Nature Podcast 11 October 2007

This is a transcript of the 11th 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 mailto:podcast@nature.com.

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Adam Rutherford: Coming up, is this how we will be speaking in 500 years' time?

Erez Lieberman: He was a well-breeded man from the 26th century. So, it really stings when they said his grammar stunk, stinks, the time traveller corrected.

Adam Rutherford: We take a look at the evolution of language.

Kerri Smith: And we will be talking about the Nobel Prizes and their somewhat less prestigious cousins.

Mike Hopkin: Viagra helps hamsters get over their jetlag and big problem in business world, hamster jetlag.

Kerri Smith: This is the Nature Podcast. I am Kerri Smith.

Adam Rutherford: And I am Adam Rutherford. First today, in 2005 the Cassini probe, a spacecraft twice the size of a double-decker bus made passes of a small moon of Saturn called, Enceladus and took some photos. One of the big surprises was that some of these snaps featured jets blasting out of the rocky surface. This week, Joseph Spitale and Carolyn Porco have coupled these plumes with visible hot scars called tiger stripes cut into the surface of the planet. Earlier I spoke to Jose Spitale and started by asking him to describe what Enceladus looks like. Nature 449, 695–697 (11 October 2007)

Joseph N. Spitale: Enceladus orbits about four-Saturn radii from the planet. Its size is 250 kilometres across, I believe, so it is not a huge satellite, but it is large enough to be a big, round, planet-like satellite. It is probably mostly ice, some rock in the interior.

Adam Rutherford: It does not seem that remarkable until Cassini took these photos of these astonishing jets coming out of the surface of the planet back in 2005 right?

Joseph N. Spitale: Well, yes and no. Prior to that there was prediction that we might actually see activity on Enceladus. So, Enceladus was very interesting to us before we actually started to get these images because it is a small icy satellite that might be tidily heated and that sounds a lot like Europa which was very exciting during the Galileo mission.

Adam Rutherford: The images from Cassini picked up these beautiful jets coming out of the surface and what your study has done is to analyze where the jets are coming from and associate them with some of the features on the landscape, can you tell us how you did this?

Joseph N. Spitale: The short answer is we triangulated, in other words, we took images that were taken from various viewing directions and we basically just looked at an image and drew a line on a jet and so those lines, those project into circles around the planet, you know the ground track which tells you that the jet must have come from somewhere on that big circle, so if you view that from various directions and all those circles make all sorts of intersections and so what we had to do is untangle which of those intersections actually must correspond actual sources.

Adam Rutherford: Do these sources include the circled tiger stripes, these sorts of scars near the south pole of the planet?

Joseph N. Spitale: Yes, when we sorted everything out we wound up with eight sources, but they pretty much fell on the tiger stripes.

Adam Rutherford: So, these tiger stripes are visible from the photos by Cassini, what do they actually consist of?

Joseph N. Spitale: Well, they basically look like large cracks. When you are looking at very high resolution, there may be ridges associated with them, but basically they look like four large striations straddling the South Pole.

Adam Rutherford: So, you have associated these jets as coming out of these tiger stripes on the surface, what does that mean for the association between the jets and the fractures?

Joseph N. Spitale: Well, first of all the tiger stripes were hypothesized to be the source, when you look at these jets they appear to be coming from south pole and you look at the south pole and you got these big cracks, well, over a series of instrument, this is an infrared camera, Infrared detector on the Cassini spacecraft looked at the south pole and relatively high resolution for that instrument and saw that there were elevated temperatures in the vicinity of the tiger stripes and they actually were these hotspots. So, this was what we produced here I think is the final piece in the puzzle saying, yes the tiger stripes are very, very likely to be where the material is coming from primarily.

Adam Rutherford: Jose Spitale from the Cassini Imaging Central Lab for Operations or CICLOPS in Boulder, Colorado and you can see beautiful images of the jets on Enceladus at http://www.saturn.jpl.nasa.gov.

