Nature Podcast

This is a transcript of the 21st January 2016 edition of the weekly Nature Podcast. Audio files for the current show and archive episodes can be accessed from the Nature Podcast index page (http://www.nature.com/nature/podcast), which also contains details on how to subscribe to the Nature Podcast for FREE, and has troubleshooting top-tips. Send us your feedback to mailto:mailto:podcast@nature.com.

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Adam Levy: This week, the remains of a crime scene emerge through the sand near an ancient lake.

Marta Mirazon Lahr: I never expected in any dream that I would find the remains of a massacre or the earliest massacre recorded in history.

Kerri Smith: And the brain sensor that melts away after use.

John Rogers: In the future we envision a kind of bioresorbable, bioelectronic medicine, so to speak.

Adam Levy: Plus what happens when domesticated chickens go wild? This is the Nature Podcast for January, the 21st 2016. I'm Adam Levy.

Kerri Smith: And I'm Kerri Smith.

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Kerri Smith: Humans have been carefully domesticating animals for thousands of years, but sometimes their hard work is reversed. Ewen Callaway went to meet the feral chickens of Hawaii. Nature 529, 270–273 (21 January 2016)

Ewen Callaway: If you speak to anyone who has visited the Island of Kauai, they'll probably mention two things. Number one, the place is gorgeous: white sand beaches that go on forever, 1000m- deep ravines. The whole island is a postcard. And, number two, there are chickens everywhere: on beaches, in parks, even outside the KFC. Kauai wasn't always full of feral chickens. Eben Gering, an ecologist at Michigan State University, says that locals blame it on a pair of hurricanes in the 80s and 90s.

Eben Gering: The local residents say that the hurricanes blew the chickens all over the island. The destruction those storms wrought on the island was so severe that, you know, the grocery stores were closed, the power was out, people were struggling to find clean water and so on. And so, it would make sense that at that point in time a lot of backyard chickens would be left to their own means.

Ewen Callaway: They went to the jungles where they encountered their distant cousins?

Eben Gering: Yeah, something like that.

Ewen Callaway: A couple of years ago, intrigued by the heritage of the chickens, Gering travelled to Kaui to gather some of their DNA. He discovered that they are probably hybrids between regular domestic fowls that escaped and Polynesian chicken that have been roaming the Jungles of Kauai for hundreds of years. Now he is back on the island to learn more about the feral chickens.

Eben Gering: To learn how this diverse gene pool that hybridization has created is being moulded by the selective environment in which these animals live.

Ewen Callaway: Or in other words, to figure out what happens when chickens go wild. In order to study them, you first have to catch them. But the chickens can be wary. We drove to a popular grazing spot for the chickens: a grassy outlook near a waterfall.

Dominic Wright: So this morning we are headed for the lookout falls just near Opaekaa.

Ewen Callaway: Evolutionary Biologist Dominic Wright has a simple method of catching the birds. He ties a piece of string to his big toe and then ties the other end to a spring loaded net. Then he waits.

Dominic Wright: As long as you don't focus your attention on the chickens, it's not too hard. The problem is as soon as you – the reason it has to be toe operated – it's just a piece of string attached to the trigger. As soon as you bend down or focus any of your attention on them, the birds immediately get suspicious and start moving backwards. So, we have kind of, in true field biologist style, have settled on this more ad hoc solution, i.e. a piece of string attached to my toe to trigger the device.

Ewen Callaway: After our short drive to the waterfall, Dominic sets up the trap. I gather this involves a lot of waiting…

Dominic Wright: Absolutely. The nicest thing with this is it kind of involves waiting in kind of, rather beautiful surroundings so it is not nearly so bad. The greater our insouciance, the more relaxed the chickens are.

Ewen Callaway: It takes about 15 minutes but finally a hen is tempted by the seed. We casually look away and then Dominic's toe pulls the trigger.

Dominic Wright: We activated our little goal trap. And now, we are just gently removing the female and we have a little cage for her. Just pop her in there.

Ewen Callaway: With our bird in hand, we drive back to the lab where the chicken will be sacrificed and its anatomy examined.

Dominic Wright: So that's a body weight of 1204 grams, so that's an incredibly heavy female. That will be much more akin to a domestic size female. Huge in comparison to some of the other birds we've had.

