Host: Shamini Bundell

Welcome back to the Nature Podcast. This week, we’ll be hearing how to combat hate speech online.

Host: Benjamin Thompson

And finding out how to uncover the first fossils. I’m Benjamin Thompson.

Host: Shamini Bundell

And I’m Shamini Bundell.

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Host: Benjamin Thompson

First up on the show, reporter Geoff Marsh has been tackling a topic which is sadly a mainstay of online discourse.

Interviewer: Geoff Marsh

If you’ve ever been on the internet – which I assume you have – it’s likely that you’ve come across some pretty unsavoury views. Almost any topic seems to spawn shouty Twitter outbursts from enraged individuals who hold opposing views to you. It can often feel like people’s behaviour online is governed by different principles and etiquette to the outside world, but there’s an altogether more sinister ecosystem of hate which goes on in the more private setting of online groups, communities and pages, which draw people with similar viewpoints together. In these online niches, dangerous narratives – things like white supremacy, religious extremism, anti-women – these narratives can develop and spread, and evidence suggests they can spark real-world aggression.

Clips from news headlines

I’m Victor Blackwell in El Paso, Texas, in a massive crime scene here were 20 people were killed.

It began in what is becoming a familiar, horrifying way. The white van here on the left was driven down the pavement on London Bridge.

Just to confirm, the New Zealand Head of Police did say one man has been charged with murder. He didn’t give the name…

Interviewee: Neil Johnson

Clearly, from what we hear in the news, we know that people involved with a lot of these mass shootings had online activity, online manifestos.

Clips from news headlines

He posted that manifesto and ran that livestream, that was the point at which they became aware of him.

Interviewee: Neil Johnson

You’ve got people in the real world, people online, people carrying out then events, it feeding back in the online world. I think it’s an absolutely unique ecology.

Interviewer: Geoff Marsh

This is Neil Johnson from George Washington University. Neil and his team studied the behaviour of online hate communities over the space of a few months. Neil said that inspired by his work as a many-body physicist, he’d taken a fresh approach to studying this online hate ecology.

Interviewee: Neil Johnson

Instead of having to deal with billions of particles and describe them exactly, the key to understanding the behaviour of a system lies in repackaging all of the behaviours of these particles into other objects, clusters. We’ve got water boiling in front of us. We’re going to make a cup of tea. The description of that doesn’t need you to know everything about every molecule. What you really need to understand is the true physics of how something boils – it lies in the correlated clusters of molecules.

Interviewer: Geoff Marsh

Neil looked at Facebook and a Russian social media platform called VKontakte to understand the network connections between these clusters of hate and to track how members of one cluster can go on to join others. Once they’d understood the dynamics of these hate clusters, they then proposed a set of policies which they say could provide effective interventions to combat the spread of online hate.

Interviewee: Neil Johnson

The reason we’re able to provide these policies is because we’ve understood how these clusters interconnect, and in some sense what their Achilles heel is, which is the fact that they’re a self-organised system, and so going in and dealing at the cluster level is almost like stopping water boiling by removing the bubbles.

Interviewer: Geoff Marsh

Neil suggested a range of policies – four to be exact – to suit the organisation implementing them. Can they target individuals or bigger groups? Do they prefer a top-down or a bottom-up approach? Depending on those two factors, Neil says that one of these policies should be a good fit. For example, if you’re a platform or regulator and you are able to exert top-down pressure but you didn’t want to target individuals, then policy 1 might work for you, where you intervene at the level of the clusters.

Interviewee: Neil Johnson

We give a detailed, mathematical description of which clusters to intervene in.

Interviewer: Geoff Marsh

Why would you not just find the biggest, nastiest cluster and get rid of that?

Interviewee: Neil Johnson

One might think you just go for the biggest, nastiest cluster, but of course that leaves then numbers two, three, four and five, which are not the biggest but would easily then merge into something that could be even bigger. The best solution would actually be to put up with the largest cluster because in some sense, one could then maybe engage. That largest cluster, tends to have more powerful people behind them. Some of these clusters, the large clusters turn around and sue when attempts are made to shut them down. Going for the smaller clusters, they tend to be weaker, they will be the ones that develop into the largest in the future.

