The Naked Scientists discuss why the sequence of how four-legged animals move their legs is commonly misrepresented; Wi-Fi, the gaping hole in our internet security; why eating too much is bad for your brain; fossilised evidence of dinosaurs fighting; what makes locusts swarm and could they be 'deactivated'; why you have your DNA to thank for the party animal inside you and what this means for your health.
Plus in 'Stuff and Non-Science', are lemmings suicidal?
Chris Smith: Coming up this week, how scientists have discovered what triggers locusts to swarm.
Stephen Rogers: The first thing we did was look to see how strongly correlated the amount of serotonin in the central nervous system was, with how gregarious they’d become, and when we did that we found that the more gregarious they were behaving, the more serotonin they had in the thoracic ganglia. So the first thing we did was we gave them drugs which interfered with the synthesis of serotonin, we could tickle them or crowd them, or show them other locusts and that had no effect on their behaviour, they remained solitarious.
Chris Smith: Stephen Rogers who’ll be along shortly to explain how that discovery could be used to stop plagues of locusts, and not just biblical ones, because they’re a big problem even today. And also on the way, how your DNA affects how you make friends and influence people.
James Fowler: We studied a thousand twins and compared identical twins to fraternal twins to see whether or not the identical twins had more similar positions in the network. And the way you measure this is by measuring things that are very intuitive, like how many people name you as a friend. So we found that that was about half nature and half nurture.
Chris Smith: So is there a popularity gene? Well, we’ll be finding out when James Fowler joins us later in the show. Plus, in this week’s ‘Stuff and Non-Science’, we push another old wives’ tale off the cliff, and that’s because it’s all about the science of lemmings. Hello, I’m Chris Smith, and this is Breaking Science which is brought to you in association with the Open University.
First, with news of duelling dinosaurs, why Wi-Fi is a security risk, why when it comes to man’s best friend we’re barking up totally the wrong tree, here’s Helen Scales.
Helen Scales: Yes, how do dogs walk? No, that’s not a joke, but it seems that as a nation we are being misled in how we think dogs, horses and all other four-legged creatures move their legs when they’re walking, because about half the time we get it wrong. And that’s not just for toy makers and cartoonists but it even goes for the folk at natural history museums, taxidermists, and even the people who write scientific text books would you believe.
Chris Smith: So what you’re saying, that when people try to give a representation of a dog moving, say in a picture, they put their legs in the wrong place?
Helen Scales: Exactly, that’s right. You can tell from the way an animal is drawn based on which legs it’s lifting up, and which ones it’s bending and which ones they’ve got straight, as to the sequence of the legs and how they’re moved. And we get it wrong half the time. Do you know how a dog moves its legs?
Chris Smith: Well I do now, because I was so intrigued by this I actually went and read the paper. But I thought, probably many people with me thought that camels were particularly special because I saw camels moving when I was in Africa, and I saw them move the back leg on one side of the body forward then the front leg on the same side of the body, and then they do the other thing with the other side of the body, and I thought this was very unusual and it was just camels but, apparently, that’s what all quadrupeds, four-legged creatures, do.
Helen Scales: The mad thing is we’ve known this for over 100 years, in fact it was some research back then that showed that all of the, like you say, all the quadrupeds do the same thing when they’re walking at slow speed. And this astonishing fact that we’re still getting it wrong now came from a study by Gábor Horváth of Eötvös University in Hungary and his colleagues. And what they did was they went round museums, they looked through toy stores and looked through books to look for all these depictions of four-legged animals to see how they were drawn and how they were walking, and showed that lots of them were actually in the wrong sequence.
Chris Smith: The really worrying thing though is from what you’re saying the text books have got it wrong. So if we’re teaching vets the wrong thing, what hope is there?
Helen Scales: I know, exactly. I think perhaps for some things it doesn’t really matter, but our toy animals, they’re not as stable as they could be, which I think is ridiculous, a rather poor thought.
Chris Smith: That explains a lot because I had a little farm when I was young and all my horses kept falling over in the field. Now I know why, presumably?
