Sometimes being interested in lots of different things can be a curse. Just at the moment I’m being very strongly reminded that attending scientific conferences is without doubt one of those times. At a large conference there are almost always too many presentations for them all to be held one after the other. So what usually happens is this. Talks on roughly the same subject are grouped together and the different groups run in different lecture theatres at the same time as so-called parallel sessions.

This is all very well except that those of us who are interested in a broad range of (in this case) evolutionary biology have to keep running between sessions to catch different talks and it inevitably means we end up missing some great presentations on fascinating subjects. I’ve definitely had one of those days.

Of course, I went to some very interesting, well presented talks as well. Mohamed Noor from Duke University in North Carolina, for example, on the genomics of speciation where as part of his talk he presented data on the possible causes of divergence between two species of the fruit fly Drosophila.

Amongst other differences between the two, there are large pieces of DNA that have had their order in the chromosome completely switched around in one species relative to the other, closely related species; what are known as chromosomal inversions (logically enough).

If these inversions were involved in generating the split between the two species, we would expect to see them dated to the time when the two species are thought to have split. However, the data show that the split between the two species likely pre-dates the inversions, so the inversions probably weren’t involved in the initial split, although his data show that they've played an important role in keeping them separate. Simple but logical and neat.

It’s a sad fact that well carried out pieces of science that address interesting and important questions but which nevertheless find a negative result, like the one Mohamed Noor reported, rarely get the attention they deserve. Finding something doesn’t happen isn’t going to get you on the BBC science news page. But, as every science undergraduate gets told repeatedly, this is an essential part of the scientific process.

When presented with a number of different explanations for something you need to carry out experiments to see which is the most likely to be right. Having good evidence that one of those explanations cannot be the one you’re after means it can be crossed off the list. This is important. It stops you wasting your time going after the wrong explanations and can lead you to explanations that are not only more accurate but often a lot more interesting.

The way this is phrased is at fault. All too often you read that the experiment “…failed to find a result”. But there are two ways this can happen. Either the experiment was done badly and it really was a failure or it was done well and has shown that a possible explanation doesn’t hold water. The second one sounds an awful lot like a success to me.

About the author

Paul Craze is an evolutionary ecologist based at the Universities of Bristol and Sussex. He's an invited contributor to our Darwin and Evolution forum and contributes to The Open University's Evolution course. Paul also performs in an unusual band with some editors of Nature.

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Talking to David Sloan Wilson about group selection, one of the most controversial areas of evolutionary biology.

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Paul Craze: So here we are again at the European Society for Evolutionary Biology meeting, and it’s almost a cliché that all the really interesting science goes on outside of the main meeting, and here we are in the evening in this very nice square in Turin with some fine Italian wine and it’s a nice warm evening, there’s some singing in the background, and of course being a lot of biologists we’re sat around talking biology. And I’m here with David Sloan Wilson, and one of the things that David’s been very interested in, for a long time, is this idea of group selection, and it’s one of the sort of naïve ideas about evolution that organisms act for the good of the species and that that’s often an idea that you come across, and that conflicts with the prevailing view that organisms act to maximise their individual benefit, their individual fitness. And there's another sort of halfway house between that, which is called group selection, where organisms act for the benefit of the group and not necessarily for their own individual benefit, and this has been a controversial view for some time, and it’s been a bit of a dirty word in evolutionary biology for some years, but David, you're looking at this again in a new way?

David Sloan Wilson: Well, to continue to set the stage, as you know, at this morning’s plenary by Hanna Kokko, at the beginning of her talk she turned to group selection and showed a cartoon slide of a man so panicked that he was about to jump out the window, and this represents basically the standard reaction of an evolutionist to the very mention of the name group selection.

Paul: It’s a bit of a kneejerk reaction, isn’t it?

David: And so this is a subject with a long history, and it’s an idea that was rejected in the 1960s and became such a pariah concept, so taboo basically, that most people don’t want to go there. And yet I, who have been working on the subject for, now, 35 years, all this time has been basically attempting to show, and I believe I’ve been succeeding, that actually group selection was falsely accused and it’s a perfectly legitimate concept and so it deserves to be revived, and has been revived, and so my talk was based on a series of blogs that I’ve written called Truth and Reconciliation for Group Selection. Type that into Google and you’ll get there.

Paul: We can maybe sort out a link for that I think.

David: And this was basically a summary of what I’m attempting to do in this series of blogs, which is to have a thorough review of this controversial idea, why it became controversial, what happened in the 1960s and what needs to be done today.

Paul: So how did it become such a thorny topic? I mean, what is the problem with group selection for most evolutionary biologists?

David: It’s actually easy to state what I call the original problem, you know, what’s all the fuss about? The fuss is about this and it will take me, dear listener, one minute.

Paul: Oh, that’s a good one. We like that.

David: Okay, so here we go. Now, some traits are just plain good for the individual. If you take a polar bear with thick fur and a polar bear with thin fur, the one with the thick fur evolves even though they’re standing next to each other. But other traits like altruism are not like that. If you put an altruist and a selfish individual together, side by side, it’s the selfish individual that wins, not the altruist. And so we have a very interesting class of traits that we hope they evolve but they’re not locally advantageous. So how the hell does something evolve in the total population when it is disadvantageous within each and every locality that it occurs?

