NATURE PODCAST

Podcast: Economic downturns and black holes

Join Benjamin Thompson and Shamini Bundell for the latest from the world of science.

This week, the effects of recessions on public health, and simulating supermassive black holes.

00:45 How downturns affect health

Global recessions have been shown to be bad for people’s health, but that might not be the whole story… Feature: How the next recession could save lives

07:47 Research Highlights

Leafcutter ants clear debris, and supercooling molecules. Research Highlight: Ants build superhighways without bosses or blueprints; Research Highlight: A superchilled molecular gas nears the quantum limit of coldness

08:47 Computing cosmic giants

Researchers are investigating how supermassive black holes form. Research article: Wise et al.

15:58 News Chat

The evolution of efficiency in human brains, and how researchers are preparing for Brexit. News: Pioneering brain study reveals ‘software’ differences between humans and monkeys; News: How UK scientists are preparing for a chaotic no-deal Brexit

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Transcript

This week, the effects of recessions on public health, and simulating supermassive black holes.

Host: Benjamin Thompson

Welcome back to the Nature Podcast. This week, we’ll be finding out how economic downturns affect public health.

Host: Shamini Bundell

And simulating supermassive black holes. I’m Shamini Bundell.

Host: Benjamin Thompson

And I’m Benjamin Thompson.

[Jingle]

Interviewer: Benjamin Thompson

Over the past few weeks, there have been some rumblings in the press of an economic downturn, and potentially even another global recession in the not-too-distant future. This week, Nature has a feature article looking at the effects that times like these have on public health. In particular, the article looks at the effects of the Great Depression of the 1930s and the Great Recession which began in the late 2000s. It makes sense that these downturns would be pretty bad for a population’s health, but that may not be the whole story, as Lynne Peeples, the feature’s author, explains.

Interviewee: Lynne Peeples

It’s a mixed bag. So, obviously, intuitively you might guess that economic crashes would result in some health harms to at least individuals in the population that are directly impacted. Some researchers have found that losing a job actually increases the odds of developing conditions such as hypertension, arthritis, diabetes, and mental health problems are certainly the one health consequence that’s been very consistent in the literature. Certainly, suicide rates have generally risen during times of recession. And then there’s some less obvious impacts, a little less direct. For example, in California during the Great Recession when there was a foreclosure crisis, there was actually an uptick in West Nile virus because these swimming pools in backyards of California homes were left abandoned and mosquitoes, that’s where they breed in stagnant water. So, there are kind of a whole range of ways in which an economic downturn could harm the public health.

Interviewer: Benjamin Thompson

I mean quite far-ranging there then, and obviously serious for a lot of people, but perversely if you zoom out to maybe a population level, there can actually be some positive health trends, and this was something that was noticed way back in the 1920s.

Interviewee: Lynne Peeples

Right, yeah, going back to before the Great Depression. Scholars who looked at how the death rates respond to the economic crashes of the time – they were surprised to find that death rates actually dropped, which obviously is pretty counter-intuitive. And those findings were largely forgotten and it wasn’t until maybe 20 years ago that researchers really started looking more closely at the data and indeed, those patterns continued – that same surprising result that death rates actually do drop generally population-wide when the economy crashes.

Interviewer: Benjamin Thompson

Well, that does sound quite counter-intuitive but do we have any reason why this might be?

Interviewee: Lynne Peeples

One, there might be fewer work accidents – fewer people on the job, and those that are on the job perhaps are more highly skilled. And along with that, if there are fewer people working or fewer people with the money to take leisure vacations, there might be fewer vehicles on the road that would translate to fewer car accidents. Also, if you’re working less you might argue that there’s less work stress. You might also have less free money to spend on beer or cigarettes.

Interviewer: Benjamin Thompson

And what I will say there, Lynne, is – I think you said ‘may’ and ‘might’ a few times – is there the risk of focusing on correlation rather than causation? Have there been any studies that show a direct x-to-y relationship?

