Nature Podcast

This is a transcript of the 23rd October 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 podcast@nature.com.

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Adam Rutherford: Coming up in this week's show a surprising finding from a stationery cupboard.(Sound of peeling tape)

Seth J. Putterman: People studying lightning get all excited about the possibility of getting 10 kilovolt X-rays out of lightning and here we can peel a tape and get 50 KV X-rays out of peeling tape.

Kerri Smith: And how putting rock samples in plastic bags might throw out your dating methods by, billions of years.

Birger Rasmussen: There have been papers published that were claiming, sort of new biomarkers based on compounds from plastic bags and it certainly puts a bit of a question mark in a lot of biomarker studies of these very old rocks.

Kerri Smith: This is the Nature Podcast. I'm Kerri Smith.

Adam Rutherford: And I'm Adam Rutherford.

Adam Rutherford: Since the discovery in the 19th Century of one of the most famous fossils ever, archaeopteryx there has been speculation and research into dinosaurs with feathers. This week we publish a discovery of a small Jurassic creature by a team from the Chinese Academy of Sciences. No they indeed do not have feathers and it has got a carnival style plume as well. To talk us through the significance of our ancient feathered friends, one of Nature's best preserved fossil's biology Editor Henry Gee has joined us in the pod. Henry, since archaeopteryx, what have we learned about where feathered dinosaurs fit into evolution? Nature 455, 1105–1108 (23 October 2008)

Henry Gee: People have long suspected that dinosaurs would have had feathers, but this was only made real as it were in the 90s when some spectacular discovery started coming out of China; dinosaurs with feathers on, really, and truly feathers and kind of hairy stuff that people call protofeathers but are certainly a kind of fluffy skin covering to a lot of these carnivorous forms.

Adam Rutherford: And given that these feathers were developing on some dinosaurs which were flightless, what function did the feathers have?

Henry Gee: Well clearly, it wasn't for flying. People have had all sorts of ideas about this. They could be just insulation, they could be sexual display and they could be all of these things and there's even some rather more wild ideas that some of these dinosaurs actually had flying ancestors, so that flight might have originated well back in the dinosaur tree. That's a very weird idea at the moment but it keeps coming back to all people.

Adam Rutherford: All right, so tell us about this new discovery, whose name I am struggling with somehow, Epidexipteryx, I think, it is called.

Henry Gee: You said it, and I am not even going to try. This creature was about the size of a pigeon and it lived around a 160 million years ago, that's middle to late Jurassic or Early Cretaceous in China and it's a small lightly built, carnivorous dinosaur, although it doesn't seem to have many teeth. It's more like one of the Oviraptor type dinosaurs and it had all over its body a coating of this kind of furry protofeathers, but the remarkable thing is sticking out of its tail, were 4 very long single feathers. So we had a kind of tuft on its tail or very, very long feathers which was long as the body.

Adam Rutherford: Okay, so let's just talk about those feathers for a second. What are they for, are they sexual traits for attracting females, may be?

Henry Gee: It's very, very hard to say. Plainly they're not for flying because there are no other signs of flight feathers on this creature and it could be for sexual display.

Adam Rutherford: Potentially rather like peacock feathers.

Henry Gee: Potentially, there are some fossil birds with long tail feathers a bit like this. There is one called Confuciusornis, which is a proper bird and almost distinguished by very, very long tail feathers like this. So, all these ancient dinosaurs and bird-like dinosaurs and dinosaur-like birds and really truly all birds went in for this sort of display plumage.

Adam Rutherford: And so this fits into an evolutionary lineage in which dinosaurs eventually lead to modern-day birds, is that the current thinking?

Henry Gee: The current thinking is this creature is as close as possible to the lineage of birds without actually being a bird. Of course, that is, you know, subject to a great deal of revision. There's been a lot of work on the evolutionary relationships of birds and other dinosaurs that are kind of close to it; Troodons, Dromaeosaurs and other things. So it's going to be some revision. But what interests me, is that there was a lot of evolutionary experimentation with feathers and plumage and integument and it shows that flying was just one thing they did with feathers. And even know there're still feathered dinosaurs of new sorts coming out of China more than 10 years after the first one.

Adam Rutherford: Okay, thanks for joining us Henry. Coming up later in the show, all the science news you'll ever need from Nature's blogger-in-residence.

Kerri Smith: And I report back from the meeting, addressing the many faces of autism.

Adam Rutherford: But first Charlotte Stoddart finds out that oxygen-producing bacteria are not quite as ancient as we thought.