Paul: So that’s what you mean by local, that it’s within a small area, it’s just the organism they attract?

David: Yeah, within, among the individuals that are actually interacting with each other this is not the most fit trait, and yet it evolves, or at least can evolve, and we want to know how that happens. And so the answer, the group selection answer is, even though there’s traits such as altruism, as locally disadvantageous, if we increase the scale it becomes advantageous that groups of altruists are more fit than groups of non-altruists even though non-altruists beat altruists within single groups. And so, if the advantage of the larger scale is sufficient to outweigh the disadvantage at the local scale then the trait can evolve. That is the concept of group selection. Now, events transpired in the 1960s that this very plausible idea was judged to be not the case, that the local advantage always trumped the higher level advantage; that is what became dogma, and what can be shown – please see my blog – is that very simply this idea literally deserves to be revived that it often is the case that the larger scale advantage can outweigh the smaller scale disadvantage, and so basically the rejection of group selection in the 1960s was just plain wrong. And this is a case where I actually have, one of the blogs is called, ‘If you make a mess should you clean it up?’

Paul: Okay.

David: Okay? And it begins with a little story about my cat had diarrhoea and I stepped in it and tracked it all through the house before I realised what I had done. Did I clean up that mess? Of course I did, anyone would. And yet if you expand that to a field-wide basis, if a whole field makes a mistake, makes a mess, do they clean it up decades later? Not necessarily.

Paul: Yes, okay.

David: And so I claim this is a case where the field made a mess, and yet there is such reluctance after you, and you can’t believe how much this mess is celebrated. This was like a watershed event in the history of evolutionary biology, the rejection of group selection was really thought of as a turning point in which you could reject all kinds of things and then go on this triumphant path towards the idea that everything that evolves is a form of self interest.

Paul: So I can imagine what a lot of people are thinking at this point is well isn’t this, this has all been sorted out with the selfish gene and that that explains altruism so why do we need this extra level of selection at the group and that just seems unnecessary?

David: Well the selfish gene, as it was developed by Dawkins, based on the work of George Williams, is that because genes are selfish then group selection doesn’t occur. Selfish genes were thought of as an argument against group selection. And this idea was actually falsified in the eighties, and Dawkins himself acknowledged this in his book The Extended Phenotype, and yet it lingers. And at my talk I actually provided an example of an article in The Economist this year which continues to commit this fallacy that group selection doesn’t occur because genes are selfish. That is an apples and oranges argument because every group selection model has always been about a gene for altruism that evolves compared to a gene for selfishness, therefore altruism becomes selfishness because the altruistic gene is most fit, all things considered, but that’s not the point. The point of any group selection model is to show how does this gene evolve despite being locally disadvantageous? So, the concept that genes are replicators is basically no argument at all against group selection, although it was considered so for a good decade by the cognoscenti and still in a wider sphere you hear all the time that group selection doesn’t happen because genes are selfish as if this is some kind of silver bullet when it’s nothing of the sort.

Paul: Okay, so you feel that this is coming back as a concept and it’s going to be sort of brought back into the mainstream of evolutionary biology or is it still very much on the fringes?

David: It’s not on the fringes, by no means, as I said in my talk I am not the Lone Ranger, even though I’m often represented that way, and what you find if you were to get a hundred evolutionists in a room is a Tower of Babel. A pretty good proportion would think, as I do, that group selection was falsely rejected and now it’s a just fine framework for studying evolution. And then we have all these other positions, including downright rejection, to the idea that there's equivalence, basically there’s more than one way to see things and either one is okay, this is like evolutionary postmodernism in some ways.

Paul: Oh right, yeah.

David: And then we have the idea that there was an old group selection that deserved to be rejected and now we have a new group selection which is somehow different.

Paul: Yeah, stick a new name on it and it’s something different.

David: And we have the terrible problem of old wine in new bottles is that you can see it’s kind of human nature that if this, the g-word basically has been stigmatised, and if you're studying something that anyone would have called group selection back in the sixties, well maybe if we just don’t use the g-word we won't get people upset, and so we have all kinds of stuff which anyone would have called group selection back then but which it’s really hard to say because basically people don’t want to know the g-word. And by the way, group selection has been so stigmatised that I have numerous examples of colleagues who submitted a paper to a journal such as Nature in which they frankly talked about it in terms of multilevel selection; that paper was rejected. They then re-described it using, everything was the same except they took out the g-word. And guess what? The paper was accepted.

Paul: Oh, that’s very interesting.

David: And so if you want to publish, if you want to get your grant accepted, if you want to get along with your colleagues, isn’t it easy just to take out the g-word? Now the problem is, is that means is the whole field has been tracking its mess around for decades and decades, and on the one hand we are teaching our students that for the good of the group traits never evolve, and on the other hand we’re giving back exactly what we took away. And I’m very idealistic about science, I think that scientists have an obligation to have a kind of integrity that other people, such as politicians, we wish they had it too but they don’t, but scientists, if anybody’s going to be held accountable for the history of ideas then it has to be scientists, and scientists have to be able to say, even though it’s hard, that this great event, which seemed to be such a turning point, actually turned out to be mistaken.

Paul: It sounds a very good argument for not being dogmatic in science and not taking received wisdom and always being prepared to question things?

