The bodies and genes of organisms can be thought of as a history book detailing how other creatures lived long ago. Richard Dawkins, inaugural Charles Simonyi Professor for the Public Understanding of Science at Oxford University, joins host Krys Boyd to discuss why the bodies of animals resemble their environments from thousands of years ago, and why sequencing these genomes offers a time machine to previous stages of evolution. His book is “The Genetic Book of the Dead: A Darwinian Reverie.”
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Transcript
Krys Boyd [00:00:00] As far as we know, it is impossible to build a time machine that could physically transport us into the past. Let us poke around and make observations and then return to our own time to share whatever we’ve seen. But it’s entirely possible to know a lot about what the world was like before any human was around to experience it. From Kera in Dallas, this is Think. I’m Krys Boyd. We can count tree rings in petrified wood. We can dig up and examine fossils and take core samples from the permafrost and make highly educated guesses. But we can actually do better than that as we learn to read the genetic codes of all living animals that exist right now. We can gain an astonishing amount of information about the conditions in which their most ancient ancestors evolved and the reasons bodies contain genes that in the present moment don’t seem to have any utility at all. Some of this is already possible, even visible to the naked eye. And my guest is hoping his new book will inspire the scientists of the future to tackle this kind of biological translation with the better tools and deeper knowledge we hope they will have available to them. Richard Dawkins is the inaugural Charles Simonyi, professor for the Public Understanding of Science at Oxford University. His latest work is called “The Genetic Book of the Dead: A Darwinian Reverie.” Richard, welcome to Think.
Richard Dawkins [00:01:20] Thank you very much.
Krys Boyd [00:01:22] You remind us that Darwinism is really all about survival and reproduction and specifically about gene survival. Whatever sorts of bodies evolved to contain them. The ultimate winner of natural selection is not at the level of species rate, but at the level of the individual gene.
Richard Dawkins [00:01:38] That is correct.
Krys Boyd [00:01:39] Tell us more about that.
Richard Dawkins [00:01:41] Yes. The thing about bodies is that there is that they are mortal. Genes are potentially immortal. So there could be genes sitting inside you that were around 10 million years ago. The ones that really do stick around for that long are the successful ones, and the way they become successful is by programing the embryonic development of bodies. So I see the body as a throw away survival machine for the genes that ride inside it. The bodies that are successful are the ones that survive to preserve and propagate the genes that ride inside them.
Krys Boyd [00:02:21] So what can the genes that animals carry today? Tell us about the conditions of the distant past on planet Earth.
Richard Dawkins [00:02:28] Well, this is really a vision of the future, as you said in your introduction. This cannot be done at present to any great extent. But my conception is that in the future, a scientist of the future will be able to read the genes and read them as a book describing the world in which our ancestors survived to pass on the genes that actually built us.
Krys Boyd [00:02:55] Sometimes today this is obvious, even to the naked eye. Talk about animals that sort of wear these pictures of their past environments on their bodies.
Richard Dawkins [00:03:04] Yes. Well, the best examples are animals that are camouflaged. Things like moths sitting on tree bark, things like desert lizards, which have sand and stones almost literally painted on their back. So this gives us a vision of how powerful natural selection is. Natural selection is powerful enough to paint an extremely accurate picture of the environment of the animal, or, more precisely, in the environment of its ancestors on its back. Now, my conjecture is that in the future, scientists will be able to read not only the external body of the animal, the external skin of the animal, the back of the animal, but every bit of the interior of the animal, which must be influenced by natural selection to the same detailed extent, the same perfection must govern every every detail of the inside of the animal.
Krys Boyd [00:04:04] Can you remind us what a palimpsest is?
Richard Dawkins [00:04:07] A palimpsest is a parchment which has been erased and reused again. In the days when there was no paper and parchment was precious. People used to reuse the parchment. They would erase what was written before and write over it again. So the Genetic Book of the Dead is a palimpsest in the sense that ancient writings are at least partially overwritten by more recent writings, which are in turn partially overwritten by even more recent writings and so on.
Krys Boyd [00:04:40] So the genetic coding or writing laid down early may remain within an animal’s genome, But what comes later, I guess, will always supersede what came earlier.
Richard Dawkins [00:04:52] Well supersede is a strong word to use because I suspect that some of the original writings are still there. That’s the that’s the point. And there will be some superseding, no doubt. Yes.