Charlotte Stoddart: Atmospheric oxygen is essential for almost all life on earth. Without it, there'd be no plants, no animals, no people, no Nature Podcast. Imagine that! But our planet hasn't always been so rich in this life-giving gas. Around 2.4 billion years ago, the amount of oxygen in our atmosphere suddenly increased and this is known as the Great Oxidation event. The oxygen came from photosynthesizing single celled organisms called Cyanobacteria, but exactly when these oxygen-producers first appeared is up for debate. Fossil evidence suggests 2.7 billion years ago, but this is a puzzling 300 million years before that Great Oxidation event. So Birger Rasmussen from the Curtin University of Technology in Western Australia has re-examined the evidence. Nature 455, 1101–1104 (23 October 2008)

Birger Rasmussen: The most widely accepted evidence for the appearance of Cyanobacteria which are oxygen producing prokaryotes stems from hydrocarbon biomarkers extracted from shales from Australia and those shales were about2.7 billion years old and they provided certainly the most robust evidence for the beginning of oxygenic photosynthesis.

Charlotte Stoddart: And this date, 2.7 billion years ago, does this fit with everything else we know about the early biosphere?

Birger Rasmussen: In some ways no, when these results were first published it did create a slight anomaly in that the geochemical evidence and the geological evidence from the rock record suggested that the first major increase, over rise in atmospheric oxygen occurred by about 2.3 billion years ago, so there was some who said they were oxygen producing micro organisms at 2.7 did create an anomaly or a puzzle in turn to why it did take 3 to 400 million years for oxygen to rise in the atmosphere.

Charlotte Stoddart: And so what you and your team have done is you have re-examined the evidence? You've gone back to these, what we call molecular fossils and had another look at them. So what have you found?

Birger Rasmussen: The molecular fossils or biomarkers were extracted from shales and the carbon isotopic composition of those biomarkers were found to be quite, quite similar to, sort of, modern organic matter but what was thought was that the whole rock carbon composition of the same samples was extremely depleted in carbon 12, so that was a quite possible. So what we did was, we looked at the shales and we found organic matter in particular, solidified oil droplets and those oil droplets, we were confident had formed in the shales and were indigenous. So we analyzed those and found that it had a very similar isotopic composition to the whole rock organic matter but was very different to the hydrocarbon biomarkers and that made it very difficult to explain that the biomarkers were indigenous to those rocks.

Charlotte Stoddart: So if these biomarkers then weren't indigenous to the rocks what does that mean for the origin of oxygen producing photosynthesis?

Birger Rasmussen: Well certainly, our work suggests that the biomarkers were not indigenous and therefore entered the rock much later and therefore it means that the biomarker evidence for the emergence of oxygenic photosynthesis does not stand up.

Charlotte Stoddart: So what's the next bit of evidence that we have for the origin of oxygen producing photosynthesis.

Birger Rasmussen: Certainly the oldest unambiguous fossil evidence is about 2.15 billion years old which places it well after the Great Oxidation event and eukaryotes the oldest probable fossil evidence s about 1.7 or 1.8 billion years old.

Charlotte Stoddart: So effectively this closes the gap between the evolution of oxygen producing life and this increase in oxygen in the atmosphere that we see.

Birger Rasmussen: That's right. It essentially or potentially removes this puzzling delay.

Charlotte Stoddart: You have established that these biomarkers, these hydrocarbons must have entered the rock later than the rock formed. So how did they get into the rock then?

Birger Rasmussen: There are lots of possibilities; it could have entered the rock hundreds of millions years after the rock was deposited. It could have happened during drilling of the coal; drillers often put grease and also the exotic material into the drilling fluid, so that could have contaminated the rocks. Also just handing of the material in the lab Jochen Brocks the co-author in this paper has shown that just putting samples in plastic bags can contaminate samples and they can be quite difficult to remove that.

Charlotte Stoddart: Gosh!, So rather than being 2.7 billion years old these markers could in fact just been just a few years old.

Birger Rasmussen: Potentially yes. There have happen papers published not that long ago that were claiming sort of new biomarkers based on compounds from plastic bags, so, yes, yes it is surprising. And it certainly puts a bit of a sort of question mark on a lot of biomarker studies of these very old rocks.

Adam Rutherford: Birger Rasmussen talking to Charlotte.

Kerri Smith: We have more chemistry related goodness for you in ChemPod our bi-monthly chemistry show including a colour-changing polymer that could be used in electronic books, the extraordinary life and work and Ernest Eliel aka 'Mr. Stereochemistry' and an exclusive interview with one of this year's Nobel laureates Martin Chalfe – that's out tomorrow, find it at http://www.nature.com/chemistry/podcast.