Interviewee: Lynne Peeples

There have. Certainly, scholars are hesitant to be concrete about these links, but there are studies that have found that air quality does increase when the economy falls, and we know that air quality is linked with cardiovascular disease, asthma, infant mortality. There have been studies that have shown that there are fewer work accidents during recessions. With more data, we’re getting better and better at finding some of those true causations.

Interviewer: Benjamin Thompson

I mean do you think that large population level effects risk masking the effects on individuals?

Interviewee: Lynne Peeples

Absolutely. This is one of the key points that comes out right now and that researchers are emphasising, is that if we are just looking at the overall population impacts – that slight drop in the death rate – that there are segments of the population that are obviously getting harmed. Their health is suffering and that can get lost.

Interviewer: Benjamin Thompson

There are rumblings in the press about potential recessions and what have you. Certainly, in Europe here it’s been in the news a little bit recently. I mean we’ve got this data now from the 1920s through to now, and obviously we have a wealth of public health data. What can we learn about where to maybe invest our money or our public health responses to try and help people the best when an economic crash does happen?

Interviewee: Lynne Peeples

Looking at how money has been spent or not spent in past downturns can yield a lot of information. For example, in the aftermath of the Great Recession, countries such as Sweden, Finland and Malaysia seemed to generally escape a lot of the consequences that were seen elsewhere by investing in retraining workers, maintaining other social safety nets and other public health policies.

Interviewer: Benjamin Thompson

Well, the phrase, ‘Those who don’t learn from history are doomed to repeat it,’ seems kind of apt here. If this next recession does happen – and hopefully it won’t affect too many people too drastically – but if it is to happen, do you think enough lessons have been learnt to negate its effects?

Interviewee: Lynne Peeples

It’s hard to say at this point but we can certainly hope that with decades now of experience in the ups and downs of the economic cycles and more attention being paid especially over the last couple of decades to these patterns, that policymakers have been paying attention and may glean some lessons from the past and implement potentially more effective responses in the future.

Interviewer: Benjamin Thompson

That was science journalist Lynne Peeples. You can read her feature over at nature.com/news.

Host: Shamini Bundell

Coming up in the show, we’ll be finding out how researchers in the UK are preparing for Brexit – that’s in the News Chat. Up next though, Anna Nagle is here with this week’s Research Highlights.

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Anna Nagle

Many leafcutter ants use complex trail systems to transport pieces of leaf back to their nests. These trails are created by removing debris and flattening soil, but which ant is the boss? Who’s guiding the construction of these highways? To find out, a team of researchers used paper barricades to block ant trails, both in the lab and a Costa Rican rainforest. They concluded that clearing a trail relies mainly on independent ant decisions that together add up to unintentional teamwork. Head over to the Proceedings of the Royal Society B to read that paper. But that’s not an order.

[Jingle]

Host: Anna Nagle

Scientists have managed to make a gas of molecules so cold that they bump up against the limits of quantum physics. Supercooling gases composed of individual atoms to the point where quantum effects take hold is one thing, but doing so with complex molecules is much more difficult. To try and do it, scientists in the US cooled millions of individual rubidium and potassium atoms, before using a magnetic field and light pulses to bind the atoms into a gas made up of tens of thousands of molecules at temperatures of 50 billionths of a Kelvin, well below the temperature at which strange quantum effects start to appear. The authors say that gases like this could provide fresh insights into chemistry at the quantum scale. Read that cool research in the journal Science.

[Jingle]

Host: Benjamin Thompson

Right, it’s time for everyone’s favourite part of the show. It’s the ‘complete the song lyric round’.

Host: Shamini Bundell

We don’t have a ‘complete the song lyric round’?

Host: Benjamin Thompson

Yeah, but this one ties in really well with our next story.

Host: Shamini Bundell

We don’t even have rounds?

Host: Benjamin Thompson

Complete the lyric: ‘You set my soul alight, Glaciers melting in the dead of night, And the superstars sucked into the…’

Host: Shamini Bundell

Ah, I only really know show tunes.

Host: Benjamin Thompson

Oh, come on Shamini, it’s Muse!

