In Our Time - Alfred Russel Wallace

Episode Date: March 21, 2013

Melvyn Bragg and his guests discuss the work of Alfred Russel Wallace, a pioneer of evolutionary theory. Born in 1823, Wallace travelled extensively, charting the distribution of animal species throughout the world. This fieldwork in the Amazon and later the Malay Archipelago led him to formulate a theory of evolution through natural selection. In 1858 he sent the paper he wrote on the subject to Charles Darwin, who was spurred into the writing and publication of his own masterpiece On the Origin of Species. Wallace was also the founder of the science of biogeography and made important discoveries about the nature of animal coloration. But despite his visionary work, Wallace has been overshadowed by the greater fame of his contemporary Darwin.With:Steve Jones Emeritus Professor of Genetics at University College LondonGeorge Beccaloni Curator of Cockroaches and Related Insects and Director of the Wallace Correspondence Project at the Natural History MuseumTed Benton Professor of Sociology at the University of EssexProducer: Thomas Morris.

Thank you for downloading this episode of In Our Time, for more details about In Our Time, and for our terms of use, please go to BBC.co.com.uk slash Radio 4. I hope you enjoy the program. Hello, in the reign of Queen Victoria, a young British naturalist travelled to remote parts of the world, collecting vast numbers of animals and plants in an attempt to understand where species came from and how they change. He published a best-selling account of his travels, and in 1858 proposed a theory of evolution by natural selection, an event which made the scientist famous and forever changed our understanding of life on Earth. The scientist I'm describing isn't Charles Darwin,

although the facts fit his life as well, but his contemporary Alfred Russell Wallace. Wallace was a remarkable self-taught biologist, he left school at 14, who came up with the theory of evolution independently of Darwin. He was famous during his lifetime, not just as an evolutionary scientist, but as the greatest authority on the geographical distribution of animal species.

But since his death, his reputation has declined. Today, his name is far less well known than that of Advardarwin, although arguably both men played a significant role in the development of evolutionary theory. With me to discuss the work of Alfred Russell Wallace are Steve Jones, Emeritus Professor of Genetics at University College London, George Becalone, curator of cockroaches and related instincts and director of the Wallace Correspondence Project at the Natural History Museum, and Ted Benton, Professor of Sociology at the University of Essex.

Steve Jones, before we turn to Wallace himself, Let's get a bit of background here. What were the dominant view of where species came from in the first half of the 19th century before those two got cracking? There was plenty of discussion of change. It was a sort of simplistic view that said everybody believed that in the Garden of Eden and everything had happened on October 4, 2004 BC with an act of creation. That wasn't true at all.

The biological world, particularly across the channel in France, was alive with speculation about the fact that, creatures were related to each other, and if they're related, they must share in some sense share ancestors. But the great difficulty that there was nearly all those ideas shared is that they depended not on a sort of mechanism, a scientific mechanism, but on a vague, beneficent feeling of goodwill that there was a sort of force for life to get better. The famous proponent of that particular idea was the French biologist Le Maher. And everybody knows perhaps about Lamarck and his giraffe's necks getting longer because,

they stretched towards the highest leaves, the inheritance of acquired characters. But in fact, Darwin kind of believed that too, but he didn't like Lamarck at all, because Lamarck had this inner feeling that there was a force for life for giraffes to get longer necks to become, if not perfect, at least French, in other words, to reach a higher pinnacle of being. And none of these people, great biologists, as they certainly were, none of them had a mechanism. and what both Wallace and Darwin independently came to was a mechanism whereby such changes could happen. So there wasn't one dominant view of where species came from.

That hadn't kicked in as something to aim for and discover. There wasn't an explanation. There was lots of speculation. It got frightfully terribly closely closely philosophy, which is always a sign that science is sinking into the morass. And really Darwin and Wallace rescued it from that, although I have to say a Wallace later in his life began to push it back in that direction. Can you give us some context for Wallace's work?