Krys Boyd [00:05:03] If we look at genomes as this genetic Book of the dead that you mentioned, the earliest writing, though, is still present somewhere. Is that the idea?
Richard Dawkins [00:05:12] I think that’s right. It may be partially obscured. It may be rather difficult to read. It may be sort of a little bit misty, a little bit cloudy, but I think it must be still there. I mean, we know that we are descended from fish, for example, in the very distant past. And we have traces of that not just in our genes, but in our anatomy and our embryology. We have the remains of gill slits that are left over from our fishy ancestors. Our blood is salty probably because we come from the salty sea originally.
Krys Boyd [00:05:44] So in a sense, evolution uses the past to predict the future.
Richard Dawkins [00:05:50] Yes, I think it’s it’s probably right to say that the genes are predictors of the future. And to the extent that their predictions are correct, they will survive. To the extent that they get it wrong, they will not survive.
Krys Boyd [00:06:04] An animal’s body can be understood then as a description of the past in some sense. You note that it’s also a model of the future, and I wonder if you mean model in an experimental sense, like is this a test of how well that organism’s genetic makeup will prepare it to survive and reproduce?
Richard Dawkins [00:06:23] Yes, that’s right. I think that if we take the the nervous system, for example, I think that the nervous system builds up a model of the world in which the animal lives. So what we see is not a kind of cinematographic picture of the outside world that is presented to our retinas. What we see is a model which the brain puts together on the basis of the information coming in from the sense organs. And the nature of that model will depend upon the needs of the animal. So for a flying animal as hunting insects like this one, for example, the model will be suited to that way of life. For a model that lives on the ground in darkness, the model will be suited to the underground way of life.
Krys Boyd [00:07:13] What is it that you think scientists of the future, as they pay attention to all of this, will be able to understand better than we can as they develop better tools for deciphering genomes?
Richard Dawkins [00:07:26] I think it will be similar to what we know already, but much more detailed. We can already to some extent, decode the genetic Book of the dead. Not so much from the genes at present, but from the anatomy and behavior and physiology of the animal. And quite a lot of the book is actually not about genes, but about what we can read by looking at the anatomy of the animal. But I think in future, it will become more and more reliant upon the genes.
Krys Boyd [00:07:52] We should note here your focus is on animals, but could we also conceivably write a genetic book of the dead for plants?
Richard Dawkins [00:08:00] Yes, definitely. I happen to be as a ologist and so my interest is largely lies with animals, but it applies to plants and fungi and bacteria as well.
Krys Boyd [00:08:11] So another important thing to understand that I took from the book is that what really matters here is less the genome of any given individual but of the species, because each individual’s genome is basically just a sample, right, of the gene pool available to the species.
Richard Dawkins [00:08:27] You have read it with remarkable thoroughness, if I may say so. Thank you. Yes, that’s that’s great, because the any given individual animal is a sample from the gene pool of the species. And it’s the gene pool of the species which is being sculpted, being shaped by natural selection. And when you look at any individual animal, it’s a sort of random sample, not quite random, but it’s a sample from the gene pool of the species.
Krys Boyd [00:08:57] So talk more about that term that you’ve chosen to sculpt. How does evolution sculpt the genome of a species over time?
Richard Dawkins [00:09:04] It’s a kind of poetic image. Natural selection can be seen as a kind of a sculptor, because a sculptor with a chisel carves away, removes bits from the marble. And in a way, that’s what natural selection is doing. And the entity that is being carved can be seen as the gene pool of the species because it’s the gene pool of the species which actually changes under the influence of the sculptor. The chisels of natural selection.
Krys Boyd [00:09:35] Is it environments that perform that sculpting of the gene pool? In practice.
Richard Dawkins [00:09:41] It is the environment which performs the sculpting. But remember that the environment includes evolving entities themselves. So there is an arms race between predators and prey and arms, race between parasites and hosts. So although part of the environment is the inanimate, the climate, things like that becoming adapted to ice ages and droughts and things like that. The most important thing, I think, is the arms race against prey against predators, which are themselves evolving. So as prey animals like antelopes get faster and faster at running away from predators, the predators get faster and faster at running after the antelopes. And so each one is escalating against the background of the other, the environment, which is especially important in shaping the most detailed and complex adaptations living parts of the environment in the arms race.
