Snails in Art and the Art of Snails

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Snails play a surprising part in art. Dali used them as images of impotence, while medieval painters included them in paintings of the Virgin Mary, due to the belief that their shells meant that their modesty was protected and they reproduced without sex. Gravestones are sometimes etched with snail images for they are seen as creatures that undergo resurrection when, after a long period of drought, it rains and thousands of snails that had been dried up start crawling around. Dutch flower paintings often include snails for the message behind those works was that, beautiful as the flowers are, they will soon be consumed, like human flesh, by worms, by insects - and by snails. Many other aspects of the biology of snails have an echo in art, and some art-works hint at the question why some species are so genetically variable in shell colour and pattern? Perhaps we can learn from the world of painting, as a hint that the two cultures may, at least in the world of molluscs, be uniting to form one. 



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19 February 2014   Snails in Art and the Art of Snails   Professor Steve Jones     I am glad to see a reasonable audience here. I have to say that incest brings more people in off the street, the one I gave last time I was here. But I think you may find some fairly hair-raising stuff even when I am talking about snails.   This is one of my books, which is not one of my best books possibly, but it is got a good title: it is called “The Single Helix”. I decided to call it “The Single Helix” after probably the best-known popular science book, after “The Selfish Gene” that is to say, which is Jim Watson’s book “The Double Helix”. And I thought, I know that my book is not half as good as Jim Watson’s book, but if it sells half as many copies, I will be very happy indeed! But it did not. But even so, that is “The Single Helix”, and on the screen there is a picture of the snail, which I work on, whose Latin name was helix. It then changed and it has now gone back to being called helix. That is the snail I work on, and I will try to explain to you why I actually do that.   I was once asked – people often wonder why people, why scientists, biologists, work on snails.  There are many reasons. We have just heard about bulinus and bulimulus – they are actually vectors of tropical diseases, freshwater tropical diseases.   This one I work on because it is very beautiful, not really, but there are good reasons for working on them. I was once at a dinner party where people always insisted on asking “do I eat them?” and I replied, “I know what they eat so I do not eat them!” And then somebody out of the blue, there were several Greek people at this dinner party, asked me, “Well, what do you call somebody who works on snails?” and I said, “Oh, it is a Malacologist,” and, to my great surprise, the Greek section of the audience fell rolling to the ground in laughter because the root of the word “malacologist” is the Greek “malaca”, which means soft and floppy, and is something very rude in Greek!  So, I learned something at that dinner party.   But there are, in fact, a number of surprising ties between the world of malacology, or conchology, which is the study of shells, and the world of art and also the world of science, and I hope I will manage to suggest to you that they do overlap with each other.   That overlap has been around for a long time. This is Erasmus Darwin’s, Darwin’s grandfather, his book plate, “Everything from Shells”, “E Conchis Omnia” and that was actually painted on the side of his carriage, and he collected snails and became famous as a result. But the good general rule is that plenty of people collect snails and do not become famous. In fact, there is an even better rule, that if they stop collecting snails, then they become famous.     Here is an example of just that. This is a book published in the 1880s called “The Conchologist’s First Book”. The conchologist is somebody who studies snails’ shells, rather than the soft and floppy bits of them. There it is, a handsome cover, “The Conchologist’s First Book”, “A System of Testaceous Malacology”, schools, shells, by Edgar Allan Poe. That was Edgar Allan Poe’s first book.   I am not sure what actually became of him.   Here is another one, this chap here, who is of course Lewis Carroll. He was an amateur naturist, as many people were in those days, an amateur snail collector, and of course he is famous for his poems.   “Beware the Jabberwock,” and so on, “Beware the Jubjub bird, and shun the frumious Bandersnatch”. Well, I do not know what a jabberwock is, and I am by no means clear what a Jubjub bird is, but I discovered, to my surprise, a few years ago, what the Bandersnatch was…   Here we have a German Bandersnatch. This is a paper about my snail, “Polymorphismus bei den Banderschnecken”, so a “banderschneck” is a banded snail, so that is the origin of the Bandersnatch. As soon as Lewis Carroll had given up working on snails, he too became famous.   So, there are many, many images of snails in the visual arts. Some of them are direct and literal – there are the gargoyles on the Barcelona cathedral, the Sagrada Familia, beautiful snails carved there, as you can see, Gaudi. Some of them are rather more figurative but still give you a literal account of a snail.   There, of course, is Matisse and his famous paper cut-out of a snail.   Some of them are simply decorative. If you go into medieval manuscripts, you find again and again these rather pretty images of snails, and there are lots of them. There are probably dozens or hundreds of them. Nobody really knows why, but there are lots of them there, and again, they are all very pretty.   But some of them, and this is what I want to explore, some of these snail images have a deeper message, so they really talk about sex, age and death, and as a biologist and as a evolutionist and as a geneticist, that is what my job is, to make sex, in particular, boring, but by doing that, perhaps to understand a little bit about age and about death. Snails and snail images tell us something about all those things.   