Host: Nick Petrić Howe
Welcome back to the Nature Podcast. This week, why some animals age quicker than others.
Host: Benjamin Thompson
And what the war in Ukraine might mean for energy, emissions and food prices. I’m Benjamin Thompson.
Host: Nick Petrić Howe
And I’m Nick Petrić Howe.
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Host: Nick Petrić Howe
First up on the show, reporter Dan Fox has been investigating a paradox at the heart of animal ageing.
Interviewer: Dan Fox
Why do some animals live so much longer than others? And what is it that causes the variation in the ageing process? One theory suggests that somatic mutations – changes that accrue in our bodies over time – could be part of the answer. Here’s Alex Cagan to explain.
Interviewee: Alex Cagan
Somatic mutations are the mutations that accumulate in the DNA of our cells as we age. So, they’re distinct from germline mutations, which is what people traditionally think of when they think about mutation, which are the mutations that are passed down from parents to offspring. These rather are the mutations that occur in different cells in our own bodies as we’re ageing, so there’s good reason to suspect that somatic mutations that are altering the DNA could be having deleterious effects on cellular function. They could lead to breakdown and kind of consequences that we see in ageing.
Interviewer: Dan Fox
For example, somatic mutations are known to cause cancer, which can in turn reduce lifespan, and so it would stand to reason that larger animals with more cells to mutate might have a higher chance of developing cancer somewhere in their body and thus have lower lifespans. But this theory doesn’t necessarily align with what we see in the animal kingdom. With a few notable exceptions, larger animals often have far lower rates of cancer than smaller ones – a phenomenon known as Peto’s paradox.
Interviewee: Alex Cagan
From everything we know about somatic mutations and cancer, we would expect that the more cells you have, the higher your chance of cancer because you just have more cells where you could be unlucky and accumulate somatic mutations.
Interviewer: Dan Fox
What’s more, some of the longest lived animals in the world are also the largest, despite having so many cells which could be deteriorating through mutations. If somatic mutations are linked to ageing then something else must be going on, and now Alex and his colleagues have delved into the somatic mutation rates of a range of mammals for the first time, in the hopes of finally unravelling some of these mysteries. Somatic mutations can be caused by lots of things, like errors in DNA replication or exposure to mutagens like ultraviolet radiation. Despite being very common, their effects are still not fully understood.
Interviewee: Alex Cagan
The most well-known consequence that’s very well established is cancer, but what’s less well understood and still debated is whether somatic mutations could be playing other roles. Crucially, for example, what is the role of somatic mutation in ageing? Because we know that as we age we’re accumulating somatic mutations, but kind of the key question in the field is are these a consequence of ageing or a cause of ageing?
Interviewer: Dan Fox
Alex and his colleagues wanted to measure the rate these somatic mutations were acquired, not just in humans but across as wide a variety of mammals as possible. So, they set about collecting tissue samples.
Interviewee: Alex Cagan
So, we worked with a variety of partners, including the London Zoo, so ZSL Institute, and the CSIP which is the Cetacean Strandings Investigation Programme, who I’d never heard of before but they’re essentially like CSI for cetaceans or whales. So, we worked with partners like that in different zoos to collect tissue samples opportunistically from when animals had died from other causes.
Interviewer: Dan Fox
And once they had these samples, they could then compare them.
Interviewee: Alex Cagan
And so, we wanted to get a tissue type that we could compare across mammals because we know from human studies that different cell types in the body have different mutation rates, and so to compare across species, we wanted to pick one cell type. And we settled on intestinal crypts, which are these small, kind of crypt-like structures that line the intestine. And so, basically, by sequencing these intestinal crypts from 16 different mammalian species and 56 different individuals, and knowing the ages of those animals when they died, we could count and say, ‘Okay, in this harbour porpoise that’s x years old, there are this many mutations, while in this mouse that’s maybe a few months old, we count this many number of mutations.’ And then we can figure out the mutation rate across these different species and see to what extent they are similar or to what extent they vary.
Interviewer: Dan Fox
Their results allowed them to investigate whether mutation rates can help explain Peto’s paradox – the curious observation that larger animals don’t appear to develop more cancers despite having more cells to mutate. And it turns out that size is actually a fairly poor predictor of the rate of somatic mutation. For instance, cows, giraffes and horses weigh much more than an average human, but their somatic mutation rates don’t follow the same pattern. It’s clear that having more cells doesn’t mean you have a higher chance of developing cancer, but the weak correlation between body mass and somatic mutation rates across species suggests that lower mutation rates are not behind this, and that large animals, like elephants, must have another trick for lowering their cancer risk. However, there was one factor which seemed to correlate strongly with somatic mutations – a factor that is very relevant to ageing – lifespan.