Helen Scales: Exactly. That’s exactly it. Because the way they should be is by having three feet on the ground at any one time in a very stable triangle. It changes when they move faster but that’s what’s going on. And I think, rather wonderfully, the only place that we get it right is in Hollywood, and in fact in films like ‘Jurassic Park’ of the dinosaurs and in ‘Lord of the Rings’, with all the horses galloping around, they did seem to get it right. And that’s probably because all that wonderful CGI computer animation going on, that relied heavily on advice from experts in biomechanics and animal locomotion to make sure they hit on an authentic look.
Chris Smith: Well talking of computers, rather worrying news this week about Wi-Fi, which could be reason to suspect there’s a gaping hole in our internet security there. Tell us about this.
Helen Scales: Well yes, it’s hard to deny that having wireless access to the internet is incredibly convenient for all of us whether we’re at home or at work, but Wi-Fi is actually putting our security at risk it seems. And a group of scientists this week have published a paper in the journal PNAS, and they used computer models that are usually used to predict the spread of infectious diseases through people and animals, and they used these models to show just how susceptible we are because of our Wi-Fi networks, because they obviously can be susceptible to their own bugs. They now call them malware, which is this combination of viruses and worms that have become really malicious.
Chris Smith: So what are they arguing? That when you have lots of people who have Wi-Fi in their homes for example, because the range of my home Wi-Fi overlaps with my neighbour’s Wi-Fi someone could come along and write a bit of program which would go into my wireless network router and make it talk to the house next door, and the house next door talk to the house next door, and you could have this sort of conduit for naughty programs to spread, which doesn’t have to go through traditional routes where we’ve thought of protecting with things like virus software and stuff like that?
Helen Scales: You’ve absolutely got it on the head there. This particular model, which was built by Alessandro Vespignani from Indiana University, they used actual, real geographic distribution of Wi-Fi routers in some major US cities, in New York and in San Francisco and various places, and they’re so close to each other, they are like a network of kids at school, if you like, who are susceptible to a disease. All it takes really is a few kids to come in who will pass on diseases to those other kids that they come into contact with.
Chris Smith: So what are they saying we should do about this, and why is this happening? Haven’t we got passwords?
Helen Scales: Well we do have passwords, but I think the problem is a lot of people don’t actually change their passwords from the ones that they’re given when they originally get the software, and they don’t change them through time, and they make them really obvious things that people can guess. So one thing that they do recommend is that you change your password to something that no-one’s going to know and don’t tell anyone. The other thing is there is software that can actually encrypt and stop Wi-Fi routers from being able to talk to each other, but that isn’t used enough yet.
But the interesting thing is, you don’t actually have to have every single router with this encryption technology, only possibly, in the models they looked at, about 60 per cent, and if you do that then you really can stop this wildfire spread. Because what they found was, we should add this, it’s 10,000 routers they think could be infected within a week with just a few being infected at the beginning. And most of the infection’s spread within the first day, so it really could happen extremely quickly if we don’t make steps to become a bit more secure.
Chris Smith: So tighten up security on your router. Now, another thing to consider is tightening up security on your larder to stop people eating too much, because eating too much is bad for your brain.
Helen Scales: It could be, yes. We have new evidence this week published by a team of researchers led by Veronica Witt and her colleagues from the University of Munster in Germany, and they showed that possibly by cutting down the daily calorie intake of elderly people it might actually have a link to improving their memory. Now statistics show that we are living in an aging population, and that’s thanks to modern medicine that in general people are living longer than ever before. But even if our bodies live longer our brains don’t always do as well, and there is an increasing incidence of all sorts of neurodegenerative diseases among elderly people.
So is there really a brain-healthy diet? Well, various studies in the past have shown both in people and in laboratory animals that have hinted, really, that restricting calories in the diet and cutting down on saturated fatty acids could help to protect the brain later in life.
Chris Smith: But do we know chemically why doing that – is it just that if you eat a healthier diet you have better blood vessels and therefore you don’t have a stroke, or is there something biochemically going on that makes the brain fitter if you watch what you eat?