Sex, of course, the world of malacology, appropriately enough, is filled with that. Here we have Dali, who called himself the great masturbator, and here’s Dali’s “Woman with Snail” and you can see it is clearly an image of impotence. Dali should be really called the great malacologist maybe, and he obviously knew what the root of the word was. So, that is Dali, “Woman with Snail”, impotence and snails, because they are soft and floppy.   However, there are some slightly more surprising sexual or asexual references in the snail world.  Here is the Annunciation of Francesco del Cossa, and you can see, there is the Virgin Mary, and about to be her annunciation as being a virgin, and across the bottom, perhaps you can see, is crawling this unlikely creature, the snail. So what the hell is that doing there? And the answer is that there is a text that says: “If the dew of the clear air can make the snail pregnant, then God in virtue can make His mother pregnant,” Jesus’s mother pregnant. The reason that people thought that snails could get pregnant without having sex was that they had shells and obviously you could not penetrate the shell so they must be doing it in some other way. They were a statement, in some senses, of purity. Well, I have to say, that is far from correct, because snails are really about as far from purity, insofar as that it has got any biological meaning, as it is possible to imagine. Many snails, not all of them, but many snails are in fact hermaphrodites.   Here we have Bernin, the Sleeping Hermaphrodite, both simultaneously male and female, but of course Hermaphrodite was the child of Hermes and Aphrodite and what he did was make the mistake of embracing a water nymph and she managed to absorb herself into him, ending up with this slightly odd individual here. Well, all snails, all the ones I work on at least, are hermaphrodites, simultaneously male and female, boy-girl meets girl-boy. They are actually cross-fertilising hermaphrodites, and that is rather unusual because what it means is that the male part fertilises the female part of the opposite number, and vice versa. Now, there are some rather interesting negotiations that go on if you are a hermaphrodite and you are mating. What you want to do is to be the boy. Obviously, you want to be the boy because that is much easier – you do not have to pay the school fees and that kind of stuff. So, hermaphrodites often mate for a long time and go in for all kinds of tricks to persuade or force the female part of the partner to function and stop the male part of the partner from fertilising the other individual.     Here we have another one of these slightly irritating medieval snail paintings or drawings, and you can see, what we have got is an archer firing, for no obvious reason, an arrow at a rabbit.  Strangely enough, snails do exactly that. I slightly wonder whether the person who drew this actually knew that, because snails have what used to be called a love dart, and a love dart is of course a common image in art.   There is a Boucher, Cupid wounding Psyche, and that of course is the arrow which is being inserted into Psyche and forcing her, persuading her, to fall in love with Cupid. It is a pretty image, and snails do exactly the same thing. Now, that arrow, I suppose, in human terms, comes up to your knee.     Here is a snail love dart. In human terms, if you were a snail, that would be up to about there, so it is a pretty impressive looking object. It used to be called a love dart, and the idea was, somehow, in an unformulated way, and you can see them, if you put two snails together in the right season of the year, they will try and mate with each other, and in the morning you will see two or three of these darts scattered about, perhaps on the bottom of the plastic box they are in, and there was this sort of feeling it was Cupid and Psyche and all rather romantic and that they held themselves together with it. That is not true at all. It is a classic case of male manipulation because what happens is, in snails, and in many other creatures that are hermaphrodites, and not just hermaphrodites, is that females have the ability to store sperm. They have special organs in their reproductive tract which can, if they are mated with, they can accept the sperm from a male and store it there, and if they find a better male, they will use that male’s sperm, and if they do not find a better male, they use the first male’s sperm. We know a lot about this and it turns out that actually, that dart, when it is fired into the individual that is acting as a female, contains a hormone which forces the female to use that male’s sperm, so it is a kind of anti-contraceptive. It is a fertility hormone for male advantage, about as far as you can get from Cupid and Psyche.   But things go beyond that, both in the art world and in the malacological world, because, if you want to see genuinely bizarre behaviour, take a look at slugs. Boy-girl meets girl-boy. And slugs too mate, and you may see, have seen them quite often, see them early on a spring morning, on a damp morning, you will see them often hanging from a tree and spinning from a metre-long rope of mucus, and spinning back and forth and sort of wriggling, with these large white objects – they are the penises and what they do is they hit each other with their penises in order to try and persuade one to be the female. We did some work on this once. This can go on for twelve hours, it is a long and difficult job being a boy-girl or a girl-boy. We did some work on this once and we were surprised to find some slugs did not have a penis, and that was because what happens is that their partner chews it off, and we invented the word, which is now in the scientific literature, which is called Apopholy. Apopholy, which means cutting off the penis, and of course, under those circumstances, it is great, because if you bite off your partner’s penis, (a) she, as she now is, can no longer fertilise you, and (b) she is now forced to accept sperm from you. So, that too, strangely enough, has a rather unexpected effect, because this is not quite castrating your opponent, but it is effectively the same – you are making your opponent’s maleness non-functional.   