Interpreting Darwin's theory

Robyn Williams: So how does natural selection work? Let's go back in time to Oxford and a room where Darwinian history had been made. Here's John Durant to introduce an occasion as significant for evolution as Nadal versus Federer was last week to tennis.

John Durant: It was in this place, standing, I believe, directly opposite from me, that the great Victorian champion of evolution Thomas Henry Huxley (Darwin's bulldog, so called) delivered his famous Romanes Lecture on evolution and ethics.

On that occasion he said the following; 'Natural knowledge tends more and more to the conclusion that all the choirs of heaven and furniture of the earth are the transitory forms of parcels of cosmic substance wending along the road of evolution, from nebulous potentiality, through endless growths of sun and planets and satellites, through all varieties of matter, through infinite diversities of life and thought. The cosmos,' he said, 'assumes the aspect, not so much of a permanent entity, as of a changeful process, in which nought endures save the flow of energy and the rational order which pervades it.'

Half a century after those words were spoken, Thomas's grandson Julian Huxley returned to this same theatre to give his equally famous Romanes Lecture on evolution and ethics. He said on that occasion; 'Evolution from cosmic star-dust to human society is a comprehensive and continuous process, it transforms the world's stuff, it is creative in the sense that during the process new and more complex levels of organisation are progressively attained.'

Thomas and Julian Huxley are justly renowned today both for their contributions to evolutionary theory and for their abilities to expand the principles of their subject before general audiences. Grandfather and grandson shared a high regard for the work of Charles Darwin, though naturally they differed on matters of emphasis and interpretation, and each man capitalised on his considerable scientific and literary skills to advance the public understanding and appreciation of Darwinism.

I think our speakers tonight are the Huxleys of our age. They are the two foremost representatives of evolutionary biology today. Like their great predecessors in the past, they combine a powerful vision of the evolutionary process with a rare ability to expand it before general audiences. Like their predecessors they share a high regard for Charles Darwin, though naturally they differ on matters of detail and emphasis. As we look back to the works of Thomas and Julian Huxley, I confidently predict that future generations will look back to the works of Stephen Jay Gould and Richard Dawkins as the finest expressions of the evolutionary thought of their time. The purpose of this dialogue is to allow our two speakers to share and exchange ideas about their respective visions of the evolutionary process.

With those introductory remarks, let me turn to our first speaker. He is a lecturer in the Department of Zoology in this university and a Fellow of the college where once Julian Huxley taught and researched, New College. He began his research career in the 1960s as a research student with the Nobel Prize-winning ethologist Niko Tinbergen, and ever since then his work has largely been concerned with the evolution of behaviour.

Since 1976 when his first book The Selfish Gene encapsulated both the substance and the spirit of what is now called the socio-biological revolution, he's become very widely known both for the originality of his ideas and for the clarity and the elegance with which he expounds them.

Subsequent books and essays as well as a number of television programs have extended the notion as the gene as the unit of selection and have applied it to biological examples as various as the relationship between hosts and parasites and the evolution of cooperation. His most recent book The Blind Watchmaker is a passionate defence of Darwinism against all comers. One review has compared that book with Galileo's Dialogues which, as they said, made reasonable the Copernican revolution in the 17th century.

Ladies and gentlemen, I am delighted to welcome Dr Richard Dawkins.

Richard Dawkins: As a connoisseur of enigmatic titles, I'd be proud to have thought of The Panda's Thumb, Hen's Teeth and Horse's Toes, An Urchin in the Storm. I'd also incidentally be proud of the contents as well.

But the Gouldian title that gives me most pleasure is a joint paper, Clams and brachiopods: Ships that pass in the night, in a learned journal. Bivalve molluscs, clams, have traditionally been blamed for the extinction of brachiopods, that large phylum that look like bivalve molluscs but aren't. The argument has been that bivalves drove them extinct through competition. Gould and Calloway argued on the contrary that bivalves and brachiopods had little impact upon one another's lives, they were 'ships that pass in the night'.

