lattice that is incredibly strong. Meanwhile, in graphite, each atom bonds to only three others, forming flat sheets of hexagons. Now, researchers have calculated that carbon could also take a form they call ‘pentadiamond’. Its atoms are arranged in pentagons, with some atoms having four bonds and others three. Pentadiamond will have low density similar to graphite and should also act as a semiconductor. The material's structure also means it will actually get thicker when stretched. Learn the full extent of pentadiamond's predicted properties at Physical Review Letters.

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Interviewer: Nick Howe

Next up, all over the planet, living organisms use things like sugars and other so-called organic carbon-based molecules as energy sources. Now, some microbes break from this norm and can use inorganic molecules of energy – things like ferrous iron, ammonia or hydrogen. But for the last 100 years or so, researchers have toyed with the idea that some bacteria can use the inorganic element manganese to provide energy. For decades, it's been known that certain bacteria can perform chemical reactions with manganese, but it's never been shown to be the source of their energy. This week in Nature, though, microbiologist Jared Leadbetter has shown that some bacteria can use manganese to grow. I called him up to probe further into this manganese metabolisation. And so, for this paper then you were interested to see if there were bacteria that were able to use manganese. How did you go about that?

Interviewee: Jared Leadbetter

So, part of the back story here is that I was not engaging in research on this topic. In a sort of different area of research, I had made a substrate. I had made it with something called manganese carbonate, which is sort of like a chalk-like material, to use in an experiment, and when I was done with the experiment and done with this manganese carbonate, I forgot to clean the glassware that I had stored it in. So, it's basically a peanut butter jar that had contained this material. It had dried on the side and I’d forgot to clean it. And then I had gone to rinse it out, and because it had dried on the side, it didn't rinse out. And so, I filled it with water from the sink, and I went away for two months, and when I came back, this glassware was still soaking in the bottom of my sink. I had completely forgotten about it. And the material had gone from being sort of a chalky white to a dark brown-black. I sort of picked this jar up and I thought about it for a few minutes trying to remember, ‘What is this? Why is this here and what might this be?’ And it occurred to me that, ‘Huh, well, if these organisms existed that people have wondered about for a century, this might be what it looks like. And so, before I pour this down the drain, this experiment that I never even started, maybe I should ask myself whether this is actually what people have been looking for.’ And to make this long study short, that's exactly what it's turned out to be.

Interviewer: Nick Howe

So, just so I’ve got this straight, you had basically some of this manganese material, manganese-containing material, left it with some tap water in, essentially, and came back after a couple of months and it had changed in some way so it had presumably been metabolised by something?

Interviewee: Jared Leadbetter

Exactly, and it was a complete surprise and I wondered, ‘Wow, could it be that easy? There's no way it's that easy. It must be the chlorine in the water.’ And it really forced me to have maybe a freshman biology 1A moment where you ask yourself, ‘How do you know if something's alive? How do you know if something is biological or whether this is just a chemical reaction that has no relationship to biology?’

Interviewer: Nick Howe

So, how did you show it was indeed biological and wasn't something else in the system?

Interviewee: Jared Leadbetter

Initially what I was looking for was some sign that manganese oxidation is dependent on some unknown thing in this glass jar that can be propagated like a plant, if you will. And so, the way you do this is you do some controls where you heat the sample to a temperature which might kill some organisms but may not kill chemical reactions, and you sort of establish that there's a temperature sensitive component to this, and that temperature sensitive component is sort of a hint that it's biological because oftentimes when you start to increase the temperature of a reaction, it also increases the rate, and when all of a sudden you get to a certain temperature and now that rate drops off to zero because you’ve basically boiled your organisms, that's a sign that you probably have an organism doing it.

Interviewer: Nick Howe

And were you able to isolate these organisms?

Interviewee: Jared Leadbetter

There were some challenges with this. We knew it was biological and we have sort of modern, genetic methods that you can use to examine what's in this mix, and we initially knew that there were on the order of 70 different species in this mix, and none of the standard techniques for trying to bring this down to one worked. But through some effort, we were able to get this down to two species, and what we don't know is whether it has to be done by two species or whether we just are unable to separate those two species.

Interviewer: Nick Howe

So, do we know anything about these two organisms? Are they similar to anything you’ve seen before or are the totally new things?

Interviewee: Jared Leadbetter

One of the organisms, which is about 90% of the cells there present, is not closely related to anything that's ever been studied before. We can say that it belongs to a certain subgroup of bacteria, a major subgroup, but it's not a kissing cousin to anything that's been studied. It's as different as a spider is from a redwood.