Now, that too, we can find an echo in the world of art. Here we have one of the black paintings of Goya, painted late in his life, his horrible paintings, painted on a black wall, and this is Cronos devouring his children, a horrible picture, and Cronos actually castrated his father, Uranus. Now, who was the daughter of Uranus? Well, the daughter of Uranus was in fact Venus.    There is Botticelli’s Venus. There is Venus, emerging from the foam, and a shell, a snail shell, or at least a mollusc shell there. There you see the foam. What is the foam? Well, actually, when Uranus was castrated, Cronos threw Uranus’s genitals into the sea, and the material that emerged became the sea. So that is not really foam at all, it is something quite different. So, that is actually another unexpected tie perhaps of an overlap between biology and art.   Now, there are other aspects to snail biology that actually begin to talk a bit more precisely about what I am going to talk about in the scientific part of this talk. Lots and lots of snails are seen as images of death. In some places, in Wales, for example, West Wales, where I come from, you often see pictures of snails on gravestones. Well, that might seem an odd thing, but the reason behind it is that, actually, they are seen as an image of resurrection, because what happens, in some snails – this is a Southern European snail called theba. If you have been in Southern Europe in the summer, you have almost certainly seen them. What they do is they climb way up above the ground. They seem to be dead and yet, when the rains come, they are resurrected and reborn and that is why you get this tie between death and snails because snails are also an image of the resurrection. That actually ties rather closely, as I say, to my own scientific interests because the reason they do this is not to give us a theological lesson, they do it in the summer to get away from the heat, and actually, it is a well-known fact in ecology that the hottest part of any environment is on the ground. If you sit, even on a British hot summer’s day on a black park bench, you will get up pretty damn smart if you are wearing shorts because dark things heat up more, and the lower they are, the more they heat up because there is no wind and that kind of stuff down there. So, the way to get away from that is to climb and to escape from the super-heated air. That is true in humans too, as we will see.   There are other things which overlap between the snails and humans. It turns out that snails are often eaten by various creatures – birds, thrushes most of all, and, some of you may know, it gets into the school books, it is not really entirely true, that the colours of the shells act as a camouflage, so that, in woodlands, the relatively well-hidden ones, the ones which are reddish and brownish, are favoured, in grasslands, the alternative kinds, which are rather stripier and perhaps yellowish-green in colour, are also favoured the other way. As we often say when we are out in the field collecting snails, we pick them up – and there are only two snail jokes – you pick one of them up and you say, “This one has got shellshock,” and then the person you say it to has to say, “Yes, it comes from a broken home!” But that is certainly true, and there is some truth in that camouflage story, and of course, that gives me an excuse to give you some camouflage art.   We actually know a lot now about the sensory perception of camouflage. It turns out that what it needs to do is to match the graininess of the background. So, if you look at military camouflage, in a forest, where there are lots of patches of brown and green and grey, you will see the patches are very small. In the desert, where you have patches of different sand colours, the patches are much bigger and that is what counts. So, we have actually done quite a lot of work on that with snails.     And you can see that in art. There is the famous Wadsworth painting from the First World War of a dazzle ship, and dazzle ships were painted with these black and white lines to break up their profile on the same scale as the breaking waves around them. That is common in zebras, common in toads and frogs and that kind of stuff.     Famously, Bridget Riley uses that very effectively in her art, and you will see, in different bits of Bridget Riley’s art, high dazzle in some places, high grains in others.      So, that is another aspect. But the aspect I really want to talk about is this species here. This is the snail I work on, which is on the front cover of my book. We call it Cepaea nemoralis – that is its technical name. A thing which is striking about it is that it is tremendously variable, from one individual to the other, and from one different place to the next place, over many different scales. That is actually why I work on it, and really, when I started working on this thing - I hate to admit this, but I have been working on it for more than 50 years – and if you put yourself back into the pre-history of my field, which is genetics, then there is almost nothing you could work on.     Genetics is the study of differences. That is what genetics is. If everybody was the same, if every creature was the same, there would be no genetics and there would be no evolution. Those differences, genetic differences, are the raw material of evolution – if they did not exist, then we would still all be in the primeval slime, and there could have been no evolutionary advance at all.     