Helen Scales: Well what these guys did, first of all they actually wanted to see the link to the memory of restricting diet, and they took a group of volunteers, who were aged between 50 and 80, and put some of them on a diet that restricted their calories for three months, some of them they put on a diet rich in unsaturated fatty acids, and some of them they just left as a control. And what they found was by testing their memory before and after this time, the ones who were on the restricted calorie diet did in fact have a better memory before and after.
Chris Smith: So it does look like there’s a real effect going on there, but what do we think in terms of hormones and chemicals and the biochemistry is causing that?
Helen Scales: Well what they also did was measure various things in their blood before and after, and one thing that seems to stand out is insulin. And there seems to be this link that essentially the people who were on the restricted diet had lower levels of insulin in their blood after this fast, if you like, this three months of lower calories, and it seems to be that insulin plays a very important role in our brains in terms of how connections are made between nerve cells in our brains, and that’s linked to learning. So when we’ve got this lowered sensitivity to insulin that could actually be through a series of steps leading to problems in forming memories.
Chris Smith: So healthy diet, healthy mind. Well let’s finish off this week with a wonderful story which is published in PLoS ONE this week isn’t it, where there is fossilised evidence of dinosaurs fighting with each other.
Helen Scales: Yes, this is a wonderful way of recreating things, events that happened long before we were ever around. I’m afraid, yes, we weren’t around when dinosaurs were around. These are the triceratops, these wonderful nine-metre-long beasts that roamed the earth in the cretaceous period about 70 million years ago until around 65 million years ago, when, as we all know, the dinosaurs didn’t do so well and most of them disappeared, except for the birds.
Anyway, this is a wonderful study which was conducted by a team of researchers led by Andrew Farke who is curator of Raymond M Alf Museum of Paleontology in California, and what he and his team did was they went around scrutinising the lumps and bumps on triceratops skulls in museum collections, and in particular they were looking for calluses associated with healed or healing fractures and something called periosteal reactive bone, which is the upshot of when a superficial injury pulls the membrane away that lines the outside of bones and can lead to inflammation and then a scar on the bone. Because what they were looking for was evidence that triceratops attacked each other.
We don’t know why they have these three wonderful horns. Now they think they’ve found some evidence that indeed triceratops did fight each other. And the key to understanding what these bumps and lumps they found on the skulls were was by looking at another group of dinosaurs, the centrosaurs, which in many ways are quite similar to triceratops, they too have three horns, and in fact they found that the centrosaurs had far fewer of these battle scars than the triceratops did.
Chris Smith: How do they know that the battle scars, these injuries on the bones were inflicted by triceratops? Is it because of the relationship of the scars to each other, they map onto the same sort of shape configuration of the spikes coming off the head so that’s how they know what made them?
Helen Scales: Well they were actually, most of these scars were in fact on the frilly bone around the back and the neck, if you like, of the triceratops. Which if you can imagine probably is where the triceratops horns would poke if they were wrestling with each other. And we think what might have been going on is a bit like deer do now, and antelope with horns, they lock horns and wrestle with each other. Another thing they think could be that it’s unlikely to be other predators, other dinosaurs doing this because why weren’t the centrosaurs covered in scars as well. So that’s another piece of evidence that we think it really was these wrestling triceratops, which is a lovely idea I think.
Chris Smith: Indeed. What do you think they were fighting over though?
Helen Scales: Who knows? I mean they were probably fighting over mates to be honest. I mean that’s the main thing in life isn’t it, it’s passing on your genes, so it was probably the male triceratops fighting for ladies, fighting for territory. We don’t know what kind of social system they might have had but I think it probably was, they’re probably showing off, you know. You know what men are like.
Chris Smith: Yes, and female triceratops weren’t terribly good drivers either I’ve heard. It’s reassuring to know that stereotypes were alive and kicking even 65 million years ago. Thank you, Helen. That was Helen Scales from the Naked Scientists with a look at some of this week’s top science news stories.
If you’d like to follow up on any of those items, the details and the references are all available from the Open University’s website at open2.net/breakingscience.
In just a moment, why you have your DNA to thank for the party animal inside of you. But first, to the friendships that are forged by locusts. Locusts are typically solitary but sometimes they gather into enormous clouds of quite literally biblical proportions, which can, and regularly do, devastate crops. In 2004, for instance, a swarm some 250km long and containing about 69 billion of the insects descended on Morocco, and at the same time whole regions of the Sahel in North Africa were subsequently left with a serious food shortage. But what triggers this behaviour from the locusts in the first place? Here’s Stephen Rogers.