It's all too easy to see competition and struggle where there is none. I myself have been accused of erecting a pessimistic competitive bloodthirsty view of nature. People also sometimes exaggerate the amount of adversarial struggle that goes on between scientists. During the weeks building up to this occasion I've grown rather tired of people coming up to me and saying, 'I'm looking forward to your punch-up with Stephen Gould,' expecting us to be opposite one another in those two pulpits on either side of the building.

But the truth I suspect is that Stephen Gould and I are more like ships that pass in the night. Where we appear to disagree, it's usually because we are interested in different things. We're both Darwinians, but he stresses the pluralism of Darwinism. By his lights I'd be called a monist Darwinian, and I'm quite happy to accept the label. I emphasise natural selection at one level in the hierarchy of life, a low level. He's a pluralist Darwinian in that he sees selection going on at many levels in the hierarchy of life, even up to the level of selection between species and possibly even higher.

He agrees that only selection at a low level is capable of explaining adaptation, he just insists that adaptation is not the most important thing that needs explaining. And I agree that selection at his levels may go on, I just insist that it cannot explain anything really important, like adaptation.

If we seem to disagree, it's because we're interested in different things, we are ships that pass in the night. Incidentally, the obsession with adaptation is not in my case based on a lifetime study of natural history. I never collected beetles or flowers, which may be a disappointing fact to certain historians of science because I'm English, and historians of biology are fond of tracing a 'tradition', as they call it, of dilettantish butterfly collecting in English evolutionary biologists to contrast with more philosophic interests of Continental ones. My interest in adaptation, as a matter of fact, I think is largely philosophical.

The diagnostic property of life anywhere in the universe is that it's complex. Complex means statistically improbable. Take Fred Hoyle's famous metaphor for his misunderstanding of Darwinism; a hurricane blowing through a junkyard and having the luck to assemble a Boeing 747. The point is that this is very improbable because there are so many more ways of putting together a heap of junk which are not Boeing 747s. But so far the argument is incomplete. Any heap of junk with hindsight is just as improbable as any other. The precise arrangement of matter in the Oxford rubbish tip is just as improbable with hindsight as a Boeing 747. The thing that's special about a Boeing 747 is that it flies. Very few out of all possible heaps of junk are capable of that.

The thing that's special about an ostrich is that it runs and booms and mates and lays eggs that hatch into new ostriches. Living things are not just any old heaps of junk, they're highly improbable in that they're good at doing whatever it takes to make new living things like themselves. And that's a very difficult thing to do. There are far, far more ways of being dead than of being alive. Living things are statistically improbable, not just with hindsight like a rubbish tip, but in the direction of being good at something.

The point I want to make is that only natural selection is capable of solving the riddle of how such adaptive complexity can arise. As I've shown in The Blind Watchmaker (or tried to show), no other theory that's ever been suggested is capable even in principle of providing an adequate explanation for adaptive complexity, not just on this planet but wherever life may be found in the universe. To put that another way, if there is life elsewhere in the universe, we so far know nothing about the details. It may be based on silicon chemistry rather than carbon chemistry, it may flourish near the centre of hot stars, or it may flourish near the absolute zero temperature, it may be too small or too large for us to see or apprehend with our senses. But one thing I believe we can already be sure of, it will have evolved by a form of Darwinian selection, and this is why, for me, the most important thing Darwinism has to offer is its explanation of adaptation.

Suppose, to take an analogy, a substance is discovered which turns out to be a miracle cure of AIDS. Nothing else is known that can cure AIDS and this wonder substance is infallible. Now suppose that this substance also turns out to be useful for stuffing cushions. Shall we refer to it as a cure for AIDS or as a cushion stuffer? Of course it's both, but we should think of it mainly as a cure for AIDS because firstly lots of other substances can be used to stuff cushions, whereas no other substance is known that can cure AIDS, and secondly curing AIDS is a lot more important than stuffing cushions anyway.

The apparently designed nature of adaptive complexity has always been a powerful reason for invoking a supernatural creator. If religious belief in this context is a disease of the mind, then Darwin and Wallace discovered the cure. Of course Darwin and Wallace did much else besides; you can use their ideas to stuff lots of biological cushions. But the really important thing they did was to plug a massive yawning gap in our world view.