Ewen Callaway: This stout specimen is one of the largest feral chickens we have seen and size is just one of the many traits that evolution has tweaked in the feral chickens after 30 years on the loose. Their plumage looks more like their wild ancestors: brilliant reds and greens in roosters and drab browns in hens. But the occasional white feather hints at their domestic ancestry. And the researchers have noticed that they often sit on their eggs before they hatch – a behaviour that was bred out of domestic chickens to make their eggs easier to collect. For Gering, these changes offer important lessons on how animals respond to new environments and besides he just loves to watch it in action.

Eben Gering: Fundamentally, I am just fascinated with evolution. That's the real, the simplest answer.

Ewen Callaway: That was Eben Gering at Michigan State University. And before him Dominic Wright who is at Linköping University in Sweden.

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Kerri Smith: Ewen Callaway there, who wrote about his visit to Hawaii in a feature. Plenty of chicken pics up there as well.

Adam Levy: Coming up in the news chat; researchers are being kept in the dark after a French clinical trial went wrong.

Kerri Smith: But first Noah Baker reports on a new way of monitoring the injured brain. Nature (2016)(Ambulance and hospital sound effects)

Noah Baker: Every year in the US, hundreds of thousands of people are admitted to hospital with traumatic brain injuries. The most severe cases result from things like car crashes or gun shots and they often require surgery.

John Rogers: Folks who suffer from traumatic brain injuries… When they are admitted to the emergency room one of the first things that the neurosurgeon will do, will be to insert sensors in to the intracranial space.

Noah Baker: That's John Rogers from the University of Illinois in the United States. The sensors he's talking about measure the pressure and temperature of the intracranial space, the area inside the skull which houses the brain.

John Rogers: Pressure and temperature are critical parameters that dictate, you know, an individual's health. If those parameters fall outside of the very narrow window then the surgeon needs to take immediate action otherwise, you know, one is facing a risk of brain damage.

Noah Baker: These sensors are a vital part of medical practice, but the current technology is far from perfect.

John Rogers: The standard device for this type of application, you know, involves hardware that inserts in to the intracranial space and then connects to external data acquisition equipment with hard-wired connections and they remain in operation during that critical risk period for the patient, which might be several days to a couple of weeks as they recover from their injury. The wires are coming out through a suture site and that interface point represents a nidus for infection, inflammation and haemorrhage. And then furthermore, you know, because the devices are not needed forever but just through that critical operational period, they have to be extracted using a surgical procedure and that procedure opens up the patient to additional risk.

Noah Baker: Rogers and his team of engineers and clinicians are trying to find a solution to some of these problems by making a sensor which will simply melt away when its work is done; what researchers call, bioresorbable.

John Rogers: So the vision was to create a device platform that could insert into the intracranial space, measure pressure and temperature with the same accuracy and precision of the current clinical gold standards, but build them out of a complete suite of materials that would biodegrade over time, simply dissolve and disappear completely without a trace, thereby eliminating the need for surgical extraction.

Noah Baker: That means using materials which are unconventional in electronics; copper wires just won't cut it.

John Rogers: There are other metals that, you know, are electrical conductors at a decent level, are relevant for these kinds of applications, that are at the same time biodegradable. So, magnesium is one example. It reacts to form magnesium hydroxide which is biocompatible. In fact magnesium is a recommended component of a daily diet, so if you look at a multivitamin it will have magnesium in it. So we used magnesium.

Noah Baker: Roger's team combined the magnesium with a host of other body friendly materials like silicone to build a temperature and pressure sensor. Then they made it wireless. That reduces the risk of infection at the site where the wires exit the skull.

John Rogers: The wireless embodiment involves two subsystems. One of those subsystems is the actual sensor that goes in to the intracranial space. The other subsystem provides wireless data communication that mounts just under the skin of the skull. So it's outside the intracranial space. Now the patch in the current embodiment is not 100% bioresorbable. It's about 85% bioresorbable but because the device, that part of the device that subsystem, is located outside of the intracranial space there is very little risk to the patient for a small residual amount of non-bioresorbable material just under the skin.