Interviewee: Alex Cagan
By far, for us, the most striking finding was we found this strong inverse correlation between lifespan and somatic mutation rate.
Interviewer: Dan Fox
For example, the naked mole rat is about 23,000 times smaller than a giraffe, but they both live for around 20 to 30 years. And this new research presents an explanation for such similar lifespans in such different creatures – they have nearly identical somatic mutation rates.
Interviewee: Alex Cagan
And so what that tells us is that somatic mutation rate is evolutionarily constrained. So, there’s some reason that evolution is shaping somatic mutation rate to be similar at the end of lifespan across species. And this is consistent with the somatic mutational theory of ageing – that somatic mutations play a causative role in the ageing process.
Interviewer: Dan Fox
Across the animals tested, somatic mutation rates proved a reliable predictor of lifespan, and that provides strong evidence for the theory that somatic mutations are a cause of ageing, not a result of it. But the team isn't finished yet. They want to expand their study as far and wide across the tree of life as possible.
Interviewee: Alex Cagan
From evolutionary theory and what we’re seeing in mammals, species with longer lifespans seem to have lower mutation rates. So, if we can start to understand how species with even longer lifespans than humans are maintaining their genome integrity and lowering their mutation rate, there’s a potential to kind of learn from the solutions that nature and evolution have already found to potentially find ways to lower the somatic mutation rate. Whether that will one day be possible, I don’t know, but in principle if one could lower the somatic mutation rate, that could be a very effective way to lower things like cancer risk or slow the ageing process. So, that’s kind of the moonshot, far-future thinking of how this kind of research can potentially be relevant.
Host: Nick Petrić Howe
That was Alex Cagan from the Wellcome Sanger Institute here in the UK. For more on this story, check out his paper and a video that we’ve made. There’ll be links to them in the show notes.
Host: Benjamin Thompson
Coming up, we’ll be looking at the impacts that the ongoing war in Ukraine is having on global energy markets, and the effects this may have on carbon emissions and food prices. Right now, though, it’s time for the Research Highlights, read by Shamini Bundell.
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Shamini Bundell
During pregnancy, chronic high blood pressure can raise the risk of serious health problems – or even death – for both parent and baby. This is known as hypertension, and if a pregnant person has severely elevated blood pressure, doctors will usually treat it. But for milder cases where there’s a less severe elevation in blood pressure, the question of treatment has been controversial. To address this uncertainty, researchers conducted a randomised clinical trial of over 2,000 women with mildly high blood pressure who were less than 23 weeks into their pregnancy. Some received medications to treat their condition, while others did not, unless they developed severe hypertension. The women who received treatment experienced fewer pregnancy-related complications, with lower incidents of developing cardiovascular complications or severe hypertension. Infants born to women in the treatment arm also fared better. If these findings are confirmed, it’s thought that this could warrant a change in current treatment recommendations. Read that paper in The New England Journal of Medicine.
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Shamini Bundell
Astronomers have discovered the largest ever radio galaxy – a structure 16 million light years across – and studying it could help explain how these colossal objects form. Giant radio galaxies like this one contain enormous regions of radio-wave emission that extend well beyond their visible structure. About 1,000 of these objects have been identified so far, but the mechanisms responsible for their remarkable growth remain uncertain. Now, a team has discovered the largest giant radio galaxy yet – at least 100 times wider than the Milky Way’s disk of stars. The team has named it Alcyoneus after a giant of Greek mythology. While the new find seems similar to other giant radio galaxies, the team think it may be in a lower-density environment than its kin, which could have facilitated its extraordinary growth. Head over to Astronomy and Astrophysics to observe that paper.
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Interviewer: Benjamin Thompson
The war in Ukraine, caused by Russia’s unprovoked invasion of the country, is well into its second month. The conflict and the humanitarian crisis are ongoing, but away from the immediate region, the conflict is looking to have profound short- and long-term impacts on things like global emissions and food prices. Senior US correspondent Jeff Tollefson has been writing about these impacts for Nature, and I gave him a call to find out more. Jeff, thank you so much for joining me today.
Interviewee: Jeff Tollefson
Thank you. It’s good to be here.
Interviewer: Benjamin Thompson
So, you’ve been looking at the potential wider impacts of the war then, and central to a lot of these is energy.
Interviewee: Jeff Tollefson
Yeah, I mean any time you rile the energy markets, you also rile geopolitics, you rile food markets, and the result is that those ripple effects ripple through the entire economy and it’ll hit poor people the hardest everywhere.
