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Michael Hopkin: This week astronomers hunting for life outside our solar system find methane.

Mark R. Swain: That is the first organic molecule ever detected in an exoplanet atmosphere.

Kerri Smith: And punish and be damned.

David G. Rand: Giving people the option for costly punishment is a kind of like giving them guns. The National Rifle Association here in the US has a slogan which is "guns don't kill people, people kill people" and so we say the same thing about punishment, "punishment isn't stupid, just the people that choose to punish."

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

Michael Hopkin: And I am Mike Hopkin. First up this week, the state of the world's drinking water. An estimated 3,900 children die each day across the world as a result of contaminated water. A review in this week's Nature rounds up the new technologies that might be brought to bear on the problem. Here's lead author Mark Shannon, Director of the WaterCAMPWS at the University of Illinois at Urbana-Champaign. Nature 452, 301–310 (20 March 2008)

Mark A. Shannon: Water purification has been extremely successful, particularly in major metropolitan areas in the developed world, but this really only works for about 1 billion out of the 6.6 billion people on Earth. The rest of the people on Earth really can't use the water treatment systems that we currently use because they require chemicals, large plants, energy, large amounts of energy. So, it needs a place that has all that infrastructure. So if we are really trying to approach and treat water for another 5.6 billion people on Earth, we need to think of new ways of doing it.

Michael Hopkin: What are some of the ways that people who aren't lucky enough to have clean water like you or I have, what are some of the ways that they currently use to try and clean up the water themselves?

Mark A. Shannon: Well, there are many methods. Most just don't clean it; if they can find it, they just drink it or use it directly. Some will take cloth and try to strain the large particles out, but most people then just put it in jars or basins and let it set and then dip hands into it, which is problematic. Bad water is one of the leading causes of illness and malnutrition and actually death among the very young and old. Unfortunately, since the millennium challenge of 2000 to try to have the number of people without access to clean water has actually not halved at all. It has increased and the numbers of deaths per year now, are up to 2.5 million worldwide, which exceeds death from other more well-known diseases such as AIDS and HIV.

Michael Hopkin: What are people trying to do about this? What kind of technologies can we bring to bear on the problem?

Mark A. Shannon: Well that's one of the major points of the article that we wrote is that there are new ways that are being developed that can disinfect water from pathogens and disease-causing micro organisms that we know about, but also viruses which have gotten much less attention even in the West and even in the developed World, water-borne viruses are a major cause of diarrhoeal diseases, so we are looking at developing new materials that can disinfect water using, say sunlight or using nanoparticles of silver and other compounds that is when the water is in contact with it, naturally disinfect the water without having to add bleach or chlorine or ozone or many other chemicals that we use in the developed World.

Michael Hopkin: And what about chemical contamination of water because that's one of the big things that we often read about, for example, in Bangladesh where a lot of the water that people use everyday is full of arsenic.

Mark A. Shannon: Well arsenic, in particularly is a worldwide problem; it of course is at a crisis stage in East India and Bangladesh, where some, you know, 30 million people are suffering from some levels of arsenic poisoning. It's probably one of the single greatest health problems facing the World. There are certainly many methods in the developed world that one can use to remove arsenic, but these methods typically are not translatable to a lot of the other parts of the World. They often use large amounts of iron oxides, which in most of the World are difficult to come by, so we are looking at new methods to dramatically change and absorb arsenic with materials that potentially are much lower cost in utilizing biology. There is recent discoveries that certain organisms, biological microbes, when there is sulphates present they will take arsenic bring it inside of the organism and take sulphates and then form arsenic sulphide which is an insoluble form of arsenic and if you then take this mass of microbes and expose them to ultraviolet light, the biological part will decay away leaving only very small amounts of volume of arsenic sulphide behind and if one could build this into a system such as a membrane bioreactor one could then potentially be able to bind up large amounts of arsenic with low cost and very little residuals left over to dispose off.

Michael Hopkin: So what would you say as a sensible achievable target for giving clean water to people? You said that the millennium development goal really hasn't made any headway, so what should we aim for?

Mark A. Shannon: That's an excellent question, of course I think we should aim for eliminating the 1.2 billion who do not have access to clean water and the 2.6 billion who have no access to sanitation and of course these problems become coupled because particularly during storms, when you don't have sanitation they end up cross-contaminating water supplies, but a reasonable goal I would hope would be that in 20 years we can have the number of people who do not have access to clean water and don't have access to sanitation, but that will require concerted efforts by governments, by NGOs, and by researchers all over the World.