And in my day, in the 1960s, when I was a student in Edinburgh, there were really very few creatures in which you could go out and look at differences – count the numbers of genetic variants within a population and from place to place. This was one of the very few in which you could do it. If you look at these creatures, you will see some of them are light-coloured, some of them are very dark-coloured, and some come in deep pink and yellow, and they vary different numbers of stripes on them, several on that, just one on that one. We have bred all these up, and these are under straightforward genetic control, and there are thousands and thousands of possible different kinds.   This is a sample collected in Poland, part of this operation called Evolution Megalab, which I will not talk about particularly now. But they are tremendously variable.     Now, everything has changed. After I started working on these things, in fact in 1966 it was, people began, for the first time, to look at human differences, not just the boring ones, like skin colour, which are a tiny proportion of the total differences, but in those days, first of all, looking at differences in the proteins in your blood, and it was a great surprise to everybody, and astonishing really, to find that if you looked at the differences in proteins, the stuff that genes make, everybody is different from everybody else.     Of course, we can go much further and we can look at differences in DNA, and the differences in DNA are completely spectacular. Here, we have got a length of DNA – as I always say to students, “Get this down – it is going to be in the exam!” – with the various letters of DNA, GATC, arranged and sequenced from one end to another, and of course, we can read this stuff off now at an astonishing rate. There are 3,000 million letters in everybody’s DNA code, and we can read it now in about two or three hours for about a thousand dollars. Now, given that it took fifteen years to do the first job, at the cost of many millions of dollars, that is an astonishing rate of progress. And there is a lot of DNA about. Every cell of your body has got two meters of DNA in it, which means that, if any one of you, paralysed by boredom at this talk, and I really would not blame you, was to leap screaming out of the room and cross from that deadly roundabout to escape from the Museum of London and be hit by a speeding bus, the DNA in your body would stretch from the damp spot on the pavement which was once you to the Moon and back 8,000 times, so there is a huge amount of DNA there. We can read it from end to end, and it turns out that, on the average, about one site in a thousand, along these 3,000 million DNA sites in every cell, can vary from person to person. There are just two of them here – you will see, there is an A or a C, on line number eight, or whatever it is, and at the bottom, you can have an A or a G.  There are about three million of these which can happen. It is like a hand of cards – they can be reshuffled every generation by… That is what sex is – sex is re-combination, reshuffling the order of DNA. And that means that everybody in this room is different from everybody else in this room, of course, unless you are identical twins. As it happens, my mother was an identical twin, although I do not think that is why I became a geneticist. You are different from everybody on Earth. You are different from everybody who has ever lived. You are different from everybody who ever will live, and even more remarkably, every sperm and every egg ever made is different from all the others.     There is a huge amount of genetic variation there, and to put it frankly, we simply do not know why it is there. Some of it, we can pick it up because it causes diseases. Some of it apparently makes you gay, apparently, at least so the Daily Mail would have us believe. But most of it, we just do not know why it is there, and that is why we started looking at this snail stuff. We looked at these snails because it was said that this variation in the colour of the shell and so on could not be important. Who cares what colour? Why should a snail care what colour its shell is? What difference does it make? It is what we call neutral variation. And you get exactly that same argument now when you are talking to people who study DNA. They say, “Oh, it is just random noise – it just comes in and it goes out again, and it is not important, we are not interested in it.”  I am pretty sure they are wrong, for reasons that I hope we can talk about a little bit in the future.  So, that is the snail – that is the variation.   It varies not just from individual to individual, but from place to place, as indeed we do. We vary from place to place, of course, in skin colour – we all know that. But you may not know that we vary from place to place in the ability to cope with alcohol. Those black spots are places where up to 80% of the population find it biologically impossible to drink alcohol, and if they do, in China, among Chinese people, for example. I am sure none of you have ever done this, but when you were fifteen or sixteen and you had your first bottle of Strongbow cider, there was that moment of hilarity and joy, which we have of course all been trying to re-capture ever since, and you have had the first buzz of this stuff, and then, suddenly, you felt terrible, you began to sweat and shake, your face went red, and you may have thrown up. I certainly did – I am not ashamed to admit it. And that is what these people who cannot digest alcohol – they have that every time. They lack the enzyme which breaks down alcohol. Now, this varies in frequency from, effectively, zero – everybody in Glasgow can break down alcohol, to almost 100% in parts of China and, conveniently, of course, in parts of the Islamic world. Why that is, we do not really know, but it is a statement of these differences from place to place that happen in humans, and they do certainly happen in snails.   Well, as I said, what happens in snails is, if you look at snails, what they have are differences in whether they are dark or whether they are light. These are kind of extremes. In fact, if you draw a map of the frequency, the abundance of the dark and the light kinds, from the North to the South of Europe, and this is based on several hundred thousand snails which I have collected over the years, there is a striking tendency for the relatively light-coloured individuals to be common down in hot places, and the relatively dark, pinkish-coloured individuals to be common in cold places up in the North.     