[Jingle]
Interviewer: Adam Levy
Hello and welcome to this week’s Nature Podcast. This week we’re uncovering the brain’s control of ageing and looking at a brain-inspired computer.
Interviewer: Shamini Bundell
Our third story is, sadly, not brain-themed. We’re looking at Al Gore’s new film on climate change and asking what the risks are of politicians communicating science.
Interviewer: Adam Levy
This is the Nature Podcastfor July the 27th2017. I’m Adam Levy.
Interviewer: Shamini Bundell
And I’m Shamini Bundell
[Jingle]
Interviewer: Shamini Bundell
Woody Allen once said, ‘I don’t want to achieve immortality through my work, I want to achieve it through not dying’. It’s a bold ambition but what if you could do both? What if achieving immortality was your work? This week I’ve been talking to scientists who study ageing. It’s a fact of life that our physical bodies wear out. From cells to organs, to organ systems, nothing lasts forever. Scientists may not be looking for the fountain of youth but they do want to extend our life spans beyond the current physical limits.
Interviewee: Reinier Boon
Many people claim to have found the key to ageing. Whether you can solve ageing of the entire organism with just one molecule, one pathway, it’s probably not the case.
Interviewer: Shamini Bundell
This is Reinier Boon who studies the role of long non-coding RNAs in the ageing of the cardiovascular system, but that’s just one area of research. People are studying all sorts of possible ageing culprits. There’s levels of DNA methylation in cells, the length of telomeres that protect the end of chromosomes, restriction of calorie intake, metabolic rate. Whether there is one answer or many, as research continues, even more possible factors appear.
Interviewee: Reinier Boon
So, one of the things that pops up a lot is microRNAs. MicroRNAs are very tiny RNAs as the name already says. They are about 20 nucleotides long, made by cells and they are regulators of gene expression profiles which means that these single, tiny RNAs can control behaviour of the cell by controlling which proteins are present at a given time.
Interviewer: Shamini Bundell
MicroRNAs feature heavily in a new paper on ageing out this week. I called up one of the authors, Dongsheng Cai, who explained that the research started off looking not at RNA but at the brain. They started by considering the 300 neurons that make up the nervous system of a worm, C. elegans.
Interviewee: Dongsheng Cai
I experimented only with changing a few neurons of those ones. It could be sufficient to change the life span. In some cases it can extend the life span.
Interviewer: Shamini Bundell
A mammal brain is a lot more complex than a worm’s. Dongsheng’s team decided to focus on a particular area called the hypothalamus.
Interviewee: Dongsheng Cai
Because the hypothalamus has a classical function to regulate the whole body’s physiology, the whole body’s homeostasis, so there’s a natural logic for us to reason that the hypothalamus might be involved in the ageing, which has not been studied before.
Interviewer: Shamini Bundell
Previous work had established that the hypothalamus is somehow involved in ageing though no-one knew how. Other work had been looking at the effect of stem cells upon the ageing of various organs, so Dongsheng and his colleagues were very interested by the discovery a few years ago of stem cells in the hypothalamus.
Interviewee: Dongsheng Cai
So I’m now thinking of putting these two threads together, the hypothalamus and the stem cells. So then we will ask these questions: does this group of cells work to somehow affect or contribute to the functions of the hypothalamus in regulation of ageing?
Interviewer: Shamini Bundell
Dongsheng and colleagues first looked at the hypothalamuses of mice over their lives and found that ageing was associated with a big loss of these hypothalamic stem cells. The next step was an experimental intervention.
Interviewee: Dongsheng Cai
So to test if there’s a cause and effect relationship between the loss of stem cells and the ageing phenotype, we devised experiments to destroy this group of cells in mice. We found the loss of these cells lead to the acceleration of ageing speed.
Interviewer: Shamini Bundell
So, there was a causal link but what could it be? How’s the hypothalamus influencing ageing in the rest of the mice’s bodies? The answer may be in the microRNAs that we mentioned earlier.
Interviewee: Dongsheng Cai
We found hypothalamic stem cells have a unique ability, a very strong ability, to secrete microRNA and the microRNA is very small so it is produced and recent research has said it can be secreted to outside of the cells and in fact in other cells, the neighbouring cells, some distant cells.