Krys Boyd [00:10:39] So you’ve described an arms race, but this is all happening by way of, for lack of a better term, accidental mutations over time, right? I mean, maybe one could describe, you know, individual genes as having a will to survive and reproduce in millions of years into the future. But this is just happening by happenstance, right?
Richard Dawkins [00:11:01] That’s right. Although, metaphorically, you can talk about a will. What’s really happening is that some genes survive and some genes don’t survive. So it’s a purely materialistic account. It’s not in any sense a conscious desire to survive.
Krys Boyd [00:11:18] To go back for a moment, just to the surface level, observable ways that animal bodies are shaped by their environments. Some animals that use camouflage to disappear into their surroundings, you describe as paintings and others are statues. What is the difference?
Richard Dawkins [00:11:33] Yes, that’s a very interesting difference. A painting is something which doesn’t work if you remove the animal from its background and place it on, say, a white sheet of paper or a green lawn, because then it stands out and is immediately eaten by a predator, for example. So that would be a painting, a sculpture. On the other hand, is a statue. A statue is an animal which still looks like an inadequate, like an inedible object. Even if you remove it from its background and place it on a different background. So something like a stick caterpillar or stick insect, which looks like a stick, it still looks like a stick. Even if you pick it up and put it on paper. And so it might still be overlooked by a predator because it still looks like a stick, but a moth which resembles the tree bark. Well, it still will it will look like a like a moth. If you put that on paper, it has to be sitting on its proper background, namely tree bark in order to escape being eaten.
Krys Boyd [00:12:39] There’s a beautiful illustration in the book of an owl that almost disappears into the bark of a tree in which it’s sitting. But the giveaway is the fact that the owl’s body is quite symmetrical and of course the tree isn’t perfectly symmetrical. What does that tell us? The fact that so many animals are just extraordinarily symmetrical about the sort of evolutionary biological value to animals of being physically symmetrical.
Richard Dawkins [00:13:08] Yes, this is very interesting. Symmetry is a giveaway, and that’s all that you talk about. You really do see it because it’s symmetrical. And you could say, well, there’s something about the embryology which makes symmetry, which makes symmetry compulsory somehow you can’t get away with you can’t do away with symmetry. But it could be that symmetry also has its advantages. And we do know that in sexual selection, in sexual attraction. Symmetry is itself an attractive feature. So it’s possible that there’s a conflict between the need to be camouflaged on the one hand and not to be symmetrical and the need to be sexually attractive on the other, which would be the need to be symmetrical.
Krys Boyd [00:13:51] Richard These forms of visual camouflage are slowly perfected over many generations of a species existence until they are shared by functionally every living member of that species, which is a very neat trick. You think it’s likely that other changes happen the same way, right? To internal organs and brain wired behavior? Patterns of different species.
Richard Dawkins [00:14:13] Yes, that’s really the main thesis of the book, that the camouflage is just the tip of the iceberg. And and the same kind of perfection is going on throughout the whole of the animal.
Krys Boyd [00:14:25] Let’s go deep, deep into the past and think about the earliest emergence of life, which almost certainly was in the sea. You suggest that the lowest level of the palimpsest tells a story of water. How is that story echoed even in the bodies of animals that long ago evolved to live on land?
Richard Dawkins [00:14:45] The biologist JBS, holding the very famous British biologist, speculated that the reason why our blood is salty is that we come originally from the Salt Sea. That may be slightly fanciful. There may be other reasons why it’s salty, but there are plenty of other there’s plenty of other evidence that we do come from the sea, that we do come from fish ancestors.
Krys Boyd [00:15:08] How would the first creatures able to leave the water, even temporarily, have been rewarded with a better shot at survival?
Richard Dawkins [00:15:16] Yes. That’s sort of unknown in a way, because it happened a very long time ago. One possibility is that they lived at a time when they were subject to drying out. And so they were although they were fish living in water, they might have found themselves stranded in pools, in puddles as maybe as the tide went out, maybe as low as there was drought. And so there would have been a premium on the ability to flap across, to sort of waddle across from one drying out pool to another and thereby save their lives. That’s one possibility. Another possibility is that there was a rich source of food already on land because plants had already emerged onto the land, and therefore there was the possibility of perhaps making a quick smash and grab raid onto the land to get some food and then dive back into the water again. There there are various possibilities.