Interviewer: Nick Howe

And do we have any sort of sense of how this metabolisation of manganese actually was progressing, how it was working?

Interviewee: Jared Leadbetter

So, we started to do growth experiments where you look at how fast does this oxidisation occur, how fast do these organisms grow? The question we had was whether or not the rate of oxidation also mirrored this exponential growth of the organisms, and the answer is yes. So, this correlation where you have this ever-increasing acceleration in the oxidation rate and then this ever-increasing acceleration in the number of cells which are present in this culture, and the two are sort of running parallel to each other is in itself a very good indication that an organism is using this substrate to drive growth.

Interviewer: Nick Howe

So, is this then a whole other type of energy source that is available to bacteria and do you think this is an isolated case as well because obviously, this was originally from tap water so maybe it's quite common?

Interviewee: Jared Leadbetter

Yeah, so there are several questions sort of embedded in that one question. One is how prevalent is this activity in the environment, and are there some environments where it occurs at higher rates or is more prevalent than in others and, at the moment, we don't know that. We do know that turn on the sink in my laboratory and collect some tap water and they’re in that tap water. So, almost certainly, this organism is from the subsurface, from an aquifer, and possibly any place on earth that there is ground water and maybe this substrate, this manganese carbonate, present, this process might occur. Now, we’ll find out. But almost certainly, it's not restricted to the sink in my office in a laboratory building.

Interviewer: Nick Howe

That was Jared Leadbetter from the California Institute of Technology in the US. If you want to know more about these bacteria and how Jared went from peanut butter jar to Nature paper, we’ll put a link to his paper in the show notes.

Host: Shamini Bundell

Last up, it's time for the weekly briefing chat, where we discuss a couple of articles that have been highlighted in the Nature Briefing – that's Nature's daily pick of science news and stories. So, Nick, what's caught your eye this week?

Host: Nick Howe

Well, I’ve been looking into a new paper that has shown that there is DNA evidence that ancient Polynesians and ancient Native Americans came in contact with one another.

Host: Shamini Bundell

So, could you maybe just start off by giving me a bit of a geography lesson here, Nick, about where these two relevant locations are?

Host: Nick Howe

Yeah, that's kind of important to the story, and the reason it's so surprising is these two places are quite far apart, like thousands of kilometres. So, Polynesia refers to a group of islands that are in the Pacific Ocean, so think Hawaii, New Zealand. These are part of the Polynesian islands. And the Native American DNA that I’m talking about in this case is from South America.

Host: Shamini Bundell

Okay, so, difficult for these two people to meet, and what does the DNA evidence say?

Host: Nick Howe

So, basically, this has been a theory that's been going around for a long time, that these two peoples interacted in some way. There's some evidence that in Polynesian places they had South American influences. For instance, they had sweet potatoes which are very much South American. And the DNA evidence has basically looked at certain stretches of DNA in individuals from Polynesia and shown that they likely interacted and interbred with peoples from South America around 1150-1230 AD.

Host: Shamini Bundell

Right, I’m going to need a history lesson now. This is going to be a very educational episode of the podcast. So, what was going on in the world in terms of sort of ocean travel around, what did you say, 1150 AD?

Host: Nick Howe

So, this is before sort of European colonisation of the area. This is before the big circumnavigation voyages around the world and these big ships that you might think of as colonising the Americas. But even so, it has been thought for many years that the peoples in these regions did have the capability to travel great distances. In 1947, a Norwegian explorer showed using what was essentially the tools they would have available that you could sail thousands of kilometres, and this DNA evidence seems to go along with that, showing that there was interaction between these people. Now, that isn't to say that Polynesia was colonised by South America. There's a lot of evidence showing that actually it was from people from Asia originally, but definitely there was some sort of interaction.

Host: Shamini Bundell

This is very much reminding me of Moana, just to bring the Disney references in here. And there's a lot of questions about how humans, both ancient and modern, managed to make the way across the world and get to all these different islands, so I guess this is another piece of evidence showing that we’ve maybe underestimated the ocean-faring skills of different groups throughout history.

Host: Nick Howe

Yeah, I mean the Polynesians were no strangers to ocean faring. They colonised the Polynesian islands, for instance. But they’re all relatively close together, so you can hop from New Zealand to a little island to a little island and there's lots of things in between, whereas this, between the Americas and the Polynesia, was like a vast stretch of thousands of kilometres of ocean that was basically empty. So, yeah, it could show that they were able to do far larger voyages than we previously thought.

Host: Shamini Bundell

That is very cool. I’m going to be humming Moana songs for the rest of the day now.