Host: Shamini Bundell

Yeah, but is it from a Muse-ical?

Host: Benjamin Thompson

Sighs. Oh dear. Well, I’m sure some of our more cultured listeners will have recognised the lyrics to Supermassive Black Hole by Muse. There’s not a lot more detail in the song about this particular cosmological phenomenon and perhaps we can forgive them that, as it turns out that supermassive black holes are a bit of a mystery even to scientists. Luckily though, we have reporter Lizzie Gibney on hand to help us out. She’s been chatting to astrophysicist John Wise about some new research into just how these cosmic heavyweights form. She started off by asking him what supermassive black holes are, and exactly how supermassive they can get.

Interviewee: John Wise

You find supermassive black holes at the centres of almost all galaxies, and we’re talking about objects that are around a million and a billion times the mass of our Sun, but since they’re so dense, they’re pretty small. And it’s a mystery of how they actually came to be in their early universe – I mean did they form with the galaxies or did they form before the galaxies and how did they grow, and so on. I mean it’s always been a mystery of these exotic objects.

Interviewer: Lizzie Gibney

And how big are they, or how heavy or massive are they compared to what we would consider to be a regular black hole?

Interviewee: John Wise

They’re around 100,000 to 1,000,000 times more massive than just typical stellar mass black holes.

Interviewer: Lizzie Gibney

So, you’ve been trying to answer the question of how do these really massive kind of black holes form. What are some of the most popular theories at the moment?

Interviewee: John Wise

So, there are three competing theories. The first scenario is where normal stars, they go supernova, and they form black holes, and then they grow slowly overtime into supermassive black holes. The second scenario involves stellar mergers, and these mergers of stars, you build up more massive stars and eventually you get a very massive star that’s probably around 1,000 times the mass of our Sun, and then that creates a black hole. But what we focused on is the third option in which you have a massive gas cloud that doesn't break up into individual stars but forms one or a few very massive stars that are around 1,000 or 10,000 or even 100,000 times the mass of our Sun, and these go on to collapse into a massive black hole.

Interviewer: Lizzie Gibney

And is there a reason to think that this massive collapse in one go is a more likely way of formation than this kind of slightly slower accretion of bringing together different stars or mergers?

Interviewee: John Wise

We focused on this because it’s really hard to grow a supermassive black hole, so if you start massive to begin with then it’s very easy to grow into one of these supermassive black holes, and one clue is that astronomers have found these supermassive black holes only a billion years after the Big Bang. So, there’s very little time for these supermassive black holes to grow and if you start big, that’s easier to actually get to this supermassive black hole stage.

Interviewer: Lizzie Gibney

And then I guess generally it’s hard to observe any of this in action – we can’t rewind to the early universe – so how do you go about figuring out which mechanism is most likely or how formation really happens?

Interviewee: John Wise

So, we use simulations and these simulations, they’re large scale, they’re cosmological in nature. They follow thousands of galaxies forming and their black holes as well. And we try to match these simulations to actual observations of galaxies and black holes.

Interviewer: Lizzie Gibney

And tell me more about the model in this case. Presumably, given the amount of matter that we’re talking about in a supermassive black hole, it must have been pretty data-intensive?

Interviewee: John Wise

Yeah, these simulations are very intensive. This one took nine months to run and it produced 500 terabytes of data, so it was an intensive process of actually running the simulation, but also to analyse the simulation data as well. And once we sifted through all this simulation data we actually discovered that we had candidates where these massive black holes could have formed.

Interviewer: Lizzie Gibney

So, when you ran your data then through this simulation, it turned out that you had the ingredients and the right environment for black holes to form, is that right?

Interviewee: John Wise

Yeah because for these massive black holes to form in this third scenario that I was talking about, what you need is you need primordial gas from the Big Bang. So that means it’s only composed of hydrogen and helium mostly because if you’re enriched by heavy elements like carbon and silicone, for instance, you can actually spark the formation of stars, whereas if you just have hydrogen and helium, you would only form a single supermassive star which then forms a supermassive black hole.