David: Absolutely, and soI think that one of the things that’s so bothersome about this is that there’s so much dogmatism and so much that in a patriotic concept we would recognise as a patriotic history of nations. You know, the silliness of nations that glorifies its own history is exactly what’s taking place in our field of evolutionary biology. And so, we’d like to think that there’s not dogma in science, but this subject is an embarrassment when it comes to dogma in science.

Paul: Well, thank you very much, David. I think that’s something we can all learn from that; to be not dogmatic and to question things and to think about things, thanks very much.

About the author

Paul Craze is an evolutionary ecologist based at the Universities of Bristol and Sussex. He's an invited contributor to our Darwin and Evolution forum and contributes to The Open University's Evolution course. Paul also performs in an unusual band with some editors of Nature.

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Talking to Professor Samir Okasha of Bristol University about altruism and evolution:

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Paul Craze: One of the good things about a subject like evolutionary biology is just how it can bring in so many ideas from lots of different disciplines and lots of different areas of science and investigation of human knowledge. And one of those areas is philosophy, and that has a lot to say about exactly how natural selection operates on organisms and, in particular, the level at which selection acts. Does it act on genes, we’ve heard a lot about the selfish gene, does it act at the level of a gene or at individual organisms or populations, this so-called levels of selection debate that’s been going on for sometime, and I’m here today with one of the people who’s done a lot of work on this, Samir Okasha, from the University of Bristol, the Department of Philosophy at the University of Bristol. So this levels of selection debate, Samir, what is all that about?

Samir Okasha: It’s a foundational problem in evolutionary biology that goes back to an issue that was discussed by Darwin himself, so for the most part Darwin thought of natural selection as operating at the individual level. So what that means is that it’s individual organisms that survive, compete and reproduce in Darwin’s scheme, leading to traits which enhance their potential to do that. So the Darwinian view of things, in the first instance, applied at the individual level, leads us to expect that individual animals and plants will possess traits that enhance their own chances of survival and reproduction that give them a competitive advantage vis-à-vis other individuals. However, we indeed do find that process in operation throughout the living world. However, it’s also the case that we sometimes encounter traits, and Darwin was aware of this point, which seem not to serve any particular advantage to the individual organism that bears or expresses the trait. So, for example, in many social animals, we find animals engaging in so-called cooperative or altruistic behaviours which can in fact impose a cost to themselves and yet benefit other or other members of their local group or population or species.

Paul: So you say a social species, would that be humans or some other species?

Samir: Certainly, we find this in humans, but we find it much more generally. I mean, a striking example of this sort of cooperative or altruistic behaviour are traits that we find in insects; in particular in so-called eusocial insects which live in, often in very complex colonies. So ants, wasps, bees and termites, all contain species which live in extremely elaborate colonies, where the vast majority of members of the colony do not in fact reproduce at all but devote their whole lives towards indirectly assisting the reproduction of the queen. So they’ll devote their whole lives to building the nests, foraging for food, guarding the nest, tending the queen’s eggs, tending to every need of the queen and, in fact, forego reproduction themselves.

Paul: And would this explain something like the probably apocryphal stories of bees killing themselves and pulling the sting out of them and…?

Samir: That would be another example.

Paul: Yes, but they obviously can’t reproduce then?

Samir: Yeah, I mean any animal that engages in self-sacrifice, in fact self-sacrifice isn’t particularly common but it does happen, that clearly is not doing anything to enhance its personal fitness. I mean if you engage in a behaviour that reduces the number of offspring that you leave, and in some cases reduces it even to zero, by altruistically sacrificing yourself for the good of your group then clearly that’s doing nothing to enhance your individual fitness. And on the face of it such behaviours, which are quite common through out the living world, pose a puzzle, pose a challenge to the theory of evolution by natural selection, because that theory leads us to expect that animals, individuals will behave in a way that enhances their own prospects for survival and reproduction, not those of others, so why is it that we find examples of animal behaviours, particularly in social species including humans, where the behaviours seem detrimental to the individual fitness of the organism? Now, there are very many possible explanations you can give of such traits but one quite standard way of thinking about them is to argue that they are evidence or they reflect the operation of natural selection at a higher level than that of the individual organisms.

Paul: So this is why it is called the levels of selection?

Samir: Precisely. So in the levels of selection type problem we typically see a conflict between what’s individually advantageous for an organism and what’s advantageous for the whole group or species of which the organism is a part. So this problem goes, sometimes it’s called the tragedy of the commons, and also it’s called, in economics it goes under the name of public goods problem, where we find a conflict between individual self-interest and group welfare. And often in such circumstances, then individual self-interest wins out and we find individuals behaving in ways that don’t enhance their group welfare. As for example, when individual nations all pollute the natural environment to such an extent that it becomes detrimental for everybody - the problem there is that there's no individual incentive to cease to do so.

Paul: Yes. It’s usually in their economic interests to pollute as much as possible.