Stephen Rogers: Locusts are animals of the deep desert and they eke out a living in very low population densities, but every so often it will rain quite heavily and when that happens the vegetation springs up, the desert blooms and then it’s suddenly the good times roll in for the locusts and the locust population explodes.
Chris Smith: So what do you think’s going on, and how have you tried to identify why these animals transform this behaviour in response to the desert suddenly blooming?
Stephen Rogers: Well what happens when the desert blooms is, of course, is it’s a good time for the locusts and they breed like mad and the population expands. But being the desert these rains don’t last and you have these vast numbers of locusts being funnelled into ever-shrinking patches of greenery, and when that happens they come into one another, and this is what triggers this change in behaviour.
Chris Smith: So it’s not just the locusts seeing other locusts and thinking I’ll get together with these other locusts because I’ve got a full belly, there is actually some physiological behavioural change taking place in the nervous system of these locusts making them do this?
Stephen Rogers: Absolutely. What drives them is seeing and smelling other locusts. And the other major trigger for this behavioural change, which was quite surprising when we first found it, is that simple touch can drive it, and particularly touch directed to the hind legs, which means in the laboratory we can make locusts change phase simply by tickling them with a paintbrush for a couple of hours if you have the patience to do it.
Chris Smith: So that’s not a short time is it, to tickle a locust’s legs. So what you presumably did is you took some locusts in the lab, put them into solitary and stimulated them to mimic brushing by other locusts?
Stephen Rogers: Yes, I mean we have a solitary colony in the department in Cambridge and a gregarious colony, and we rear them under sort of very strict purdah really, they can’t see or smell other locusts and the only time they ever see another locust is when we introduce them to one another to mate, and that only happens once.
Chris Smith: So what is actually happening when you’re doing the stroking or you’re stimulating a locust so it wants to become gregarious, to adopt this flocking behaviour?
Stephen Rogers: Well we’re really interested in this question, and to begin with we did a sort of very broad sweep analysis of changes in brain chemicals within the nervous system of the locust. And what we found in that study is that only one substance was really changing, and this substance is called serotonin, which is a really quite common and ubiquitous chemical messenger in the nervous system of animals. I mean human beings have it as well.
Chris Smith: Was it changing everywhere or were there discrete bits of the, I want to say locust brain but locust nervous system, in which you can see a little peak in the levels of serotonin under these conditions?
Stephen Rogers: They have much more decentralised control, so it’s best to think of their brain a bit like a string of beads with separate mini-brains strung along each segment of the animal, and what we found is that this increase in serotonin was actually occurring at this sort of downstream part of the brain in parts of the nervous system which normally are controlling how the legs work.
Chris Smith: And so you get this peak in serotonin, how do you know that that is linked to this flocking behaviour, this ability for them to go from being solitary to wanting to be together?
Stephen Rogers: Well we took a sort of three-fold approach. The first thing we did was we looked to see how strongly correlated the amount of serotonin in the central nervous system was with how gregarious they’d become, and when we did that we found that the more gregarious they were behaving the more serotonin they had, was being produced in the thoracic ganglia.
Chris Smith: And the other two ways?
Stephen Rogers: So the first thing we did was to try and block the action of serotonin and prevent it being made in two separate experiments. And what we found is when we did either of those two things, we gave them drugs which interfered with the synthesis of serotonin, we could tickle them or crowd them or show them other locusts and it had no effect on their behaviour, they remained solitarious.
Chris Smith: And what about if you inject serotonin, or do the same trick that doctors do with people who have Parkinson’s Disease, they put the chemical that is used to make the chemical that people with Parkinson’s are lacking, they put that into the brain and people’s symptoms get better. What if you do that with a locust?
Stephen Rogers: Well that was also really exciting and sort of confirmatory result that if we gave them serotonin, and we had to sort of directly inject that into the animal’s nervous system, we found that we could shift their behaviour towards being gregarious.
