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Interviewer: Adam Levy
Welcome to the Nature Podcast. This week we’ve got maps of tiny minds and stories from a nineteenth century eclipse.
Interviewer: Shamini Bundell
Plus, two fossils reveal what early mammals were doing in the shadows of the dinosaurs. This is the Nature Podcastfor August 10th2017. I’m Shamini Bundell.
Interviewer: Adam Levy
And I’m Adam Levy.
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Interviewer: Adam Levy
There’s a real skill to making a good map and the more detailed the map the harder it is to make. For example, a rail network in a city will likely have a lot of nodes and branches but not too tricky. The roads network is more intricate and might include winding streets and back allies. Below the surface may be a sewer system, adding a whole extra level of complexity. Now, researchers are refining a very different kind of map: brain maps. There’s a long history of maps describing various different chunks and regions of brains. But imagine how hard it would be to make a map that included every single neuron. Well, you don’t have to imagine because this week Natureis publishing a feature and a paper all about these neuroscientist cartographers. The paper is looking at the brains of fruit fly larvae. These maggots can show a couple of dozen different behaviours: simple enough to be study-able, but more than enough to make their minds interesting. I called up paper author Marta Zlatic who’s based at the Janelia Research Laboratory in Virginia to find out why she’s studying these tiny brains.
Interviewee: Marta Zlatic
So what’s interesting about them is what’s generally interesting about the brains of all animals. They have to learn and make decisions about what to do when but what’s very special about the fruit fly larval brains is the fact that they are very compact so it is possible to actually visualise the structure of large portions of the brain. The fruit fly larva offers this unique opportunity to really understand how the structure of neural circuits relates to that function.
Interviewer: Adam Levy
And how simple actually are they? How simple is this brain?
Interviewee: Marta Zlatic
It’s compact. I don’t know how simple it is. I wouldn’t say it’s simple. It has very complex neural circuits capable of pretty complex behaviours.
Interviewer: Adam Levy
How good a map do we now have of the fruit fly larvae brain?
Interviewee: Marta Zlatic
So, bit by bit we’re slowly completing the entire nervous system. Now, how long will it be until we have the entire nervous system? I don’t know. It will be a few years but not very many.
Interviewer: Adam Levy
Of course, the interesting thing about a map is that ideally you could link that schematic to behaviours. What work have you been up to, to do this?
Interviewee: Marta Zlatic
When we have the structural maps then we can go in a targeted way and manipulate specific cell types and then relate the activity to various defects in behaviour or we can manipulate decisions. We can alter the way animals learn. We can induce memories and so we can find out what roles specific circuit motifs in these maps play in behaviour and in decision making or in learning and memory.
Interviewer: Adam Levy
So by tweaking the maggots’ brains, you’re able to find out how different circuits affect different behaviours and how the maggots actually learn things. So what’s an example of a behaviour that you’ve been studying?
Interviewee: Marta Zlatic
So, for example, like all animals, the larvae, they have different modes of locomotion in the same way that a horse can walk, trot or gallop and it has to select which of these to do at any given time point and this selection occurs based on multiple senses at once and now we are looking at how memories are used to influence the decision whether to crawl or to turn or to roll. So it’s really about choice.
Interviewer: Adam Levy
That was Marta Zlatic. Her paper on fruit fly larvae brains is out in this week’s Nature. But that’s not all: there’s also a feature all about these kinds of ambitious brain maps. We’re now joined by the author of that feature whose voice may be familiar to some listeners. It’s former Nature Podcastco-host, Kerri Smith. Welcome back to the studio, Kerri.
Interviewee: Kerri Smith
Hi Adam, nice to be back.
Interviewer: Adam Levy
Kerri, how long has this work to extensively map out brains been under way?
Interviewee: Kerri Smith
Well, it kind of depends which kind of brain maps you mean and it depends which resolution you’re interested in but these ones that we’re talking about in the feature this week are really, really precise. They’re trying to capture every wire, every neuron, and every connection each neuron makes in a given brain or a spec of a brain. And it’s really only in the last kind of – if I’m being generous – a decade, that that’s been possible because technically it’s very difficult.
Interviewer: Adam Levy
And presumably researchers are interested in brains beyond just fruit fly maggots?
Interviewee: Kerri Smith
People are trying to work on bits of more complex brains as well. The adult Drosophila has a magnitude more neurons than the larva so that’s what some people have chosen to work on. Then the next step up would be something like the zebra fish which is a bit more like humans because it’s a vertebrate at least. And people are also working on little specks and crumbs of the mouse brain or they’re trying to look, for example at how many different cell types there might be in the mouse retina.