Interviewer: Geoff Marsh

Policy 2 is another top-down, hands-on approach, aimed at platforms or regulators who are able to intervene at the level of the individual.

Interviewee: Neil Johnson

We’ve shown that by targeting then a small, random selection – it’s important it’s random – first of all, the regulator isn’t seen as then targeting a particular type of narrative, because it’s random, and the second is we’ve shown that just taking out randomly these individuals, the network falls apart.

Interviewer: Geoff Marsh

Policies 3 and 4 are a bit more organic or hands-off. The beauty of these bottom-up approaches is that once they are initiated, they would theoretically require less direct intervention by administrators. Neil’s research showed that there are reasonable numbers of active anti-hate users online, so the thinking for policy 3, for example, is that social media platform administrators could organise them to act as a sort of human immune system, as they engage in narrative debate with the hate clusters.

Interviewee: Neil Johnson

It’s a neutralisation, not of clusters against each other, but by putting in almost like a peacekeeper it almost provides a middle ground for debate so that, for example, they’re not fighting over their different nationalistic views but they’re being drawn in a cleverer way, maybe by subject-matter experts, maybe from social science engagement, into almost like a therapeutic narrative.

Interviewer: Geoff Marsh

Policy 4 works to exploit the disagreements that exist within hate groups and set them against each other.

Interviewee: Neil Johnson

I don’t really want to be banning clusters or individuals. I want to plant something that causes it to self-destruct. For example, two clusters may be anti-women or anti-immigrant but they differ in terms of nationalistic views, and by setting those narratives against each other, you can get them to implode.

Interviewer: Geoff Marsh

All four of those policies sound quite sensible. Could a country or a social media platform or a government not just employ all four and see what happens then?

Interviewee: Neil Johnson

They absolutely could. Of course, it’s a little bit like if I put four types of weed killer in the garden. Is that going to be bad? Should I just have one? It can only be answered if there’s some kind of mathematical modelling in there to see what the interplay is. That’s something we’re looking at now and we are actually interacting with platforms and regulators about the implementation of these. We should all realise, based on our study, that this is a much more global issue. It crosses platforms. It’s bigger than any one government and so in any way that can support directing the conversation towards that rather than the typical, ‘it’s Facebook’s fault’, ‘it’s this government’s fault’.

Host: Shamini Bundell

That was Neil Johnson of George Washington University in the US. You can find his paper, along with a News and Views article, over at nature.com.

Host: Benjamin Thompson

Later in the show, scientists have developed a very special ring.

Host: Shamini Bundell

Ooh, is it a ring forged in the fires of Mount Doom before being lost in the midst of time?

Host: Benjamin Thompson

Not in this case, Shamini, no. What I was going to say was, scientists have developed a very special ring – one that’s made entirely of carbon – and listeners, you can hear all about it in the News Chat. Right now, though, it’s time for the Research Highlights, read this week by Josie Allchin.

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Josie Allchin

Gallstones are exquisitely painful lumps of solidified digestive fluid that can grow as large as golf balls in a person’s gallbladder. The precise way that these pebble-like deposits form is unclear, so to get a better idea, a team of researchers analysed gallstones that had been removed from people during surgery. Alongside crystals of calcium and cholesterol – the basic ingredients of a gallstone – the team found that the surface of the stones contained an abundance of DNA. This genetic material was produced by a group of white blood cells called neutrophils. These immune cells can use sticky webs of DNA to trap bacteria. In the gallbladder however, these webs can also trap calcium and cholesterol, helping gallstones to form. The researchers showed that giving mice drugs that reduce neutrophil activity or prevent the nets from forming slowed the growth of gallstones. They hope that their findings will offer new routes to target these agonising aggregates in the future. Head over to the journal Immunity to read more.