Kerri Smith: In just a minute we will be hearing how journalists should avoid the rocky territory of geological metaphor, but first how do nuclear inspectors know when all is not as it seems. We sent Geoff Brumfiel to join some inspectors in training as they learn the ropes at the Los Alamos National Laboratory. Published online 10 October 2007 Nature 449, 656–657 (2007)

Geoff Brumfiel: I am standing outside what could be the entrance to a high-security prison. Beyond the guard post and fence lies a tan windowless building that stretches about a city block. This is the building where nuclear weapon scientists at Los Alamos National Laboratory in New Mexico apply their trade. Inside they do experiments that help keep the United States nuclear arsenal in fighting form, but I am here for a different reason. I have come with 17 new nuclear inspectors from the International Atomic Energy Agency. The IAEA is the United Nation's body charged with ensuring that the world's nuclear facilities are being used for peaceful purposes. The inspectors I am with are the agency's eyes and ears on the ground. They are at Los Alamos to learn how to measure highly enriched uranium and plutonium so that if they see the stuff in the field they can sound the alarm. Now, I have got to stop here for a minute and make an incredibly nerdy confession. When I was younger I thought I might want to be a nuclear inspector. I imagined travelling the world with a diplomatic passport, turning up unexpectedly at super secret facilities and matching wits with local despots, but the truth is, I learned in my two days on the course is more tedious and demanding than my James Bond fantasy would have led me to believe. Inspectors are part scientist, part detective, and part diplomat. They must measure nuclear material, keep meticulous logs of reactor operations and they have got to do it while following the letter of international law. We passed through the guard house and across the neatly manicured lawn. On a table sits an unattended thick-neck box. Our escort jokes 'that is the advantage of working behind the fence; nobody is going to steal your lunch'. Through another turnstile and we are in the belly of the building, glass barriers line the hallway to protect heavily armed guards in case of attack. Security is tight. So much so that we have to keep inside of our escort at all times, but the room where the inspectors will spend the next two weeks seems welcoming, friendly looking instructors chat over coffee near eight tidy lab stations. The scene more resembles a university physics lab than a high-security nuclear facility. Inspectors rely on two kinds of radiation to identify nuclear material, gamma rays and neutrons. The neutrons tell how much material there is while the gamma ray spectrum tells them about what types of isotopes are present. The measurements are simple and the equipment cheap and easy to use, but in the real world things can get tricky quickly. Shielding can block neutrons from escaping their container; contaminants can confuse the gamma ray measurements. The shape of the sample and the quality of calibration can also mislead inspectors and that is just a small taste of what the inspectors face. Over lunch one of them named Giuseppe tells me that they often find themselves under enormous pressure in the field and high profile cases like I ran inspectors work in teams, but on routine trips to commercial power stations they usually work alone. They could spend more than three months to a year on the road travelling to unfamiliar places where they do not speak the language. Given that people typically build nuclear plants in out-of-the-way locations, it is not uncommon to find yourself lost on an unimproved country lane or checking into a lonely hotel in an isolated town far from civilization. Once you arrive at a plant, Giuseppe tells me, you have 10 people standing behind you talking in a language you do not understand, operators, sometimes rush inspectors in an attempt to keep their facility on schedule. If you are not prepared, Giuseppe says, people can sometimes prevent you from doing what you are trying to do. You have to be very sure about your rights. Despite the hardship, Giuseppe and others I talked to love the job. It is a very dynamic kind of life. You do not know exactly what to expect, he tells me, but it is exciting as it all sounds, I am not sure I would be cut out for it. For one thing I am not especially diplomatic. For me and the globe's non-proliferation efforts it is for the best that I gave up my fantasy and took up the notepad.

Kerri Smith: Geoff Brumfiel choosing words over weapons. Now, why do words for some things sound the same in many languages while others with the same meaning are unrecognizable and why do some verbs, to the frustration of language learners remains stubbornly irregular. The key to both these questions is how often words are used. I spoke to Mark Pagel from Reading University in the UK. His team have looked at why words such as those for the number two are similar in different languages whereas other words diverge. Nature 449, 717–720 (11 October 2007)

Mark Pagel: We started with the observation that some words in the Indo-European languages evolved very rapidly and other words evolved very slowly, for example, take the English word for the thing that we call a bird, the Italians called it uccello, the French call it oiseau, the Spanish call it pajaro, the Greeks say pouli, and the Germans say vogel, but then you take the meaning two, two objects, English-speaking people say two, the French say deux, the Spanish say dos, the Italians say deu, all Indo-European-speakers use a related sound for that meaning of two whereas we use very different sounds for the meaning bird. We wanted to understand why that was the case.