So if we are ships that pass in the night, how shall we conduct this Darwinian dialogue? The most constructive thing we can do is identify some points that we might learn from each other. For my part, I'm prepared to learn from him something about the importance of embryology in evolution. And for his part, he might possibly be persuaded that the idea of the gene as the unit of selection is actually rather sophisticated and not the simplistic, reductionististic, atomistic idea he may think it is.

Nobody in modern times has done more than Dr Gould to show how evolutionary changes are realised as changes in embryology, often quantitative shifts in the timing of embryological events. And few have done more than he to remind us that mutation can act only in the form of feasible changes in existing embryologies, with the inevitable historical inertia that results. I've always paid lip service to this. For instance, long ago I contrasted evolution with the invention of the jet engine. Imagine what the jet engine would look like if instead of it being designed from scratch, the designers had had to evolve the jet engine rivet by rivet, screw by screw from the propeller engine. It would be a very odd sort of engine indeed.

But although I paid lip service to the negative idea of embryological constraints on evolution, I only recently took a more positive view of it. Certain kinds of embryology might even be actively eager to evolve, while others are not. There may be an evolution of evolvability, a kind of selection among embryologies, not for their qualities of short-term individual survival but for their qualities of long-term evolutionary potential.

For me this realisation came from playing around with my computer program called Blind Watchmaker. I suppose I'd realised it before but there's a difference between just understanding something and deeply absorbing it into the marrow of your bones so that you feel like being eloquent about it.

This program draws animal-like shapes on a computer screen. I call them biomorphs. The exact shape drawn depends upon nine numbers which I call genes. The biomorphs on the screen can have children, mutant children, and these can be selected on the screen. It's artificial selection, like breeding cattle or breeding roses. And when you do this, when you play with it, the program is rather good at giving people what Dr Gould has called in a slightly different context, a 'feel for the aggregated importance of small but continuous change'.

I myself was genuinely astonished at its power to evolve a remarkable variety of forms resembling insects, spiders, many other kinds of animals, as well as fighter planes, coffee pots and the Wykeham Professor of Logic. But I have to admit that I was also frustrated by the shapes that it could not breed apparently. There were certain things that I couldn't breed, however hard I tried. I wanted to breed letters of the alphabet, for instance, but there were only rather few letters that I could read, the others obstinately refused to come.

At this point Dr Gould would have had every right to say, 'I told you so. Your biomorphs, however variable their genes, all share the same basic embryology. This particular embryology can generate only a restricted range, albeit a numerically very large one, of morphologies. If you want to breed other kinds of animals or letters of the alphabet, you must change the fundamental plan of your embryology.' Well, change my embryology is what I did. I added seven more genes. My present version of the program, the one that WW Norton have published as a disc, has 16 genes instead of the original nine.

When we allow the additional seven genes to mutate as well, the range of morphologies that can be bred expands dramatically, it's now possible to breed most of the letters of the alphabet, for instance, and I've succeeded, I'm proud to say, in getting a letter delivered through the post to Professor John Maynard Smith entirely addressed in characters bred by Darwinian selection. Fortunately he's not John Maynard Keynes because even the 16-gene version of the program has obstinately so far refused to yield the letter K, which is the point I'm trying to make.

The most biologically interesting of the new genes concerns segmentation. Think of a centipede, each segment is much the same as any other segment, though not in detail, and the centipede is made by stringing the segments together like the trucks of a train, and we too are segmented of course, though in less obvious ways. I made segmentation happen in the computer embryology by making the program draw one biomorph as one segment and then draw another one behind it and another one and so on, so that each segment was an original biomorph. The point is that as soon as segmentation was introduced, it was as though a great sluice gate of evolution had been opened, a flood of exciting new morphology started pouring out of the program, far more lifelike forms, both animal-like and plant-like started to evolve, almost without my having to select them.

Presumably the first segmented ancestor of a centipede, and the same goes for our own first segmented ancestor, would have been a monstrous freak. It had a double or a triple body et cetera where its parents had a nice, tidy single body. We know it survived because its descendants are still with us. But I wouldn't be surprised if it survived in that primeval sea only by the skin of its teeth. What matters is not whether it was good at surviving, what interests us is its potential to evolve.