Host: Nick Howe

What can I say except you’re welcome. So, what have you found this week, Shamini?

Host: Shamini Bundell

Well, I’ve got some good news and some bad news for you, Nick, mainly because I couldn't pick one of the stories from the briefing, so I’ve kind of picked two. But they’re sort of both happy and sad news involved.

Host: Nick Howe

Well, the bad news will definitely make this more of an editing job for me, but let's start with the good news. What have you found in the good news column this week?

Host: Shamini Bundell

I mean this might just be good news to me because I’m really excited, but they’re going to reintroduce some bison to be able to live wild and free in an area of Kent in the UK. This is after the bison, I mean there used to be bison in the UK but we’re talking 6,000 years ago. So, from a personal point of view, I think it will be very exciting and fun to be able to go and see the bison living in Kent. But more importantly, there is a conservation and ecological angle as well.

Host: Nick Howe

Right, I mean, there's a lot of information here. So, first of all, there were bison in the UK. That is completely new information to me. And secondly, they’re reintroducing them. Are these guys going to be wild or are they going to be contained in some way? I just can't imagine bison roaming the fields of Kent.

Host: Shamini Bundell

Yeah, so bison are the biggest land mammal in Europe, like they are chonky, if I may say. But apparently, it will be possible to use just sort of normal cattle fence to keep them in, but the idea is that they would live totally wild. They wouldn't be fed or anything. So, they would be roaming around through these woods, having a great time and there's a lot that they do that's actually going to be really good for insects, birds, other mammals living in this area, particularly because of their interaction with trees. They like rub against trees and create loads of dead bark for insects. They kind of like clear areas so there's more sort of little clearings in wooded areas where different species can grow. So, all in all, hopefully quite good for the local wildlife.

Host: Nick Howe

So, they may be having a beneficial impact on other animals and things. That's really cool. So, what is the bad news then? We’ve got good news. What's the bad?

Host: Shamini Bundell

I can't believe you didn't ask for the bad news first. That's definitely – just FYI – the wrong way around because now we’re going to end on a sad note. It's going to be rubbish. Okay, so, the bad news is – I mean it might not sound like very new bad news – it's another species gone extinct. It is, in this case, a species of fish, and really unusually, it's a species of marine fish, something that's been living, until modern times, in our oceans that has now become the first modern marine fish to be declared officially extinct.

Host: Nick Howe

And is this a fish that we like to eat? Is this because of overfishing and things like that?

Host: Shamini Bundell

This is quite a deep sea fish. I don't think we usually eat it. I’m not particularly sure. Looking at it, I wouldn't necessarily want to eat it. It's a kind of handfish. It's the smooth handfish, and do image search handfish because they have hands and they’re quite strange looking. I think they’re relatives of the anglerfish so you can kind of get a bit of a sense about that for them as well, but they’re just these little gloopy things with hands sticking out. And this smooth handfish was quite common. It was recorded historically when Europeans went to Australia as being common in that area, but it's been really sort of endangered and vulnerable for a while, not necessarily from overfishing directly, but general overexploitation of the environment, trawling, climate change as well, and they basically haven't seen one in long enough that they’re pretty sure it's gone.

Host: Nick Howe

That's very sad, and so is there anything that can be done? Can we protect other species of fish like it or is it indicative of a broader trend?

Host: Shamini Bundell

I think people have thought the oceans so huge that things can survive there. How much damage can we puny humans possibly do to this huge ecosystem? But there are a lot of endangered species now living in our seas, so hopefully this is a bit of a wake up call for us to actually do something. There are a lot of other endangered species out there, and there are actually other species out there that might already be extinct and we just haven't really been able to confirm it yet. So, pretty important that action be taken.

Host: Nick Howe

Indeed, well let's hope that it's somewhat of a wake up call. Well, thanks for speaking with me, Shamini, and listeners, we’ll put links to everything we’ve discussed in the show notes. And if you’re interested in more but instead as an email delivered daily, then make sure you check out the Nature Briefing. We’ll put a link to that in the show notes as well.

Host: Shamini Bundell

You might remember that last week we heard from Lizzie Gibney in the United Arab Emirates talking about their Mars mission. Well, we’ve got more on that story for you. Over on our YouTube channel, we have a video exploring why there are three Mars missions blasting off in the next few months, so there’ll be a link to that in the show notes and do check it out.

Host: Nick Howe

That's all for this week. As always, if you want to get in touch with us then you can reach us on Twitter – we’re @NaturePodcast – or send us an email – we’re [email protected]. I’m Nick Howe.

Host: Shamini Bundell

And I’m Shamini Bundell. Thanks for listening.

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