Nature Podcast

This is a transcript of the 2nd April edition of the weekly Nature Podcast. Audio files for the current show and archive episodes can be accessed from the Nature Podcast index page (, which also contains details on how to subscribe to the Nature Podcast for FREE, and has troubleshooting top-tips. Send us your feedback to

Kerri Smith: This week you can bury carbon dioxide under ground, but will it stay?

Chris J. Ballentine: The portions of some of the fields that we have looked at, we're looking at between 90 to 99% of the carbon dioxide that was initially injected into the gas fields now being dissolved into the ground water systems.

Charlotte Stoddart: And the perils of picking professors as presidential policy people.

Robert Dallek: When experts become too political, detach themselves, so to speak, from the expertise that they bring to their job at the White House, they are prone to make big mistakes.

Charlotte Stoddart: This is the Nature Podcast. I'm Charlotte Stoddart.

Kerri Smith: And I'm Kerri Smith. Firstly, a new finding about autism. We know that autistic people have difficulties with the social world with communication and often show repetitive behaviours and obsessions. And there is another skill they lack: older children with autism don't pay much attention to the distinctive movements made by living things -- a concept referred to as biological motion. It's a crucial skill enabling us to recognize other beings who might help or harm us. So are autistic children looking at something at something else instead and is the same pattern seen in very young children? The younger we can diagnose autism, the more we can help those with the condition. So, this is what Ami Klin, Warren Jones and their team at the Yale Child Study Center in New Haven wanted to find out. Here's Ami first to explain a little more about biological motion. Nature advance online publication (29 March 2009)

Ami Klin: In humans, this is a very important ability because it is part of our capacity to look at people and process things, such as gaze direction and facial expressions and gestures. And it is an ability that is known to be a precursor for our capacity to attribute the intentions to others and so it is something that is also very important for social cognition for the ability to interact successfully by this.

Kerri Smith: And at the Yale Child Study Center, where your group works, you've been studying children with autism and as it happens, these things that perceiving biological motion allows us to do, seem to overlap with those characteristics what children with autism have problems, is that right?

Ami Klin: Yes indeed. In fact, all of those abilities that I've just mentioned are abilities that children with autism have difficulty with. They have difficulty detecting for example, the change of a person's direction of gaze; they have difficulty interpreting people's emotional expressions, facial expressions and gestures; and they have difficulty with imitation All of those abilities really are the hallmark of successful social interaction.

Kerri Smith: So Warren turning to you then, this experiment that you've just performed and you're just reporting in Nature, test whether toddlers with autism paid any attention to biological motion. Can you talk us through the setup?

Warren Jones: That's exactly right. We showed these children with autism, animations of biological motions. Essentially these animations look as though they were white dots on a black background and white dots at each one of the major joints on a person's body. So in essence it's almost like a constellation of stars that moves and that movement, for typically developing individuals, clearly shows a person. Now on the other side of the screen there was an inverted figure, basically the same point light animation but rotated a 180 degrees upside down and actually playing in reverse and that inversion actually disrupts the perception of biological motion in young children. So we presented these animations on a screen and they were played along with a sound track and the point light figures in our setup actually performed games and routines that would be typically familiar to 2-year-old children.

Kerri Smith: And so these animations showed things like people playing, pat-a-cake and peek-a-boo and that kind of thing. So tell us then how interesting did these groups of children find your point light animations.

Warren Jones: Well, the two control groups spent significantly more time looking at the upright point light animation than they did at the inverted animation, but what was interesting was that the 2-year-olds with autism were actually random in their looking back and forth, they appeared to be random in their looking back and forth, between the upright and the inverted animation. So they spent about 50% of the time looking at both the upright and the inverted animation.

Kerri Smith: So this brings the question, well what were they looking at, instead? Did they find anything about these animations interesting and I gather that there was a rather serendipitous case study within these point light movements that helped you to answer that?

Warren Jones: That's exactly right. We began this work some years back with an insight based on one young girl with autism. We showed her these same sets of animations and within her results, we noticed something quite unusual. We noticed that one of the animations she watched was a pronounced outlier from the rest of her results and in that case, in that one animation, she actually spent 94% of the time looking at the upright figure. We went to see what clue there might be for why she had changed her behaviour in this way and it turned out that it was an animation called pat-a-cake and actually I'm going to pass the phone back to Ami here for one minute to describe a little of what happened there.