If you draw a diagram of the fit between the incidence of one of the light-coloured variants, the yellow shell colour, and mean summer temperature, it is absolutely a linear fit. That makes sense because, talking about that black iron park bench again, if you sit on a black park bench on a sunny day, you get a lot hotter than if you sit on a white park bench. Dark objects heat up much more in the sun. So, it would make more sense, or so it seems, to have relatively dark coloured objects in the north and light coloured objects, snails, in the south.   It is worth reminding ourselves how much we all live on what is sometimes called a thermal cliff.  We all have – because I am a thermal biologist, I cannot think in centigrade, so I will think in Fahrenheit. We all have a body temperature of about 98 degrees Fahrenheit. If you go five degrees above that or five degrees below that, you are dead. It is very, very tightly controlled.  And we spend an enormous amount of our efforts in keeping that temperature right. I notice that almost everybody in this room, for example, is wearing clothes. That has a lot to do with it. This room is being heated, and that too has a lot to do with it. In fact, something like 60% of your total income is spent on keeping warm, in the widest sense, and by that I mean including eating lots of food to burn it to keep your body warm.   Now, snails and insects and so on cannot do that. They cannot keep warm by virtue of their own internal furnaces. They can only keep warm by heating up or being heated up or hiding in the shade, being heated up in the sun or hiding in the shade – they are what we call ectotherms, and they live on this thermal cliff. They have to spend their time constantly aware that they are in danger either of overheating and dying of thermal shock or of not being warm enough and not being able to find food, find a mate and that kind of stuff. So, it is really important to them to keep their temperature within a surprisingly narrow range, and that makes sense in the context of this dark forms common in the North and the like.     In fact, we too do the same thing. Some of you may have seen that Tate Modern piece, rather dramatic really, which must be three or four years ago now. I have forgotten the name of the artist – Eliason was his name..? I cannot remember. Of course, it was called the Weather Project, and it had this enormous Sun at the end of the Tate Modern, shining down. It was actually really quite impressive, I think. It was much better the silly helter-skelters which then followed it. It was interesting to watch people’s behaviour. Because, at the bottom, as you can see, people are lying in the sun, looking with amazement at it, and if you want to get tanned, of course, you lie in the sun, but if it is a hot day, you surely do not do that because you very quickly become deeply uncomfortable, too hot, because you are down on the ground. And that is particularly true actually of people with black skins compared to white skins, so that is the story is the same there. But there is the people in the Tate Modern.   It is now generally accepted that one of the main reasons why we stand upright was actually that, when we came down from the trees, which was several million years ago, when the climate dried and the savannah replaced the forest, we came down from the trees and we immediately faced this problem: that if we went on all-fours, in Africa, you constantly got overheated, and so the evidence is quite strong that, actually, that is why we became bipedal, and as soon as you become bipedal and you can balance on two feet, then all kinds of other things can happen. You can actually travel much faster. You can run with much more efficiency than an ape can, and you can run down animals, even deer, because, although they can go fast for a while, they cannot keep it up. So, this was, this behavioural thermoregulation, as it is called, standing up to avoid the heat of the surface, was important even for us, as indeed, you may remember I just said, it was important for that snail, theba, as well. And it turns out that actually exactly that drives an awful lot of the snail story.     Now, this is some experiments we did, rather silly experiments, a student of mine did, where we collected snails from Scotland, in the north, and to Spain, to the Pyrenees, which is where I do much of my work, and asked, in a laboratory, we made this thing called the molluscatron, and the molluscatron was simply a big plastic pipe. You would put them in the bottom and you would come back in the morning and you would ask how high have they climbed, and there was an absolutely striking tendency from the ones in the South, the hotter places, to climb much more than the ones in the North. So, that too suggests that there has been a behavioural shift.     There is also another thing you can do which is rather weird. It turns out they have evolved, in the North and the South, different ability to withstand the pain of heat.     I was once talking to a colleague of mine about the genetics of pain sensitivity, and there is a lot of genetics to pain sensitivity. It is absolutely the case that people with red hair are much more sensitive to pain than people with other colours of hair, so that is not just an old wives’ tale – it is actually true.   This friend of mine worked on the genetics of pain sensitivity in inbred mice, which he had crossed different lines to see if he could find the genes, and he has found several genes involved, including hair colour genes. I said to him, “Well, how do you measure pain sensitivity in mice? I mean, do you hit them with a hammer and see how loud they squeak, in a Monty Python kind of way?” He said, “Oh no, I have got this machine here which is a hotplate.” It is not really a hotplate. It is a warm-plate, and it is a plate which you can turn the temperature up to about 40 degrees Celsius, and you put your mouse on the plate, and mice, for some reason – it is not damaging at all, you can put your hand on it and it is warm – and mice hate having their feet hot.  