Noah Baker: The team can see these sorts of devices being used in other organs and systems for a wide range of other functions.

John Rogers: These same materials could be, you know, configured in different ways to measure other properties of clinical interests. So I think one of the reasons why we are excited is because, you know, we have a technology that I think is addressing a very specific and an important known clinical need, but it's a platform, right, so we can imagine different kinds of sensors used in other parts of the body as well. And not just for sensing, it turns out you can do electrical stimulation, you can do thermal therapy, you can do programmed drug release. So in the future we envision a kind of bioresorbable, bioelectronic medicine, so to speak, where the devices are sensing but they are also intervening in a therapeutic sense all in a hardware platform that eventually bioresorbs and disappears after the function is no longer needed.

Noah Baker: The device has been shown to be effective in rats but it's yet to be tested in humans.

John Rogers: We think we have a set of materials and a practical manufacturing route. Where we're going now is to demonstrate the technology in larger animal models with more advanced device designs and materials to allow stable operation of the sensor beyond the time frames that we are demonstrating now just to kind of over engineer the functionality and eventually step through the regulatory framework that's ultimately needed to, you know, use this kind of device in humans and that's the kind of where we are going. This is the early days on that effort but we don't see any fundamental road blocks for getting there.

Kerri Smith: That was John Rogers speaking with Noah Baker. You can find out more about the sensors in the paper at http://www.nature.com/nature.

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Adam Levy: Stay tuned for research into an ancient murder mystery but before that it's time for the Research Highlights with Corie Lok.

Corie Lok: Since the industrial revolution of the 1800s, the oceans have absorbed a lot of the heat from the planet's warming climate. New research shows that the oceans have taken up nearly half of all that heat just in the past two decades. Scientists looked at ocean temperature data dating back to the mid-nineteenth century. They found that most of that heat has built up in the upper layers of the oceans but more than one-third of the heat was found below 700 metres. That amount is rapidly increasing as the climate warms. The paper was published in the journal Nature Climate Change. Nature 529, 258 (21 January 2016)Astronomers have spotted the brightest ever supernova. The exploding star is more than a hundred times brighter than ordinary supernovae and about twice the brightness of the last record holder. The supernova is low in hydrogen and seems to come from a massive galaxy that is brighter than the Milky Way. The researchers are baffled by how it originated and what is fuelling it. They are now using the Hubble Space Telescope to figure out more about the supernova's home galaxy. You can find the study in the journal Science. Nature 529, 259 (21 January 2016)

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Kerri Smith: Adam, I've got to warn you this next story is a bit gruesome.

Adam Levy: That's okay. I'm very brave.

Kerri Smith: Okay, then if you're sure. Well it concerns a brutal case of mass murder. A whole community group by the look of it: men, women and children.

Adam Levy: What happened?

Kerri Smith: They were shot with bows and arrows or hit in the head.

Adam Levy: My God! When was this?

Kerri Smith: Well, it was about 10,000 years ago. And that makes it the earliest known case of violence involving two groups. The researchers are even calling it the earliest case of warfare. The skeletons were found poking out of the ground in a region of Kenya already well known for more ancient human remains. Twelve skeletons were still lying in the positions they had died in – ten or so more, in fragments. Some of them had arrow heads embedded in them made of a black rock called Obsidian sharpened to a point. Shamini Bundell has put on her detective hat and picked up the case, ably assisted by chief case investigator Marta Mirazon Lahr whose team discovered the crime scene at a place called Nataruk near Lake Turkana. Marta is still near the field site now hence the wind you'll hear in the background. Nature 529, 394–398 (21 January 2016)

Marta Mirazon Lahr: So Nataruk today is a barren area of semi-desert and yet what we find is that the 10,000 years ago it was the edge of a lagoon very close to the edge of actually Lake Turkana and it was full of animals and wild life, which obviously also attracted hunter-gatherers.

Shamini Bundell: How did you find the site and the human remains?