Interviewer: Benjamin Thompson
And thinking about energy then, and energy from Russia specifically, what’s the picture as the conflict continues?
Interviewee: Jeff Tollefson
So, if you look at what’s happened so far, I mean, we had a big round of international economic sanctions. One place where those did not hit was energy in particular. The lone exceptions to that are places like the United States, the United Kingdom – these countries have put basically embargos on Russian oil, right. But one of the reasons that they’re able to do that is because they don’t really depend on Russian oil. In Europe, it’s a very different story. A lot of countries are heavily dependent on Russian oil and gas. Some countries are entirely dependent on Russian gas. And therefore, it's been really hard for the European Union to kind of extricate itself from the situation. And, in fact, they haven't, although now there's a move to ban Russian coal, but again that's the easiest one that you can get rid of.
Interviewer: Benjamin Thompson
In fact, in your feature article, you say that, in some cases, countries are buying more fossil fuels from Russia since the conflict has begun.
Interviewee: Jeff Tollefson
Yeah, you've got a lot of political rhetoric on one side of this. But if you look at the reality of what's been happening since the war, it's exactly the opposite so far. And the result is that Europe is sending on the order of €700 million per day to Russia for oil and gas alone. And inevitably, regardless of how you kind of do the accounting, that money is subsidised in the war and the European Union is very aware of that.
Interviewer: Benjamin Thompson
So, obviously, European countries are trying to extricate themselves from this Russian fossil fuel. But that's easier said than done because the levels are staggering.
Interviewee: Jeff Tollefson
Yeah, so in a powerhouse economy like Germany, the country gets about half of its gas and half of its oil and a third of its coal from Russia. So, it's hard to suddenly stop importing that without having lights go out, without having buildings go cold. So, that is the challenge that Europe is facing right now – how do you move quickly away from Russian oil and gas in particular?
Interviewer: Benjamin Thompson
And this is at the crux of what you've been looking at then and what impact this might have. It seems like there's potentially a bit of a crossroads here. And in some cases, there is a real risk of countries retreating back to coal-fired power stations to wean themselves off of Russian gas in particular. Of course, though, the IPCC said just a few short weeks ago that emissions need to peak in the next couple of years, and it's really hard to kind of square those things, right?
Interviewee: Jeff Tollefson
If you want to kind of quickly reduce your use of Russian gas, the easiest way to do it is to take existing facilities like coal-fired power plants and run them more. And in a place like Germany, that's likely to happen. It might happen in other countries as well. The other thing you can do is bring exports of natural gas from other countries, and this is undoubtedly going to happen as well. The big fear is that this boosts emissions in the short term, or it promotes investments in fossil fuel infrastructure when, in fact, we know that we need to be shutting down this fossil fuel infrastructure and shutting down these investments. So, the general feeling that I get talking to academics is that, in the short term, this is not going to be a good thing for emissions, and I think European leaders recognise this risk and the goal is really to quickly move away from fossil fuels. And if you look at the medium to long term, that's where you can actually completely extricate yourself from Russian fossil fuels. If you move to wind and solar, you're producing your energy domestically, and then you're completely free of this kind of geopolitical risk. And this is something that environmentalists and scientists have been talking about for a long time. In many ways, the green agenda merges with the energy security agenda over the long term, and the Russian war has provided a sudden impetus for this very discussion.
Interviewer: Benjamin Thompson
And what is potentially being done then and what have researchers told you about these efforts, how realistic they are, for example?
Interviewee: Jeff Tollefson
I think they're are very realistic. In a place like Europe, they were already teeing up this agenda as a result of the Paris Agreement, as a result of COP26. Europe has been in planning mode to shift its economy towards renewables for a while. Now, maybe it's going to happen faster, and one advantage to having all those plans is that they kind of know what they need to do. Germany is accelerating its efforts, for instance, to move to 100% carbon-free power by 2035, 5 years early, and 80% by 2030. These are staggering numbers. But now, you might say, ‘Oh, it's expensive to do these things and it's difficult politically.’ When you've got an enemy right next to your borders, and you are financing that enemy through the purchase of fossil fuels, it makes it a lot easier to bear the economic cost of what needs to be done to shift towards renewables. So, I think that's the hope.
Interviewer: Benjamin Thompson
I mean, of course, we've looked at Europe, specifically there, Jeff, which is intrinsically linked to Russian fossil fuels. But of course, we live in a globalised society and ripple effects will be seen all over the world, of course. What have you seen going on in other places?