I do not know why. So, they are on the plate, and you turn it up, and it suddenly starts doing this to cool down, and the more sensitive they are, the faster they do it. So you can measure the heat sensitivity.   Well, in fact, I thought that is really weird because, if you look at snails in Southern Europe, standing on a rock on a hot day, they will do this – they will flip their front, then they will flip the back, they will flip the front, then they will flip the back. So, we started doing that with the snails, and lo and behold, we got exactly the same story, that, in the North, in North Wales this time, rather than in Scotland, the snails were much more sensitive to heat – they responded immediately if they were heated up – than in the South, and the effect was really quite big.      Again, we are building up this story that it is actually thermal relations in sunshine, dealing with the heat that comes in from outside, which is driving a lot of their biology.   Well, let us get back to the art, briefly. You are all familiar, of course, with Dutch flower paintings, and Dutch flower paintings are very beautiful things, and, like many paintings of that period, they have a religious message. The message is an oddly depressing one, which is: admire these beautiful, beautiful flowers, and then look more carefully, and in all of them, you will find caterpillars, grubs, worms, and the reminder is, however beautiful these flowers are today, they will be dead tomorrow and will be eaten up by worms, and that is going to happen to you, so repent! That is the message.   Now, this particular one, I rather like, because the animals doing the job are snails. In fact, they are clearly my snail, capaea, and, as you can see, here we have one of them, there, blown-up, and here we have another one…there, blown-up, and they are about to bring their theological message by eating these flowers.   But the interesting thing is that, if you were to glance at this painting, you probably would not spot the snails – you have to look fairly hard in order to get the message. And that is what I am going to be talking about for the rest of this talk: how do snails deal with living in such a complicated environment as this? This is a very complicated environment, both in terms of the species of flowers that are there – there are several different kinds of flowers, and also what we might call architecturally, the way it is built together – there are all kinds of patches of dark and light and that kind of stuff. It is sometimes a very beautiful thing, but it is also, as I say, it is quite a metaphor for the way that snails actually do live.      I have a good general rule, which is you should never work on any creature that does not live in national parks, and my snails appear – and I have spent many years down there – reaches its enormous abundance in the Pyrenees. The Pyrenees is the snail capital of Europe – they are everywhere, these things. It is a remarkably interesting and dramatic place, being – I first went there 50 years ago, and it is being considerably ruined by motorways and skis now, but certainly a lot of it is still utterly magnificent. The snails live all over the place – they live from sea-level, basically, on the west end anyway, right the way up to about 2,600 metres, so they have got an enormous range.   Here we have the place I work in called the Valle de Aran. The Valle de Aran, it is actually in Spain, but it is on the north side of the range, it is a little enclave in the Pyrenees. It did actually have a revolution in 1945 to try and break away from Franco, but Franco sent in his troops and put a stop to that. The Valle de Aran is a dramatic kind of place, snails everywhere, and you get snails, for example, commonly, in this kind of habitat here, which is not as beautiful as that vase of flowers, but it is the same kind of architecturally, and botanically maybe, complicated habitat, so you have plenty of snails there.   Then you can go up to the top and you will find snails there, and there, you will find them all over this grass, which is, at first sight, a much, much simpler kind of habitat, and if you plot out the abundance of the different kinds of snail in different places, what you find is that the relatively dark ones are down in the bottom, and the relatively light ones are more common up at the top.  There are many, many thousands of snails in this diagram, but it is pretty consistent. And, up at the top, if you go up to the top, if any of you ever ski, which I never do, because it seems to me an utterly pointless pastime, but still, you will know that if you ski, or if you go walking in the mountains on a sunny day, you will get severely sunburnt because, if you are a long way up, there is much more ultraviolet, much more energy coming out, coming in, so that is where the real thermal stress is – up there. The air temperature may be relatively cold, but the solar energy is far, far greater.     So, for a snail, it is a pretty challenging kind of environment. So, the question arose, how do the snails cope with this? And the interesting question is not the fact, which is certainly true, that you get dark snails in Scotland and dark snails down in the valleys here, and light snails in Spain and light snails up at the tops of the valleys here, no, the more interesting question is that, almost everywhere, wherever you are, in Montrose, which is where I did my first work, 1965, where the sun never shines, or down in the South here, where the sun shines most of the time, wherever you are, in nearly all these snail populations, even though they are 90% dark-coloured in Montrose and 90% light-coloured down here, you nearly always get some of the other forms, and that is really weird. I mean, why do they stay variable? Why does not one form just take over, as white skin took over in Europe when we left Africa, for example? That is the interesting question.  