Kerri Smith: And how did you go about doing that then?

Mark Pagel: So, as evolutionary biologists we began with a sort of genetic perspective and we realized that some genes evolved very rapidly and other genes evolved very slowly and one of the things that happens in genetic evolution is that the rate at which a gene is expressed in your body how often it is used can be related to how rapidly it evolves and so we sought an analogue to that in language and what we came up with was the idea that in language different words are expressed at different frequencies in normal speech. What we discovered was that the words that are used very frequently in every day's speech are highly conserved across the Indo-European languages and the words that are used infrequently in common speech are free to evolve at a high rate and so you take words for the numbers like two, the example I gave, it is used very, very frequently in speech and it evolves very slowly and you take a word like dirty or bird or some other words they are used very infrequently and tend to evolve at high rates.

Kerri Smith: Now, you have come at least from the, as you were saying earlier you are an evolutionary biologist, are you surprised by the degree of correlation between how language seems to evolve and how genes evolve in biology?

Mark Pagel: Oh, we are not so much surprised with the correlation between genetics and linguistics. I think what we are more surprised by is that a single factor, you know, the rate at which, the frequency with which a word is used in common every day's speech can predict so much the variability across the Indo-European languages and how rapidly a word evolves and so this single factor the frequency with which we use words can explain about 50% of the variability across languages. Before our work no general linguistic mechanism had ever been advanced to explain this.

Kerri Smith: Well, some words stay similar in different languages through time other linguistic rules means that some words converge as Erez Lieberman and his colleagues at Harvard University have found, they poured over grammar textbooks from old and middle English and have come up with a rule for how pesky irregular verbs become regularized over time. I asked Erez about this linguistic evolution, but to help give you a flavour of Middle English, here is a clip from Chaucer's, The Knight's Tale. Nature 449, 713–716 (11 October 2007)

Here Beginneth the Knight's Tale Whilom, as olde stories tellen us, Ther was a duc that highte theseus; Of atthenes he was lord and governour, And in his tyme swich a conquerour, That gretter was ther noon under the sonne.

Erez Lieberman: Our paper is about the life and the death of rules, basically how rules in a language emerge and how they die. In general, the way that a rule in a language forms is that you have some new emerging rule and then there are tons and tons of exceptions to it and what we showed is that for the case of the ed rule, which we used to form the past tense, today I help, yesterday I helped, the exceptions actually died over time and the half-life of an exception. So, it's sort of expected life time is proportional to the square root of the frequency with which it is used. So, if an exception is used a hundred times less often it will regularize ten times as fast.

Kerri Smith: Which would explain why the very well used verbs like 'to have' and 'to be' have stayed irregular over all this time?

Erez Lieberman: Exactly! What is happening is that we are really preferentially losing the really low-frequency verbs, but the high-frequency verbs disappear so slowly that verbs like be and have will probably be around in their irregular form for the life time of the language, really common exceptions are very, very stable.

Kerri Smith: What resources did you use to look at how a language is changing like this through time?

Erez Lieberman: We looked at about a dozen grammar textbooks from old and Middle English and this was really a heroic work by Tina Tang and Joe Jackson in particular. Just looking at many, many grammar textbooks of old and Middle English and grammar textbooks usually lived exceptions to the various rules, so we just went through grammar textbooks after grammar textbooks and annotated everything that did not obey the weak conjugation.

Kerri Smith: That does sound indeed like it was a laborious process. Now, your team are from the program for evolutionary dynamics. How alike are linguistic and biological evolution?

Erez Lieberman: That is a very big question. Biological evolution we will get tons of data, you can get the complete genome of any species and that gives you at least a rough approximation of what the evolutionary information is within that species. There is not a good equivalent for a language. So, one very big difference between studying biological and linguistic evolution is in the context of biological evolution you have got tons of data, in the context of language evolution you do not and it is so bad that you know you might spend years of your life and widen your library reading middle and old English grammar textbooks just to get a dataset suitable. That is it. It is well known that in the case of biological evolution, very simple mathematical models will be extremely explanatory in terms of describing the changes of an organism and in particular the genome of an organism over time. The jury is still out in the case of language evolution. Our paper is one of very few examples of a simple mathematical principle really capturing the change in a language over time.