When did Darwin start in the idea of evolution and what's Wallace doing? Well, there's a whole industry which basically picks the lint out of Darwin's navel, really. When did he get the idea? When did he get the idea? In fact, the first line of the origin of species, which reads, when on board HMS Beagle as naturalist, I was much struck with certain facts in the distribution of the inhabitants of South America. That actually is kind of an evolution. thoughts. That was written in 1859, but he was in the 1830s when he was on the Beagle.

And what about Wallace? When do we, when does he register? Well, Wallace, I think, had the idea much later. He was in the Malaya archipelago at the time and he was collecting many, many thousands or more than a hundred thousand specimens as a taxonomist, as a curator of creatures, rather than an analyzer of creatures. And he had a fever, 190 recounts, and the idea appears fully formed in his mind. It's using. Data are going to be important in this, so he might sort of get this right.

He was, that was in about 1857, I think, or even 58, even. 1858, yeah, 1858. Okay, George McAllone, would you tell us a bit about Alfred Russell Wallace's early life in his upbringing? Yeah, sure. Well, Wallace was born to

downwardly mobile parents. His father had actually studied to be a solicitor but never practiced law because he had inherited a sum of money. And he made various bad investments and was forced to leave London to try and find a cheaper way of living. So he ended up in a small village outside the town of Usk in what's now Wales, but at that time was actually part of England. And Wallace was born there on the 8th of January 1823.

He was the seventh of eight children, and only five of which survived to adulthood. And he lived in near Usk for five years, then moved to Hartford, where he had his only formal education at Hartford Grammar School. But his father's finances got worse and worse, and he was forced to leave school when he was only 14. He then went to stay briefly with his brother in London

and then got a job as an apprentice Landseverer with his older brother, William. and he basically spent the next 12 years travelling around southern Britain, England and Wales, doing lanceveing. And it's actually quite an important point because it was his only really formal training and a lot of his later work

you can see stems from his training in making maps, etc. And it was during that period of time that he got interested in natural history at first botany. He bought some books on how to identify plants and formed a small collection of press plants. It's a fascinating example of an autodidact, isn't it? Because he's on this land surveying. He has been at a grammar school until he was 14.

His father was a librarian or so he knew about libraries. But even so, he's out on the road on his own and developing a passion for knowledge in this particular direction. Yes, absolutely. And it was in about 18... 43, I think, that Lance Vane work got scarce, so he was forced to

do some teaching work in Leicester, and it was there that he met Henry Walter Bates, who was an amateur naturalist, and it was Bates who got him really interested in entomology and collecting beetles. Bates said that a thousand species of beetles were found within a short distance of the town. Wallace was

sort of hooked. Bates himself, can you give us just a tiny bit about Bates? Because Bates was a big influence. He was a mentor influence on what was his life. He'd come up against a man who knew a great deal about what he wanted to know a great deal about. And this man was willing to help him, work with him and was his companion

for a while. He's his professional companion. Yes, I mean, Bates at the time was an amateur naturalist. He was, I think his business was in hosery. His father owned a hosery business. And he was a very keen beetle collector, butterfly collector, and he became

fairly famous in later years, especially for the theory of Batesian mimicry in butterflies where unprotected tasty species evolved to mimic poisonous ones. So you've this man was much of an age gap

between the two, they're in Leicester, they're working, they decide, they're going out on jaunts at weekends collecting stuff basically. They're about the same age. Yes. And then Wallace then moved to Neith in Wales and kept up a correspondence with bait. And it was in 1845 that Wallace then read this very influential book called Vestages, which proposed that

life on earth had evolved from earlier forms, but didn't give a mechanism. And it was a sensation in Victorian times. Everyone was reading it, including Prince Albert, was reading it to Queen Victoria on the afternoons. And, you know, it was a hot topic of discussion. And it converted Wallace to be an evolutionist. He thought this is an ingenious, you know, hypothesis that life on earth has evolved from earlier forms and he then set off in his mind to try and discover the mechanism by which this occurs. And it was then that he had proposed to Bates

that they both go off to the Amazon to collect species, study them, and try and discover the mechanism of evolution. Just before we go to the Amazon, this book was published then and honestly, but we now know it was by Robert Chambers. And you did have a huge influence on Darwin, right across the intellectual landscape,