Interviewer: Lizzie Gibney

What did we learn then from the model about how these black holes formed? Was there anything that was surprising?

Interviewee: John Wise

It was surprising because the previous thought on how these massive black holes formed in the early universe was that you had to suppress cooling in some manner because this gas cloud needed to be dense and fluffy so it doesn’t break up into stars. So previously, researchers thought that you need to be near to a massive galaxy or a group of galaxies where the radiation from those galaxies prevented this gas from cooling down, but the surprising thing is that wasn’t the case at all. In our simulations, we saw that these gas clouds actually grew very rapidly and this suppresses normal star formation within that gas cloud and that can produce these supermassive stars that then go on to form massive black holes.

Interviewer: Lizzie Gibney

So, astronomers know that there are lots of these supermassive black holes out there, and indeed we think there’s one right in the middle of our own galaxy. How well does your simulation fit with what we see today? Are there the right number of these rapidly growing gas clouds in order to create the number of supermassive black holes that we see out there?

Interviewee: John Wise

Yeah, definitely because the number of these supermassive black holes at the centres of galaxies, we can take that number in the present day and compare that to what we find in our simulation, and these numbers do indeed match up. And that suggests that these supermassive black holes do have a common origin in being massive to begin with.

Host: Shamini Bundell

That was John Wise from the Georgia Institute of Technology in the US talking to Lizzie Gibney. You can read his paper describing the results of the simulation over at nature.com/nature.

Interviewer: Benjamin Thompson

Finally then this week listeners, it’s time for the News Chat and I’m joined here in the studio by Nisha Gaind, European Bureau Chief here at Nature. Nisha, hi!

Interviewee: Nisha Gaind

Hi Ben.

Interviewer: Benjamin Thompson

Well our first story today, Nisha, is a neuroscience story and it’s comparing the brains of primates, but maybe rather than the sort of structure of the brains themselves, it’s looking at the activity within them.

Interviewee: Nisha Gaind

Yes, so in a paper published in Cell, a group of neuroscientists have looked at the brain signals in two regions of the brain, the amygdala and a region called the cingulate cortex, and they looked at these regions in both humans and monkeys, and what they found is that the activity of single neurons in monkey brains is more robust and the activity in human brains is less robust but more efficient.

Interviewer: Benjamin Thompson

Right, so robust versus efficient – what does that mean?

Interviewee: Nisha Gaind

So, robustness and efficiency are two properties that the researchers sought out in this data about the activity of single neurons and robustness means that the neuron signals are more synchronised and essentially, they’re less ambiguous, so if a primate sees a tiger coming towards them, their brain is sending robust signals that basically say run away. But this property of efficiency is seen in more evolved areas of the brain like the cortex, and it means that there’s a greater richness of signals in these activity patterns and that allows for a more considered response to an animal’s environment.

Interviewer: Benjamin Thompson

So potentially a more nuanced response then, but looking at these kind of single neurons sounds like a real challenge. How does one go about doing that?

Interviewee: Nisha Gaind

Yeah, so that is the really cool and unusual thing about this study. The researchers looked at two sets of data – one from humans and one from monkeys – and the human data was collected from people with epilepsy who had electrodes implanted in their brains while they were undergoing a type of treatment. Now, these electrodes allow researchers to track this single neuron activity and then they had the same type of data that was collected from macaque monkeys and they also collected a little bit more. So, together they had these huge datasets that they could search for these properties.

Interviewer: Benjamin Thompson

Well what does this mean then, Nisha, and maybe where does it lead us to?

Interviewee: Nisha Gaind

So, this research reveals that humans have sacrificed this property of robustness for this property of efficiency and they’ve taken this trade-off further than other primates. Now this has allowed the researcher to hypothesise that this trade-off could be one explanation for humans’ unique intelligence.

Interviewer: Benjamin Thompson

Some big claims there, but I guess with this very specialised treatment for these people with epilepsy, there’s not a huge amount of folk involved in the study. Where do we need to go with it?