Kerri Smith: Mark Shannon there and that review forms part of a special, well you could call it a water feature, in this week's Nature. Visit for more on water and its related issues including droughts, crops and the surprising fact that scientists still don't know water's exact chemical structure. Now as well as being essential for life here, water is of great interest to astronomers looking for signs of life on other planets. The same goes for organic compounds and that's what an article this week has found, Geoff Brumfiel reports. Nature 452, 329–331 (20 March 2008)

Geoff Brumfiel: Ever since astronomers spotted the first planet outside our solar system, they've been desperate to try and learn more about them. In particular, planetary scientists would like to understand what these planets are made of and whether they could support life. A paper in this week's Nature marks an important step in exoplanet chemistry, the first detection of an organic compound, methane, outside our solar system. I called up Mark Swain at the Jet Propulsion Laboratory in Pasadena to talk about the planet, which has the sexy title HD 189733b.

Mark R. Swain: What we've done is taken the spectrum of an exoplanet when it passes in front of it's parent star, so we see the starlight filtering through the planet's atmosphere and the molecules which are in the planet's atmosphere can leave a fingerprint in the starlight and we measure that fingerprint as telltale dips in the amount of light transmitted and so what we found were two molecules, we found water and we found methane. Methane is exciting because it's the first organic molecule ever detected in an exoplanet atmosphere.

Geoff Brumfiel: And where is this exoplanet, it's got the very sexy name HD 189733b.

Mark R. Swain: Well let's see, this planet is located about 63 light years away and it's around a relatively bright star, so this star is close by astronomical standards, in fact very close and that's part of why we are able to make this measurement.

Geoff Brumfiel: Now what kind of planet is it?

Mark R. Swain: Well, this is what's called a hot Jovian planet. It is a planet that's about the mass of Jupiter, but it is in an orbit of 2.2 days, so every 2.2 days, this planet has gone around its parent star. Now there is something else interesting about this planet, it's what's called tidally locked, which means the planet rotates on its axis at the same rate as it goes around the parent star, so a day and a year have the same length on HD189733b.

Geoff Brumfiel: That is interesting. Does that have any sort of significance for the measurement you've taken?

Mark R. Swain: Well, it means that the planet has a permanent dayside and a permanent nightside, so one side of the planet is receiving all the stellar radiation and because the planet is so close to its parent star, the stellar radiation is extremely intense. This means that for the side of the planet which is the night side or the colder side to receive any heat at all, there need to be winds, which circulate the heat from the day side to the night side.

Geoff Brumfiel: So this is a gas planet, it's going around the Sun or its sun very quickly and only one side is facing the Sun, I guess, even though methane is an organic molecule, this doesn't sound like a very likely place to find life, is that right?

Mark R. Swain: That's right, this planet is rather hot. The temperature of the atmosphere in the regions that we were probing with these measurements is probably around a 1000 Kelvin, so this planet is too hot to support life as we know it; however, methane as you mentioned is one of these key molecules that was supposed to have existed on the prebiotic Earth and it is thought that methane under the right circumstances may play a role in the emergence of life-like molecules.

Geoff Brumfiel: So, looking ahead then what's going to be happening in the future, presumably at some point, you'd like to take spectrum of Earth-sized planets in fairly normal orbits about their stars?

Mark R. Swain: That is certainly in the future, but that is still down the road, quite some ways. What this measurement that we've done is really significant for, is it starts letting us do chemistry of the exoplanet atmospheres. We didn't just find the molecules, water and methane, we also measured their abundances. Now we can also take a spectrum of this planet that measures the abundance on the dayside and in fact that's work that is going on right now. So we are beginning to get to the stage where we can try to look for chemical gradients, where we can try to infer the abundances of molecules and from that understand something about the chemistry of the planet, so we're really starting to use the molecules as detailed probes of conditions, composition and chemistry of exoplanet atmospheres.

Kerri Smith: Mark Swain of the Jet Propulsion Lab at the California Institute of Technology.