Samir: To continue their selfish polluting behaviour, that’s right. But interestingly, in the evolutionary sphere we also encounter a whole range of cases where natural selection doesn’t seem to have produced the purely individual self-interested solution that’s detrimental for group welfare but, on the contrary, seems to have moulded individuals, in some cases, to behave in ways that are in the interests of the larger community, one of the larger groupings to which they belong. So, social insect colonies are one such example, other possible examples come from human species, and from any group living species, and indeed the concepts can apply more generally. So you can think of a multi-celled organism, like you or I, or any multi-celled organism, be it plant or animal, as a cooperative grouping of cells. So as we know multicellularity is obviously not the ancestral state. I mean before multicellularity evolved, however many millions or billions of years ago, then life existed in the single cell stage for a long, long time, and the transition to multicellularity arose independently I think perhaps some fourteen different times, so clearly there was an advantage to it. But it’s striking that a multi-celled organism can be thought of in many ways as analogous to a cooperative group, all of the cells working together to enhance the welfare of the whole, and sometimes of course that cooperation breaks down, and that’s when you find things like cancerous cell lineages and the development of tumours that are detrimental for the organism as a whole.

Paul: Right, so this is cells going off on their own, really.

Samir: That’s right, that’s right. So this is the conflict between individual and group played out at a different level, where the individual is the cell and the group is the whole collective of cells, and indeed at a lower level still, within a cell, then you can find conflict between the different genes in the cell. So, for example, there can be conflict between the nuclear genes and the mitochondrial genes, even within a single cell, which arises because their mode of transmission to the next generation can be different.

Paul: So these are genes which are in the nucleus of the cell and then there are some which are in the other parts of the cell?

Samir: Yeah, that’s right, which are found in little intracellular organelles called mitochondria, and other organelles, which exist in the cell but outside the nucleus. Then you can even have conflict between genes within the nucleus, between nuclear genes, within the same cell, within the same organism, can be in evolutionary conflict with each other, and that arises basically because reproduction isn’t clonal, so the genome in a sexual species isn’t passed on intact to the offspring generation but is broken up and recombined, and that can create interesting situations where the different genes, within the same genome, are in a sense in a conflict with each other, have different interests. So, one very nice example of this arises in virtue of the fact that genes in the mitochondria are only transmitted down the maternal line, so in a…

Paul: So you just inherit those from your mother?

Samir: That’s right. You only inherit those from your mother.

Paul: It’s not because they’re in the, they’re outside of the nucleus?

Samir: That’s right, that’s right, so they’re not contained.

Paul: You just get that from the egg?

Samir: Yeah, so the sperm doesn’t contain any mitochondria, and the same applies in plants. So in hermaphroditic plants, that’s plants which contain both males and females, which devote resources to both male and female sexual function, you can get an interesting conflict where the mitochondrial genes have an interest in the plant only producing females, but the other, the nuclear genes have an interest in devoting resources to producing males as well, and that conflict can lead to striking evolutionary phenomena. So that’s just one more example of this more general point that in any multilevel scenario, we get potential conflict between what’s optimal at one level and what’s optimal at a higher or a lower level, which is the source of the sort of levels of selection problem.

Paul: And it’s fascinating that that’s such a, we’re really talking about something very fundamental here, the transition between single-celled life and multi-celled life and…

Samir: We are. We are. We’re dealing with a phenomenon that’s not at all peripheral, I mean, and the history of this debate is striking in that originally in the 1960s there was a large discussion of the concept of group selection, and many authors came to the conclusion, rightly or wrongly, that it was a relatively peripheral and minor aspect of evolutionary biology, not something you needed to worry about too much, but we’ve since come to realise that the idea of group selection and more generally multilevel selection is in fact fundamental to the evolution of life. And so the very things that we call individuals, organisms, multi-celled organisms, like you and I, from another perspective can in fact be regarded as groups, and the fact that individuals function so well and so cohesively most of the time is testimony to the power of selection at the group level to shape these entities which then become so cohesive that we cease really to think of them as groups and think of them as individuals themselves. So, in short, the levels of selection discussion and controversy is by no means a minor and peripheral one, as it was sometimes thought to be, but in fact permeates the biology of pretty much all life forms on Earth.

Paul: It’s certainly fascinating to think of yourself as this collection of cells. We think of ourselves as just the individual things but as a collection of cells…

Samir: That’s right. It is fascinating, and the phenomenon of carcinogenesis, of cancerous tumour development, does indeed illustrate this because I mean what’s happening in a case of cancer in effect is some rogue cell lines ceasing to behave in the interests of the whole organism; replicating themselves very fast to gain a short term replicative advantage that’s then detrimental to everybody in the group because it unfortunately often kills the host organism, as we know.

Paul: I think there, if anyone was looking for a reason for studying evolution and biology, you know, who didn’t just think that it was interesting, I mean there is an obvious example.

Samir: There would be potential practical applications.

Paul: Definitely, well Samir, thanks very much indeed.

Samir: Thank you.

About the author

Paul Craze is an evolutionary ecologist based at the Universities of Bristol and Sussex. He's an invited contributor to our Darwin and Evolution forum and contributes to The Open University's Evolution course. Paul also performs in an unusual band with some editors of Nature.

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A little surprisingly, not much is being made of Darwin’s 200^th birthday at the 2009 meeting of the European Society for Evolutionary Biology (ESEB). Then again, perhaps it’s not so surprising. Evolutionary biologists don’t exactly need a special occasion to get them thinking about evolution! If the anniversary is making its influence known at all it’s in the general feeling of evaluation there is at the conference.

There is a sense of examining how we’ve got to where we are with the understanding of evolution and where we go with it in the future. And it’s the prospects for the future that make major scientific conferences so exciting and the thing I’d forgotten through not having been to one for a few years. There is that sense of being led not just to the cutting edge of a subject but encouraged to peer over that edge at what might be coming next. While the view of the near future might not always be perfectly clear, one thing that few if any would deny is that the cutting edge of evolutionary biology has moved a long way from the school or even undergraduate textbook version. A very long way.