Ami Klin: So, if something really special happened that she was actually acutely sensitive to something other than the social nature of the animation, it might be the clapping because in pat-a-cake, the cake claps and as we watched the video scene we could see this little girl was actually spending all of her time looking at exactly the point in the screen where the clapping was occurring and that gave us the hypothesis that she was acutely sensitive to a physical contingency, the fact that those dots were hitting one another and they are making sounds. And that generated the hypothesis for the current study. And what we found out is that indeed the 2-year-olds with autism we could account for 90% of the variance of their visual behaviour on the basis of this physical contingency.

Kerri Smith: Wow! What a striking result - 95%. So staying with you for the time being then Ami, does this attention to the physical contingency, the kind of match between the audio and the visual characteristics of these pictures explain any other features of autism that we see?

Ami Klin: Well indeed. In a previous study, Warren and I and colleagues looked at a way that the same 2-year-olds with autism would look at adult care givers approaching them and those children spend less time looking at people's eyes and more time looking at people's mouth than their peers. And that was puzzling because the eyes are really the window for the soul, they are the way that we experience people, their emotions and their intentions. And so we are puzzled by the fact that they showed increased attention to the mouth. And of course with this new paper and the new insights, we raised the hypothesis that the reason why they were looking at mouth is because the mouth is the part of the face that contains the greatest audio-visual synchrony, lip movements and speech sounds co-occurring. Now, that of course leads to implications. It could be that those children are actually watching faces without necessarily experiencing them as people.

Kerri Smith: Ami Klin and before him Warren Jones. The team say that next they are keen to study what changes in the environment might help autistic children to engage more with others and they also want to look at the newer biological underpinnings of this impairment.


Charlotte Stoddart: Coming up shortly, we ask whether burying carbon underground is really such a good idea and I dive into a big pile of dark matter. But first, Natasha Gilbert called UCLA's emeritus professor of history, Robert Dallek for a lesson in president's past and their policy advisers.

Natasha Gilbert: So, well you've written an essay for Nature, outlining Barack Obama's choice of science advisers at the White House. Obviously, it's a great thing to have lots of science advisors at the White House, but you say that we should be cautious and not get over complacent. Nature 458, 572–573 (2 April 2009)

Robert Dallek: Yes. Because while academics are schooled in certain fields of study and understanding, there is no guarantee that their presence at the White House is going to translate into extraordinarily successful policies. Actually, this business of using academics or intellectuals in the government gained pretty much with Woodrow Wilson who himself at the beginning of the 20th century was an American president. He was a Princeton professor and then the president of the Princeton University and he at the end of World War I organized or set up something called 'The Inquiry' - a group of academics who were assigned the task of figuring out how to reorganize Europe at the end of World War I.

Natasha Gilbert: Have there been any other good examples?

Robert Dallek: Yes, there have been some striking examples of great success. I think, most notably Robert Oppenheimer, the brilliant University of California physicist who was the principal architect of the atomic bomb during World War II. Oppenheimer had very strong political views. He was very much on the left and had considerable doubts about building an atomic bomb, but the compelling reasons for doing it overwhelmed his own political judgment and so he was successful in the sense that he devoted his scientific knowledge to building the bomb and of course they carried that out successfully. And the theme of the essay I've written is that when experts become too political, become too caught up in the current political cross-currents and detach themselves, so to speak from the expertise that they bring to their job at the White House they are prone to make big mistakes and when they are much more inclined to use their expertise and they focus principally on that they have a much better chance of being successful.

Natasha Gilbert: So it's where the science advisers have kind of overstepped their mark and become politicized. They haven't remained independent, when they overstep that mark it is fouled.

Robert Dallek: Yes, and of course it's impossible to be entirely objective. You can't, if you're doing environmental protection, it is so clearly hard science that you can only speak out of scientific judgment. There is going to be a certain degree of subjectivity and politics one might say that will enter into the conversation. You know, Sigmund Freud once said there are three impossible professions - they are psychoanalysis, education and government. So politics is one of them, then we just have to live with it, but I think they do the President a much greater service if they stick to their science, stick to their expertise rather than morphing into being a politician.

Natasha Gilbert: So what are the key lessons that history has taught us? What advice could we give to these new president's advisers?

Robert Dallek: I guess the lesson is be true to yourself, be true to your science, be true to your expertise as much as you possibly can, understanding also that you are human and you do have biases and do have a predilection to support the man in the White House who has given you the exalted position that you hold.

Natasha Gilbert: Given the crop of new advisers that president Barrack Obama has picked and looking at the examples from history, are you quite hopeful that these characters will be able to fulfil that role of an adviser properly and effectively.