Interviewer: Adam Levy
What’s the end goal of all this? Is it feasible that one day we could be applying this kind of thing to the human brain?
Interviewee: Kerri Smith
That seems remarkably difficult to imagine at the moment but I think particularly because these techniques are just really invasive, right. You’ve got to stimulate neurons with light and chop brains up and that’s not anything we’d like to be doing in the human brain but even in this tiny little useless animal with its 30 behaviours, you can still ask yourself this really fundamental question: how is the brain making behaviour?
Interviewer: Adam Levy
And how useful are these schematics for answering those questions? Do they give you the complete picture or are there aspects of the brain that you need to know about that a map just can’t tell you?
Interviewee: Kerri Smith
In all of this conversation we haven’t mentioned the fact that there are layers of complication involving neurochemicals, involving all the little iron channels than open on cells to convey signals from one place to another and none of that is really factored into these earlier models so that could be – that’s going to keep people busy for a number of decades.
Interviewer: Adam Levy
That was Kerri Smith. Here feature is out now at nature.com/news and make sure to check out Marta’s paper at nature.com/nature.
Interviewer: Shamini Bundell
Still to come in the news: genetically engineered salmon finally makes its way onto the dinner plate and a surprisingly simple intervention to lower the risk of premature births. Now though, north-eastern China has proven to be a real gold mine for ancient vertebrate fossils. Palaeontologists have dug up feathered dinosaurs, early bird relatives, amazing flying pterosaurs and more recently, some unusual early mammal relatives. Today’s mammals have flourished into a wide range of shapes and sizes, fitting them into a variety of ecological niches. They come in three basic groups: the placentals (that includes us); the marsupials, and the monotremes. Monotremes are those peculiar egg-laying mammals like the duck-billed platypus. But during the Mesozoic, around the time of the dinosaurs, there was a completely different array of mammal-like animals. Many of them had lifestyles that appeared to be eerily similar to their modern relatives. Two new fossils from the Tajikistan formation of north-eastern China are estimated to be around 160 million years old. They show just how varied the lifestyles of these primitive mammals were. Reporter Geoff Marsh spoke to palaeontologist ZheXi Luo at the University of Chicago in the United States who led the studies.
Interviewer: Geoff Marsh
So usually when I do these interviews people are just calling me from their office but you’re actually in the, sort of, fossil preparation lab.
Interviewee: ZheXi Luo
Yes, very much so.
Interviewer: Geoff Marsh
And the reason I’m speaking to you today is because you’ve, this week, published two new early mammal fossil papers that date back to about 160 million years ago. Is that right?
Interviewee: ZheXi Luo
That’s absolutely correct. We have named them as Maiopatagium and Vilevolodon. Maiopatagium means mother with the wings and we can safely call that the first winged mammals. Vilevolodon means colliding tooth and these are, to be very precise, extinct relatives to modern mammals, although they are not modern mammals themselves.
Interviewer: Geoff Marsh
We’ll discuss where they fit into the sort of mammalian family tree in a moment but the first thing that struck me is that if we look today at the mammals, they are such a diverse group; we’ve got swimming and flying and gliding, living under the ground, in the trees. There was also a similarly astonishing diversity 160 million years ago?
Interviewee: ZheXi Luo
Yes. In the last 10 years or so we have discovered many very different ecological adaptations in these early mammals. To put the present discoveries in the broader context, they have already developed colliding adaptations just like some of the modern mammals.
Interviewer: Geoff Marsh
So these two new mammal fossils that you’re reporting this week, they were both gliders, they were like the flying squirrels that we know today?
Interviewee: ZheXi Luo
Yes, exactly. They are preserved with this gliding membrane. They are also herbivorous mammals and this is entirely consistent with what the modern mammalian colliders are in all regards except they did not have some of the critical modern mammal features which excluded them from the modern mammalian group but only placed them as near relatives to modern mammals.
Interviewer: Geoff Marsh
Now there’s lots of confusing terminology in palaeontology with all the different group names but there’s one I think we should talk about which is the haramiyids which both these specimens fit into.
Interviewee: ZheXi Luo
Yes and the haramiyids have already developed teeth, specialised for herbivorous feeding since Triassic and early Jurassic and essentially they are very effective in grinding plants.