Take one of the first sessions of the meeting as an example. This examined an idea that even as recently as the last decade would have been laughed off the agenda; the idea that natural selection may not always act at the level of the individual organism after all. And before anyone reaches for their copy of The Selfish Gene to point out to me that it’s all been done, matey, I am not talking about evolution below the level of the individual but above it, principally at the level of groups of organisms.

To summarise the argument in just a few words: there are cases throughout biology where the interests of the individual and the interests of the group containing that individual conflict. The book we recently discussed in Darwin’s Book Club (Maynard-Smith and Szathmary’s The Origins of Life) gives many examples. By and large, what the authors call the Major Transitions in the history of life involve a reduction in the immediate fitness of the individual in return for greater fitness for a collection of individuals. The transition to multicellular life, for example, involves most individual cells giving up their own opportunity to reproduce so that some of the cells in their ‘group’ (for ‘group’ read ‘organism’) can produce more offspring than they would have done if they were on their own.

At the Major Transitions, the group benefits so outweigh the individual benefit that a new, group identity results. While many (including at least one of the authors!) would not have used the phrase to describe it, this is to all intents and purposes something called ‘group selection’.

If you mention the phrase group selection to most evolutionary biologists the very least you will get is a pitying look for being so naïve. Use it as an argument in an essay for a biology degree and a large, red, multiply-underlined and exclamation-marked “NO!!!!” is what you will get, along with a big, uncompromising zero. And yet here are working scientists and philosophers prepared to question whether the scorn poured on ideas of group selection (admittedly by many of the previous generation of working scientists) was not a little hasty.

There is a problem, of course, and it will be one familiar to anyone who followed the threads on the Darwin and Evolution forum thread on the topics of altruism and the Darwin’s Book Club thread on Lee Dugatkin’s The Altruism Equation. The problem is to distinguish “true” group selection from kin selection or inclusive fitness. If the group for which you are giving up your own fitness is composed of organisms that are genetically similar to you (which means often, but not always, your close relatives), then you are not sacrificing fitness at all. You are instead increasing your inclusive fitness. There are those (including some of the people at the ESEB meeting) who would argue that this is just group selection under another name.

There are others (again, some of them are here: I must choose my words carefully!) who would say group selection really is operating and the fact that the organisms carry the same alleles is neither here nor there. This is a difficult one since it makes it impossible to tell if carrying the same alleles as other members of the group is important or not. It is not enough to look at present examples and see that the organisms or cells or genes on a chromosome (remember gene duplication etc?) are related. That would be the inevitable consequence of existing in a more or less self-contained group for just a few generations but it may not have been a cause of the group forming in the first place. It all becomes much more complicated than the textbooks would have us believe. What is lacking, of course, is the killer example where a group forms and remains stable despite the things that make it up not being related and not even becoming related once they have grouped. Sadly, that may be impossible to find (I would genuinely love to be told of an example).

I think it’s true to say that whichever way this problem is finally resolved, it is perhaps more important and heartening that the people who spoke at the meeting, such as Samir Okasha and David Wilson, are prepared to step back from the received wisdom and re-examine this entire topic. Except for those ideas that become nonsensical in the light of new data and perspectives (once the Earth was known not to be the centre of the Solar System, for example, no amount of re-examination would be able to kick the Sun out of its central location, no matter how honest and courageous the questioning) there are few ideas in science that are worth accepting as permanently and unquestionably wrong. If new experiments are devised and the accepted ideas remain solid and useful, so be it, that’s absolutely fine. But to never allow currently accepted ideas to be questioned in the first place is to impose unnecessary limits on science and the enlightening insight it can bring us. Three mighty cheers for the undogmatic questioners, and four even mightier for those who then accept the data!

About the author

Paul Craze is an evolutionary ecologist based at the Universities of Bristol and Sussex. He's an invited contributor to our Darwin and Evolution forum and contributes to The Open University's Evolution course. Paul also performs in an unusual band with some editors of Nature.

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What is MRI?

Magnetic Resonance imaging (or MRI as it is known) is one of the most amazing developments in medicine of the 20th century. It relies on the fact that we have lots and lots of hydrogen atoms in our bodies and that the magnetic behaviour of the nuclei of those atoms depends ever so slightly on the environment of the atom – in other words whether it is a hydrogen atom in fat, or in water, or in brain tissue, and so on.

To do MRI it is essential to place the patient in a strong magnetic field. This is best created in the type of long tube that you saw Jem and Dallas going into in episode 3 of Bang Goes The Theory.

Patient going into an MRI scanner. [Image of Signa HDx scanner, courtesy of GE Healthcare]

Once the subject is in the bore of the magnet, additional complicated sequences of smaller but rapidly varying magnetic fields are created by currents in coils of wire around the bore of the machine.

As the currents in the coils change the coils move, and this creates the noise that one can hear inside the scanner. These varying magnetic fields are used to create an image of the part of the body under investigation.

MRI is really effective for imaging soft tissue and has a wide variety of uses. One of the best uses is for diagnosing joint problems - as in this image of a knee.

MRI scans are excellent for showing up soft tissue such as ligaments and tendons in joints. This is an MRI scan of a knee. [Image courtesy of GE Healthcare]

What is the difference between MRI and fMRI?