Robert Dallek: Well, what gives me hope about the current administration and in particular about president Obama is that he is a man who seems to value criticism. He wants to hear a dissenting opinion. He doesn't want to have simply a group of men and women, who offer knee-jerk advice or responses to his own biases or own judgments. So, remember in Obama we have an academic professor of constitutional law at the University of Chicago and actually, I believe the first professor in the White House since Woodrow Wilson. I'm hopeful that Obama will remember his academic lessons so to speak and continue to value the independent judgment of his most-thoughtful advices and evaluate things in a more detached way than Bush was able to.

Charlotte Stoddart: That was Robert Dallek of UCLA.

Kerri Smith: In just a moment, whether buried carbon will stay buried. But first, hardly a week goes by without mention of a dark matter or dark energy experiment.

Charlotte Stoddart: The hunt defined this missing mass and energy, is moving at break-neck speed and this week's Nature, there is yet another report of yet another signature of dark matter. Joining us in the studio is Nature Physical Science's editor, Ana Lopes, who has produced a cut out and keep guide, to what we know and what we don't. So Ana could you start by reminding listeners what is dark matter and what is dark energy? Nature 458, 587–589 (2 April 2009)

Ana Lopes: Well in fact we don't know much about dark matter and dark energy. We don't what these elements are about. We just know that there is 75% of dark energy, 20% of dark matter and 5% of normal matter. This is basically ordinary matter like us. So this means us that we only know about 5% of the energy budget of the universe.

Charlotte Stoddart: My goodness, so most work so far has focussed on dark matter. How close are we to finding this missing mass?

Ana Lopes: Well, we are not that close actually. There are a lot of experiments going on. There are about 20 projects out there in Europe and in the US trying to figure out what dark matter really is.

Charlotte Stoddart: What are these projects looking for, I mean what are they going to detect that will tell them, this is dark matter.

Ana Lopes: There are direct methods and indirect methods of trying to find dark matter. The direct methods look at how nuclei in detectors on earth recoil when dark matter particles originating from our galaxy collide with these nuclei and make them recoil. So they measured the recoiling energy deposited in their detectors and try to isolate these dark matter signals from backgrounds of terrestrial origin. So this is actually a very challenging task.

Charlotte Stoddart: Okay, so that's a direct method of detecting dark matter. How about the indirect methods?

Ana Lopes: Well those look at the abundance of anti particles such as positrons which are anti-electrons or anti-protons and what they see in their experiments is an excess abundance of these antiparticles. The question is, is this excess abundance due to dark matter annihilating non galactic halo or is it due to another astrophysical source.

Charlotte Stoddart: Right and one experiment that is looking at these antiparticles is PAMELA. It uses an instrument strapped to a satellite and this week the PAMELA team report what may be a signature of dark matter as Piergiorgio Picozza from the University of Rome Tor Vergata explained to me. Nature 458, 607–609 (2 April 2009)

Piergiorgio Picozza: With our instrument you can measure positrons and electrons. It means that you can measure a particle and antiparticle. In our case we found that these antiparticles, positrons are much higher than expected. Many, many theoreticians think that this is a signal of their matter because this is increasing it is in agreement with tradition of very many models of dark matter. At the same time, other theoreticians study the possibility that some contributions could come from these neutron stars that rotate very fast. Their name is pulsar and if the energy emitted from this pulsar are enough high it is possible to have some contribution of positrons.

Charlotte Stoddart: That was Piergiorgio Picozza telling us about the PAMELA finding in this week's Nature. So Ana what do you think? Have they really found a signature of dark matter or is this something else.

Ana Lopes: Now, they are not sure again it could be due to pulsars but it could also be due to dark matter. There is another study published recently in Physical Review Letters that actually gives weight to the case of the pulsar interpretation. This is a result obtained from PAMELA observations as well but instead of looking at anti electrons, it looks at anti protons. So actually we are a left with more questions than answers.

Charlotte Stoddart: So this is certainly not the last we will hear of dark matter on the Nature Podcast. Ana thank you very much.

Ana Lopes: You're welcome.


Charlotte Stoddart: You'll find both Ana's guide to dark matter and dark energy plus more on the PAMELA finding in this week's magazine and online at

Kerri Smith: Next up Richard Van Noorden reports on one proposed solution to our carbon dioxide problem.