You can certainly find that the relative abundance of these forms varies from place to place, but why do you still have diversity? That is what we started looking at, with some success, I flatter myself.   Now, if you go to that first place, down at the bottom, very complicated architectural place, this is the sample that comes from there, and there are both kinds of animal there, dark ones and light ones. Up at the top – this is the picture I took on codachrome film, a long time ago – nearly all the animals are light-coloured. So, we began to ask what is going on? What is making this difference? Why do we have this difference, and why do we retain both kinds?   The first observation was, if you look at a hedgerow or a nettle patch down in the valley, that is obviously much more botanically diverse than an alpine meadow, up at the top, as I thought, naïvely, but that is not true at all. We captured a botanist and took her with us, and we should have known this anyway. In fact, the most diverse in terms of different numbers of species of plants, kind of habitat, is an alpine meadow. If you go there in the spring, you will see these thousands of different kinds of flowers, so these meadows are actually much more biologically variable in the numbers of species of plant they have got than down in the valley. So, that did not work. But, in some sense, it was clear that they were less variable. We knew that snails and sunshine had a lot to do with each other, so we began to look at that.   The question was: how much does the sun penetrate these different kinds of habitats? Now, this is a field that is called sun fleck ecology, and it may seem rather silly but, in fact, it is not – it is really very important because what determines how fast crops grow, among other things, is how much sun gets into them, and a huge amount of quite sophisticated research is done on the optimal planting distance of one maize plant from another, how tall should the maize plant be, that kind of thing, so we know a lot about it. You can buy enormously expensive machines, and it can be done by satellites too, which tell you how much light is going to get into a crop and how much it is going to be broken up into sun-flecks, as it goes in.   I was working on a British research grant, so we did not have any money at all, so we decided, under those circumstances, that we had to start thinking about it, and I invented this technique, which, rather regrettably, has picked up the name of Jones’ Balls.   The argument was let us think like a snail, alright, which I have been doing for some years now, and the argument is, a snail is sitting there, and may be exposed to lots and lots of sunlight, and the logic was to take some snail-sized polystyrene spheres and chuck them in, so we chucked them in there, and define oneself as being the sun. We did not have a satellite, but we did have a stepladder, and the argument was to go to the point where the sun comes up, in the east, on June the 21st, and to climb up this stepladder and climb down the other side of the stepladder, counting the number of balls you could see at different times of day – dawn, 8 o’clock, 10 o’clock, 12 o’clock and all the way round till the sun goes down. In a place like this, even if you started at dawn looking at ground level, and noon, you would be looking from the top, you would see quite a lot of balls, quite a number of these spheres, at each position, but in a place like this, you would see fewer, and in a place like that, you would see fewer still. So, it looked as if there was some fit between the extent to which these artificial plastic snails were hidden by the vegetation and the amount of sun, which they might actually experience.   You can take a snail’s eye view, and this is a picture taken with what is called a fisheye camera, and a fisheye camera, as you probably know, has got this big lens you put at the bottom of a wood or the bottom of a hedgerow, and you take a picture through it and you can use a computer to work out the patches of dark and light, how patchy is it. Well, we did not have a fisheye camera, took this off the Internet, and it would be too difficult and expensive to do, so we thought of something else.   This was an attempt to measure the amount of sunlight which falls upon particular individual plastic balls, or particular individual leaves, or particular individual snails, during the course of a day, a week, a month, and it turned on the observation, which would have been very easy to make in the 1960s, which was that everybody who was anybody wore jeans, and if you wanted to show what an extraordinarily sophisticated and hip individual you were, you wore faded jeans – you got jeans which faded in sunlight. I was up in the Pyrenees one day and I thought that is a good idea, we will do some gene manipulation – weak joke, but it is what we did. We got some denim jeans, cut out little squares, and stuck them onto snails, the argument being that, if they were out in the sun, they would fade more, and if they were not, they would not fade. Well, that did not work. They quickly lost their jeans, their jeans fell off, but, actually, then we went a step further, and I thought, well, why do we not just find out what the name of the blue dye is – it is actually called Coomassie Blue – inside in these jeans, what do they fade them with, what do they dye them with, it fades in the sun. We took the blue dye, bought some of it, and mixed it with a stable yellow paint, actually used to spray cars, and if you put blue and yellow together, what do you get? You get green, and if you put the green paint onto a snail or onto a plastic ball or onto a leaf, it fades, and it works, to my surprise, remarkably well.   Here is one of the things we did. This is called a spider, and it is called a spider because it is a little disk with some wires attached to it, which you can replace those balls we just saw, we can wire this disk where the balls fell, and we can ask how much variation is there in a particular place, and the answer is, as you can see, that when there is a lot of variation in the fading of those spiders - some of them will be deep in the vegetation, some of them will be up at the top – then there is more variation in the snail population. The more variation there is in the snails fits on the amount of variation there is in the fading score, so that was nice.   