The invention of a segmented embryology was a watershed event in evolution. There haven't been many watershed events. After each one, nothing was ever the same again in evolution. Other watersheds I conjecture were the invention of the eukaryotic cell, the multicellular organism, miosis and sexual reproduction, and (stretching a point perhaps) the invention of human language. The general conclusion is that there may be a kind of lineage selection or embryology selection in that lineages whose embryologies equip them to evolve, to radiate adaptively, will be the lineages that inherit the Earth. I find this a more plausible formulation than the species selection favoured by Eldridge and Gould.

I take it that Dr Gould would be in broad sympathy with the idea of the evolution of evolvability, and for me it's a kind of concession to his way of thinking. But now I must turn to an area where there may still be some disagreement, and where I hope to persuade him to change his mind, and this is the idea of the gene as the unit of selection, and going on to the extended phenotype.

In his essay 'Caring groups and selfish genes', Dr Gould writes; 'Individuals are the units of selection. In the last 15 years challenges to Darwin's focus on individuals have come from above and from below. From above, Scottish biologist VC Wynne-Edwards raised orthodox hackles 15 years ago by arguing that groups, not individuals, are units of selection, at least for the evolution of social behaviour. From below, English biologist Richard Dawkins has recently raised my hackles with his claim that genes themselves are units of selection, and individuals merely their temporary receptacles.'

Let me begin my reply with an analogy. Dr Gould has told us that it's simplistic to regard human intelligence as a single variable, a one-dimensional scale, and no doubt the same is true of the left-right continuum that we so glibly use to classify people's political opinions. I want to tell you that there is not a one-dimensional spectrum of theories of units of selection with the gene at one end, the species at the other and the individual organism somewhere in between. It sounds like a nice, neat hierarchical scale, but this is a view that does not stand up to analysis. Genic selection and individual selection are not two different ideas, they are two different ways of expressing the same idea. If you must think of a hierarchy of levels of selection, the individual and the gene are not one above the other, they are side by side on the same rung of the ladder.

When modern Darwinians say that they are individual selectionists, they really mean exactly the same thing as I mean when I say I'm a gene selectionist. They mean that individuals are selected to maximise not their own survival but their inclusive fitness. And inclusive fitness may be informally defined as that property of an individual organism that will appear to be maximised, when what is really being maximised is gene survival.

In the same essay Dr Gould goes on to say; 'Selection simply cannot see genes and pick among them directly. It must use bodies as an intermediary. If, in favouring a stronger body, selection acted directly upon a gene for strength, then Dawkins might be vindicated. If bodies were unambiguous maps of their genes, then battling bits of DNA would display their colours externally and selection might act upon them directly. But bodies are no such thing. Bodies cannot be atomised into parts, each constructed by an individual gene.'

This eloquence, if you think about it, would be just as appropriately directed against the whole of Mendelian genetics, not just against the idea of the gene as the unit of selection, yet Mendelian particulate genetics is of course a flourishing subject, which something rather like atomising into parts goes on every day. Of course no geneticist believes that one gene is solely responsible for making one bit of body. Of course there's no one-to-one mapping between genes and bits of body, but there is a one-to-one mapping between individual differences at the genetic level and individual differences between bodies.

So my view of the gene as the unit of selection is more naively atomistic than the following is from Stephen Gould himself in a different context; 'Evolution is mosaic in character proceeding at different rates in different structures, and animals' parts are largely dissociable, thus permitting historical change to proceed.' Of course then natural selection can't see genes directly. Natural selection can't see genes any more than we can see the magnetic particles on a magnetic recording tape. Just as we judge a recording tape by listening to its read-out through a loudspeaker, so genes are judged by natural selection through their readout in embryonic development.

My attitude to the individual body is to see it as a useful vehicle for genes, a survival machine for genes, programmed by them to carry them about and eventually propagate them. If human genes could propagate themselves by being sneezed out of one human and breathed in by another they probably would because they could short-cut the tedious 20-year generation wait and multiply in a matter of days. They would, in short, become viruses, and that's probably what viruses are.