Krys Boyd [00:16:09] It’s fascinating to think about times when species that made homes and lives on land evolved to once again return to the sea. How might this have played out for aquatic mammals like whales?
Richard Dawkins [00:16:22] This is very interesting. It’s rather remarkable in the way that having taken the trouble to emerge from the sea onto the land, quite a lot of animals then turned around and went back again. Much later on, of course, in evolution. Whales are an outstanding example. Clearly, they haven’t gone right back to the sea and never come on land at all. Same with dugongs and manatees. Seals and sea lions go back into the water to feed, but they then return to the land to reproduce. The same is true of turtles. They, when they lived almost all their life in the sea, but they not sea turtles, but they come on land just in order to lay their eggs. Land tortoises are remarkable in that they are descended from sea turtles, so they are subject to a double doubling back. Their original ancestors were fish in the sea. They then emerged onto the land. They then went back into the water as sea turtles, and then they came back yet again onto the land as land tortoises, some of them living in very dry conditions indeed. I think that’s a unique example of a double doubling back.
Krys Boyd [00:17:35] Well, gills work really well for fish to process oxygen, but aquatic mammals still rely on the lungs they developed when they were land animals. Why did these mammals not revert to something like gills instead of lungs that their ancestors had evolved?
Richard Dawkins [00:17:53] I think that’s a big puzzle. I think it is a remarkable fact that when land animals went back into the water, the one thing they did not do is redevelop gills, although they could have easily done so because they I think I mentioned it earlier. We all we all all land animals do have the the traces of gills in our embryology. And so it would not have been a difficult thing, you’d think, to redevelop gills. But they didn’t do that. They stuck with lungs and so they have to come to the surface in order to breathe. They’ve compromised in a way by making it by only having to come to the surface very seldom. I mean, a whale can stay underwater for half an hour to an hour and and only very occasionally come to the surface in order to breathe in a huge great gulp. So they’ve. Although they’re stuck with lungs, they’ve kind of made the best of a bad job there.
Krys Boyd [00:18:49] When you said that older scripts that remain in the palimpsest can turn out to be constraints on perfection. What do you mean?
Richard Dawkins [00:19:00] There are examples of animals that look very badly designed, something that a designer would not have tolerated. In fact, the German biologist Helmholtz said that if he’d been presented with the vertebrate eye, he would have sent it back. The reason being that the retina of the vertebrate eyes sort of backwards. My favorite example is the laryngeal nerve of land, vertebrates, reptiles and mammals, which is one of the cranial nerves. It starts in the brain and the end organ, the organ, the destination organ of this nerve. The recurrent laryngeal nerve is the larynx, the voice box. But instead of going straight to the voice box, it goes right down into the chest, loops its way around the aorta, a very big artery, and then goes back up the neck to the to the larynx and in a giraffe. That’s a very considerable detail in in a large sauropod dinosaur. It’s an even longer detail. This seems to be a relic of history in our fish ancestors. The equivalent of this of this nerve went to one of the gills. And in those days it was the direct route to the end. Organ was below the the, the artery. We’re talking about fish don’t have a neck. When the neck started to evolve and when when mammals start to evolve a longer and longer neck reptiles longer, longer neck. The the detail became ever so slightly longer with every generation. And so the marginal cost of lengthening the detour was small compared to the major cost of jumping the nerve over the blood vessel over the artery. And that’s why we are stuck with this apparent bad design, something that no designer would have tolerated because of historical legacy.
Krys Boyd [00:21:04] I see. So some individual vertebrates might have had mutations that could have repositioned that nerve, but in the meantime, maybe they would have been out survived by other individuals making do with laryngeal nerves that were good enough to get the job done.
Richard Dawkins [00:21:19] Exactly right. That’s spot on. Yes.
Krys Boyd [00:21:22] What are so-called junk genes or pseudo genes?