Kerri Smith: Now some sad news this week, Science Fiction writer Arthur C. Clarke has died at his home in Sri Lanka. Clarke was considered one of the most important Science Fiction writers of 20th century and only in December we celebrated his 90th birthday. Clarke has left a rich legacy of contributions to science fiction and science. Here's Nature's Oliver Morton describing one of them, known as Clarke's Laws.

Oliver Morton: I think the best and most famous one is Clarke's third law, which is that any sufficiently advanced technology is indistinguishable from magic and it's a very good line, it also speaks quite strongly to the heart of the man, I mean, the sense in which technology and magic are indistinguishable and in which a, sort of, mystical wonder is absolutely congruent with scientific understanding, is what Clarke is all about, this sense of, the thwarted or slightly off to one side mystic that comes with this incredibly rationalist filter, that's what makes his work much more powerful than you might normally expect.

Kerri Smith: Oliver Morton talking about Arthur C. Clarke who has died at the age of 90. You can hear that full interview on the Nature news blog: The Great Beyond. Coming up in just a moment, Mike will be finding out that spikes is not always the best strategy, but first our podium speaker puts in a plea for a scientific study of incompetence. Here's Marc Abrahams, Editor of the magazine, Annals of Improbable Research and organizer of the Ig Nobel prizes.

Marc Abrahams: It's shameful when valuable data goes unused, especially when that data was produced at great public expense. In October of the year 2000, we presented an Ig Nobel prize to the authors of a study called, Unskilled and Unaware of It: How Difficulties in Recognizing One's Own Incompetence Lead to Inflated Self-Assessments. Let me read that title to you again, Unskilled and Unaware of It: How Difficulties in Recognizing One's Own Incompetence Lead to Inflated Self-Assessments. Almost exactly a month later in November 2000, the United States began an experiment, a very expensive experiment, that's been running now for 7 years. I will tell you briefly about the study; then I will tell you about the ongoing experiment. The study was done by two psychologists David Dunning and Justin Kruger at Cornell University. They begin their report by telling this story. In 1995, McArthur Wheeler walked into two Pittsburgh banks and robbed them in broad daylight with no visible attempt at disguise. He was arrested later that night less than an hour after videotapes of him taken from surveillance cameras were broadcast on the 11 o'clock news. When police later showed him the surveillance tapes, Mr. Wheeler stared in incredulity, but "I wore the juice", he mumbled. Apparently, Mr. Wheeler was under the impression that rubbing one's face with lemon juice rendered it invisible to videotape cameras. Dunning and Kruger then recount how they tested people on various skills, mostly logic and grammar. They discovered that people who are incompetent simply don't recognize that they are incompetent. Dunning and Kruger did their experiment on college students. The 7-year experiment, I mentioned, is on a whole different level. It is producing data about high-level government officials. Throughout the upper strata of the US government, thousands of competent executives and managers have been systematically replaced with incompetent people - people who have little or no experienced skill or ability at their jobs. It has been documented in numerous places if you're curious one good place is to look is the web site These managers and executives are hard at work everyday, diligently applying their incompetence. It would be a scientific privilege to interview them, to observe them closely under what is known as naturalistic conditions - direct observation of course is more accurate than second hand accounts. Psychologists and anthropologists have only a few months left to gather this mother load of data. Come January 2009, many of these appointees will exit left, pursued metaphorically by bears. If these observations go unmade, future social scientists will curse their 2008 predecessors for laying a bed while so much incompetence was lying in the fields waiting for harvest. The data is there right now, ripening and rotting. Let's collect it and study it and see what we can learn from it and let's put it on display; otherwise, our descendants will dismiss it as just myth and legend.

Michael Hopkin: Marc Abrahams there, finally this week: Are spite and vindictiveness useful social traits? No, according to a new game theory experiment published in this week's Nature, which shows that nice guys really do finish first. It is a twist on the classic prisoners dilemma adapted to give players the option of paying to punish each other. Earlier in the week, we got the chance to try it out for ourselves, perhaps unwisely, with the help of researcher David Rand from Harvard University. Nature 452, 348–351 (20 March 2008)

David G. Rand: In this study, we looked at the role of costly punishments, sort of spiteful punishments in cooperation games to see if people that use punishment do better and if punishment makes the group do better.

Michael Hopkin: And how is spiteful punishment simulated in your experiment?

David G. Rand: So in the standard prisoners dilemma, which is the paradigm for studying these cooperation scenarios, people have two options – they can either cooperate which means paying a cost to give a benefit to the other person or they can defect which means stealing from the other person and so costly punishment or spiteful punishment is a third option which is bad for both people, its like I pay points to make you lose points.