Interviewer: Geoff Marsh
And I guess you probably have some idea about what kind of plants they would have been using those teeth to grind because this is – we’re talking about a time now before flowering plants even evolved, aren’t we?
Interviewee: ZheXi Luo
That’s another very interesting aspect. In late Jurassic, flower plants have not yet become a dominant part of the plant world but their plant eating teeth are really good at grinding down very soft plant parts or some nutritious plant parts such as seeds or the seed bearing part of the plants. Whereas, the modern mammal gliders are associated with flower plants as if this ecological association of gliding and herbivory happened twice in very different circumstances.
Interviewer: Geoff Marsh
Certain eras were dominated by dinosaurs, plesiosaurs, pterosaurs, but in all the gaps between those spaces we mammals were allowed to diversify.
Interviewee: ZheXi Luo
Yeah and we did a pretty good job with that as well.
Interviewer: Geoff Marsh
Have you got any idea about the reproductive biology of these animals?
Interviewee: ZheXi Luo
We can speculate to some extent because the modern mammals have monotremes and the monotremes are egg-laying mammals. We can assume that before the rise of modern mammals, they probably just had the same egg-laying reproductive strategy.
Interviewer: Geoff Marsh
Gliding herbivorous egg-layers that were less scared of dinosaurs than was once thought.
Interviewee: ZheXi Luo
That’s absolutely true and you really put it in a very good way.
Interviewer: Geoff Marsh
Do we know that at the same time as these flying herbivores that you found – do we know what kind of mammal would have been the ancestor of all three modern groups of mammals today?
Interviewee: ZheXi Luo
I think probably some very small insectivores but this does not preclude that extinct mammals would differentiate themselves into a spectacular amount of diversities.
Interviewer: Adam Levy
That was palaeontologist ZheXi Luo talking to Geoff Marsh. Find the paper in the usual place.
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Interviewer: Shamini Bundell
This week I learnt a new word: umbraphile. An umbraphile is a person that travels the world chasing eclipses: literally, shadow-lover. On the 21stof August, umbraphiles will gather in particular regions of the US. It’s the first time a total eclipse has crossed the span of America in almost a century. Many umbraphiles are hooked on the majesty of the spectacle itself but for some it’s scientifically fascinating too. One shadow lover, David Baron, has written a book on one very special eclipse.
Interviewee: David Baron
It didn’t take me long to discover that the best eclipse stories are not from today but from the nineteenth century because the mid to late nineteenth century was a time when total eclipses were not just fascinating natural spectacles but they were really important to science.
Interviewer: Shamini Bundell
David’s book is about the eclipse of 1878 which was visible across America’s Wild West: darkening skies from Montana to Texas, via Wyoming. In a guest slot for this week’s show, Scientific American’s podcast host, Steve Mirsky, sat down with David to find out more.
Interviewer: Steve Mirsky
In the book you talk about the three big scientific issues that research done during the very brief period of a total solar eclipse could help you figure out.
Interviewee: David Baron
One of the most important – probably one of the two most important – was trying to figure out what the sun is made of and what the corona, which today we know as the sun’s outer atmosphere, what it was made of and that’s really what made total eclipses most important in that era, was the advent of spectroscopes which enabled scientists to actually look at the light coming off heavenly bodies and look for fingerprints. What particular colours would show up in a spectroscope that would tell you what chemical elements were up there but also very important was using the eclipse to look at what’s right around the sun in the inner solar system. There was good reason to believe that Mercury was not the closest planet to the sun. Mercury did not behave quite the way it should based on Newtonian mechanics and so astronomers assumed that there was another planet, maybe several planets, closer to the sun than Mercury which were tugging on that planet and causing its orbit to be perturbed and I should say the planet generally was referred to as Vulcan, for the Roman God of fire, because it was so close to the sun it must have been a very hot place. And it won’t surprise anyone that of course we know in hindsight that there is no Vulcan and they didn’t find anything but that wasn’t clear at the time. And thirdly, any time you had a total eclipse, it was a chance to update your equations of the moon’s motion. So astronomers back then were actually very good at precisely identifying where in the skies various celestial objects were and then would use math, would make calculations, forecasting where those celestial objects would be in the future and that included charts of where the moon could be found on any given night weeks in advance.
Interviewer: Steve Mirsky
The way you tell the story of the eclipse watching and study for this 1878 eclipse: there’s a whole cast of fascinating characters and we can’t get into all of them but who did you find really interesting and what were they doing for the eclipse and why were they out there?