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Adam Rutherford: This is the Nature Podcast. Now, back to biological evolution with Mike Hopkin.

Mike Hopkin: We have all been taught in biology classes that evolution is driven by random genetic changes. Usually we think of these mutations as being tiny, but new research on brewer's yeast now shows how much larger changes can also be favoured by natural selection. In this week's Nature geneticists tell an intriguing tale of how a gene with two different functions in sugar metabolism gained a new lease of life by duplicating itself allowing the two functions to be honed separately and as a researcher Chris Todd Hittinger of Washington University in St. Louis told me such gene duplications may be an important general mechanism of evolution. Nature 449, 677–681 (11 October 2007)

Chris Todd Hittinger: Well we think gene duplication is an important general mechanism for evolution in that it can allow otherwise prohibit it or slightly deleterious mutations to actually become adaptive because it frees up evolution to work with two genes so that they can be hold by natural selection in two different directions and perhaps exploit this sort of molecular change that we see in the configuration of activating binding sites in a way that it could not have done with a single gene.

Mike Hopkin: And what genes in particular did you study and this was in yeast, wasn't it?

Chris Todd Hittinger: That's right. So, we selected the brewer's yeast, Saccharomyces cerevisiae for two main reasons, the first is that it is arguably the most experimentally tractable model organism for a geneticist such as myself and the second reason is because so many of the genetic regulatory pathways are so well understood and in particular we selected the genetic switch of the galactose utilization pathway, which has been a model system for explaining how genes are regulated for decades now, in particular the first enzyme of the pathway GAL1 and one of the key components of the regulatory switch that co-inducer GAL3 are actually descended from a multifunctional gene that performs both the roles. We know this because of genome comparisons that can reveal the genome contents of related yeasts and because another yeast, Kluyveromyces lactis has also had considerable work done on it. So, it is clear that at least in this Kluyveromyces lactis a single gene was performing both functions whereas in the modern brewer's yeast we have two genes performing two distinct functions.

Mike Hopkin: And how did you manage to spot this ancient gene duplication that seems to have helped the yeast along its evolutionary pathway?

Chris Todd Hittinger: Well, the duplication has been previously characterized by comparisons in genome contents. So, we have a number of complete genome sequences for yeast-related Saccharomyces cerevisiae and by doing a sort of comparison of gene content it is pretty clear that there was a whole genome duplication of yeasts very closely related to Saccharomyces cerevisiae and then yeasts more distantly related tend to only have one copy of a lot of the genes including the genes in this pathway that were duplicated.

Mike Hopkin: Talk us through what actually happened in the evolutionary story of this yeast and how its genetics actually evolved?

Chris Todd Hittinger: Well so, what our data suggest happened is that we have ancestral situation where you have a gene that has sort of been co-opted to perform two functions, the enzymatic function required to breakdown the galactose that is shared between all domains of life and sometimes ancient in the yeast lineage it appears that this enzyme was co-opted, sort of, in the passion that evolution does tinkering with the parts it has to perform a regulatory role that is specific to the yeasts related to Saccharomyces cerevisiae and Kluyveromyces lactis and we believe this setup as sort of conflict what has been called an adaptive conflict where you have one gene performing two functions that may not be able to be optimized at the same time because some types of changes might benefit one function but might hinder another function and so, this situation is unstable in that the gene is sort of being pulled in two ways. Now, if a fortuitous event, a gene duplication comes along and then if both duplicate copies are obtained this allows evolution to pull and natural selection to pull one gene in one direction and the other gene in the other direction and thereby result the adaptive conflict.

Mike Hopkin: And how common do geneticists think this sort of mechanism of evolution might be, is this the first time it is being seen?