Richard Dawkins [00:21:26] Well, pseudo genes are genes which no longer do what they once did, but you can tell what they once did because they still have the same genetic code as they did. And so they they’re still sitting there in the genome doing nothing. They’re never actually decoded. Well, then if they were decoded, they would do something useful. The best example I know is there is genes for smell in humans. Humans, as you know, have a rather inferior sense of smell compared to other mammals like dogs. But the remarkable thing is that we still have the genes. For having a much better sense of smell. It’s just that they’re never turned on. They’re just sitting there idle doing nothing. Relics of the past. Which, by the way, is a very difficult thing for creationists to explain. It’s not easy to see why the creator would have littered the genome with defunct, outdated genes that no longer do anything. But you can see what they once did.
Krys Boyd [00:22:26] Your conclusion is that there wasn’t an intelligent creator, that this is all happened by natural selection.
Richard Dawkins [00:22:32] Obviously, yes.
Krys Boyd [00:22:33] I just want to make sure that we keep you on brand here for this conversation. Yeah. So over time, genes may no longer be expressed within a species, but they are not erased from the book of their genomes. Why not? Why wouldn’t they just fall away? Fall out of the genome of animals?
Richard Dawkins [00:22:51] Well, that’s a very good question. Why don’t they just. Just disappear? I think it’s a bit like a computer disk. You know, computer disk. When you erase something from your from your hard disk, it doesn’t actually go. All that happens is that the system is told. You can now regard this area as up for grabs. You can use it again. And so it is more economical to do that rather than to actually go to the trouble of erasing it. And it seems to be something like that in the case of the genome, just as the computer disk is littered with old documents that are no longer of any interest, they’re still there until they’re positively reused again. The same seems to be true of the genome. And so the genome is the kind of dustbin of old genes that are no longer in use.
Krys Boyd [00:23:41] Do we know how genes get disabled over time, such as the gene that made human ancestors much hairier than we homo sapiens are today?
Richard Dawkins [00:23:51] Well, I think it’s probably a matter of economics. If if it’s not necessary, then the the the cost of making these things would cause them to to disappear in the case of why we lost our hair. That’s there’s probably a more positive reason for that. But nobody knows what it is. I mean Darwin thought it was sexual selection. He thought it was sexy to be to have bare skin rather than to be hairy. But more, more probably in in most cases it’s just a matter of the cost of of making these things that are no longer necessary.
Krys Boyd [00:24:29] How much to what extent can we decode those pseudo genes as things that still remain within the genome but are not being expressed with current technology?
Richard Dawkins [00:24:41] Well, this is something that dates from Watson and Crick discovery of the of the structure of DNA. And following on from that, it’s become possible to read the DNA code itself. It can actually be read less. Have a letter. Exactly. Is it it was text. And so yes we can read energy now and it’s becoming cheaper and cheaper and quicker and quicker to do so.
Krys Boyd [00:25:07] Is this precisely the same thing? Is reverse engineering the bodies of modern animals to understand how they came to be the way they are?
Richard Dawkins [00:25:15] It’s not the same thing. Reverse engineering is is a different matter. This is a matter of reading the code. Reverse engineering would be looking at something and working out what it must be for something like when the so-called anti-cantherim mechanism was dug up in a in a an ancient Greek ship and engineers looked at it and said, this must have been designed for something. What was it? What would it be good for? And they worked out what it would be good for if a designer had designed it. That’s what reverse engineering is. So when you look at something like the eye, you can see it looks just like a camera. And so you reverse engineer it. You work out what it was for, what it is for, which is for forming an image on a retina.
Krys Boyd [00:26:04] Teeth and guts in modern animals, I guess can suggest a lot about what a species distant ancestors had to eat, right?
Richard Dawkins [00:26:13] Yes, they immediately suggest what it eats itself and that. But in turn, that’s what that’s really telling you is what his ancestors had to eat. If you look at the if you compare the guts of, say, herbivorous mammals and carnivorous mammals and herbivores tend to have very long, complicated guts and carnivores tend to have rather shorter, simple guts. And so there are numerous examples like that of working out what an animal or what an animal’s ancestors fed fed on by looking at its guts and its teeth.
Krys Boyd [00:26:48] Richard, what can reverse engineering tell us about convergent evolution, the development of similar body forms and systems in animals that are not at all closely related?