Interviewee: David Baron
The first person who just sold me on this story was Thomas Edison. 1878, that was the year he had just come up with the photograph and as soon as he came back from Wyoming, he started work on a new invention and that was the incandescent lamp. So wedged between his two most famous inventions he has these several weeks when he goes out to the Wild West to see a total eclipse. First of all he had invented a device for the eclipse called a ‘tasimeter’, which was an incredibly sensitive heat detector, essentially an infrared detector that he was going to use to study the solar corona to see if that mysterious aura around the eclipsed sun gave of heat as well as light.
Interviewer: Steve Mirsky
This tasimeter that he creates, it really doesn’t work very well at all but in a way he does anticipate infrared telescopes.
Interviewee: David Baron
That’s correct. In essence, what he had developed was an infrared telescope, that is when he attached his tasimeter to a telescope and it was a clunky device. At the time there was one newspaper report that said the tasimeter was going to be bigger than the photograph and obviously that never happened but it’s interesting that right after the eclipse Edison was talking to the press about how he wanted to use his tasimeter for astronomy generally and that was to attach it to a large telescope and to look for objects in the heavens that you couldn’t see with visible light but you could detect their heat. And in essence that was the idea for infrared astronomy.
Interviewer: Steve Mirsky
So he’s out there and a whole bunch of other people are out there. We have to talk about Maria Mitchell because she’s such a fascinating case.
Interviewee: David Baron
Maria Mitchell, back in the nineteenth century, was by far the most famous female scientist in America. She had discovered a comet back in the 1840s and in 1878 at a time when there were all of these men who were assembling eclipse expeditions out to the west and receiving government support and she was excluded. Mariah Mitchell decided to take it upon herself to put together an all-female expedition to Denver, both as a scientific endeavour but also as a bit of political theatre to prove to an American public, a sceptical public, that women could be scientists.
Interviewer: Steve Mirsky
The two biggest things that maybe come out of the eclipse are Maria Mitchell’s exhibition, really, to the public about what women could do in science and the overall boosting – there’s almost like a Sputnik effect. You write about how American science really started to rise up and match European science.
Interviewee: David Baron
The era is just so interesting because this is the gilded age in America – a time when America was getting rich and in fact America’s reputation was that all we cared about was getting rich but from an intellectual stand point America didn’t get much respect. Europe was the clear centre of western culture. That’s where most of the respectable literature and art and music came from. And Europe was the clear centre of science in the world. But there was this small group of American scientists that were determined to show that we could take on Europe and the eclipse of 1878 was exactly what they needed; it was a high profile event that the whole American public could get involved with. So in that way the eclipse of 1878, its importance goes beyond the science itself and more into its effect on American culture and American politics.
Interviewer: Shamini Bundell
That was author and umbraphile David Baron talking to Steve Mirsky. You can listen to the longer version of that interview on Science Talk: Scientific American’s weekly podcast. Find that at scientificamerican.com or on your favourite podcasting app.
Interviewer: Adam Levy
Time now for this week’s News Chat and Richard van Noorden has popped down to the studio. Hi Richard.
Interviewer: Richard van Noorden
Hi Adam.
Interviewer: Adam Levy
So, genetically engineered salmon have finally arrived on Canadian dinner plates. It’s been a really long journey to get to this point, right?
Interviewer: Richard van Noorden
Yes, this is AquaBounty Technologies, a company in Massachusetts and they announced in August that they’ve sold some of their genetically engineered salmon to customers in Canada for eating. You really wouldn’t be able to tell the difference between a genetically engineered salmon and a normal salmon but they reach market six in about 18 months. Normal salmon takes twice as long.
Interviewer: Adam Levy
And they weren’t genetically engineered recently. This technology has actually existed for some time.
Interviewer: Richard van Noorden
It’s quite astonishing when you think of all the fuss about gene-editing and modern gene-editing. This was first done 25 years ago. In 1989 scientists gave salmon a growth hormone gene from another salmon and some regulatory elements from a third species and this allows the salmon to produce a continuous low level of growth hormone. AquaBounty formed in the 1990s it’s then spent almost 25 years waiting to be approved for consumption, which the USFTA did in November 2015 and Canadian authorities did 6 months later. But it’s Canada where the fish has been sold first for food and that’s because political battles in the US have stalled the salmon’s entry into the market place. There’s a law sitting at the budget for 2017 and it includes a provision that tells the FTA to forbid the sale of transgenic salmon until it’s developed a programme to tell customers that they’re buying a genetically engineered product. Right now in Canada the salmon is not labelled as genetically engineered. And in America this is still very inflammatory. The senator who inserted this provision in this budget law has called the salmon fake fish and activists are still demanding regulators to reconsider their decisions.