Interviewer: Shamini Bundell
MicroRNAs can be secreted from cells and travel around the body in vesicles, tiny sacks of membrane, but no-one yet knows what the microRNAs produced by the hypothalamus are actually doing.
Interviewee: Dongsheng Cai
We don’t know whether microRNA is secreted to directly affect the rest of the body, or it’s possible the microRNA is secreted in the brain and affects different parts of the brain and then the brain can affect the whole body. So we still have a very limited understanding and very limited information.
Interviewer: Shamini Bundell
Even so, Reinier Boon is intrigued.
Interviewee: Reinier Boon
What is super interesting about the new paper is that it actually provides a link between the brain and the ageing of the body. It was known that the stem cells in the hypothalamus contribute to that but what exactly gets the signal from the hypothalamus to the entire body was not known.
Interviewer: Shamini Bundell
Reinier thinks the discovery that microRNAs are involved is bound to interest people looking for a way to prevent ageing.
Interviewee: Reinier Boon
I’m pretty sure that people will die from this because if it is something you can use systemically, you can also inject these vesicles. The authors also showed that it can be done in mice and it rejuvenates the mice basically. It prevents ageing. So if this can be translated to humans, of course this would be the elixir of life basically.
Interviewer: Shamini Bundell
But, even ignoring our limited understanding of this mechanism so far, has this paper actually found this elixir of life: the one answer to the question of ageing?
Interviewee: Reinier Boon
That’s part of the answer, yes. I’m pretty sure that if you only look at that, that you will only have part of the puzzle. We still see in the paper that these mice still die of old age. These mice don’t survive indefinitely. Their life span is not doubled. So it’s only part of the puzzle but of course it’s an important piece of the puzzle and it’s scientifically also a very interesting mechanism by which this works.
Interviewer: Shamini Bundell
That was Reinier Boon from the VU Medical Centre in Amsterdam. You also heard from Dongsheng Cai from the Albert Einstein College of Medicine, New York. Dongsheng’s paper is available now at nature.com/nature.
Interviewer: Adam Levy
What I got from listening to that was that the secret to eternal life is basically a brain transplant?
Interviewer: Shamini Bundell
Well, it makes a change from having to drink the blood of young beautiful people in order to keep your looks.
Interviewer: Adam Levy
Is that even a thing?
Interviewer: Shamini Bundell
I’m sure that happens in a fairy tale somewhere, doesn’t it?
Interviewer: Adam Levy
Not any fairy tales that I was read as a child… slightly concerning. I’m going to keep my youthful blood and my beautiful brain cells away from you just to be on the safe side.
Interviewer: Shamini Bundell
That is probably sensible.
Interviewer: Adam Levy
Coming up later in the show, measuring the mass of protons and finding out when superbugs got so super. That’s in the Research Highlights.
Interviewer: Shamini Bundell
Now though, Adam has been taking a look at the sequel to one of the most famous documentaries of all time.
Interviewer: Adam Levy
Eleven years ago, a film came out which changed the way many people thought about climate change. The film was called An Inconvenient Truth.
Audio Clip: extract from An Inconvenient Truth
If you look at the ten hottest years ever measured, they’ve all occurred in the last 14 years.
Interviewer: Adam Levy
This film laid bare many of the scientific realities of global warming. But it wasn’t presented by a scientist. Instead, it followed US politician, Al Gore. The film made a big splash with critics. It won two Oscars, including one for best documentary feature, and Al Gore received the Nobel Peace Prize for his work on communicating climate science. But according to science historian, Naomi Oreskes, the film also had a huge impact on audiences.
Interviewee: Naomi Oreskes
An Inconvenient Truth was seen by millions of Americans and it was a very powerful film. It was beautifully made and very well produced and very thoughtful. And opinion polls show that people who went to see An Inconvenient Truthfelt they understood the issue better and were motivated to do something about it after seeing the film.
Interviewer: Adam Levy
A lot has changed in the decade since An Inconvenient Truth, both in the climate and our society. Emissions have increased; the world has continued to warm; renewables have become cheaper; in Paris the world agreed to halt global warming and a couple of months ago, Donald Trump decided to pull the United States out of this agreement. To explore this changed world Al Gore is releasing a follow up to his 2006 film.