Marta Mirazon Lahr: The site was actually discovered by this young man called Pedro, Pedro Ebeya So Pedro has been working with us since 2009. So the first day of the season in – the field season – in 2012, Pedro said through translators because we don't speak the same language. He said, I have got bones for you. So we went to the site and indeed on the surface there were broken human remains but then I saw the back of the skull of a person that was just eroding from the ground and I thought well, either this is just a back of a skull broken or there is a whole person there. The chance of finding articulated skeleton is small so we were extremely excited when we found the first one and it just so happened that the first that we excavated was lying face down – that's why we saw the back of the head – and the head had been smashed in on both sides. And then the second skeleton to come out of the ground was another one found face down, another man lying prone on his stomach and he had the Obsidian bladelet embedded in the skull, so by then we thought okay, here we have something really special.

Shamini Bundell: Now, that sounds pretty violent. So they're the kind of injuries that would definitely kill you?

Marta Mirazon Lahr: Yes, so the injuries suffered by this man crushed both the side and the front of the head inwards, breaking, causing a number of fractures that radiated throughout the skull and the neck is also broken. So, I'm sure the second blow killed him.

Shamini Bundell: This unfortunate man was only one of a number of murder victims found at the site. What else did you find when you excavated?

Marta Mirazon Lahr: There were twelve skeletons that were still articulated in the ground, some better preserved than others and of those ten had evidence of having died violently. So among these, four had injuries that are consistent with projectiles, presumably bows and arrows. Another four skeletons have blows to the head and then there are some individuals that show fractures to the knees, to the hands, to the ribs – all consistent with the pattern of conflict wounds. Among the most unusual finds for me are actually, one was this young lady who was found sitting and she had her hands crossed between her legs, lying on the feet that were also crossed. That may suggest that she was bound at the time of death and she was pregnant so that was actually a moment that we all stopped to think.

Shamini Bundell: Would the range of ages and both sexes being present – this looks like a whole community.

Marta Mirazon Lahr: Yes, my interpretation is that this was a small community, a foraging party, and that they were surprised by an attack.

Shamini Bundell: Oh! It's pretty brutal, huh?

Marta Mirazon Lahr: Yes, actually it is. But that's one of the things – I think that there are cases of serious violence before. There is even a Neanderthal that has lethal injuries to the head. But we don't know if it was a one to one situation or if it involved many individuals. I think that what is unique about Nataruk is that it provides conclusive evidence of something that must have been an inter-group conflict. Evidence for that before you have sedentary society, before you have villages and cemeteries. That is very unique.

Shamini Bundell: Is this mystery solved now or are there more questions you want to answer?

Marta Mirazon Lahr: No, I think that the discovery at Nataruk raises a number of questions, so was this a foraging party? Did they have a base camp somewhere? What did the base camp look like? What was it that they had that was worth raiding for? We don't know if they killed everybody. Perhaps others survived or were taken. Even to think well where are the sources for the Obsidian that somebody was exploiting to make these weapons?

Shamini Bundell: So you have got lots of questions for future episodes of CSI like Turkana?

Marta Mirazon Lahr: Well, part of the work of the archaeologist and the anthropologist is to act like detectives in a crime scene. In the team we have people who are trained in Physical Anthropology and Osteoarchaeology which for skeletons are the same skills that forensic scientists have. I never expected in any dream that I would find the remains of a massacre or the earliest massacre recorded in history. It had never crossed my mind.

Kerri Smith: That was Marta Mirazon Lahr. Case closed? Not exactly. Excavations continue apace at Lake Turkana, looking for remains from all periods of human prehistory. To find out more about this murder mystery make sure you head over to our YouTube channel where there is a video about the finds. That's http://www.youtube.com/naturevideochannel.

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Adam Levy: Time now for our news chat and Ewen Callaway is back with us. Hi Ewen.

Ewen Callaway: Hello!

Adam Levy: Our first story is regarding a clinical trail which tragically went very wrong in France. What actually happened here? Nature 529, 263–264 (21 January 2016).2016.19189

Ewen Callaway: This was a clinical trial in Northern France in the city of Rennes. It was operated by a company called Biotrial which was doing safety tests for a Portuguese company called Bial. And what happened is that five patients, who were taking this drug, fell ill quiet severely and when one of them died over the weekend his brain showed signs of necrotic damage and then haemorrhaging.

Adam Levy: The main story here though seems to be what we don't actually know.