Interviewer: Adam Levy
And although people will have eaten genetically engineered food before in America and in Canada, this is the first genetically engineered animal that people might eat.
Interviewer: Richard van Noorden
Yeah, it’s the first time that a genetically engineered animal has been sold for food on the open market. So AquaBounty’s chief executive, Ron Stotish, says the larger the market is viewing it as a predictable and sustainable source of salmon or so he hopes.
Interviewer: Adam Levy
25 years: a quarter of a century to get to this point for just one species. Is there any expectation that other animals might arrive on dinner plate a little more efficiently and quickly?
Interviewer: Richard van Noorden
Well someone’s got to be first so they’ve fought this battle. They’ve navigated all the regulatory systems and they’ve got some consumer acceptance and everyone else can just follow in their paths so yes you would expect other genetically engineered animals for food to follow more quickly. If they had failed it could have killed off the engineered livestock industry for generations says James West. He’s a geneticist who co-founded AgGenetics.
Interviewer: Adam Levy
So their attitude is sort of – better late than never.
Interviewer: Richard van Noorden
Exactly.
Interviewer: Adam Levy
Let’s move onto our second story which is about premature birth, which to me seems like something with incredibly complex origins but there’s a new study which reveals there might actually be quite a simple factor that influences it.
Interviewer: Richard van Noorden
Yeah, this is an analysis of medical records from almost 3 million pregnant women in California and it suggests that getting better sleep might help to address the issue of premature birth.
Interviewer: Adam Levy
How big a factor actually is sleep in influencing when a baby is born?
Interviewer: Richard van Noorden
Well, women have been diagnosed with sleep disorders such as insomnia or sleep apnoea are twice as likely to deliver their babies more than six weeks early, than women without such a disorder. And in absolute numbers we’re talking about 5% of women with sleep issues delivered their babies at less than 34 weeks of pregnancy. A typical gestation is 40 weeks, compared to 2.9% for women without a diagnosis, without a sleep problem.
Interviewer: Adam Levy
This seems like something that could quite easily have been spotted earlier. it’s not a very complicated thing to investigate, I wouldn’t have thought.
Interviewer: Richard van Noorden
Yeah, it is odd that this study hasn’t been done before but what this is effectively is scientists who are mining huge quantities of historical data to try and pick out signals, and this is called the pre-term birth initiative. It’s a 100 million US dollar effort to study prematurity and the researchers here got loads of birth certificate, millions of birth certificates scrubbed of identifying information but linked to hospital records and again they found that this sleeping disorder link just stared out at them as one of the main things that then led to premature babies. Now, it doesn’t mean that a lack of sleep could be a direct cause of the early births because this is a correlation but a hugely statistically significant one, so what’s going on here? Perhaps it could trigger other processes like inflammation that eventually result in the premature birth. This is all very uncertain and I think the researchers are just excited to see this relationship because they just don’t know what interventions might make a difference to prevent premature births.
Interviewer: Adam Levy
Now that we know that sleep may be a factor in leading to early births, are there steps we can take to improve the quality of sleep that people have?
Interviewer: Richard van Noorden
Well, absolutely. We all know that there are non-medical interventions: don’t watch screens before bedtime; make sure that your sleep environment is very dark; get the temperature right. And essentially, what doctors are saying, according to Louis Muglia who’s the director of the Center for Prevention of Preterm Birth at Cincinnati Children’s Hospital in Ohio, he’s saying, well I counsel women on how to have the best pregnancy outcome and now he might start asking, do you get a good night’s sleep, which is not really a question which doctors have thought to ask before.
Interviewer: Adam Levy
Richard, thanks for joining us. For more on both stories head to the usual place: nature.com/news.
Interviewer: Shamini Bundell
As ever, we love to hear from you. Drop us an email – podcast@nature.com– with your thoughts on the show.
Interviewer: Adam Levy
Or, if your thoughts can be squeezed into 140 characters or less, drop us a tweet, @naturepodcast. Stay tuned for next week’s show for a red super giant mystery. I’m Adam Levy.
Interviewer: Shamini Bundell
And I’m Shamini Bundell.
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