Audio Clip: extract from An Inconvenient Sequel
It is wrong to pollute this earth. It is right to give hope to the future generation.
Interviewer: Adam Levy
This is An Inconvenient Sequel: Truth to Power. To veteran climate scientist Michael Mann, this film is more than an update to its predecessor.
Interviewee: Michael Mann
This is much more about the larger public battle and the urgency that is apparent in comparing what we’re seeing today in terms of climate change impacts with what we were seeing just ten years ago when Gore did An Inconvenient Truth.
Interviewer: Adam Levy
Both films are presented by Al Gore, and for many, Gore has become the figurehead of climate change. Although Michael reckons he’s done an admirable job communicating climate science, this job has come with its pitfalls.
Interviewee: Michael Mann
He’s perhaps the most vilified public figure when it comes to the communication of climate change and I should know.
Interviewer: Adam Levy
Michael should know because sceptical politicians and members of the public have aggressively attacked his prominent climate research. But the attacks aimed at Al Gore have been even more extreme. Michael tells me that critics have targeted everything from Gore’s personal life to his weight. Naomi reckons the reason he’s so vilified is precisely because he is so successful in communicating climate change, but his political background may also limit his success.
Interviewee: Naomi Oreskes
So obviously a politician who is associated with a political party, a particular set of ideological positions, is unlikely to be affected speaking to people on the other side of the aisle, and so in that respect I don’t really expect that a lot of hard-core conservatives will go and see Al Gore’s new film or be persuaded by it.
Interviewer: Adam Levy
Gore’s political background – he’s a democrat and former vice president – could be more than a barrier to certain audiences. Michael feels that it may actually have has negative consequences for discussions about climate change.
Interviewee: Michael Mann
By becoming a prominent spokesperson for the climate issue, I think that Gore played into the hands of climate change deniers. It allowed them to create a wedge. It allowed them to say, hey look, just as we had told you all along, this issue is entirely about politics and look who’s the figurehead, it’s Al gore, this failed politician as they would call him. I think it’s difficult to fault Al Gore for that but the fact is that they were able to exploit the fact that he’s a partisan political figure to great effect.
Interviewer: Adam Levy
There certainly is a deep divide on climate change in American politics. A 2015 study published in Politics and Policycompared the views of conservative parties in nine countries around the world. It found that of all the parties, only the Republican Party in the US denied climate change. Sceptics may have exploited Al Gore’s political career to strengthen this divide.
Interviewee: Naomi Oreskes
You know, maybe it would have been better from the get go if scientists had done a better job of explaining it but they didn’t so that’s one of the reasons that Al Gore got involved early on.
Interviewer: Adam Levy
The effects of having a politician as a spokesperson for science are complex. But Naomi and Michael both agree that the solution isn’t for Al Gore to stop making films. Instead, they think it’s crucial that as many people as possible from as many fields as possible communicate climate change.
Interviewee: Naomi Oreskes
So this film begins as a scientific question but it doesn’t end there, in fact it ultimately isn’t a scientific question, it’s ultimately a political, social and economic question because of the profound impacts that climate change will have on all of us. So it’s absolutely essentially in my mind that other people become involved as spokespeople: politicians, business leaders, even celebrities.
Interviewee: Michael Mann
There’s no one magic bullet. We need all of these people and institutions and voices out there because we are talking about the greatest challenge that we’ve ever faced as a civilization.
Interviewer: Adam Levy
That was Michael Mann who’s based at Penn State University. You also heard from Naomi Oreskes who’s based at Harvard. An Inconvenient Sequel: Truth to Powercomes out on 28thof July in America and 18thof August in the UK. Some cinemas are also broadcasting a live conversation with Al Gore before screenings of the film on Friday the 11thof August. Check out Michael’s review over at nature.com/booksandarts.
Interviewer: Shamini Bundell
The news is still to come where reporter Ewen Callaway is joining us to discuss the threat of gene drives, and, financial incentives to protect trees. Now we’ve got the Research Highlights read by Charlotte Stoddart.