Jingle

Adam Rutherford: In just a minute another use for sticky tape, but first Kerri you are just back from a meeting in Pittsburgh.

Kerri Smith: Yes I am. I was in the home of Andy Warhol in the City of Rivers and Bridges as they call it for the Carnegie Symposium on Autism and this was one of the series of symposium they have annually. This is the 35th one that has been from the Psychology Department of Carnegie Mellon University and it was just looking at many faces of autism basically from lots of different approaches so fMRI, imaging studies, genetics, and there was even a historical view of the condition that was a follow up of Hans Asperger's original patient from the 1940s.

Adam Rutherford: So what were the particular highlights of this conference?

Kerri Smith: Well, I was looking forward to seeing Temple Grandin who is a Professor of animal science at Colorado State University, but she is also a famous autistic and she has actually been profiled before in Oliver Sacks' book An Anthropologists on Mars. So here's a clip of her telling me just how differently autistics think.

Temple Grandin: I am a visual thinker. I don't think in a language; I think in photorealistic pictures. In fact my mind works like Google for images. You know, you are asking me about something, I like to search all the database I have in my mind, but its all photorealistic pictures, even when I think about abstract things. It was very interesting for me to discover that other people don't visually think the way I do. Words just narrate the pictures in my mind, you know, if someone asked me think about a church steeple, I see specific ones and I put those in a church steeple file folder. I don't get some vague generalized image; I was shocked and I found out some people get a vague generalized image.

Adam Rutherford: You know, I don't think I would actually mind too much if my mind worked like Google images. So did any themes emerge?

Kerri Smith: Well, one useful feature of the conference was that they had a rap up session at the end of every day which, at larger conference you don't really get and you don't therefore get a sense of where a particular field is headed and they were really useful. One of the themes that emerged from those talks is the idea that researchers have really got to remember why they are looking into this and that is really to find some kind of treatment or cure for autism. But that in itself was another issue. Kevin Pelphrey from Yale University who is the co-organizer of the conference talked at the beginning about how we should be trying to find a cure and I almost felt some of the audience members bristled slightly at that because as we had seen from Temple's speech you know may be this isn't something we need to be thinking of completely curing in a very black and white sense. So after dinner on the second day, I spoke to Kevin Pelphrey and I asked him what he feels of that.

Kevin Pelphrey: Saying that you're going to cure something that is more or like a difference in cognitive style, I think is what people were bristling at, but at the same time I see this as a neurodevelopmental disorder and so even though there is great heterogeneity, there is this commonality and people with autism are sort of lack of social engagement that manifest this part of brain disorder. And so that's important to remember that you know ultimately we would like to prevent children from having this brain disorder and find a cure for it. So I think that even though I understand the controversy but I used that word and that's really the goal and I have two sides of this view, I am a parent of a child with autism and I am also a neuroscientist studying it, so I am, sort of, comfortable with the idea of curing it in the sense that I would like my daughter to have, you know, the greatest outcome possible. And so even though at the same time you know she is a person and has these differences and some days it's hard to decide whether it's just that she's different or if she truly has, you know, a disorder and what parts of her personality and her way of being represent the disorder versus her struggling with the disorder.

Adam Rutherford: Okay that was you talking to one of the organizers Kevin Pelphrey.

Kerri Smith: Yes indeed and I will have more from him and from the other speakers that I interviewed at the conference in the next issue of the neuroscience podcast Neuropod which is going life hopefully in the next few days.

Adam Rutherford: Okay next up, Geoff Brumfiel gets himself into a sticky situation with an X-ray.

Geoff Brumfiel: Think back to the last time, you had an X-ray. It was a pretty involved process. You were probably lying down in a doctor's office or a dentist's chair wearing a lead bib and someone was pointing that big expensive X-ray camera at you. Well, a group of scientists at University of California, Los Angeles have come up with a much easier way to make X-rays. It's actually a simple as peeling sticky tape. Nature 455, 1089–1092 (23 October 2008)(Sound of a tape being peeled)

Seth J. Putterman: People studying lightning get all excited about the possibility of getting 10 KV X-rays out of lightning and here we can peel tape and get 50 KV X-rays out of peeling tape.

Geoff Brumfiel: That's Seth Putterman a researcher at UCLA who takes a keen interest in unusual energy focusing phenomena. In this week's issue of Nature, his group shows that peeling tape can create high power X-rays. The phenomena is a little like static cling, think about when you rub your feet on the carpet, you build up a net charge that can really sap whoever you touch.

Juan V. Escobar: And we had heard that adhesives could do something similar and we didn't believe it at first.