But to be able to go one step further, we needed, of course, to ask the snails themselves, and here we have a picture of two snails, one of which has chosen, if that is the word, not to go out in the sun very much - this guy here, as you can see, has still got dark green. This guy here, from the same place, has spent more time in the sun. And now we marked thousands of these snails.  We did it in the wild, but that turned out to be problematic, so we set up this thing here, which is the University College London Snail Ranch, which is at Wytham Hill near Oxford, that is one of the older provincial universities. That has got this enormous estate, Wytham Estate, beautiful place, and a huge field in the middle of it, and we put up a hundred cages. It took a hell of a lot of time to make them. They are a metre across, ten of them that way, ten of them that way. We used those in these experiments, and what we did was to take snails, dark and light ones, and put them in the cages, and asked the question: is it the case that, within a particular population, the dark and the light ones choose to live in different parts of the habitat, and choose to experience different amounts of sunlight? Very gratifyingly, the answer was yes, that the dark ones tended to spend more time exposed to sun than the light ones, and the light ones tended to spend less time exposed to the sun. We did this again and again, with many modifications of the experiment, and the effect is really quite striking. So, what the animals are doing, they are choosing to live in different parts of this bush, over a period of a month or so. You could never see that by simply looking at them because they never do anything interesting – they just sit there and waggle their tentacles now and again, and go in for a bit of furtive sex. But if you can mark them, you can add up the number of hours they spent in the sun, over a month or so, and that is what we did.   We then did the obvious second experiment, which is to take some dark ones and paint them white, and some light ones and paint them black, so we reversed them, what you might call phonetic rather than genetic engineering, and lo and behold, they changed their behaviour. The ones which had tended to hide away because they were relatively light-coloured, when we painted them with black paint, they tended to come out more. So, that was, I thought, rather cunning, and I could talk a lot more about that experiment and those experiments, but I think it is an ingenious, though I say it myself, it is a rather ingenious technique which has never really been picked up.   I did an experiment once. I was working in South Africa, I was then, with a friend of mine at a Hospital in Jo’burg, which is rather a frightening place because people keep coming in with terrible wounds, but in South Africa, and in West Africa too, quite surprisingly, there is a relatively high incidence of albinism among some African populations, Africans who have no melin in their skin, and that is really quite problematic because they nearly all used to get skin cancer, and so what they had to be told when they were kids was to be absolutely sure not to go out in the sun and always wear these hats and that kind of stuff. It is slightly off the beat, but it shows how this stuff could be used. And I said to my friend, Tom Jenkins, I said, “I have thought what we can do – we can give them hats which have been soaked in this fading paint, and then we can tell how much time they spend in the sun and how much time they have gone in.” It did not work because they wanted to help us so they left the hats out in the sun to make it work. But still, I think it could be more widely used.   That is the take-home lesson really, that actually it is the nature of science, what succeeds in science is taking totally different fields and putting them together. In some ways, I think that is also the nature of art. That is what the nature of art is: taking totally different media, totally different ideas, and bringing them into a harmonious whole. That is much more perhaps the nature of modern art than of the art of the Middle Ages, but that is really what it is. So, science and art, in that sense, have got quite a lot to do with each other.     I was talking to somebody once whose name was Finlay Taylor. He is an artist and he called me up once and said, “You work on snails – I want to make an artwork based on snails.” I said, “Really?! An artwork based on snails? You know, Matisse has done it…” He said, “No, no, I want to do it, something more subtle than that.” So, the idea was, after some discussion, that this would be his artwork: he would take a copy, not the first edition because that is worth a huge amount of money, but a nineteenth century copy of the Origin of Species by Darwin, and a copy of one of my books which is called Almost like a Whale, which is an attempt to update and re-write the Origin of Species, as if it were being written today, or in 1999 when I wrote this book, and he put them both in his garden, which was infested by snails, and ask which ones do they prefer to eat?! Here is the result. It turned out that molluscs much preferred to eat Darwin compared to Jones, so that, as well as being beautiful, that proves that they too have got good taste! So, I will stop there – thank you…       © Professor Steve Jones, 2014

This event was on Wed, 19 Feb 2014


Professor Steve Jones

Visiting Professor of Genetics

Professor Steve Jones is Emeritus Professor of Genetics at University College London and an author of several popular science books. He is one of the world's top six experts on the genetics of snails (and the other five agree) and has also studied the genetics and evolution of fruit flies and humans

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