[Jingle]
Interviewer: Charlotte Stoddart
Protons just got a little lighter. Well that’s not strictly true. Researchers just got a little better at measuring the proton’s mass. They trapped one in an electromagnetic field and measured how it moved. The team then compared this to the movements of a carbon-12 nucleus. This gave the proton mass to an accuracy of 32 parts per trillion. The researchers are positive that their new value is lighter than the current figure: 296 parts per trillion lighter. Next, physicists want to measure anti-protons just as accurately on the off chance that they spot a tiny difference. That paper is in Physical Review Letters.
[Jingle]
Interviewer: Charlotte Stoddart
The famous antibiotic resistant superbug MRSA is an arch nemesis of hospitals all around the world. It’s continually out-witted attempts to use different antibiotics to treat it and now it looks like MRSA bacteria had already evolved resistance to one of these antibiotics, methicillin, before doctors even discovered it. Researchers looking into the genome of MRSA, or methicillin-resistant Staphylococcus aureus, determined that a particular methicillin resistant gene evolved in the 1940s. But methicillin didn’t enter widespread clinical use in Britain until 1959. It sees that earlier drugs like penicillin could have inadvertently selected for the resistant gene. That paper is in Genome Biology.
[Jingle]
Interviewer: Shamini Bundell
Artificial Intelligence is getting really impressive. Nowadays, AI computers can beat humans at fiendish games like Go and complicated tasks like image recognition. Their intelligence is borne out of algorithms that emulate the behaviour of neural networks in the human brain where nodes work together to crunch data, spot patterns and learn from their successes. But, unlike the brain, the powerful devices that process these algorithms, consume immense amounts of power: ten thousand times more than our own fleshy computers. That’s in part because they still use transistors, just like the ones in your phone or laptop. These act like simple switches, meaning they need to be arranged in large, energy hungry networks. So, a group of researchers in France have decided to take yet more inspiration from the human brain and create miniature magnetic oscillators which can process vastly more data than a simple transistor. This means the networks can be a fraction of the size on our computer chips. Reporter Geoff Marsh called lead author Julie Grollier, director at the National Centre for Scientific Research in France.
Interviewee: Julie Grollier
Computers are made with transistors, however, a transistor is just a switch and if we want to emulate neurons and synapses, we need much more than a switch. A synapse has a lot of memory and a lot of ‘tunability’. And so if we want to emulate that with transistors, we need to assemble a lot of them. It takes a lot of area on a chip. It means that we want to make Nano-neurons and for this we need to fabricate new devices, new Nano-devices. Devices that we are using are magnetic Nano-oscillators which are like a tiny compass and when you send an electrical wave the compass is going to start to gyrate and these magnetic gyrations are then converted into voltage oscillations. It’s this transformation that is at the heart of the computation.
Interviewer: Geoff Marsh
And that output is analogue as opposed to digital or binary transistors that we use today?
Interviewee: Julie Grollier
Exactly, that’s the point. It’s analogue and what is important is that this transformation is what we call non-linear. In fact, neurons are non-linear. If you excite them with a constant input they are going to spike periodically and you see they are non-linear oscillators in that sense.
Interviewer: Geoff Marsh
Right, so just like a neuron in the brain, what your oscillator spits out isn’t directly proportional to its input. Tell us about the task that you had your oscillator do then.
Interviewee: Julie Grollier
What we chose is to recognise spoken digits, a kind of bench mark task for cognitive computations. So, there are different speakers that pronounce the digits from zero to nine and the goal is to recognise the digit independently of the speaker who pronounced it. And on this spoken digit recognition task, we have obtained a success rate of 99.6%.
Interviewer: Geoff Marsh
Presumably this spintronic oscillator, this tiny, tiny, single unit has got some powerful conventional computers on either end of it to send the signal and receive and process the data.
Interviewee: Julie Grollier
Right, so for now we are using a computer to complement our neuron. In the real neural network you have neurons but also you have synapses. And these synapses are important to learn and for now we emulate them with a computer.
Interviewer: Geoff Marsh
And just to be clear, when you say synapses, you mean connections between the neurons?
Interviewee: Julie Grollier
Yes, in that case these are connections between the neurons towards an output.
Interviewer: Geoff Marsh
Right, so you sort of simulated a network?
Interviewee: Julie Grollier
Yes.
Interviewer: Geoff Marsh
Right, but there’s only a single unit though in your experiment so does it sort of do it lots of times?