At the end of an essay on human equality, Dr Gould invites us to say five times before breakfast the slogan 'Human equality is a contingent fact of history'. Human races, in other words, didn't have to be as similar as they are, it just so happens that they are very similar. The differences between them are only skin deep. It might have been otherwise, but as it has turned out it isn't. Now, I invite him to say before breakfast 'The existence of the individual organism is a contingent fact of history'. Don't say it five times, that would be going too far, say it once rather tentatively. It's at least worth thinking about. [laughter] He doesn't eat breakfast, he says.

You can have a vision of genes reaching out beyond the individual body wall, manipulating the world outside. You see a beaver dam as a phenotype of beaver genes, no less than a beaver's tail is. The whole subject of animal communication can be seen as a matter of genes in some animals having phenotypic effects in the bodies of other animals. Far from being atomistic or reductionistic, this view of life can see an entire ecosystem as a crisscrossed web of phenotypic power coming from genes distributed only incidentally in individual organisms.

Dr Gould with his hierarchical pluralistic vision of Darwinism wants to downplay the individual organism by emphasising higher levels of selection such as the species. I want to sail with him in downplaying the individual organism, but I don't want to do it by going to an opposite extreme, as he may think I do. I downgrade the individual organism in a different way, by showing that the individual organism is only one possible manifestation of the phenotypic power of self-replicators in a vast interacting web of extended phenotypes. Thank you very much.

John Durant: It's now my pleasure to introduce our second speaker to you. Our guest is a professor of geology, biology and the history of science at Harvard University. For over 20 years he has researched and written simultaneously in the fields of palaeontology, evolutionary biology, and the history of these and related subjects. In 1976 his book Ontogeny and Phylogeny successfully combined all three of these fields in a major study of the evolutionary theory of recapitulation. Subsequent book-length studies have dealt with the attempt to quantify human mental characteristics The Mismeasure of Man, and the concept of time in the earth sciences Time's Arrow, Time's Cycle.

Our guest has produced several volumes of essays, based for the most part on his monthly column in Natural History magazine. Whether concerned with 'the misunderstood Irish elk' or the architecture of cathedrals, with the question of whether dinosaurs were dumb, or the physiognomy of Mickey Mouse, these essays combine elegance, wit and erudition with what I recognise as a distinctively Darwinian ability to make the smallest details of nature and history speak to the largest issues in evolutionary science. His are the only scientific works I've ever taken on holiday with me and read right through.

Ladies and gentlemen I am delighted to introduce Professor Stephen Jay Gould.

Stephen Jay Gould: I'm afraid I have to start with the same caveats my colleague did, that I feel very strongly that in a sense some people are probably not getting what you came for but by now you know you're not. This event was ballyhooed even across the Atlantic puddle as though it were going to be some kind of great battle ground between the two of us. It's not a debate. It's not because we don't disagree a lot, we do. It's not that an exploration of these disagreements would be uninteresting, it might be very interesting. It's just because really debate is not right in science.

I'm somewhat overly sensitive to that issue because of experiences with the creationist movement in America, you'll understand. But debate...of course I need hardly tell you in a country that developed it...is an art form about the winning of arguments, not the ascertaining of truth. Truth is a weapon in debate...not the best one, by any means. You just don't do science by vote and you shouldn't win by verbal dexterity, that's not what it's about somehow, even though we're both not bad in those departments.

The reason I did want to resist so strongly the notion of debate has nothing to do with modesty, which I'm not at all, it's really because the very notion that this would be a debate, it trivialises, it dichotomises, it personalises one of the greatest ideas in human history. Evolution and Darwinism is a set of notions of enormous beauty and power and importance, both directly for our lives and in the abstract. It has been a series of notions long debated by folks in whose shadow we can scarcely walk.

This ridiculous notion on the advertising poster that we stand here before you as 'the world's two leading evolutionists'...we're pretty good...as I said, I'm not particularly a modest person, but we're here only because we have certainly literary and oratorical skills that may not be particularly shared but which are not that relevant to the development of the fundamental ideas. I think that's the only reason. The main point is, though, that I just can't bear the thought that something as deeply important as the structure of evolutionary theory should somehow come down as whether Johanson got in two left hooks before Leakey delivered the right cross or not. It's just not what it's about. Okay, I think we all agree about that. I had my say.