because as Steve Jones was saying at the beginning of the programme, the idea it wasn't a dead move from the world was created on a Wednesday, 6,000,000 years ago. People were drifting towards this Lamarck and others and fudging around in this area, but this boldly said, perhaps it's why it was anonymous, look, there is an evolutionary thing, but it didn't say how it happened. Absolutely. And the book was important in preparing people's minds for what was to come, next in later years

the Darwin Wallace theory. Ted Benton, as George Rekulani has mentioned, in 1848, Wallace and his friend Henry Bates traveled to Brazil. It seems rather bold for two youngish men from Leicester. Oh, I think they were very bold.

And as we'll see, as the programme goes on, Wallace was unbelievably bold, given what happened to him in the Amazon, that he was up for another tropical expedition very, very soon after. Why did they choose Brazil and what did they want to get out of it? In the correspondence between them, it's perfectly clear that both were interested

in this whole question of the origin of species. And Wallace was particularly impressed by vestiges. Bates much less so. The book that George has been talking about, yeah. Bates much less so. But I think Wallace was interested in it not so much because of the substantive account that it gives of evolution. but because it raised the question that they could then collect facts

and think about those facts in relation to this hypothesis that species change. And that was the motivation for going to the tropics. It does seem bold in many ways. Neither of these men had much, if any, money, but they went out and they were going to subsidise it. You tell us. Yeah, through collecting. And sending them back.

So there was a mania for collecting around this country, otherwise they wouldn't have had a market back here. Well, there were private collectors, but also the museums and Kew Gardens were also interested in by... This is plants, animals, insects. Yep, that's right. So they collected particularly bird skins and insects, but also some mammals and other groups,

land shells, for example. So they arrive in April 1848 at Parra, which is now Belmont. on the coast of Brazil. And together they start to explore the nearby forest. I think it's within a mile or so of Parra. Wallace says in his autobiography, the rainforests spread in all directions.

And so they had a very rigorous collecting program and they pin their insects and they skin the birds and so on. And Wallace is particular, only his autobiography particular, particularly he's very very interested in the people and this is something that was true right through his life he's not just a collector of birds and insects and so on

he's also a great observer of the diversity of human beings and George mentioned this few months that he spent in London with his brother well there was a carpenter then yeah it was a carpenter and an oenite socialist and he was taken to a mechanics institute just off Tottenham Court Road and he learnt about Owen's ideas he became a religious sceptic on the grounds that, you know,

who could possibly think that a cruel doctrine like everlasting damnation was something that you could really believe in and was worthy of humanity or even of God. And so he goes to the tropics, he goes to Brazil with those ideas already formed in his mind, as well as the question of the origin of species.

And you used his land surveying techniques to great effect there, didn't you? Especially on this, one of the longest rivers in the world. Can you tell us about that? Well, within about a year or so, for reasons that we don't fully understand and was never explained, Bates and Wallace actually decided to split up and to divide the labour. So Bates goes up to the upper reaches of the Amazon, and Wallace goes up to the Rio Negro and also to a tributer.

which I'm reliably informed should be pronounced Uape's. And that actually, an attributive to that, takes him up into Venezuela. Which he maps brilliantly, and that's the authoritative map for many years to come. So he uses his skills as a surveyor to do that. But I think the important thing that he encounters, particularly in the upper reaches of those tributaries, are indigenous people. So he's very struck in power by the...

diversity of people, all colours and shapes and sizes of people, but when he actually meets the Indigenous people, he's all struck. By their physical beauty, by the wholly distinctive form of life that they have. So he spends a lot of time describing their material culture, their belief systems, their festivals, the way they paint their bodies. And he uses that as a standpoint from where which to review his own critical relationship to his own society. But that magnificent tour ends in tears, Steve Jones, doesn't it?