Richard Dawkins [00:26:58] I think convergent evolution is one of the most fascinating things. It’s very beautiful the way animals that have the same way of life but different ancestry have converged upon similar anatomy. Outstanding examples are the Australian mammal fauna, which are marsupial because there are so different ways of making a living. When Australia broke away from gone one or the ancient continent of Gondwana. It happened to get all the US, nothing but marsupials. So all the different ways of life that had been occupied by the dinosaurs became occupied by mammals. And so you have carnivores and herbivores and large ones and small ones and borrowers and tree climbers and all the different ways of life evolving in parallel in the old world and in Australia, marsupials in Australia and percentiles in the old world. And they converged. So you have something like thylacine as the marsupial wolf, often called the marsupial tiger for no better reason than that. It’s got stripes. The marsupial wolf looks like a wolf and behaves like a wolf because it has the same same diet, the same way of life. And so convergent evolution is a very striking example of the power of natural selection.
Krys Boyd [00:28:20] So similar body forms suggest evolutionary problem solving for similar environments, but this can happen in different creatures that are separated not just by huge distances in geography, but time. Right?
Richard Dawkins [00:28:34] Yes, indeed. That’s right. I mean, this convergence of, for example, the octopus eye with the vertebrate eye, these are these will be separated by probably a billion years of separate evolution. But because the camera is a good design for an eye, both vertebrates and octopuses and squids have converged upon the camera, the camera design. There are interesting differences, but nevertheless, the the functional design of of the camera eye is the same in both.
Krys Boyd [00:29:09] So do octopuses have their retinas on the back of their eyes like vertebrates do?
Richard Dawkins [00:29:14] Octopuses do it better than us. All of us have have the retina the right way round. The vertebrates have the retina back to front, in a sense, in the wires that connect the light sensitive cells to the brain come out from the front of the retina instead of the back of the retina. If you were designing an eye camera with with certain cells, the bat he would naturally make, the ones that lead to the brain, lead to the computer at the central computer coming out from the behind the retina. And that’s what octopuses do. But vertebrates don’t. They have the wires coming from the front of the retina, so they have to travel all over the surface of the retina. And then they dive through the retina in the so-called blind spot into the optic nerve leading to the brain. And this is a historical accident. It’s a piece of bad design that results from a historical accident.
Krys Boyd [00:30:09] Going back to this idea of reverse engineering as a good way to sort of figure out animal bodies. There are also cases when human technologies have helped us understand the workings of animal bodies. How did the development of ultrasound machines by humans help us to recognize that dolphins might be able to do something like this with their bodies?
Richard Dawkins [00:30:32] When an animal is living in a place where seeing is difficult, either because it is dark, as in the case of bats or as in the case of dolphins. Where is deep water or muddy water? As in the case of river River dolphins, they have resorted to the use of sound instead of sight. They use echoes. They make high pitched cries which then bounce off objects, including prey. And they use the echoes to analyze the echoes using sophisticated but unconscious mathematics to work out where they are, what the obstacles are, and where the prey is. And this is used by humans, human technology in detecting submarines, for example. So now it’s cold there and humans discovered it during the Second World War and British before the Second World War. But bats and whales and dolphins have been doing it for millions of years. When it was first discovered in bats, the discoverers, Griffin and Columbus, when we adopted people who knew about sonar, was skeptical that bats could possibly do anything so sophisticated. And Griffin describes how his colleague Columbus was seized and shaken by the shoulders by a skeptical engineer who simply couldn’t believe that something so sophisticated as sonar could have been evolved by bats many millions of years before humans thought of it.
Krys Boyd [00:32:02] Would you call this some kind of example of convergent evolution of a human technology and and of an animal’s genetic programing?
Richard Dawkins [00:32:11] I would have never reluctance in calling it convergent, although it’s come about through a different route in the case of bats converging on dolphins. This is convergent evolution in the case of bats and dolphins converging on humans. It’s cultural evolution on the human side.
Krys Boyd [00:32:30] What sort of historic conditions? Environmental conditions seem to be associated with rapid diversification of species.
Richard Dawkins [00:32:39] The most rapid diversification of species I know in nature is the cichlid fish of the Great African Lakes. But we know this rapid because we know that Lake Victoria is no more than 100,000 years old. And yet in Lake Victoria, about 450 separate species of cichlid fish have evolved during that 100,000 years, which is extremely rapid. And there are similar numbers of species in the other great African lakes, Lake Malawi and Lake Tanganyika, although those lakes are much older. But probably Lake Victoria is telling us the story of what originally happened in those other Great Lakes. It probably accelerated in the case of Lake Victoria by the fact that although the lake itself, the Lake Basin, is 100,000 years old, the lake has continually dried up and then flooded again, dried up and flooded again, which would have left small ponds and small lakes drying up and then flooded and then drying up and then flooded. So during these periods where there were a lot of small ponds and lakes, it would have been ideal conditions for separating evolution of sacred fish with just enough time to evolve separation from each other before the Lake Basin flooded again and they became united again. So that’s probably accounts for the extremely rapid diversification of Cichlid fish in Lake Victoria over the past hundred thousand years.