My claim about the nature and status of Darwinism is that we're beginning to see the coalescence of a new and quite different theory from that that represented the strict Darwinism of the so-called modern synthesis. A new and different theory with a Darwinian core is being forged, exciting and fruitful theory in the very best sense that first of all it is quite different in many important respects from what was the standard take.

I want to start with five minutes or so of history, namely the question of what is Darwinism. Of course I'm not talking about the demonstration of the fact of evolution. Darwin always made a clear distinction between the two fundamental things he tried to do. One, to establish the fact, in which he was abundantly successful, that's why he lies at the feet of Isaac Newton down there in Westminster Abbey. Secondly, however, he tried to propose a theory to explain the mechanics of evolutionary change, the theory of natural selection, which was by no means a majority viewpoint upon his death in the early 1880s. And that's what we're talking about, his theory of natural selection.

What is the theory of natural selection? How can it be epitomised? I think the minimal requirements can be reduced to two fundamental propositions. The first is the claim not just that natural selection operates, because all non-Darwinians were happy to avail themselves of that opinion for a reason I'll mention in a moment, but that natural selection is the creative force of evolutionary change. And that's somewhat paradoxical because natural selection doesn't make anything, so in what sense of the vernacular word 'creativity' could it be a creative force? It can't be just a negative force.

All the non-Darwinians of the late 19th century, the neo-Lamarckians, the Macromutationists, the Vitalists, they all said, 'Oh yes, we like the theory of natural selection. Natural selection is that mechanism that eliminates the unfit, once the unfit has arisen by some other reason. See, we like Darwin.' But that's not Darwinism, Darwinism must hold that natural selection not only eliminates the unfit, not only the headsman and the executioner but the creative force behind evolutionary change. And how can that be if natural selection makes nothing but can only select among variants presented to it?

I think the most brilliant thing that Darwin did was to recognise that in order to have evolution work in such a way that natural selection could be seen as a creative force, that variation would have to be structured in a very specific sort of way, and in a most brilliant manner, knowing nothing about the actual mechanics of hereditary change, he correctly predicted the fundamental characteristics of the nature of variation by knowing what would be necessary in order to allow natural selection to be creative. And those are three main properties. Variation has to be copious because natural selection doesn't make anything so there has to be a lot of raw material to choose among. It has to be small in extent because if variation is so big that you can get from here to there in one step then you've gotten there by the force of variation and all natural selection does is eliminate the bad ones. Thirdly, variation has to be undirected because if variation comes packaged preferentially towards the newly adaptive form then random mortality that produced the trend don't need natural selection at all.

If variation is therefore copious, small and undirected, 'random' in the usual misused sense, then you can't get from here to there in any other way but by the slow and steady generation by generation superintendence of that variation, by the process of natural selection preserving that small portion of the variation that leads in that direction. And the 19th century knew that. If you know the 19th century literature, that's what they're talking about all the time; is natural selection a creative force? But the primary notion of creativity leaves one very important thing unanswered. Namely, what does selection work on? The notion of creativity hasn't told us it might work on organisms, it might work on larger entities like species or populations, it might work on parts of organisms, that's not clear.

And Darwin has a very definite and very interesting answer, which is the heart of his radicalism as a thinker, and it is why that has become so fundamental and why it is what Richard in some sense challenges but I think in a conservative sense, as I'll mention, namely Darwin answers very simply; natural selection works on organisms. Natural selection is the struggle among organisms, among organisms' bodies for reproductive success. Why is that so important? Why is that at the heart of Darwinism? The answer is think of what he's trying to do, think of the heart of the radical claim. He's trying to overturn Paley's natural theological argument, and that's why Richard is so right to call the book The Blind Watchmaker, that does characterise exactly the essence of what Darwin's trying to reference, Paley's notion that if you kick your foot against a watch you would know that God made it because its order is so great that there must be a designer.