Michael Hopkin: What might be an example of that in the real world of spiteful behaviour like that that harms both people?

David G. Rand: See you could imagine an obvious example, if someone does something you don't like, you could try to beat them up as opposed to, you know, stealing from them or whatever.

Michael Hopkin: Or you could spread rumours about them on the internet, I guess would be a modern equivalent.

David G. Rand: Right, right.

Michael Hopkin: I see! So I guess the best way to understand this would be to play ourselves and you've very kindly agreed to teach us here in the podcast how to play the game, so joining now me is the boss, the Podcast Chief Commissioning Editor, Sara Abdulla, who I'm going to play against. Can you let us know, Dr. Rand, the rules of the game that we would be playing to?

David G. Rand: All right, so welcome Sara and Mike, we're going to play this game. Its called the prisoner's dilemma and the rules of the game are as follows: Each round you each make a decision that will earn you some number of points and these number of points translate directly into dollars, so you guys are playing for money here, and so you've 3 moves each turn. You can either cooperate which means you pay a dollar and the other person gets 3 dollars. You can defect which means you gain a dollar and the other person loses the dollar, so it is like stealing a dollar from the other person or you can choose to punish the other person, which means you pay a dollar and the other person loses 4 dollars. So, those are the 3 moves, you guys have cards in front of you, that's a C, D, or P for each of the 3 possible moves and so each round you'll choose the move you want to do and put it face down on the table and we'll turn over both moves and we'll see what points each of you earned.

Michael Hopkin: Okay, I'm a bit nervous but lets' give it a go, okay.

David G. Rand: And we'll see what you guys will find out about each other.

Michael Hopkin: Right, well here we go, I'm ready to play the first card.

David G. Rand: Alright Sara!

Michael Hopkin: We are putting them down now, okay.

David G. Rand: All right, we'll see what we got.

Sara Abdulla: So we've got two cooperates.

David G. Rand: Oh! That's so nice.

Michael Hopkin: Lovely, lovely. So that means...

David G. Rand: So each one of you has now paid one and given 3 to the other person, so each of you have a net gain of 2 dollars each.

Michael Hopkin: Lovely! Next round. Okay, turn them over. Now, I have elected to cooperate, but Sara has defected.

David G. Rand: Oh! All right. The truth comes out.

Michael Hopkin: I think that makes me the big loser, so far.

David G. Rand: This time Sara has gotten the 3 that you gave her plus she has stolen one from you, so she has earned 4 dollars where you've lost 2 dollars.

Michael Hopkin: So I'm backed down to zero.

Sara Abdulla: All right.

David G. Rand: All right.

Michael Hopkin: And Sara, what you're on, 6 now?

Sara Abdulla: I'm on 6 dollars.

David G. Rand: All right, so Sara you're very self interested, you're a very rational player of this game.

Sara Abdulla: Right, ding ding.

Michael Hopkin: Right. Next round. I'm going to turn them over. So I have decided to defect this time and Sara has decided to punish me.

David G. Rand: Oh! man - well, I'm taking back my comment.

Michael Hopkin: So I probably gain nothing.

Sara Abdulla: I think I'm actually playing this as though as cards.(Everyone laughs)

David G. Rand: I was going to say that I have to take back that thing about you being a very rational player.

David G. Rand: So now Mike, you this turn, you gained one stealing from Sara but you lost the four that she punished you for, so you've got a net of minus 3 dollars.

Michael Hopkin: Oh dear!

Sara Abdulla: And, I what I gained 3?

David G. Rand: No. You lost 2, because you spend one to punish and then Mike took one from you.

Sara Abdulla: So we both lost.

David G. Rand: Right.

Michael Hopkin: Okay I can feel the bitterness growing in the room.

Sara Abdulla: Okay round 4.

Michael Hopkin: Okay next round and here we go. So I have defected now and Sara has cooperated.

David G. Rand: So that means now it's like the situation two rounds ago but reversed, so now Mike has gotten four dollars and Sara has lost two dollars.

Michael Hopkin: Now that puts me back me in the black, I'm on the way back, I have got one now. What do you want, revenge?

Sara Abdulla: And now I will have my revenge.

Michael Hopkin: What you're on?