Geoff Brumfiel: Juan Escobar is one of Putterman's collaborators. He may have been sceptical but then they put the theory to the test.

Juan V. Escobar: So these are Geiger counter and we are going to see as soon as you turn it on.(Sound of the counter being turned on)

Geoff Brumfiel: So what is going on here? Well as the tape is being peeled it is leaving electrons behind on the roll and when enough potential energy has built up between the roll and the tape, the electrons fly off and smash into the strand being pulled. They hit it so hard that they generate X-rays, again Seth Putterman.

Seth J. Putterman: You get a collective blast of a 100,000 X-ray photons in merely 10-9 a billionth of a second. I don't understand how such a collaborative phenomenon takes place.

Geoff Brumfiel: Now don't worry about radiating your kids during arts and crafts. This little trick only works when the tape is under vacuum because air molecules short circuit the static build up, but incredibly the effect is powerful enough to actually take some simple X-ray images and that was just with the first roll of tape that they happened to try.

Seth J. Putterman: Can the chemistry of the tape be modified so as to improve the flux of X-rays by factor of 10? How do we know that what we have here is the best one can achieve? I proposed that by studying various adhesives and what's going on in learning what's happening here, improvements for a factor of 10 or a 100 could be made.

Geoff Brumfiel: And if they could be made, that in turn might be to new applications like cheap X-ray sources for hospitals in developing countries. For the Nature Podcast I am Geoff Brumfiel.

Kerri Smith: And that study is on http://www.nature.com/nature alongside a rather spiffing film of the team who made the discovery. We nearly done for another week but we wouldn't go without rounding up a spot of science news for you, oh, very nice. Joining is in the pod today is Daniel Cressey editor of our blog, The Great Beyond. Dan, tell us why the LHC is in the news again.

Daniel Cressey: Well the LHC is obviously the biggest news story of the year but its turning into a bit of a nightmare for officials at CERN, the Europe's particle physical laboratory, because the entire Large Hadron Collider which was launched with great fanfare earlier this year is completely broken at the moment with at least 29 of its 10,000 magnets needing replacement after about 6 tons of helium was released into the tunnels earlier this year.

Kerri Smith: Yeah and there has been a report out about, sort of, that situation hasn't it?

Daniel Cressey: Yes, the initial report about what exactly went wrong says it is going to take 8 months to fix the LHC but it isn't quite as bad as it sounds, because it was going to be closed for the winter anyway but it is still going to cost them around 90,000 dollars to set right everything that has gone wrong.

Kerri Smith: And we were so looking forward to as were that half a million journalists that went to CERN for the event.

Adam Rutherford: Okay and sticking with physics it seems that another country has joined the space race right.

Daniel Cressey: That's right, India is launching its first spacecraft to the Moon on Wednesday in what's widely being seen as the most ambitious Indian space mission to date, although even those involved in the project say there are distinct geopolitical reasons for sending this mission up now as well as obvious science that's going to be done.

Adam Rutherford: So they are heading for the Moon and what are they aiming to find out, surely, we know quite a lot about the Moon already.

Daniel Cressey: We do, but there's a surprising amount we don't actually know. There are actually going to be 11 scientific instruments on this probe, 5 Indian ones, 3 from Europe and 2 from America and 1 strangely enough from Bulgaria. One of the things they are going to be looking for is Helium-3 which could potentially be used in nuclear reactors for any colony that was established on the Moon; they are also going to be looking again for water and attempting to resolve this issue of water on the Moon.

Kerri Smith: So India off to the Moon and the LHC is still in the in the doldrums. Have you got anything a bit more cheery for us?

Daniel Cressey: Not exactly cheery, but I can announce that we have a new world longest insect called Chan's megastick announced last week. It's an absolutely horrifying 56.7 cm long if you include the legs.

Kerri Smith: And megastick, I am gathering, it looks like a small tree from here. It's a stick insect.

Danil Cressey: It is called the stick insect or a branch insect which might be more appropriate.

Adam Rutherford: And if you could just put some of our listeners at ease, can you tell us where the megastick lives.

Daniel Cressey: Well it was found in Malaysia and only 3 specimens of this have been discovered so far. So they are not crawling all over everything but if you do fancy a bit, I am afraid, there are pictures of the megastick on our blog and more on all of these news stories on Nature News.

Adam Rutherford: Okay thanks for joining us in the pod Dan. That's all we have got time for this week. Join us next week to hear about frogs in parole and Econophysics. I'm Adam Rutherford.

Kerri Smith: And I'm Kerri Smith. Is it a bird, is it a plane, no it's Epidexipteryx!

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