Richard Van Noorden: One way of reducing levels of carbon dioxide in the atmosphere may be to bury the greenhouse gas in underground reservoirs; but it is not entirely clear what happens to this buried carbon dioxide over hundreds, thousands or millions of years. Does it stay safely put or escape back into the air making its burial pointless. I asked Chris Ballentine from the University of Manchester in the UK who explained to me how he and his team tracked what carbon dioxide gets up to underground in the long term which was not an easy task as he explains. Nature 458, 614–618 (2 April 2009)

Chris J. Ballentine: One of the key issues is the carbon dioxide unlike the hydrocarbons is both highly soluble but is also highly reactive. So we've got multiple things changing in the sub-surface when we inject the carbon dioxide into the system and tracing and following those processes is something that is absolutely essential if we are to understand what happens to the carbon dioxide and how safe injecting the carbon dioxide into these geological structures actually is.

Richard Van Noorden: Now don't we already have some experimental stations across the world injecting carbon dioxide into structures to see what happens?

Chris J. Ballentine: Very much. This is absolutely essential, but we have run some pilot studies and several of these pilot studies have been running for many years now. And they are gaining absolutely critical information about what happens to the carbon dioxide over the time period they are running these experiments. But another question is what happens to the carbon dioxide on a much longer time scale. So for example 500 years or thousand years or 10,000 years which is sort of the lifetime that we need to be sure that the carbon dioxide is going to be stored for and that's the questions that these pilot studies that are ongoing, can't readily address.

Richard Van Noorden: So how do you do it? You can't hang around for 500 years.

Chris J. Ballentine: What we do is looked at nature, what we've got in natural systems or environments where nature normally through volcanic activity has naturally injected carbon dioxide into geological structures thousands of years ago, tens of thousands of years ago, even millions of years ago. And these carbon dioxide filled gas traps are sitting there and they give us a vital information about the long term behaviour of carbon dioxide in these geological systems.

Richard Van Noorden: So taking an example of one of these natural carbon dioxide reservoirs, you're looking at what it would look like if I could be inside one?

Chris J. Ballentine: So these are if you like typically dome structures where the natural buoyancy of gas has displaced the water which would populate the pore space in the rocks. So if you envisage sandstone is little bit like a sponge and the gas will sit in the pore space and push the water associated with that down. So you have if you like a big gas bubble sitting in this sponge of rock and below the gas bubble you have instead of gas you have water sitting in the rock pore space.

Richard Van Noorden: So, you've had a look at 9 of these reservoirs across the world and how did you track what was happening to his carbon dioxide gas, because it didn't all remain in that state?

Chris J. Ballentine: What we've done is look at some of the trace gases that come in with the carbon dioxide and Helium-3 is an isotope of Helium which is often associated with volcanic gas for example, but Helium-3 it's chemically inert, it's totally insoluble so when we see changes with the carbon dioxide relative to the Helium-3 we know that there is something happening to the carbon dioxide. And we were able to link depletion in the carbon dioxide to another trace which comes out of the ground water system. So clearly depletion in the carbon dioxide in these gas fields is directly linked to the amount of water that these carbon dioxide fields are seeing. But then the question is what is happening to the carbon dioxide. Are we looking at simple dissolution of the carbon dioxide into the water this is natural water in geological system or is the carbon dioxide dissolving into the water and then precipitating out as carbonate minerals for example?

Richard Van Noorden: And what did you discover then? What's the answer?

Chris J. Ballentine: What we found was that we've almost no trace of mineralization occurring whatsoever and the signal we get is a clear signal of the carbon dioxide just dissolving into the water system. And what we are also able to do is quantify how much carbon dioxide is going into the water system and important system with some of the fields that we have looked at, we are looking it between 90 to 99% of the carbon dioxide that was initially injected into the gas fields, now being dissolved into the ground water system.

Richard Van Noorden: So the intergovernmental panel on climate change had a report on carbon capture and they suggested that the carbon dioxide might very well be locked up in minerals after millions of years, but you're suggesting that's not the case.

Chris J. Ballentine: Not at all. We find possible evidence for mineralization but by faulty dominant mechanism for removal of the carbon dioxide from the gas fields is simple dissolution of the carbon dioxide phase into the naturally occurring water system.

Richard Van Noorden: Where could this water go, could it escape or could it move elsewhere?

Chris J. Ballentine: It is possible that it could escape. There are plenty of geological environments where fluid is being trapped underground for hundreds of thousands if not millions of years and finding those places is what we must to do bury carbon dioxide safely. There are environments where deep fluids have escaped to the surface and it is those environments that we clearly must avoid to safely store carbon dioxide.


Charlotte Stoddart: That was Chris Ballentine from the University of Manchester in the UK.

Kerri Smith: Finally this week Dan Cressey is here and that means it must be time for the news chat. Hi Dan.

Daniel Cressey: Hello.

Kerri Smith: Now our first story this week, your first story this week is about methane on Mars.