Chris Todd Hittinger: Well, it has been suspected for a long time, at least the classic example is Piatigorsky and Wistow's work on lens crystallins in the eyes and this was an example where there have been a number of enzymes and some other genes also that have been recruited to perform sort of a structural or being expressed in high levels in the eye and that providing a medium to help refract light and many of these genes have been duplicated after they were performing multiple roles and in some cases you can see some genes lose particular functions and other genes obtained them, but what we have in yeast is really a system that we can genetically manipulate the strains and play a very sensitive competition assay to actually test the fitness consequences of specific molecular genetic changes and so really that allows us to flush out the molecular details of how the adaptive conflicts that we hypothesized was occurring here might have been resolved.

Adam Rutherford: Chris Todd Hittinger, now it is time for The Podium. Each week we invite a guest to take to The Podium and give us their thoughts on a course or something that is bothering them. This week we have Ted Neild, journalist and editor of geoscientist

Ted Neild: Ever since the first landslide victory journalistic language has been full of geological metaphor. Thus, triggered close to the epicentres of political earthquakes and their aftershocks eruptions of popular sentiment may tell of seismic shifts as tectonic plates of fixed belief move along fault lines in the bed rock of voter support sending tsunamis of opinion to raise the high ground of the political landscape. Geology itself is also frequently in the news, particularly on those occasions when mother Earth proves yet again what an unsuitable parent she is. Here are two statements. One, an earthquake of magnitude 7 has struck the island of Sumatra. Two, an earthquake measuring 7 on the Richter scale has struck the island of Sumatra. The second will be familiar from news reports, but do you feel that it told you anything new or different or in some way conveyed more information than the first? Or is it just that when I read it you and I conspired to pat ourselves on the back for being clever enough to know that earthquakes are measured on something called the Richter scale. Well here is the news. 'Earthquakes have not been measured on the Richter scale for very nearly 30 years. It was defined in 1935 by the notorious Californian nudist Charles F. Richter and his more frequently close colleague Beno Gutenburg'. Richter developed the idea of using a logarithmic scale which was specifically designed to measure the size of earthquakes in southern California using fairly high-frequency data from nearby seismographs. What eventually became known as the Richter magnitude was originally called local magnitude or ML. As more seismographs were set up around the world it soon became apparent Richter method was strictly valid only within certain frequency and distance ranges. Like many other things from California, it possessed certain magic characteristics. Richter's scheme cannot distinguish very large geological events. So, a more uniformly applicable scale known as moment magnitude or MW was developed in 1979 by two other geologists Tom Hanks, no relation, and Hiroo Kanamori. For very large earthquakes, MW gives the most reliable estimate of earthquake size and this is the measure that is today always misreported as the Richter scale. The use of the stock phrase on the Richter scale has become a self perpetuating conspiracy of ignorance between journalists and the public. It is time it stopped, but the problems do not end there. Each point on a magnitude scale betokens an earthquake releasing about 30 times more energy than one on the previous point. For this very reason, the higher the fewer. Earthquakes are happening all the time, but magnitude 8 earthquakes occur only about once every 10 years. Magnitude 9's are about once a century. Magnitude is a measure of the energy released by an earthquake and can only be calculated from seismograph measurements. Intensity however measures how much the Earth actually moves. Intensity is what really matters to people. Unfortunately, earthquake intensities are rarely published for contemporary earthquakes and if they were it would mean that everyone had to learn and understand two different scales, which is asking too much. Given that we are stuck with magnitude measurements it would be best to ensure that people at least understand what questions to ask about it and the most important question of all is how deep. Earthquake intensity is strongly affected by depths. The point inside the Earth where an earthquake actually occurs, the point where the energy is released, is known as its focus and it lies along a line between the centre of the Earth and a point at the surface directly above the focus which is of course the epicentre. Finally, earthquake magnitudes are often revised as measurements from more distant seismographs are added into the equation. So, when you read later reports that seem to conflict, do not blame journalists for once it is not our fault. It is those pesky scientists again demonstrating that nothing can ever be absolutely right, but the models of nature, like our measurements of magnitude, are not absolutes, but ever better refined approximations to elusive reality unlike the specious certainties of dogma. Absolute truth remains forever elusive to science. Truth is what all inappropriately naked people including nudist emperors like Dr. Richter, are best advised to tell the police.

Kerri Smith: Ted Neild whose new book 'Supercontinent - ten billion years in the life of our planet' was reviewed in last week's Nature.