Ewen Callaway: Yeah, the company has yet to release a lot of details about this incident. What drug they were testing? They have only said the general class of drugs. How many people received this drug previously? The safety tests that occurred in animals before humans got this drug. The dosage – I mean, you could just go on and on about the questions that are unanswered here.

Adam Levy: What would researchers actually be able to do with this information if they had it?

Ewen Callaway: The first thing people want to know is what was this drug that these people were given. The company has said that the drug inhibited an enzyme called fatty acid amide hydrolase (FAAH) and what this enzyme does, it's active in the brain and it is part of what's called an endocannabinoid system which is a system of neuro transmitters and neuro receptors, the same ones that Cannabis acts on. And the goal of drugs like this is to simulate some of the aspects of Cannabis without the negative side effects, namely a lot of people have looked at drugging this pathway to treat pain.

Adam Levy: So what stages were the clinical trials at?

Ewen Callaway: So this was what is called a phase one trial. It's, as its name implies, the first trial that's done in patients and it's only done to test for safety of the compound. It's generally done in people who don't have health problems, who're healthy volunteers who are generally paid for their time.

Adam Levy: And do we have any idea what might have caused these off-target effects of this drug?

Ewen Callaway: You mention this term off-target effects and that's something we don't even know. So we know this, this drug, is designed to inhibit this molecule in the endocannabinoid pathway, basically creating more endocannabinoid circulating to the brain. But it's possible – scientists have told me – that this compound is inhibiting or altering other proteins. We really have no idea what these are. In hopes of identifying what even this drug is some scientists have looked to the patent filings of this company and have identified a candidate molecule. As of today it has not been confirmed but they are now trying to model what are potential off-target effects of this compound.

Adam Levy: There is always some risk that a clinical trial may have adverse effects like this. Is there any reason though to think that this trail could have been operated in a safer way?

Ewen Callaway: I don't think we have enough information to answer that question, honestly. Clinical trial regulations in France are very severe. So, you've got to assume that the company did all the due diligence there. They did safety testing in animals. You know, this never would have been approved if regulators had thought it was going to cause these kinds of problems.

Adam Levy: So looking forward, do we expect to find out some more information about what happened here?

Ewen Callaway: I think eventually. There was a similar incident in a clinical trial in the UK, maybe a decade or so ago. An official enquiry was launched and, you know, had a public report, but my colleague in France who has reported on this as well, has said that French investigations tend to be very tight-lipped. So it could be some time before we actually know what's gone on here.

Adam Levy: On now to our second story. A few days ago the WHO, the World Health Organisation, announced that Ebola had been stopped in West Africa and just a couple of hours after that a case of a death from Ebola was announced. How did this happen in such short succession?

Ewen Callaway: What was announced – it was the first time that the three Ebola endemic countries – Sierra Leone, Guinea, and Liberia – had all effectively stopped transmission which means it had been 42 days since the last case. What happened though was, you know, basically hours later a young woman in Sierra Leone died of what was confirmed to be Ebola and the WHO is still investigating what cause this. But most likely explanation is that she contracted Ebola from somebody who was latently infected. We didn't know this before, but we have now learnt that even after somebody survives Ebola, they carry the virus in certain areas of their body – in semen, around their eyes – and this virus can potentially infect other people, I mean, it's happened numerous other times.

Adam Levy: How big a setback is this?

Ewen Callaway: You know, the WHO, when they announced that Ebola transmission has stopped across West Africa, they said that this sort of thing was likely. So, they were kind of planning forward, they were expecting, they weren't trying to get peoples' hopes up in being very celebratory. It shows that despite more than an 11,000 deaths and 20,000 cases, hospitals may be aren't watching as closely as they should for Ebola relapses. This woman travelled some distance on public transport, she went to hospital and reportedly was sent back with clear Ebola symptoms. So, I think, you know, this should be a wake-up call.

Adam Levy: Ewen. Thank you very much for joining us. As always, you can find all those stories at http://www.nature.com/news.

Kerri Smith: That's all we've got time for this week. As always we would love to hear your thoughts on the show so drop us an email at mailto:podcast@nature.com or tweet us @NaturePodcast. Hope to hear from you soon. I'm Kerri Smith.

Adam Levy: And I'm Adam Levy.

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