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Josie Allchin

A New Zealand stick insect species can switch between reproductive strategies in the blink of an evolutionary eye, according to new research. While many populations of this species contain equal numbers of males and females and reproduce sexually, some can be exclusively female, reproducing asexually. One of these asexual populations is found on the Isles of Scilly, a tiny archipelago off the southwest coast of the UK. These stick insects were likely stowaways that hitchhiked around the world on imported plants, perhaps as early as 1911. The genetic ancestry of these insects has been traced by researchers back to a sexual population in New Zealand. They showed that the insects likely switched strategies at some point within a 100-hundred-year period, or about 100 generations in stick insect terms. Meanwhile, two stick insect populations in New Zealand switched in the opposite direction, moving from asexual to sexual reproduction. One population consisted of entirely females back in 2003 but was 50% male just 13 years later. While the reasons behind these switches is unclear, the researchers hope that their work will help scientists understand how location can affect reproductive strategy. Head over to Evolution for more on that one.

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Host: Shamini Bundell

Next up, reporter Nick Howe is going on a fossil hunt.

Interviewer: Nick Howe

When I was a young lad, walking along Bridlington beach on the Yorkshire coast, I found a fossil – an ammonite! I had an ancient marine mollusc in my hands that had swum in the ocean maybe hundreds of millions of years ago. I felt pretty special. That was until about five minutes later when my brother found an almost identical one. As it turns out, these fossils are pretty common in the rocks along the Yorkshire coastline. For a fiver, you could even get a much better preserved one than what I had found from one of the many fossil shops. However, whilst finding fossil ammonites is mere child’s play, other fossils are a bit more challenging to come by. And when it comes to finding the earliest traces of life from billions of years ago, well, then things get real tricky. That’s what Emmanuelle Javaux, a paleobiologist from University of Liège in Belgium, has been writing about in a review in this week’s Nature. So, listener, to emulate my fossil-finding younger self, I want you to accompany me on a hunt for one of the earliest traces of life. First off, we need a time frame that we might find it in.

Interviewee: Emmanuelle Javaux

We know that the Earth was habitable since about 4.3 billion years ago.

Interviewer: Nick Howe

That’s Emmanuelle. At this time, there’s evidence of liquid water on Earth, a key ingredient in the recipe of life. So, theoretically, life could have emerged then, but even if it did, it’s unlikely that we’d find it.

Interviewee: Martin Whitehouse

We do have a fundamental problem on Earth, and this is that we don’t have any rocks that are older than 4 billion years.

Interviewer: Nick Howe

This is Martin Whitehouse, a geologist from the Swedish Museum of Natural History. Whilst rocks did exist 4 billion years ago, the Earth is a pretty active planet and so those rocks have been eroded or otherwise changed. Without early rocks, it’s pretty hard for us to find early fossils, so any evidence of life we find will be younger than 4 billion years old. But with countless years of geological processes between the traces of life and us, in many cases evidence of life may have been erased.

Interviewee: Emmanuelle Javaux

Since life appeared on Earth, most of It has disappeared. It’s not preserved. So, we have only a few pieces of the puzzle preserved and it’s the same with the rock record. A lot of things happened a lot of building, eroding or the rocks are altered from transforming into other rocks, so they can be submitted to high pressure and temperature, and this will completely erase the possible traces of life that they may host.

Interviewer: Nick Howe

Even if we find a really well-preserved rock containing what we think might be an early fossil, it’s going to be pretty hard for us to know how old that fossil is.

Interviewee: Martin Whitehouse

I mean the actual fossil material itself is essentially undateable.

Interviewer: Nick Howe

Young fossils – those a mere 50,000 or so years old – can be dated using radioactive isotopes of carbon, but for the fossils we’re after, that carbon has long since decayed. To work out the age of a really ancient specimen, we need to date the rock it’s embedded in. Fossils are most often found in sedimentary rocks like sandstone. Sadly, this too has issues.

Interviewee: Martin Whitehouse

The real problem is most sedimentary rocks are actually very, very difficult to date directly.