Chris Smith: That suggests then that if you can switch this behaviour on and off chemically could we make some kind of crop spray that as soon as you see a swarm of locusts coming, you know how to inactivate them so that they’ll stop decimating your crops?
Stephen Rogers: The issue with serotonin itself is, is because it is so universal that we need to tackle it in a slightly smart way. And I think serotonin itself may not be amenable but it’s at the head of a whole cascade of messengers within cells, and some of these are proteins which are quite complex molecules, and some of these are bound to be specific to locusts, and I think these may very well pose a specific target for action without resorting to the indiscriminate application of pesticides.
Chris Smith: So understanding what the serotonin does in these animals in the first place could provide scientists with a way to make a locust-specific spray that won’t harm other wildlife. That was Stephen Rogers, he’s in the Zoology Department at the University of Cambridge, and he’s published that work in this week’s edition of the journal Science.
From swarms of insects to swarms of friends now and why your genetics can influence your popularity. Here’s James Fowler.
James Fowler: Nicos Costakis and I have a series of papers looking at the spread of behaviours in social networks, and we’re very interested to see whether or not some of these health outcomes are related to genes via social networks. And we really started to wonder whether or not genes themselves might be a precursor of our social networks.
Chris Smith: Because one of the things that you did show previously was that if you have friends, and even friends’ friends’ friends who are overweight, this can reflect on you and make you overweight. And so you’re arguing okay, that’s shown from a social network point of view but upstream of all that is there a genetic cause?
James Fowler: That’s right. When we came out with our social network studies, it seemed like people said ah-ha, all those gene studies are wrong, I’m not doomed to be fat. But here we’re trying to make the story a little bit more complex, because now what our study I think shows is that both nature and nurture can have an impact on where we sit in the social network.
Chris Smith: So what you’re saying is that the genes that you carry do actually determine where you are socially, how many friends you make, that kind of thing?
James Fowler: I wouldn’t say determine, but I would definitely say they influence where we sit. And so, you know, we’ve studied a thousand twins and compared identical twins to fraternal twins to see whether or not the identical twins had more similar positions in the network. And the way you measure this is by measuring things that are very intuitive like how many people name you as a friend. And so we found that that was about half nature and half nurture. Another basic building block of these networks that we looked at is a thing called transitivity, which is the probability that two of your friends will be friends with one another. If all your friends know each other that means you’re deeply embedded in a well connected group, but if none of your friends know one another that means you’re connected to lots of different groups, you might be acting as a bridge between groups, and those are going to be very different places in the social network.
Chris Smith: But what does that actually imply? I mean what can you do with that information?
James Fowler: Well we are very interested in the larger question of the relationship between genes and public health outcomes, and so this is really just the first step in trying to figure out if social networks act as a conduit between genes and say the spread of obesity. And so we think that because of your tendencies to be more central to the network or to be on the edge, that’s going to affect how much we come into contact with these social contagions. And incidentally, it also has an impact on whether or not we come into contact with physical contagions like, say, catching the ‘flu.
Chris Smith: But it’s one thing to draw a correlation here, which is what you’re doing, but you don’t actually know what any of the genes are yet do you?
James Fowler: No, and that’s going to be next step, we’ll be looking for them. And in particular, there are these super-genes, I mean the dopamine and the serotonin system are affected by a few genes that have been associated with a wide variety of traits, and we think that the reason why these super-genes have such a wide ranging impact on lots of different kinds of outcomes is because possibly what they’re really doing is they’re changing the structure of our social relationships, and so that’s what we want to test next.
Chris Smith: But how will you do that? Do you find that there are some people that are just super-good at making friends and you study them and you find that they have a certain form of one of those genes, and then you’ll find people that are more prone to being a loner and they have a different form of the gene and you draw some kind of inference from that?
James Fowler: Yes, and so we have measures. We actually know the location of each one of the people in our studies, where they sit in the social network, whether or not they’re loners, whether or not they’re the life of the party. And we also have their genetic information and we also have measures from them, for example their body mass, we have measures on them how often they smoke, how often they get sick, whether or not they feel happy. And so we have all three of those ingredients going forward to be able to answer this question.