Interviewee: Jeff Tollefson
So, oil is a global commodity. Natural gas is increasingly a global commodity because it's been shipped around in liquefied form. So, you've got prices spiking and that ripples into everything, into food prices, into geopolitics. More than 30 countries have now announced that they're going to release oil from their strategic reserves to kind of keep prices down. And this is an effort to basically placate voters who might be angry about having to pay more at the pump, even though economists would say that that's precisely what you want, is people to pay more at the pump so that they use the energy more wisely. Thus far, we haven't seen lots of large announcements of new fossil fuel investments by producers. And that is what has happened in the past. And one theory on that is that they're a little bit wary of investing a bunch of money in oil and gas wells that are going to be stranded assets in 5-10 years if the world takes its climate commitments seriously. But if the prices stay high for a long time, that could change.
Interviewer: Benjamin Thompson
Finally then, one of the other things that you've been looking at is the effects the conflict is potentially going to have on things like food prices and availability, and how these are intrinsically linked to energy prices, for example. What's going on there.
Interviewee: Jeff Tollefson
So, there have been a lot of concerns raised about the loss of wheat coming from Ukraine as a direct result of the war there, and actually other food crops coming from Russia as a result of economic sanctions. So, we'll see kind of a shift in the supply of global food stocks, like wheat and crops like this, grains that are shipped around the world. But from what I've been told, the loss from Russia and Ukraine is about as large as what the world has in storage. So, theoretically, we have the grains to kind of absorb this as an immediate short-term impact, and farmers around the world will probably respond to the prices in terms of this year's planting season. And then you've got the impact on fertilisers. Russia is a major fertiliser exporter, and you've got fertiliser plants in Europe curtailing production. But again, farmers have alternatives to these kinds of mainstream fertilisers and, from what I've been told, they're likely to be able to figure out how to make do, at least in the short term, on that front as well. The one area that you can't change is the actual food price. So, the majority of the cost of food is not due to cost of farming, it's due to transport and refrigeration, and all of the things that happen between the farm and the table. And when the oil prices go up, the food prices go up. It's as simple as that. So, this is what's going to be kind of unavoidable and it will hit people all over the world.
Interviewer: Benjamin Thompson
Nature's Jeff Tollefson there. We'll put links to his feature article, and an editorial about the wars impact on food security, in the show notes.
Interviewer: Nick Petrić Howe
Last week, there was some news that sent a buzz through the physics community. After poring through years of data, researchers found something that has the potential to upend the standard model, which is physicists’ best description of particles and the fundamental forces between them. Although the model has stood up to scrutiny since it was introduced in the 70s, researchers have known for a long time that the standard model isn't quite complete, and finding out exactly where the gaps are in it could help unlock as yet unknown physics. And that's where this new result might come in. A team have shown evidence that a particular particle known as the W boson is much heavier than the theory predicts. So, what does this mean? To find out, I called up senior reporter Lizzie Gibney, who covers all things physics here at Nature. She started by explaining what a W boson is and what it does.
Interviewee: Lizzie Gibney
So, this is a boson, the W boson. So the W and Z bosons, they are the force particles that oversee a lot of nuclear reactions and nuclear processes involved in fusion, in radioactive decay, so that's the weak nuclear force. And these are created in colliders and experiments, a bit like people will be quite familiar with at the Large Hadron Collider. These ones in particular were made at the Tevatron, which is a collider that existed in the United States until I think it was 2012 or 2011. And so, these bosons were created and scientists studied them, and what they have been doing is measuring the mass, and the mass is a parameter that is the main parameter people often give when they are trying to describe a particle, and it's something else that fits into the standard model. So, they have found that the W boson is, according to these experiments, a lot heavier, like a lot heavier than the standard model describes. And the idea is, if this is correct, if the W boson is actually a lot heavier than we thought it is, the standard model in its current form just cannot be right. We are missing something, and that gives us a way of figuring out what we're missing in the standard model.
Interviewer: Nick Petrić Howe
Right, so because this doesn't fit with the standard model, it shows the ways in which it might be incorrect. So, if it were to show that, what would be physicists’ sort of next steps?
Interviewee: Lizzie Gibney
Well, the first thing that we'll need to do is check that the W boson is actually more massive than we thought. So, we're going to need to do independent experiments that would verify that. That is very, very important. From there, if we actually are completely sure that the standard model gets the W boson’s mass wrong, then we need to figure out what is wrong with the standard model. So, already, there are some theories out there, some ways in which you would modify the model that would then predict this W boson to have the mass that it's now been observed as having. There are lots of those and theorists are going to have an absolute field day. They're coming up with lots of different possibilities. But a couple that are already out there, people might have heard of the Higgs boson, which was the most recent particle to be discovered. That was kind of the last jigsaw puzzle piece in the standard model. If there's not just one Higgs but there are several, that is a way in which the W boson has a heavier mass than we've seen. There are some other theories such as supersymmetry, which has been around for a very long time. And there are lots of different versions, but most of them include the idea that each particle has a super particle, and it's much, much heavier. And if these were around in this particle soup inside these colliders, they would have a subtle effect on other particles, including boosting potentially the W boson’s mass. So, we would go from confirming this result to figuring out what explains it, and then we would need to actually test to those specific explanations and see which fits best. So, it'll be quite a long journey from here, but it's really, really thrilling because this might be that very first step along that route to figuring out physics that is completely beyond what we know it at the moment and could potentially answer this plethora of questions that are on physicists’ plates right now.