Most of the images created in hospitals using MRI show structural features of the body, but it is also possible to show some information about the oxygen consumption of tissues as well – this is known as functional MRI, or fMRI for short. When the brain is working it needs a good supply of oxygen. The oxygen is carried in the blood in the form of a substance called oxyhaemaglobin. When the oxygen has been used up the remaining substance is called deoxyhaemaglobin.

Rather fortunately for brain researchers, oxyhaemaglobin and dexyhaemaglobin have different magnetic properties, so it is possible to see which parts of the brain are using more oxygen – or working harder.

And here’s a strange fact: one might think that there would then be more deoxyhaemoglobin in the regions of the brain that are working hardest but in fact the opposite is true!

The active regions of the brain need more oxygen, so the blood supply is increased and is increased by so much that there is extra oxyhaemaglobin in the active parts of the brain.

The sequences used in fMRI will pick up this extra blood supply and therefore give us a picture of the active regions of the brain. This technique is called Blood Oxygen Level Dependence, or BOLD, and is widely used by researchers such as those at the MRC, who are looking at the ways our brains carry out certain functions. Hence the lovely images of Jem’s brain solving problems better than Dallas’! .

An fMRI scan showing with areas of increased activity highlighted. [Image courtesy of GE Healthcare]

Find out more

Daniel Bor explains neuroimaging, and what it might tell us about the mind

James Bruce on fluorescence imaging

Study Understanding Health with The Open University

It’s the season for an overstretched seaside metaphor: with around three months to go I’m beginning to sense a gathering swell of interest in the Copenhagen climate talks later this year. We’ll all be hearing plenty more about ‘COP 15’ (the Fifteenth Conference of the Parties in the UN climate policy negotiations) in the weeks to come. Tempting to bring in plenty more storm (teacup?) surf (opportunity?) and shipping analogies but I’ll resist. Enough now just to note down a few thoughts about what I anticipate about the conference and its significance. I’ll be going as a member of an OU team that will be working to make sense of the event and to analyse and communicate day by day.

2008 UNFCCC conference in Poznan.
[Image © copyright Oxfam International, some rights reserved]

COP 15 is going to have some people crying from the rooftops that this meeting decides the fate of all humanity and others sniping about another pointless UN junket. The truth is that this meeting does matter - a great deal - but it needs to be put in perspective. This is a significant moment in the development of an international political process that started in the early 1990s, and is set to go on for many years into the future. The Copenhagen meeting aims to set the next bundle of targets, timetables and mechanisms when those outlined in the Kyoto deal of 1997 run their course in 2012.

Many things are different this time around. International climate politics is more complex but also more mature. It is no longer simply a matter of the rich North admitting 'mea culpa' and obsessing about mitigating their own emissions and funnelling some 'clean tech' cash to the developing world. The booming manufacturers and sprouting middle classes of the developing world giants of India and China have made them major CO2 polluters. Political leaders and publics in the South are also much more aware of the potentially huge consequences of climate change for their societies.

Things have moved on in the North too. Levels of awareness of the science have increased, but along with this an awareness of the awkward questions raised by it (wind farms and more nuclear waste in your backyard? Higher electricity and fuel bills?). These changes and challenges North and South are neatly summarised in the shifting US and Chinese positions. The financial crash is significant too: it has revived a sense that the state has both responsibility for and can have some power over the economy and it has breathed life into phrases like 'green new deal'. Hence these talks are going on in the context of a much more cautious and critical view of unfettered markets.

But with climate change going up the public agenda around the world government ministers are now working in the full glare of media attention. The media want conflict, event and personality, and in looking for these they can distort the (dull but important) work of international policy development. Bluntly, the talks are about who cuts emissions by how much and when. Every move has consequences and it’s no longer enough to talk glibly about 'low hanging fruit' of easy emissions cuts. To meet climate change with the kind of energy and imagination that will be required will need us to rethink and rewire almost every aspect of contemporary life. The 24/7 short attention span world of the media may not allow much political space for this.

Nevertheless we are helped by the fact that plenty of new people have joined the climate change story since the talks that produced the Kyoto Protocol in the 1990s. Lord Stern is one of them. This respected economist was commissioned by Gordon Brown and Tony Blair to lay out the options for a mainstream western government. Stern found that early action to cut emissions and avoid warming ends up much cheaper than delaying action and paying big bills later to cope with the effects of climate change. And cutting emissions later is also tougher.

So the arguments have been piling up in favour of a robust deal this year. But we shouldn't raise expectations too high: as one wise head noted how people always overestimate what they can do in a year and underestimate what they can do in a decade. Also, focusing on the international politics can distract us from the fact that there are many other creative and determined responses to environmental change in play. On that note, my next post will be about a new Open University project - Creative Climate - that will work to capture the human story of environmental change from 2010 to 2020. We’ll be hoping that plenty of people in the OU community – students, associates, staff – will contribute to that work. More on that soon.

About the author

Joe Smith is a lecturer in the environment at the Open University and chair of Interdependence Day. He has written books on climate change and sustainability, the media and global issues, and the green movement.

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If you've discovered our Darwin and Evolution forum, you'll be well aquainted with Paul Craze. Paul is an evolutionary ecologist based at the Universities of Bristol and Sussex. Throughout our Darwin season Paul has been a key contributor to the forum and the Darwin Book Club that sprang from it.