Interviewee: Julie Grollier
Right, exactly so we have used a kind of trick that is called time multiplexing to emulate a full neural network with only one oscillator. So for this spoken digit recognition task we have emulated 400 neurons. Basically the magnetic pillar plays the role of each neuron, one after the other, just as an actor who would play all the characters in a movie.
Interviewer: Geoff Marsh
Now, AI algorithms at the moment are getting really good at voice and image recognition. How does your system compare to the likes or Siri, Apple’s virtual assistant on the iPhone for example, because she’s really impressive.
Interviewee: Julie Grollier
Of course our system is much simpler than Siri. Siri is able to recognise full sentences, right? Here we are only able to recognise digits from zero to nine. However, Siri requires millions of neurons and here we only imitate 400 so it really shows that even if it has this miniature size, this magnetic neuron is able to perform cognitive tasks successfully.
Interviewer: Geoff Marsh
Now this work was on a single oscillator. You obviously, as you mentioned, simulated a network but theoretically, your aim presumably is to have several of these oscillators and actually network them.
Interviewee: Julie Grollier
Exactly, so our next step will be to try to compute with assemblies of these oscillators. What we are going to try to do is to fabricate the same very densely because in that case, since the structures are magnetic, and if you put the cylinders close enough to each other, they are going to communicate with each other, so the magnetic oscillation of one, is going to influence the magnetic oscillation of the neighbouring ones, you know, like dominoes. So you can create chain reactions of magnetic oscillations which are going to emulate the neural network.
Interviewer: Geoff Marsh
So what is this going to be useful for? Am I going to have these spintronic oscillators in my phone or am I just going to be driven home in my autonomous car by them?
Interviewee: Julie Grollier
Well the ultimate goal that we have is to realise these very smart miniature chips that would have a very low power consumption, able to learn and adapt to the real world. As we said, to classify a huge amount of data in real time but you can also think of putting them to help automatic vehicles, or for medical diagnosis. Also for making prosthetic devices where you need a little bit of intelligence and very low power consumption.
Interviewer: Shamini Bundell
That was Julie Grollier from the CNRS in France talking to reporter Geoff Marsh.
Interviewer: Adam Levy
Finally this week it’s the News Chat and Ewen Callaway has popped down to the studio. Hey Ewen.
Interviewee: Ewen Callaway
Hey there.
Interviewer: Adam Levy
Now, this week we’re not talking about anyone who has long ago died in a bit of a change for Ewen on the News Chat. But instead we’re taking a look at first US defence Agencies who are trying to get their heads around a somewhat unusual threat: gene drives. So, what are gene drives?
Interviewee: Ewen Callaway
Gene drives are a genetic engineering technology that basically drives a mutation through a wild population. It does so even when that mutation is not beneficial to the wild animal. It’s a technology that’s being pursued most notably as a way to potentially eliminate mosquitoes that carry malaria or at least prevent them from carrying malaria. So this is a technology that has really a lot of promise from a public health perspective but it has raised some concerns because it’s a technology that could potentially extinct a species or alter an entire eco system. So you could think that you could do untoward things with it, or untoward things could happen by accident, hence the interest of US defence agencies.
Interviewer: Adam Levy
Where are we now with the technology? Has it actually been implemented in real world studies?
Interviewee: Ewen Callaway
No. It’s very, very, very early days for this technology which is based on CRISPR Cas-9 gene-editing, at least in its latest inception. We’ve seen a handful, really, of laboratory studies in a few organisms, mostly mosquitoes, that’s really where most of the focus has been. But there’s been a very well-funded project based here in London at Imperial College to hopefully develop the technology so that it’s ready for field trials in sub-Saharan Africa as early as 2024, but we’re a long way off, everyone admits.
Interviewer: Adam Levy
What are the threats that US defence agencies are considering and how could you tackle these threats?
Interviewee: Ewen Callaway
You could imagine some science fiction scenario where you weaponise mosquitoes, for instance. You use a gene drive to introduce a gene that encodes a toxin then it spreads to people that it bites. You could come up with all sorts of things like that. But really the biggest potential problem is these organisms escaping a laboratory when we don’t want them to, when we’re not ready to test them in the field and that’s really what I think US defence agencies and scientists who are being funded by some of these defence agencies are worried about and trying to counter.