Krys Boyd [00:34:18] You say just enough time. How many generations might it take for a beneficial evolutionary change to become widespread within a species?
Richard Dawkins [00:34:27] Well, probably only a few thousand years, because if the generation time is only one year, a few thousand generations, it is actually plenty of time.
Krys Boyd [00:34:39] You note that the most recent scripts in the Palimpsest are the ones written within an animal’s own lifetime. Give us some examples of that.
Richard Dawkins [00:34:48] Yes. Although mostly I’m talking about the genetic because the dead meaning ancestors who are no longer with us. It is also true that animals do become better adapted to their environment during their own lifetime, and learning is the best example of this. So, for example, many species of songbird learn to sing during their own lifetime by comparing this song, either directly to the song of their father or other adults, or to a a built in template of what their song ought to sound like. But learning more generally is a perfectly good example of the not the genetic book the Dead, but the non-genetic book of the living.
Krys Boyd [00:35:35] We now understand, of course, that, you know, far more animals than just humans learn, you know, change their behavior according to learning and rewards and punishments. It’s not like we understand things and make choices, and every other animal is just following a predetermined script.
Richard Dawkins [00:35:53] No, that’s right. I mean, you can regard learning as entirely unconscious, if you like. And you can. I suppose the archetypal example would be a a rat or a pigeon in in a skinner box, where it does, it behaves at random. It’s kind of like an analogy to genetic mutation behaves at random. And then if it gets a reward, it increases its tendency to do that again. So trial, trial and error, try something out. If you get food or some other reward, do it again. And that seems to be a perfectly good formula, which is rather analogous to natural selection, where mutation is the analog of trying things out at random and reward is the analog of natural selection.
Krys Boyd [00:36:38] How did genes influence the ways we are conditioned to respond to experiences that we perceive as pleasurable or painful.
Richard Dawkins [00:36:46] Pleasure and pain built into the nervous system in order to benefit survival ultimately. So the stimuli that we treat as painful are things that damage the body, which might presage actual death. What really matters in natural selection is life or death. But if you do something which injures the body, that makes it likely, increasingly likely that you might die. And so natural selection is built into the brain pain mechanisms to avoid repeating anything you do, which is followed by something damaging to the body. Pleasure is the reverse. If you if you are programed by natural selection, by the genes to repeat anything which leads, which increases your chances of survival, say by eating the right foods, eating foods that’s good for you and avoiding foods that’s bad for you, then you get pleasure from that. You get pleasure from sex because sex tends in nature to lead to reproduction. So pleasure and pain mechanisms built into the brain by natural selection, ultimately to favor survival. Remarkably, it’s been discovered that there are centers in the brain which, if stimulated electrically, lead to pleasure. This was discovered by olds, a psychologist called odes. It was already known that you could implant electrodes into the brains of rats and control their behavior by passing weak electric currents through these electrodes. What olds did, which is that remarkably ingenious thing, was he gave the rats the switch. The rats had access to the switch to turn on the current. And when you did this, he found that there were certain parts of the brain where if the rat had control of the switch, they became addicted to switching on current. Presumably to get pleasure and assembly. So great was the pleasure that they would do this for 24 hours without stopping, without even pausing to feed. It became totally addicted to these pleasure centers. And the experiment just had to, in the interest to save the rats lives, rarely take them off the air, take them out of the Skinner box, take them out of the access to the switch so that they could get on with the ordinary life.
Krys Boyd [00:39:13] So rats just want to feel good. It is interesting to think about the fact that for different species, depending on the conditions in which they have to survive, different stimuli might feel physically painful or pleasurable.