Paul's currently attending the 2009 meeting of the European Society for Evolutionary Biology. He'll be blogging from the conference for Open2 and interviewing some key speakers. His posts will appear on this blog over the course of the next week.

If you've had success with the Bang Goes The Theory challenges, you can face the latest one now: Holding Our Breath. Can you use your knowledge of science to flee from a sealed room? Try the Holding Our Breath challenge now.

We often hear about the multitude of environmental challenges facing the world: be it water, energy and/or biodiversity crises. But it is not only the earth’s physical and biological resources that are at peril, but also cultural diversity.

Kaapse Klopse Carnival in Cape Town, South Africa. Behind the diversity of performers is Table Mountain, part of the Cape floristic Region (one of the world’s biodiversity hotspots).
[image by Yoseph Araya © copyright Yoseph Araya]

Simply defined culture could mean the integrated pattern of human knowledge, belief, and behaviour that depends upon the capacity for learning and transmitting knowledge to succeeding generations. Cultural diversity is a driving force of development, not only in respect of economic growth, but also as a means of leading a more fulfilling intellectual, emotional, moral and spiritual life. [UNESCO defintion]

The disappearance of cultural diversity can at times be even worse than that of other biological diversity. For example, Professor Sutherland in his paper, Parallel extinction risk and global distribution of languages and species, notes: "Over the past 500 years, about 4.5% of the total number of described languages have disappeared, compared with 1.3% of birds and 1.9% of mammals."

Often the factors that determine the diversity of life and culture are very much similar. For example forest cover, tropical climates, heterogeneous topography and prevalence of pathogens are known to be associated with higher cultural diversity.

This emphasises the need to address the world’s heritage of biological, cultural and linguistic diversity together - as biocultural diversity.

Why?

There are many compelling scientific reasons for conservation of biocultural diversity – some of which relate to ecosystem of goods and services vital for our very existence on earth.

Moreover, extinction is forever, as the epitaph at the death of the very last Hawaiian snail in captivity sombrely reminds:

Here lies Partulina turgida: 1.5 million years BC to January 1996”

Lastly, on a more personal level, the earth is a very complex and fascinating place to live in and appreciate. The loss of a species, or the loss of human language diminishes the beauty of the world simply by removing a little of that complexity).

What can be done?

We should combine resources from all walks of life and work together to save our biocultural diversity. There are many approaches that could be tried.

Bringing awareness, documenting and sharing diversity knowledge go a long way in alerting experts as well as the general public.

Another approach is to explore new ways of linking cultural and biological diversity conservation schemes. There is currently growing interest as such e.g. religious communities are increasingly being involved into conservation activities and activism.

See, for example, BBC News reports on Faith leaders urging climate curbs or Beyond Belief: Linking faith and conservation from the WWF.

Watch: International Union for Conservation of Nature: Live Culture - An expert speaks

Not least is getting involved when possible or otherwise supporting organizations working towards this aim. Some notable examples include Terralingua and Global Diversity Fund.

Last word:

The well-versed advertisement for Patek Philippe, the Swiss watch company goes: “You never actually own a Patek Philippe. You merely take care of it for the next generation.”

Taking this analogue, it would be a great shame (if not a crime) to bequeath an impoverished earth to our future generations.

Find out more

Saving Britain’s Past

BBC News: In defence of 'lost' languages

Terralingua: Index of Biocultural Diversity

Ecological influences on human behavioural diversity: A review of recent findings
Daniel Nettle, writing in Trends in Ecology and Evolution, 2009

Parallel extinction risk and global distribution of languages and species
W J Sutherland, writing in Nature 423

Introducing Environment
Alice Peasgood and Mark Goodwin, Open University/Oxford University

OpenLearn: Diversity and difference in communication - free learning materials from the Open University.

About the author

Dr Yoseph Araya is a plant ecologist and associate lecturer at the Open University. He works on the biology and conservation of South African fynbos vegetation. Environmental education and the role of the public in research is one of his key interests.

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WARNING: This blog post contains spoilers for the fourth programme in the Bang Goes The Theory series. Don't read it if you haven't seen the space challenge yet and don't want to know what happens.

While we were planning and filming an ambitious item for Bang Goes the Theory in which an 'action man' type-figure dubbed mini-Dallas is sent up to the "edge of space" by a balloon, there was a lot of discussion among the Bang gang about whether or not we could claim to be reaching 'space', and also whether Joseph Kittinger had really "parachuted from space" after his balloon ascent to 102,800 feet (31,333 metres) in 1960.

We got our mini-Dallas to pretty much the same height, but I’m afraid that the answer has to be ‘no’ in both cases, even though the sky looks gratifyingly black in our remarkable camera shots.

Mini Dallas from Bang Goes The Theory.
[image © copyright BBC]

It’s pretty obvious if you think about it. Kittinger and mini-Dallas were both carried up by a balloon, and a balloon only goes up if it (plus its 'astronaut' payload) is on average less dense than the air that it displaces. That’s how buoyancy works.

There must still be air – albeit very tenuous – at the height reached by the balloon, otherwise it could not float.

There is not a vacuum at the height reached by these extreme balloons, but the pressure is very low. In fact it is about one-hundredth of the pressure at sea-level. This means that 99% of the atmosphere’s mass is below, and only 1% of the mass of the atmosphere is above.