Interviewer: Nick Howe

To age sedimentary rocks, we’ll need to find things inside them that can be dated – things that contain radioactive elements that don’t decay so quickly, like uranium, which can be found in the mineral zircon. So, let’s say we’ve done all this. We’ve got a lovely rock. It’s got a marvellous fossil inside which we’ve dated. Well done, us. We’re done, right? Nope, now we’ve got to make sure that the fossil we’re saying is evidence of early life is just that – life. Here’s Emmanuelle.

Interviewee: Emmanuelle Javaux

Another problem is that in several kinds of physical and chemical conditions, abiotic processes can produce organic molecules or morphologies that are similar to what life does.

Interviewer: Nick Howe

Non-biological, abiotic processes can end up resembling fake fossils or inaccurate indications of life.

Interviewee: Emmanuelle Javaux

There are also minerals that just auto-assemble and they form complex shapes like spiralling filaments or segmented filaments or little globules that look like colonies.

Interviewer: Nick Howe

So, to make sure that our fossil was once actually alive, we must ensure that it’s not a false positive, a geological ghost. Scientists still hotly debate a few claims of the earliest examples of life. Take the supposed 3.7-billion-year-old fossil bacteria found by a thermal vent off the coast of Quebec in Canada. Some scientists argue that what looks like evidence of bacteria may just be the result of natural processes in the rock. So, it turns out there are a multitude of reasons why it’s hard to pin down how old early life was or what it may have looked like. Given these difficulties, is there anything actual researchers can do to make their non-hypothetical hunts a bit easier in future? Lab experiments might help us out. Emmanuelle suggests we could try artificially fossilising organisms. This may be done by mixing them together with minerals at high temperatures and pressures to simulate fossilisation. By doing this, it could help inform how fossilisations occur in nature and so could inform researchers whether a fossil has come from a living organism or not. Also, by mixing together different commonly occurring minerals, researchers are trying to see what sorts of structures can form abiotically. Finding the earliest traces of life will give researchers insights about how the diverse biology on Earth emerged, and it may even help the search for life on other planets. Here’s Martin.

Interviewee: Martin Whitehouse

The techniques that we develop here, which we can develop in the relative comfort of a field camp or laboratory or whatever, those are absolutely portable to mars. It will be exactly the same tools with the slightly less convenient aspect of if you find something, you can’t go back a year later in another field season and have a look easily. It’s a little bit more of a luck of the draw if you land in a good place or not. So, it’s going to be challenging, for sure.

Host: Shamini Bundell

That was Martin Whitehouse of the Swedish Museum of Natural History. You also heard from Emmanuelle Javaux of the University of Liège in Belgium. You can find Emmanuelle’s review on the topic over at nature.com.

Interviewer: Benjamin Thompson

Finally then on this week’s show, it is of course time for the News Chat and joining me once again is Nisha Gaind, Nature’s European Bureau Chief. Nisha, hi.

Interviewee: Nisha Gaind

Hi, Ben.

Interviewer: Benjamin Thompson

Right, two stories today. The first one is a chemistry story, and well, it’s about a ring that maybe some researchers had given up ever making.

Interviewee: Nisha Gaind

Yeah, that’s right. This is a really lovely chemistry story and it is about the long-sought molecule C18, which chemists have finally been able to synthesise in a lab after many years of seeking it, and the reason that it’s special is that it’s the first ever ring-shaped molecule to be made that is made only of carbon.

Interviewer: Benjamin Thompson

Right, well I guess question one then is, how does one go about making a ring of 18 carbon atoms?

Interviewee: Nisha Gaind

With some difficulty. This was a several-stage process starting with some molecules and doing some traditional wet chemistry in a lab to get these chemicals down to something that was made of just carbon and oxygen, and it was this sort of triangular molecule that chemists then manipulated with an atomic force microscope. So, they used electric currents to make this carbon-18 ring which is just 18 carbon atoms arranged in a circle.

Interviewer: Benjamin Thompson

And so, is making a structure of just carbon then, is that something that’s really difficult to do?