Adam Rutherford: This week has seen the announcement of those most prestigious of science awards, the Nobel Prizes. Joining us in the studio are Alison Wright, editor of Nature Physics and Mike Hopkin. Published online Nature 9 October 2007, Published online Nature 9 October 2007

Adam Rutherford: Mike, physiology/medicine was announced on Monday.

Mike Hopkin: That is right, yeah, and it was won by the guys who gave us the technology that led to the famous knockout mouse models of various different diseases. They were Mario Capecchi at the University of Utah, Martin Evans at Cardiff University here in Britain, and Oliver Smithies at the University of North Carolina and what they are mainly being recognized for is first of all the discovery of embryonic stem cells in mice, which was way back in 1981 and that discovery once they worked out how to use those embryonic stem cells to make live mice then gave us the potential to create knockout mice because you can target a certain gene within that stem cell and then grow a mouse from it and then that mouse has that mutation throughout its whole body and therefore will mimic the disease. The first knockout mouse turned up in 1989 and today there has been more than 500 made for all sorts of diseases, cystic fibrosis, high blood pressure, heart disease, Alzheimer's. So, it has really been a useful technology.

Adam Rutherford: So, it really has revolutionized how we look at genetics and disease. Alison, the prize for physics has just been announced too.

Alison Wright: It has and it is really for the physics behind the technology that is bringing these podcasts. The winners are Albert Fert and Peter Gruenberg and it is for giant magneto resistance, which sounds a bit scary, but actually it is all about magnetic data storage. Data is stored in magnetized regions on a hard disk or something like that in your computer. As you miniaturize these things those regions get smaller and smaller. The magnetization of those regions gets weaker and weaker. So, you have got a big problem trying to read it out and what these guys did was find a process by which you could actually lay atoms of material together to create giant magneto resistance not just magneto resistance, but a giant effect and that gives you a sensitivity to actually access the data on very, very small devices. So, hence you know laptops are getting smaller and you have got loads of music in your pocket.

Adam Rutherford: So, if you are listening on an iPod, you have the 2007 Nobel Prize winners for Physics to thank and let us not forget last week the Ig Noble Prizes for the research that first makes you laugh and then makes you think. Mike who were the big winners?

Mike Hopkin: One of my favourites was a group lead by Juan Toro in Barcelona for their paper Effects of Backward Speech and Speaker Variability in Language Discrimination by Rats. They argue Pavlov's lot of speech-recognition research in human babies. I am not quite sure how it does, but it basically shows that rats cannot tell the difference between two different languages if you play them backwards.

Adam Rutherford: And neither can I!

Mike Hopkin: The other things which also hit the headlines were the Air Force Wright Laboratory in Dayton, Ohio for the pioneering work to create a Gay Bomb. I am not aware that it has been used yet in any theatre of conflict, but it is a technology they were hoping might make enemy soldiers irresistible to each other. So, I cannot really imagine that one getting off the ground and the other one which was covered in Nature's new section at the time was at work by researchers led by Diego Golombek on discovering that Viagra helps hamsters get over their jetlag and that is a big problem in the business world, hamster jetlag, but he actually in his acceptance speech thanks his colleague who actually had to go to the drug store to get the resources in.

Adam Rutherford: Alison, which do you think is more prestigious, a Nobel or an Ig Nobel.

Alison Wright: I would have to be a bit boring if I did not go for a Nobel every time.

Adam Rutherford: Mike?

Mike Hopkin: I would quite like to win either.

Adam Rutherford: Thanks Mike Hopkin and Alison Wright.

Kerri Smith: That is it for the pod this week. Remember you can write to us with Podium or Sounds of Science suggestions or any other feedback podcast mailto:podcast@nature.com is the address.

Adam Rutherford: And if you are interested in brain research you might want to listen to neuro pod on our new monthly neuroscience show. Find it on Itunes or at http://www.nature.com/neurosci/neuropod.

Kerri Smith: This week's Sound of Science is from a recent exhibition at Cambridge University where artists and astronomers have collaborated to turn dark matter into music. In this clip, x-ray data from the NASA Chandra satellite were fed through software that translates them into musical values. I am Kerri Smith.

Adam Rutherford: And I am Adam Rutherford. Thanks for listening.[Music - Sounds of Science]

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