However, that does not mean that mini-Dallas was 99% of the way to the top of the atmosphere, because the atmosphere becomes more and more tenuous with height. If you look at this diagram that shows how atmospheric temperature varies with height, you will see that 30,000 metres is only about halfway to the top of the stratosphere, and that there are layers called the mesosphere and the thermosphere above that!

Temperature variation with height in the Earth’s atmosphere. The warming with height in the stratosphere and thermosphere are because the air molecules are warmed by absorption of ultraviolet and other radiation from the Sun

Temperature variation with height in the Earth’s atmosphere. The warming with height in the stratosphere and thermosphere are because the air molecules are warmed by absorption of ultraviolet and other radiation from the Sun.

There is actually no definite boundary that marks the top of the atmosphere, but eventually it becomes so completely tenuous that for practical purposes it can be regarded as ‘space’. But where is this limit?

Well, I did some web searching, and I came up with this. Satellites can orbit 200 km above the Earth, free of any appreciable atmospheric drag. Clearly at 200 km, you are in ‘space’ (the International Space Station orbits at 320-347 km). Lower orbits down to about 160 km are possible, but there is too much drag for these to be stable.

The US government refuses to recognise a definition of where space begins, perhaps because it prefers to keep its option open.

However the Fédération Aéronautique Internationale recognises 100 km as the lower limit of space, whereas an encyclopedia of international law suggests 80 km as a practical limit between ‘air space’, potentially reachable by an aircraft, and ‘outer space’.

However you look at it, sadly 30,000 metres or 30 km is less than half way there, but it was a bold effort nonetheless.

Find out more

John Zarnecki looks back over fifty years of space exploration

Visit The Planets & Beyond

Consider The Open University course Planets: an Introduction

About the author

Dave Rothery is a volcanologist and planetary scientist at the Open University. His current research includes studying volcanic eruptions on the Earth and characterising planetary surfaces, especially Mercury.

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Tonight, Bang Goes The Theory is on-air on BBC One, and while the team try to scale a building using vacuum power, you can attempt our second Bang! challenge: Snakes by a flame

Peter Taylor explains how plastic works:

Learn more about science with Bang Goes The Theory.

About the author

Peter Taylor is Professor of Organic Chemistry at The Open University. He’s interested in public engagement and has been involved with many broadcast series such as Rough Science and Alternative Therapies.

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Flash-fried scorpions: Would you swap your prawns for them?

There was an interesting item in programme two of Bang Goes the Theory. The story is that cows produce a lot of methane (which is a more potent greenhouse gas than carbon dioxide), but that insects make protein without releasing methane to the atmosphere. So, to do our bit towards saving the planet from global warming, why don’t we eat insects "and other creepy-crawlies" instead?

Presenter Liz then offers various insect delicacies to her three co-presenters, of which Dallas is at first reluctant to partake. Eventually, he concedes that he likes to eat prawns, and wonders why he is freaking out at the thought of eating something that Liz agrees is ‘essentially a prawn’. Was she right? Read on!

Why some foods revolt us is a complex issue. As I watched for the first time, I too was thinking "go on, I bet you’d eat a prawn, so why not a scorpion or a cricket?" - but that is not actually good logic when you look into it.

Insects and prawns may appear similar, but they are not very closely related. They both have segmented external skeletons and jointed limbs, placing them in the same Phylum (the Arthropoda), but they are in different divisions - Classes - of that Phylum. Insects constitute the Class Insecta, whereas prawns belong to the Class Crustacea.

The flash-fried scorpions that we see Liz cooking belong to a third arthropod Class, the Arachnida (of which spiders are familiar members), and are definitely not insects - despite any impression that the programme my leave to the contrary. Millipedes and centipedes form two other Classes of Arthropoda.

Turning to what non-vegetarians more familiarly eat - for example haddock, chickens and sheep - these belong to three different Classes of the Phylym Chordata. Thus a prawn, a scorpion and a locust are no more closely related to each other than a haddock is to a chicken and a sheep. No problem there, you might think. If you’d eat one, you’d probably eat the other.

Sea squirt - pass the ketchup?
[Image Open University, made available under a Creative Commons BY-NC-SA Licence]

But what about a frog, from the Class Amphibia, would you eat that? Or a sea squirt (Class Ascidiacea)? Both are Classes of the Phylum Chordata. The latter are probably eaten in China, but the majority of westerners would refuse them. Yet both are just as closely related to chickens as prawns are to scorpions, and as chickens are to sheep.

On the other hand, few westerners would eat dog, and I’m unaware of vulture being on the menu anywhere in the world, yet these are far more closely related to sheep and chickens than prawns are to scorpions. Then there are the molluscs; even people who love oysters or Coquille St Jacques (Phylum Mollusca, Class Bivalvia) would probably retch at the thought of eating slugs (Phylum Mollusca, Class Gastropoda).

My conclusions after all this are: One, scorpions aren’t insects; Two, what animals you are willing to eat has little to do with what they are related to.

Find out more

Discover how to start studying biology with The Open University

About the author

Dave Rothery is a volcanologist and planetary scientist at the Open University. His current research includes studying volcanic eruptions on the Earth and characterising planetary surfaces, especially Mercury.

Subscribe to Dave Rothery's posts