Interviewee: Nisha Gaind

Exactly, this was a sort of opportunistic piece of research in that it exploits this quite unusual and rare dataset that it has collected from people undergoing this treatment. Now, very small numbers of people have ever had data collected in this way, but there is some funding from the US National Institutes of Health for more of this type of research, which is termed a neurosurgical study.

Interviewer: Benjamin Thompson

Let’s move on to our second story today Nisha, and it’s about Brexit and we haven’t talked about that for a while. Things are still kind of ongoing in the UK Parliament at the minute, but as things stand there is the potential for the UK to leave the EU on 29th March with no confirmed exit deal. Now, we’ve done quite a deep dive into what researchers are doing in sort of preparation for this. What’s been going on?

Interviewee: Nisha Gaind

UK institutions and scientists are making a broad range of preparations. That’s because if there is a no-deal Brexit, it means that Britain leaves the European Union without any trade and migration agreements in place. Now that would instantly affect travel, data collection, clinical trials, and of course, crucial supplies, including laboratory resources.

Interviewer: Benjamin Thompson

Yeah, I mean there’s been a lot in the press here in the UK about sort of car parts moving about and what have you, but in the business of science you’re thinking things like pipette tips, gloves and so on.

Interviewee: Nisha Gaind

That’s exactly right, so like for lots of supplies, many things come from the continent and we know that some universities are preparing to stockpile things like mouse bedding, culture plates, petri dishes, and even fly food, as well as yes, gloves, goggles and lab coats. More extremely, the UK Department of Health is preparing to charter a plane that would bring in very specialised radionuclides for medical screening, and these can’t be stockpiled because they’re too short-lived.

Interviewer: Benjamin Thompson

I mean that’s maybe the stuff of science – what about funding? What preparations are being made?

Interviewee: Nisha Gaind

Funding has been one of the key concerns for researchers in this whole Brexit negotiation. Now if we were to leave with no deal, it would mean that UK-based researchers would immediately be unable to access about €1.3 billion in research from EU sources. Now, the UK government has pledged that it would step in to pay for this lost EU funding in some way and they are working out how those rules would work right now.

Interviewer: Benjamin Thompson

Well if that’s things and funding, what about people?

Interviewee: Nisha Gaind

Universities are concerned that a no-deal Brexit would affect travel, but we know that for short-term visits it’s likely that EU and UK citizens probably wouldn’t need a visa which means that travel for conferences and collaborations and so on, should be largely unhindered. Now there is the question of how people who are wanting to move countries for work after no-deal Brexit would do that, and those details are still being worked out. UK universities are being advised to bring any new hires from Europe to the UK before 29th March.

Interviewer: Benjamin Thompson

Well, what about some of the other impacts, Nisha, which maybe aren’t quite as obvious?

Interviewee: Nisha Gaind

There are so many impacts to count but here are a few more. Specifically for researchers who are collaborating with counterparts in the European Union, they might need to think about how their data sharing agreements will have to change because data sharing is something that is governed by common EU legislation. The same thing goes for clinical trials, which are also governed by EU law. If there are trials that are being led in the UK but involve patients in the European Union, they might have to find a sponsor that is then on the continent.

Interviewer: Benjamin Thompson

Well, often on the News Chat, Nisha, we say, well what’s going to happen next and what have you. I suppose in this instance, we just kind of don’t know, right?

Interviewee: Nisha Gaind

That’s right. We are all watching the politics very carefully and waiting to find out.

Interviewer: Benjamin Thompson

Nisha, thank you so much for joining me. Listeners, to read more about these stories head over to nature.com/news.

Host: Shamini Bundell

That’s it for this week’s show but before we go, I’d recommend heading over to youtube.com/NatureVideoChannel to have a watch of one of our new videos.

Host: Benjamin Thompson

Yes, this one is all about the hidden blood vessels within bones. Go and check it out. I’m Benjamin Thompson.

Host: Shamini Bundell

And I’m Shamini Bundell. Thanks for listening.