Daniel Cressey: That's right according to research which was presented last week at the Lunar and Planetary Science Conference the Mars Reconnaissance Orbiter has detected a mineral called a serpentine on the red planet.

Kerri Smith: Tell us a bit more about serpentine.

Daniel Cressey: Well this is important because in December last year researchers reported finding a carbonate mineral on Mars near something called the Nili Fossae scar and then in January they reported a plume of methane in the same area and this new mineral serpentine looks like it might be something that ties both of these two findings together.

Kerri Smith: And of course we are interested in methane on Mars because we think there might be some implications for finding life there.

Daniel Cressey: Yes well, one of the interpretations is that methane can be produced by microbes and therefore seeing methane would mean life on Mars. However, the serpentine itself is produced from another mineral in a process that also produces methane and the serpentine can also be altered into carbonate.

Kerri Smith: So, does that mean that this methane then could be signature of just serpentine being there rather than life being there?

Daniel Cressey: Well, there is a slight problem with the data on that but this is certainly one interpretation although at this point it is obviously too early to rule out life on Mars.

Kerri Smith: So will future missions to Mars be taking this into account too?

Daniel Cressey: Well, at the moment future missions to Mars don't have this particular site on the shortlist that they're going to visit, but some researchers are now saying that they should add it back into consideration.

Kerri Smith: All right. Now the next story you've brought us is an entirely different kettle of fish or kettle of mice actually which is about standardizing lab experiments.

Daniel Cressey: That's right. It's been a common assumption for nearly all scientists that standardizing experiment is a good thing and that if you standardize your experiment other scientists will find it easier to reproduce it.

Kerri Smith: That seems pretty sensible but there's a paper in Nature Methods this week that suggests that shouldn't be the case.

Daniel Cressey: Right this is rather counter intuitive finding. This new paper suggests that the more you standardize the more problems you might find with reproducing it later or with other people reproducing.

Kerri Smith: So why would that be?

Daniel Cressey: Well, the researcher's theory is that the most standardized the experiments are becoming, the more influenced they are by other factors such as variations in the individual laboratories or in the staff themselves and that what you're actually finding may not be something true to the experiment but may be what they call a local truth.

Kerri Smith: So that's the idea that there is all this noise from the actual experiment itself and then some other noise from the lab and if you narrow down and take away all the noise from the experiment from the animals you're using in an equipment then all the noise from the lab is still present and much louder.

Daniel Cressey: That's right and the researchers actually go as far as suggesting that environmental standardization is a cause of rather than a cure for the poor reproducibility that some times is seen in experiments.

Kerri Smith: What's to be done about this, how do you go about un-standardizing people's experiments?

Daniel Cressey: Well they suggest a number of variables that could perhaps reintroduce some de-standardization if you like such as the age of the animals, the cage sizes, and the size of the groups, although this is obviously a very controversial area and not all researchers are going to agree wit this paper.

Kerri Smith: But I suppose it might make it easier to lay your hands on the amount of mice you need if you can just use any old mice.

Daniel Cressey: Well, the point here is also is that if you can't reproduce an experiment, you may actually be doing more experiments that you don't need to do. So by reintroducing some of this variation you might actually end up being able to get away with less experiments and obviously that's a good thing from an animal welfare point of view.

Kerri Smith: Streamlining the whole process. So finally then we've got some good news for video game lovers.

Daniel Cressey: That's right according to a paper in Nature Neuroscience playing action video games can may be improve your eye sight.

Kerri Smith: Action video games, what kind of things do they specify?

Daniel Cressey: Well, in the particular study we are talking about here they had their participants either play a shooting game or more of a strategy game. And so the researchers from the people who play the shooting games actually have an improved what they call contrast sensitivity which is the ability to spot the subtle difference in shades that appear on a background.

Kerri Smith: My favourite game is Tetris, is that going to help?

Daniel Cressey: Possibly not, in another group in this study the researchers had people playing a kind of more sedate strategy game and they showed no improved in their eye sight.

Kerri Smith: What a shame, so playing a few video games increases your ability to sense contrast. Who is that going to help exactly?

Daniel Cressey: Well, there are many people who you have debilitating problems with this contrast sensitivity issue, so it actually could help people down the line if there isn't a way without surgery or without glasses to improve the vision. Although at the moment I don't think you can get video games on prescription.

Kerri Smith: All right that's about all the news we've got time for. Check out for more. Thanks Dan.

Charlotte Stoddart: Join us next week for a story about how oxygen got in to our atmosphere and the selection of stuff from Nature's cancer issue. I'm Charlotte Stoddart.

Kerri Smith: And I'm Kerri Smith. Ta ta for now.