Chris Smith: So looking at how you would actually apply this though for a second, are you suggesting then that someone would go to the doctor and you have a genetic test as well as a social networking test and you see how the two interplay, and therefore make predictions about someone’s likely health outcomes off the back of that? How would you use the data you’re collecting?
James Fowler: Right, so the picture you just painted sounded very ‘Gattaca’ to me, so I think we’re kind of a long way off from having such an intense amount of information about each individual. And so I think that what this means is that we might actually need to ask people a lot more in the doctor’s office about their social relationships. Are you the kind of person that’s in a clique where everyone knows each other or are you the kind of person that flits from one group to another, that might end up having an effect on what kinds of treatments we offer them for example, in the same way that we’re now imagining that knowing a person’s genome might lead to personalised recommendations for drug therapy.
Chris Smith: James Fowler from the University of California at San Diego discussing how he’s on the trail of the genes that make you popular but could also affect your health. He’s published that work in the journal PNAS.
You’re listening to Breaking Science with me, Chris Smith, and time now for this week’s ‘Stuff and Non-Science’ where we massacre myths and murder urban legends. And looking at lemmings for us this week is Diana O’Carroll.
Diana O’Carroll: This week’s ‘Stuff and Non-Science’ is about lemmings. Were they really so suicidal? Here’s Olivier Gilg to explain.
Olivier Gilg: You have several species of lemming, but the myth came mainly from the Norwegian lemming, so you find them in Northern Scandinavia. So in some years when there are lots of them they migrate in the fall and they have to cross roads and rivers and lakes, and when they cross these water bodies a lot of them can actually die, can sink, and you will find them maybe on the lake shores, a pile of them. And so of course the people wanted to find an explanation for this funny behaviour, and the most likely explanation they found is that they suicide. But then when Walt Disney heard about the story and they made a film in ’57, called ‘White Wilderness’ presenting several arctic animals, but mainly the main focus of this film was the lemming suicide because the story was so exceptional, so their intention was not to make a fake film actually, they really believed that this suicide was the reality, but they paid the little Inuit people to collect lemmings and once they had enough and they went on a cliff and they throw them in the water from the top of the cliff. And they filmed this and then of course millions of people saw the film and from this time on it really became an international myth.
Diana O’Carroll: Poor lemmings, not such a death wish after all. That’s Olivier Gilg and he’s an arctic researcher from the University of Helsinki. But keep your ‘Stuff and Non-Science’ suggestions coming in; firstname.lastname@example.org.
Chris Smith: Another myth over the cliff, unlike the lemmings of course. Thank you, Diana. That was Diana O’Carroll with this week’s ‘Stuff and Non-Science’.
That’s it for this time. We’ll be back next week with another round up of global science news. Breaking Science is produced in association with the Open University, and you can follow up on any of the items included in the programme via the OU’s website, that’s at open2.net/breakingscience, and you can also follow the links to get there from the Five Live Up All Night website too.
Production this week was by Diana O’Carroll from thenakedscientist.com, and I’m Chris Smith. Until next time, goodbye.
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In the news
'Erroneous quadruped walking depictions in natural history museums'
by Horvath et al
in Current Biology, Vol. 19, No. 2, January 27, 2009
'Evidence of Combat in Triceratops'
by A.A. Farke, E.D.S. Wolff, D.H. Tanke
in PLoS ONE 4(1): e4252. doi:10.1371/journal.pone.0004252
'WiFi networks and malware epidemiology'
by Hao Hu, Steven Myers, Vittoria Colizza, and Alessandro Vespignani
'Caloric restriction improves memory in elderly humans'
by A.V. Witte, M. Fobker, R. Gellner, S. Knecht, A. Flöel
Stephen Rogers on 'Serotonin Mediates Behavioral Gregarization Underlying Swarm Formation in Desert Locusts', by Michael L. Anstey, Stephen M. Rogers, Swidbert R. Ott,Malcolm Burrows, Stephen J. Simpson in Science
James Fowler "A Model of Genetic Variation in Human Social Networks," by James Fowler, Christopher Dawes, and Nicholas Christakis in PNAS
Olivier Gilg for 'Stuff and Non-Science'