Interviewer: Nick Petrić Howe
So, if I was to throw some caution, though, onto your thrills there, as I understand it, that the W boson has been particularly hard to weigh, and there have been other experiments trying to establish its mass, and this doesn't quite agree with them.
Interviewee: Lizzie Gibney
That is right. So, this is notoriously difficult to do this, this measuring of the W boson. So, when the boson is created, you study it by looking at what it then decays into, the other particles it turns into. And the way in which the W particle decays, one part of it is called a neutrino, and that just disappears. You can't you can't detect that at all. So, you're having to reconstruct the mass of the W boson from everything that's left and from a lot of theory that gets thrown in as well. So, this analysis actually took ten years. So, it's about, I think, 9 years of data, but it then took another 10 years of analysing that data to come up with this figure. And other experiments have been trying to do something similar. So, at the Large Hadron Collider, there is ATLAS and LHCb, two experiments that have come up with their values for the W boson mass. It also took them years and years and years to do this. Their results are not as precise as those from the Tevatron, from the CDF experiment, the results that have just come out, but they do differ. Now – you’re probably familiar with the idea of error bars – these results just sit completely outside of each other's error bars. So, that suggests that there's some issue somewhere that experiments are coming up with very differing values for, in theory, what should be the same value. So, I think it's in one way very exciting because the LHC is going to be starting up again this year. And there's a third one – CMS is also going to be looking at the W boson mass measurement. So, we're going to have, hopefully in the next couple of years, more refined measurements from two of those experiments, a whole new measurement from a third. So, we will hopefully be able to figure out where this discrepancy comes from. But at the moment, I think the physics community is both really, really excited at this result, which is a really impressive result because it's so hard to do, but also has a few questions as to why it's so different from the other very recent, also very state-of-the-art experiments that have been trying to measure the exact same thing.
Interviewer: Nick Petrić Howe
I mean, that's a good point as well, like this is potentially a very momentous moment in physics, so what have been the reactions from physicists?
Interviewee: Lizzie Gibney
I think a huge amount of surprise actually because, if we think of some recent big results, you might remember, well, you might not remember, I remember because it was exciting for physicists, the result from Muon g-2 last year. That was also an anomaly that was outside the standard model, not as significant as this result. But that one, we'd had a hint of it already. There was some data pointing in that direction, so physicists were kind of expecting it. This one, people have been measuring the W boson for years. And although it's very hard to measure, so there is a lot of uncertainty, nobody thought that a result like this would come out. So, I think surprise is a big thing. I think excitement is a huge thing. And then I think caution also on top of that because of these discrepancies, because of how difficult it is to do, because of the way in which there are so many different ways that even the best experimentalists could get this wrong. We're going to wait and see if this is corroborated by independent experiments before really getting excited.
Interviewer: Nick Petrić Howe
That was Lizzie Gibney. For more on this story, check out the show notes, where there'll be a link to a news article.
Host: Benjamin Thompson
That's all for this week's show. But before we go, a little bit of good news – one of our episodes has been shortlisted for a Webby Award.
Host: Nick Petrić Howe
That's right. It's for our episode, ‘What’s the isiZulu for dinosaur?’, where we find out about efforts to translate scientific terms into several African languages, discuss the sustainability of the electric car boom, hear about a bird-eating centipede and mammoth migration. It's a pretty packed show. I think you'll agree.
Host: Benjamin Thompson
Oh, 100%. And as well as being up for the main award, we're also in the running for a People's Voice Award, voted for by listeners. And so, well, listeners, we need your help to win. If you could cast your vote for us, that would be amazing. It only takes a couple of minutes, and we'll put links on where to do so in the show notes for this episode and up on Twitter. Check out @NaturePodcast for that.
Host: Nick Petrić Howe
Speaking of which, you can always reach out to us on Twitter, or you can send us an email to podcast@nature.com. I’m Nick Petrić Howe.
Host: Benjamin Thompson
And I’m Benjamin Thompson. See you next time.