Interviewee: Nisha Gaind

Well, obviously, we know that there are other types of carbon that exist – there’s diamond, there’s graphite, there’s graphene – these are all arrangements of just carbon. But the reason that it’s difficult to make these singular chains like this ring or maybe in future just a linear chain of carbon, is that the way that chemists have hypothesised that carbon would bond in these instances would make the structures much more chemically reactive, and synthesising these types of chains or rings has usually required the inclusion of other elements.

Interviewer: Benjamin Thompson

Well, I mean how excited are chemists about this feat then?

Interviewee: Nisha Gaind

Yeah, really excited. They have all said that this is an incredible piece of work, beautiful one chemist called it, and it’s something that lots of people have been trying to do for years and actually, some have just given up on it. But it was down to some people at the IBM labs in Switzerland who finally managed to do it successfully.

Interviewer: Benjamin Thompson

And what do we know then about this new structure? What might it be used for?

Interviewee: Nisha Gaind

So, from initial studies of this carbon-18 molecule, which is called a cyclocarbon, they suggest that it is likely to be a semiconductor and that would make it useful in the production of certain types of electronic components, for example, transistors.

Interviewer: Benjamin Thompson

And how soon then might we expect these components to be used in regular electronics?

Interviewee: Nisha Gaind

Well, there is a little bit more work to do there because at the moment, these researchers can only create one molecule at a time, so they have got a bit more work to do before they can create the molecules at greater quantities.

Interviewer: Benjamin Thompson

Well, moving on to our second story then today, and it’s a microbiology and maybe a health story, and it’s all about the different ways that babies are born and what that might do to their long-term health. Nisha, what’s the background on this one?

Interviewee: Nisha Gaind

The background here is a debate that has been raging for a few years and one that many listeners may have heard of, and it’s about whether babies born by caesarean section miss out on a kind of bacterial baptism, whether they miss out on a soup of microbes that babies who are born through the vaginal canal are given, and how missing out on that might affect their health in future.

Interviewer: Benjamin Thompson

So, what’s the kind of history with this debate then, and what’s being done now to maybe try and put it to bed?

Interviewee: Nisha Gaind

So, some of this debate goes back to a study in 2010, which found that babies delivered surgically harbour different collections of bacteria than babies that were born vaginally, whereas research also suggests that C-section babies are more prone to obesity and immune diseases such as diabetes. And C-section babies make up a substantial proportion of births – in the Unites States, they make up more than 30%. So, now we’re seeing a bunch of trials that are starting in the US, Sweden and China that will see hundreds of C-section babies who will be swabbed with their mothers’ microbes. That essentially means that microbes will be taken from the mother and babies will be rubbed with them, and the outcomes of these babies will be compared with those of a control group.

Interviewer: Benjamin Thompson

So, some fairly big experiments then. What is the research community saying about them?

Interviewee: Nisha Gaind

Well, there has been a mixed reaction. This is a controversial idea and there have already been some criticisms. Some researchers fear that the trials could expose these C-section babies to infection or even encourage mothers to do a kind of DIY swabbing at home, when there’s not much evidence to suggest that there is a benefit yet.

Interviewer: Benjamin ThompsonWell, finally on this one, Nisha, this debate is still going on, as you say. How long will we have to wait to maybe find out what the results are?

Interviewee: Nisha Gaind

Well because there are several clinical trials, they’re at slightly different stages. Some are recruiting. Some have already recruited mothers to take part. It will take a few years before we find out any results because, of course, we have to wait for these children to grow up and to see how the way that they were born affects things like their weight and their allergy risk and other factors that these researchers are looking for, so it’ll be a few years yet.

Interviewer: Benjamin ThompsonWell, thank you Nisha. One to keep an eye on. Listeners, head over to nature.com/news for all the latest science updates.

Host: Shamini Bundell

And that’s it for this week’s show. There’s just time left to subtly suggest telling someone you know about the podcast. Perhaps that person over there? Yeah, them over there! Go tell them! Or maybe rather than accosting a stranger, you could tell someone you know who’s got an interest in science. That’d probably make more sense. I’m Shamini Bundell.

Interviewer: Benjamin Thompson

And I’m Benjamin Thompson. See you next time.