It does. His brother went out with him to him and he died, and it ended in flames rather than in tears, because he'd collected a vast quantity of staff and it was packed it all up, came back on a ship across the Atlantic, and the ship caught fire. And nobody was killed, fortunately,

but his entire set, almost his entire set of specimens, was destroyed, apart from a white parrot, I believe, which he kept. And they bombed around on the ocean for several days before they were rescued. And then he came back, that brought him back to Britain. But remarkably enough, and he was a very daring man. Within a fairly short time, he decided to go off of another expedition, but this side of the other side of the world to Malay. It must have been an extraordinary resilient.

I mean, this is four years' work. And he got an immense number of. rare specimens so he is obviously totally truthful. Yes, I mean, he was... He, like Darwin, was a naturalist, and that's a profession that's really almost extinct today. We now see the living world, nearly all of us, biologists included, through the glass of a television screen, or by studying our own narrow specialisation, be it cockroaches or, in my case, snails, even more obscure. But Wallace and Darwin could do the lot, and there's almost nobody left who can do that.

I think that's worth reminding us ourselves. They were at some ways at a peak from which we've declined in biological knowledge. They just went out there and did it. And did it. And so he went out there and did it by going to the Malay archipelago of Vass, where he stayed this time for 12 years. Yes, he went down in 1854. He travelled thousands of miles.

He visited places really never visited by Europeans before. He became, again, as Ted said, very much involved with the local people. He learned Malay, which is an extraordinarily distant language. which he had a close companion, a young person who helped him. And his view in Malaya and indeed in South America of the local people was quite different from that of Darwin. Darwin, when he went to Teira del Fuego, the southern tip of South America, made some damning statements about the Fuegians.

He thought them to be scarcely human. Their language was like the babbling of an animal. And their attitude is utterly different. But of course, Darwin, in modern terms, was a millionaire. Wallace, in modern terms, would be on public assistance. of some kind. We probably wouldn't be in today's terms. But they were very different in that sense. They're both attractive characters, but attractive in different ways.

So he went there and he got his great collection together there, which is an extraordinary large, George Baccolonio. We're told 126,000 specimens. And this time he wrote out of that experience in ways, before we come to the evolutionary thing, he wrote out of that experience and brought it back. It came back quite a wealthy man. Let's talk about the kind of his experience.

travels the Malay archipelago. What significance did that book have? Well, it's probably the most cited book that Wallace wrote. He wrote 22 books during his life. It's never been out of print since it was first published. Certainly his most successful book and it's still read today by lots of people who go out to Indonesia, Malaysia, etc. And it's amazingly contemporary in its style It's not sort of stilted, old-fashioned. What's it about? It's an account of all his travels in Indonesia, what's now Indonesia and Malaysia. His travels as a naturalist or does he tell us all sorts of other stuff?

Well, it's about the physical geography, the biogeography distribution of animals, what he collected in the various islands, the people he encountered. The political situation at the time is remarkably far-ranging. And, I mean, he travelled an enormous distance, 14,000 miles. on small native boats, etc., all the way from Singapore in the west to the western part of the island of New Guinea. He was actually the first westerner to live on the mainland of New Guinea.

He had the extraordinary adventures, and these are recounted in this book. But strangely enough, even though he discovered natural selection whilst he was out in the Malay archipelago, evolution and natural selection is barely mentioned in his book. And also, as I understand from the notes that I got from the three of you, although he must have been in peril, taking great risk, that is underplayed massively as well.

Well, typical British or sort of Victorian sort of understatement, you know, coming across poison snakes in his boat at night, putting his hand on a deadly pit viper, you know, he's very understated in his accounts. Well, he lived to be understated, really, really. Yeah. I think we should also, I think it's fair to say, there's also a work of considerable literary merit.

it's a really good read. It would say it'd be Joseph Conrad's favorite book. That's quite something for somebody who could write like Conrad. So Wallace was a talented man. Let's move towards a... Sorry, Taylor.