Interviewer: Adam Levy
How could you counter that? Could you build in some kind of off switch?
Interviewee: Ewen Callaway
The most recent news is that the US Defence Advanced Research Projects Agency, DARPA, which funds futuristic sounding research, has funded, I think seven groups of scientists – a total of 65 million dollars – to look at ways to better control gene-editing and applications of gene-editing, including gene drive. So some of these might be drugs that turn off CRISPR or other gene editors. Other ways you could imagine that if you’ve got a gene drive spreading a trait through a wild population that you don’t want, you could have a counter gene drive that either reverses that gene drive or it immunises unaltered populations so they’re kind of resistant to it. You’re basically using a biotechnology to counter a biotechnology but these are some of the ideas people are imagining.
Interviewer: Adam Levy
Our second story today is a lot less hi-tech I suppose. People are being paid to protect trees in Uganda. What was actually done here?
Interviewee: Ewen Callaway
Yeah, seems like a pretty sensible thing, you know. We think trees are important, trees have a value, they reduce levels are carbon dioxide in the atmosphere by absorbing them, so this experiment which is really an economic study, one is test this principle. If we pay people not to cut down their trees, well does it work, as in do they not cut down their trees? And does it pay off? That is, is the money saved from the greenhouse gas emissions that don’t occur as a result, is that offset by the amount of money that we pay?
Interviewer: Adam Levy
And in both cases they found good news?
Interviewee: Ewen Callaway
Yeah, I believe so. This is a two year project. They paid 180 people in 60 Ugandan villages a total of $20,000 to not cut down their trees and the study found that indeed, compared to villages where people weren’t paid to not cut down their trees, that there was more forest cover. And not cutting down these trees avoided enough carbon dioxide emissions to pay for the cost that was paid not to cut them down.
Interviewer: Adam Levy
How do you begin to estimate the actual value of the carbon dioxide that’s being absolved by these trees in the first place?
Interviewee: Ewen Callaway
Fortunately government agencies like the US Environmental Protection Agency have already done it for us and I think it’s based on the principle that carbon dioxide has a cost based on its effects on climate. So there’s this idea called the social cost of carbon and I think that’s what they based this carbon on.
Interviewer: Adam Levy
Paying people to protect tress isn’t some radical new idea. It’s been done before, so what’s actually new about what this study was doing?
Interviewee: Ewen Callaway
The United Nations has this programme, right, where they encourage countries to pay people to not cut down trees and they use this system which is called REDD+ to offset carbon emissions for these countries. So if you’re a country and you pay people not to cut down trees it counts as offsetting your own carbon emissions. I think in the past these programmes have not been really evaluated whether they’re effective or not, or whether they’re worth it or not. I think the same study authors evaluated a lot of these programmes and found that more than half of them you couldn’t tell whether they worked or not or whether they were good value or not. So this study, published in Science, I think is really quite unique, and showed that in this situation it was worthwhile to pay people to not cut down trees.
Interviewer: Adam Levy
Isn’t there a risk that now the study is done everyone might just go and chop down their trees anyway?
Interviewee: Ewen Callaway
Yeah I guess there’s a risk but the researchers concluded that the carbon that was offset during the study period made it worth it so it still would have been good value.
Interviewer: Adam Levy
Different communities are going to have different attitudes to their trees and maybe ascribe different financial benefits to having those trees about. Is there any indication that this study would apply to different communities as well?
Interviewee: Ewen Callaway
I don’t think so. This seems like it’s quite specific to this community and this study. I mean, I’m sure people will want to extrapolate but I wouldn’t be willing to do it.
Interviewer: Adam Levy
Okay so, so far we know at least it works for sure in this one instance so that’s a bit of progress towards understanding paying for trees.
Interviewee: Ewen Callaway
Yep.
Interviewer: Adam Levy
Thank you, Ewen, for joining us. For more on trees and gene drives, nature.com/news is the place to go.
Interviewer: Shamini Bundell
That’s all for this week. Tune in next time for the latest and greatest developments in science. I’m Shamini Bundell.
Interviewer: Adam Levy
And I’m Adam Levy.
[Jingle]