Sara Abdulla: I'm on minus two.

Michael Hopkin: Okay, so the next round here we go and turn them over.

Sara Abdulla: We've got a P and a D for you.

Michael Hopkin: So I have defected once again, Sara has punished me.

David G. Rand: All right, so that means again you get minus 3, Mike and Sara gets minus 2 and that is the end of the game.

Sara Abdulla: Okay.

Michael Hopkin: So...

David G. Rand: Well been five rounds, so

Sara Abdulla: And we're both...

Michael Hopkin: That got fairly bad tempered, fairly quickly.

David G. Rand: Yeah let's say. So Mike your final payoff was minus 2 dollars, well that's good for me I guess.

David G. Rand: And let's see Sara got zero.

Sara Abdulla: That's better than Mike, that's the main thing.

David G. Rand: Well, see that's a very interesting question – it's whether you're playing for your relative payoff or your absolute payoff.

Michael Hopkin: So it is a case of whether you're playing to beat the other person or just to do as well as possible in absolute terms.

David G. Rand: Right, because if you're a student coming in to the lab to play the game, what the other person gets doesn't matter, it's just the dollars that you take home are only affected by your own payoff.

Michael Hopkin: So what were the results when you did this, presumably you did this for longer in the lab with your students and what were the results you found? What kind of people came out on top?

David G. Rand: When we did this in the lab we found that people that cooperated in general did better than people that defected, but so then the big question that determined how you did is what happened when the other person defected, so now in our game, Mike cooperated as long as Sara kept cooperating and then once Sara had started to defect, Mike just defected the whole time, so it's a reciprocity sort of thing, it's like if you cooperate, I will cooperate and that's good, but if you defect then I'm just going to defect and so that's what the winners in our experiment did. So Mike congratulations, you've picked the right strategy.

Michael Hopkin: A hollow victory given how badly I did in the game. And so it appears from the results of your study that there is no place in a successful strategy for the punishment option, you can just simply refuse to cooperate with uncooperative people.

David G. Rand: Right, so if you refuse to cooperate you're not paying a cost to punish that person, you're just saying well all right if you're not going to cooperate I won't either and so the people that were sort of spiteful and said, "well I'm going to pay and make the other person lose," those are the people that came out worst in our experiment.

Michael Hopkin: Now how does this translate to the real world, I mean is it the case that life's real winners in business or whatever are not the kind of people who get involved in spiteful punishment stuff.

David G. Rand: Yeah, I think that's exactly the sort of implication that we have for these, sort of, interpersonal interactions, the best strategy is to work with people that contribute and then work well with and if you work with people that are not contributing, you just stop working with them and find others.

Michael Hopkin: And what about other forms of costly punishment, because when people are thinking about social punishment and how society has evolved, they hold up the idea of prison, so it does not mean that taxpayers shouldn't pay money to send people to prison and should just ignore criminals instead.

David G. Rand: Not exactly, these results are studying interpersonal cooperation and so what we think is that people clearly have an impulse to punish others and I think that this comes from situations other than cooperative situations like dominant situations, for example and so we think prison is like the state dominating the individual and getting the individual to do what the state wants them to.

Michael Hopkin: I see, but on a personal level its best just to walk away if someone's is annoying you.

David G. Rand: Right exactly.

Michael Hopkin: That was David Rand, game theorist and game show host extraordinaire. That's all for this week's show.

Kerri Smith: Our sound of science this week is attributed to that most famous and delicious of numbers "pi". Earlier this week it was Pi Day, the 14th of March, of course, 03/14, a celebration, which also happened to coincide with Talk Like a Physicist Day and Einstein's birthday. Here's Ken "Freedom" Ferrier and Antoni "Ton" Chan with American Pie. I'm Kerri Smith.

Michael Hopkin: And I'm Mike Hopkin, Thanks for listening.

[Sound of Science]

Long long time ago, long before the super bowl and things like lemonadeThe Hellenic Republic was full of smartsAnd a question resting on the Grecian heartsWas "what is the circumference of a circle?"But they were set on rational numbersAnd it ranks among the biggest blundersThey worked on it for yearsAnd confirmed one of their biggest fearsI can't be certain they cried when irrationality was realizedBut something deep within them diedThe day they discovered piThey were thinkingPi, pi mathematical pi3. 14159653589793283846264338327 (not rounded)


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