I was going to say this... I was going to say it. All right, go on. No, you say, you're honest, and I'll ask my question. Just wanted to say something about his relationship to the indigenous people. He still uses this contrast

between the savage and the civilised, which he goes to the tropics with, but actually in both places that he visits, he shatters really the connotations of that distinction because he has this tremendous respect for the indigenous people and he uses them as a foil in terms of which to kind of criticise his own society. And just going back for a moment to the Amazon, there was an extraordinary episode where he's with a group of indigenous people

out to try and shoot the cock of the rocks, which was this very beautiful bird that he was on. after. And in the evening they sit and they ask him about how the moon and the and the sun get back to where they started from after departing from us. And they talk about where the wind comes from and the rain comes from. So he's having these really scientific conversations with the indigenous people, which is really, I think, really fascinating. And it goes further. We haven't really got time, but there's a record of him. making friends with an Oran Utang, a baby Oranutang,

and actually in some strange, not sickly way, looking after it and grieving when it died and feeling that there was the likeness between the two was very powerful. In that he actually matched both Darwin and Queen Victoria because Queen Victoria went to London Zoo on occasion and saw the orangutan whose name was Jenny. And she was quite shocked by the animal, painfully and frightfully and horribly human, she called it.

So even then, and that was well before the origin. This notion that maybe, you know, Darwinian man, though well behaved, is little more than a monkey shaved. That was already coming out. Ted, I'm awfully sorry, but we've got to move on. We've got to stay, we've got to get to evolution. Sure.

There we go. Otherwise, this programme will not evolve one little bit. His first step was an essay he wrote in Borneo in 1855. Now, can you tell us about that? It was published as the Sarawak Law. Right. Okay. Well, we know at the time, because there is an extant, what's now called the Species Notebook,

we know the intellectual struggle that he was going through, which gave rise to that paper. So this is why it's over in Malaya, just so on the Malaysian archipelago? Right. That's right. That's right. And this is during the rainy season where the collecting isn't going so well. So he actually struggles with these ideas. And he makes pretty short work of theological arguments that explain.

species and their adaptation as the work of a design or a creator. We're still in that, we're quite right of you to remind us we're still in that time. Yeah. And religious explanations were held by very, very many people and strongly. That's right. But the real challenge for him is the work that perhaps up to that time had the greatest importance on him and Bates and Darwin himself, Lyle's principles of geology. and the key principle that underlies Lyle's geology is what's called uniformitarianism, which is that the forces that have shaped the history of the inorganic world

follow laws and those laws still persist today and that the changes that gave rise to the mountains and the changes in the oceans and the river valleys and so on were all gradual, bit by bit, no kind of sharp discontinuities, and according to law. And Wallace notes that if we look at the sequence of fossil remains, they seem to follow the same kind of pattern. But Lyle is still at this stage committed to special creation of each species. And Wallace says this is just, he uses the word unphilosophic.

How can Lyle really have uniformitarianism for the inorganic world? He can see the fossil relationships intimately connected. And changing. And changing. And yet he thinks that each species, each of these tens of thousands, hundreds of thousands of species have been specially created. He said, what an odd, unphilosophical idea this is. Steve Jones, three years later, I made his most important breakthrough.

Can you just tell us about that? and now we're moving right to the heart of the matter. Yes, I mean, I think after a lot of, you know, wandering in the philosophical fog, or at least seeing that it was philosophical fog, he had one of those rare moments of insight, which I'm told a few scientists have during their lives, where he had a fever on possibly a small island,

off the major island where he was staying, and suddenly fully formed, the idea of natural selection, as Darwin later called it, came into his mind. inherited differences in the chances of reproducing. And he saw that if one particular kind of creature inherited a constitution that made it more likely that it would survive, find a mate,

and pass on its very being, its genes, as we'd say today, then those genes would become more common, and in time new forms would arrive. And he corresponded with Lyle, and he then sent a letter to Lyle, which was passed on to Darwin, He then sent to let us, he then sent to Darwin, after having discussed it with Gile, on the tendency of varieties to depart from the common type.