Richard Dawkins [00:39:29] Yes, that’s right. Because, of course, as I said before, each animal lives in a model of its own construction. And therefore, for some animals, that which is defined as pleasurable will be different from that for other animals. Obvious difference would be the difference being carnivores and herbivores. I mean, a carnivore would derive pleasure from the taste of raw meat, whereas the home of what would presumably be revolted by it. And similarly, eating grass would not appeal to a carnivore. So each animal is born genetically programed to to gain pleasure from suitable stimuli and again, pain from food, supposedly for its particular way of life.
Krys Boyd [00:40:13] You mentioned that, you know, to a certain extent animals are preprogramed to experience fear or discomfort associated with certain pain or discomfort associated with certain stimuli. I’m curious about fear. How common is it for an animal to be born with a tendency to fear something?
Richard Dawkins [00:40:34] It would naturally make sense to feel fear for things that are likely to damage your survival chances. And so we can’t know. We can’t get inside the head of an animal to know what it feels. But it makes sense to think that a gazelle, for example, feels fear when it’s being pursued by a lion. So I think this is a matter of inference, and it will certainly make Darwinian sense for the nervous system to be preprogramed to feel fear under such circumstances.
Krys Boyd [00:41:08] As far as we know, no living thing is immortal. But as you mentioned earlier, the information in DNA has the potential to outlive any body or any species it inhabits as a vehicle. Is there any way to know what is the absolute oldest DNA information extant on the planet?
Richard Dawkins [00:41:27] Well, yes, you can look at the you couldn’t compare the DNA of animals whose common ancestor is known or inferred anyway to be a certain number of millions of years old. And so something like a a vertebrate and a mollusk whose common ancestor probably lived in the Precambrian, probably lived about a billion years ago, to the extent that they have the same genes and some of them do. There are some genes that are shed that you can you can infer that those genes probably date back that far and you can do that and you can do the same thing for more recent splits like the split between modern fish and modern modern mammals, for example.
Krys Boyd [00:42:15] Is it going too far to say that DNA has a will to survive?
Richard Dawkins [00:42:20] I think it’s going too far to say that DNA has a will to survive, but it’s you tend to get the right answer if you make that fanciful assumption as this kind of working rule of thumb, you don’t actually have to believe it. But it works if you make that assumption.
Krys Boyd [00:42:38] Why do you think it exists?
Richard Dawkins [00:42:40] Anything that happens to have the property of self replicating as DNA does and of occasionally making mistakes as DNA does, then automatically those variants which have the power, have the capacity to survive will be the ones that do survive. You don’t have to say they have any kind of will to survive. It doesn’t doesn’t work like that.
Krys Boyd [00:43:06] Is there anything we can guess from reading genomes as they exist today about the future forms human bodies might take, given that in the modern era, human existence and survival and even reproduction to a certain extent are very much aided and enabled by human technology.
Richard Dawkins [00:43:25] I think, as humans become have become pretty unique in this respect because we now live in a environment which is entirely dominated by culture. It’s no longer possible to do the kind of influence that we would have done before. And if we look back at the past 3 million years, we see that there’s been a tendency for the human brain to grow much bigger. There’s been a tendency for the brain to get bigger and bigger, presumably because of natural selection as favor. The brain is individuals. But nowadays, in the cultural technological environment in which we live, selection pressures such as they are will be completely different. They’ll be no longer anything like what they were during the 3 million years that separates us from Lucy. And therefore, since it’s not really possible to know what direction cultural evolution will take us in the future. And above all, because cultural evolution is so incredibly fast, when who knows what kind of culture we’ll be living in if we exist at all, if we haven’t gone extinct in 3 million years time? So be a very foolhardy biologist who would speculate about what possible future evolution might look like in the next 3 million years.
Krys Boyd [00:44:41] Richard Dawkins is the inaugural Charles Simonyi, Professor for the Public Understanding of Science at Oxford University. His latest work is “The Genetic Book of the Dead: A Darwinian Reverie.” Richard, this has been a pleasure. Thank you for making time to talk.
Richard Dawkins [00:44:54] I must say, you read this book with the greatest thoroughness of anybody I’ve come across so far. Thank you very much indeed.
Krys Boyd [00:45:01] Thank you. Think is distributed by PRX, the public radio exchange. You can find us on Facebook and Instagram and listen to our podcast wherever you get your podcasts by searching for KERA Think. Again. I’m Krys Boyd. Thanks for listening. Have a great day.