And Darwin was shattered by this. This is very important because you've said, is it on the tendency of varieties to divide indefinitely from the original type? That's it. Now, why was that so significant? Because he had, in there was a mechanism whereby change could happen. It was built into life was a system which balanced certainty, uncertainty, the uncertainty, these random changes we now call mutations, the certainty that

conditions were going to change, physical conditions were going to change, and the way that this could, was almost inevitably led to biological change, to evolution. It was simple, it was so simple it could even have been physics. The student, because, who should stop saying that to it? Students never laugh. When this letter arrived, George Bacolone, things moved very, very quickly where they'd been very slowly, and we're entering what seems to be a rather discreditable phase in the career of down. Some people think.

Now, I want to tackle that, but not to dwell on it too long, so can you do it for us? Yeah, sure. So Wallace sends this essay to Darwin, which he asked Darwin to pass on to Lyle, because it was actually intended for Lyle's to read, because Wallace knew that Lyle had taken great interest in his 1855 paper, and this was a mechanism that actually explained his Sarawak law that was proposed in the 1855 paper. And what happened next was when Darwin opened the packet from Wallace

and read the essay that was enclosed, he was absolutely horrified because he saw that Wallace had there what he regarded is his idea of natural selection that he had come up with 20 years before but hadn't actually got around to publishing. I'd been making notes on it for a very long time. He'd been making notes, yeah, building up an enormous body of evidence

to overwhelm the opposition eventually. But strangely enough, he was partway through writing a book on the subject which was actually prompted by Wallace's 1855 paper. Anyway, he was totally... So it's already on a book that had been prompted by Wallace's first paper, the Sarawak Law. And now this comes in, three years later.

Yeah, and Lyle had warned him In 1856, you know, Wallace might be on to something. You know, you better start writing for publication. That's why he started writing his big book on evolution. So anyway, he was horrified, sent an anguish letter to Lyle saying, you know, what am I going to do? You know, life's work's going to be, you know, destroyed because Wallace has come up now with this idea and I, you know,

honorably have to sort of publish it. And Lyle then contacted another of Darwin's friend, the botanist Joseph Hooker, and together they hatched a plan where they would present Wallace's essay together with two unpublished fragments of Darwin's writings on the subject of natural selection. At the same time with Darwin given precedence.

Yes, well Darwin's material presented first and the introduction by Hooker and Lyle saying that Mr Darwin had come up with this theory before Mr. Wallace and basically... Within 14 days of getting little bit without reference, referring to Wallace, of course. Yes, I mean... Sorry, that's wrong, without contacting Wallace.

Yes, without asking his permission. I mean, it would have taken time. It would have taken weeks and weeks and weeks. But that's what I believe should have been done. After all, Wallace had been looking for this mechanism for 11 years. And, you know, it seems really sort of very unjust today, as I think it did in would have done in that time to publish someone's work without actually asking their permission first.

So the paper, the essay was read out to the Lanaiansite, as you mentioned. And then only a month later, it was in print. And Darwin had had plenty of opportunity. He actually corrected the proofs of the paper, made lots of changes to his bit. And he consented to its arrangement. So I believe that, you know, he's sort of culpable. Is that something you agree with, Ted Benton? More or less, yes.

although I don't think we should get too hooked on it. No, I'm not going to have it. I'm just clearing it up, and then it and move on. I mean, Darwin was a gent. I mean, he could afford to be a gent. I mean, he came up. Well, he didn't behave like a gent here, Steve. Come on.

Well, I'm not so convinced. I mean, the point about Darwin was he was... I know Darwin is the nearest you will ever have to a saint in your life. That's true. But he did suggest at one moment that the paper just be published by Wallace, which would really have knocked it,

knocked his priorities completely to a cocked hat. And it's also the case that people knew, the people that mattered knew that Darwin was doing this. He'd spoken to all the great figures in biology. They knew that he had been working on this for years. So in some senses, in his own mind, he already had priority. But from the modern world, from biology's point of view, whatever the political reality behind the event, it was absolutely essential because it's pretty clear to me that if he hadn't got the Wallace letter, he probably would never have written his big species book.

If you read the origin of species, every now and again, you're on page and, you know, you're trudging through this enormous book. There's a little phrase that says, I have far more information on this, but unfortunately not space to place it here. And you think, thank God for that. And that's why, you know, the origin is such a marvelous book, because it's a popular science book. It's a long argument, and it works. And it works because Wallace gave Darwin an almighty kick. And I think we should remember that Wallace actually spent much of his life looking up to Darwin. a book called Darwinism.

So I think it was a collaboration more than anything else. And the interesting thing about Darwin's Origin of Species is it's actually a condensed account of the big book that he was writing. So he was able to produce origin of species in only 15 months after the joint paper because he already had a book to condense it down from. And to point to another character, Christopher, when he discovered this,

he was delighted to be published in. in the same breath as Darwin, who he admired enormously, as you say, Steve, he wrote the best book on Darwinism, the best-selling book on Darwinism, and defend it. I mean, scientists are driven by... Although he disagreed with Darwin, I'm going to come to that. Oh, he began to disagree quite markedly with Darwin.

And in some ways, he was right, and of course, in other ways Darwin was right. Scientists are kind of driven by their egos. They don't like to admit this. In mathematics, there's a thing called the Erdos number, and Erdos was a famous Hungarian number theorist. And what you can do is link yourself, through the papers published until you've published with other people,

until you get to an Erdosh number. And the number of papers you have to go through shows how unimportant you are, the more they are. Mine, I have to say, is two. Not that I'm a great mathematician. But Wallace knew about, Darwin was famous. I mean, you know, Darwin had written the voice of the beadle. And Wallace was absolutely delighted

to be linked with this marvellous character. Now, can we move to Ted Benton, Can we move to where... So in a person, Darwin was immensely grateful. He said, what a generous man you were. I can't believe you're so gracious. Now let's get on with the thing. How did...

Can you give a starting point of how they differ, the main difference? And because Wallace held his corner in these arguments. Yes. The main... If we're looking at the papers themselves, the main, very stark differences, are that Darwin begins with

human selection of domesticated species and uses that as the model, hence natural selection, Wallace starts with an absolute contrast between domestic species and those species in nature that have to struggle with every ounce of their being to survive. And he says that's the pressure that selection operates through the struggle for existence in nature. So that's one big difference.

And it was a bone of contention between the... later on. I mean, Wallace says, look, you get misunderstood Darwin by this name natural selection. People think you mean that there's an intelligence in nature which is rationally selecting, and you're not saying that, but the metaphor suggests it.

And so that's one difference. Darwin's use of domestic animals. Wallace, I'm being very, very encapsulated for you. Wallace says it doesn't get anywhere. It doesn't change much. It's out there that things are really changed because of the element of survival, which is a domestic thing doesn't obtain.

that much at all and even if it doesn't matter all that much? Well, so that's one key difference then. And the other key difference, which persisted, and this is one where I think probably Wallace, as far as we know now, turn out to be right, and that's sexual selection. The competition, as Darwin put it in that paper, between males to have access to females.

So it's not just whether you survive the predile, and get food and so on. It's also whether you actually managed to find a mate. Can we take that up with you, George? Well, these days people think that sexual selection is purely Darwin's theory, but interestingly, the modern theory of sexual selection has strong elements of Wallace's views. Darwin thought that organisms, females, had an aesthetic sense, even butterflies, and they were choosing the brightest, most pretty males. Rather than us, you mean?

Yeah, but Wallace couldn't accept that things like butterflies, you know, had an aesthetic sense. So he looked at natural selection to provide the answers. And he said that things like horns, etc., were displays of the males, you know, better genes in modern terms, that the fittest males had the biggest horns, they were the strongest, etc. And those sort of arguments are now, you know, in the modern theory, of sexual selection and they originate from Wallace's rather than Darwin's writings. I'm still not quite clear about the

distinction. Steve, do you want to give us the distinction? Evolution is never pure, really simple and that elements are both these. It's clearly the case that females of some creatures have a kind of intrinsic preference for something. For example, if you take two species of fish, one of which

has got a very long tail, the males have a long tail, which is probably sexually selected. You cut off that tail and stick it onto another species, of fish, related species, in which the males don't have a long tail. The females of that second species see this male. I think, what a long tail that is. I'll make with that.

So that's sort of an intrinsic thing. But we also have this so-called handicap principle, which George has told us, which is, look at these enormous horns. I've gone, bloody, oh, look at those enormous horns. He must have good genes. But I think Wallace was right more, was that Darwin was very keen on sexual selection in humans. And what we know about human evolution suggests to us

that actually, compared to our relatives, we're rather calm. In many ways, we're feminized apes. The differences between the sexes in humans are much less than they are in chimpanzees, let's say. We have the same number of hairs as chimpanzees do, but ours are tiny, but male chimpanzees are these enormous bristling hairs. There are certain more fundamental issues, which is before the 9 o'clock deadline.

We can't discuss in detail. between the two, which is just actually Darwin's feeling that sexual selection were very important in human evolution was less correct than Wallace's feeling that it was less slow. George, you want to come in again. Yes, you asked

what were the actual differences between their two theories in the 1858 paper. There were several, although the core theory natural selection was basically identical, Darwin concentrated on competition between individuals, whereas Wallace concentrated on environmental change

driving natural selection and evolution. And another big difference was that Darwin thought that speciation largely occurred by what he called his principle of divergence, which was basically a theory of what we call sympathetic speciation, where speciation is occurring within the same habitat through competition between closely related individuals or species. whereas Wallace believed more in what we now call Parapatric and Alapatric speciation

geographical separation of populations and I believe that Wallace is probably more right than Darwin on this. Can we turn now Ted Benton to another book that Wallace wrote which has been in print ever since which is the geographical distribution of animals published in 1876? What's the importance of that book? Well, first thing to say is it's a major achievement. I mean, the scholarship involved is just enormous

because he's collecting together information about the distribution of birds, mammals, reptiles, amphibians, invertebrates of various kinds across the world. And he's trying to make sense of the patterns of their distribution. It's extraordinary, isn't it? In relation to the fossil record. And so, I mean, part of it is, is zoological geography, where he looks at the different zoological regions of the world.

And he finds that it would be six? Yeah, he uses someone else, this guy called Sclater, who was a big supporter of Wallace's. And he tries to show how the distribution of different species in these geographical regions can help you understand

the geological history of those regions. And then there's another half of the book which is geographical zoology where he takes particular families or groups of animals and looks at their geographical distribution. So this is to look at the same problem in a sense from two different angles,

but it gives you different kinds of insights. And he's really regarded as the founder of biogeography and he still has that status and in fact there was something published in general. January of this year in the journal Science, which updates Wallace. But Wallace is there in the title. And what's most remarkable, really, is he did all this before modern geology had been invented with the idea of continental drift.

Now, now we know that the earth is not fixed. But Wallace didn't know that. He has some hints that the shapes change. I once saw a T-shirt that said, reunite Gondwana land. Okay, in Australia. And, of course, Gondwana land was this big continent which broke up. And if we look at the modern biology of mammals, it turns out that there are certain groups only found in Africa,

certain groups only found in South America and so on, but you can trace them all to this broken-up continent, which, in fact, Wallace knew nothing about. But he did hypothesise it, particularly if you look at the distribution of primates. And so, you know, these ideas were already bubbling up from this. And if I could just... I know you want to get on... I just feel to say, that terrible word finally, it's come up.

And I'm just going to have a very brief, if I can, from you, George. Why, is it possible for anyone of you to encapsulate why his reputation in terms of an evolutionist has declined and diminished so much? Yeah, I have to be sure. It's not my fault. Well, I think it's because of a period called the eclipse of Darwinism where people lost interest in natural selection until the mid and late 1930s. And when it was re-discovered, people got interested. in it again. People looked to the history, just saw Darwin's book and thought,

ah, that's where it all came from and had forgotten about poor old Wallace. Well, thank you very much, George Baccoloni, Steve Jones, Ted Benton. Next week we'll be talking about the chemistry of water. Thank you very much for listening. There are many more Radio 4 arts and discussion programmes to download for free. Find these on the website at BBC.co.uk slash Radio 4.