You see, it's so much a part of traditional British natural theology, not Continental natural theology which is why I think Darwinism doesn't emerge on the Continent, to see the good design of organisms and the harmony of ecosystems as the primary source for inferences, not only about the existence of God but his nature and benevolence. If you want to overturn that...and I think in his most radical sense that's exactly what Darwin's trying to do with the theory of natural selection, not to cause us to disbelieve in God but to get away from that argument that all apparent higher order harmony is the direct production of God's benevolence.

As I like to put it, there are two things you could do, each more radical than the other. The less radical claim would be simply to say, oh, by the way, there just isn't that much good design out there, you've been wrong all the time. There are some things that are good design but there's a lot of lousy design and inharmony in ecosystems. So if you think it reflects God, that's not the kind of God you want who would make a world like that. That would be a pretty radical argument, but it's not Darwin's. Darwin makes a much more radical argument which is, yes, indeed, what you always thought was right, there is all that order out there, there is good design, there is harmony, but guess what? Not only does it not reflect the direct production of that by God, but it all arises as an epiphenomenal side consequence of the only thing that's really happening out there in nature, and the only thing that's really happening out there in nature is organisms struggling not for higher order good but for their personal reproductive success, for the most private personal thing, and nothing else.

That's a radical argument. All the higher order harmony which used to be seen as the source of evidence of God's benevolence is epiphenomenal upon the struggle of something lower for personal gain, and that's all. Now, if that sounds to you like Adam Smith's economics translated into nature, it's no accident because one of the most interesting conclusions of recent historical research has shown the tie of Darwin's development of the theory of natural selection in 1838 to his interest in the particular view on individuality in the thought of Adam Smith and the Scottish economists. It is the same argument. Namely, that if you want the most rationally ordered economy you don't get all the smart people, sit them around a table and pass laws for higher order harmony of economy, as Adam Smith argues, you do something that seems paradoxically opposite; you let individuals struggle for profit. And the ones who do it well will knock out the others and balance each other out and you get the maximal system through the action of the invisible hand.

The analogue of profit in nature is reproductive success, it's the same argument, and it has the same radical character. At this point I usually like to make the quip that to me the extreme irony of that is that Adam Smith's economics doesn't work in economics as much as your current leader may be trying to...but it does seem to be a way of nature. In any event, Richard has tried to complete that program by simply knocking it down another level and saying Darwin didn't go far enough. In fact it isn't even organisms struggling for reproductive success, he says it's genes struggling for reproductive success. I just happen to think that argument is wrong, I don't think it's two different ways of looking at the world. I think Richard confuses bookkeeping and causality in a hierarchy.

Richard's argument is much harder to counter because Richard's argument, at least at this point (and I'll read you a quotation in a moment) is that yes, other things exist out there in nature, and yes, organised adaptive complexity based on selection among genes or organisms won't make them, but they're just not very interesting. And, you know, I don't know how to counter that. [laughter] There is no counter. Seriously, it's an issue of aesthetic preference, what can one say? If you don't like Handel, you don't like it. I happen to sing in a wonderful production of Hercules a couple of weeks ago and the reviewer for The Boston Globe wrote the most dammed review because he said it was the most wonderful performance he ever heard but he hated the piece. What can you do? There's nothing you can do about that.

So I don't know what to do except simply to appeal to you that these other issues are enormously interesting. I'll just read you one quotation from Richard and then I'll give you some sense of what I think is interesting about...this comes from the latest book The Blind Watchmaker whose title I love...don't love that much else about it. It's on page 268. It says; 'To conclude the discussion of species selection,' which Richard admits exists and even produces a lot in the geological record, 'it could account for the pattern of species existing in the world at any particular time.' I think that's very interesting. I'd really like to know why there are 500,000 species of beetles and 10 species of priapulids. It's not because priapulids are crummy organisms, they're very complex; little penis worms. They're good. I really want to know that. That's interesting. That grabs me, if it doesn't grab him. I don't know what to say.

Listen to the next sentence; 'It follows that it could also account for changing patterns of species as geological ages give way to later ages, that is, for changing patterns in the fossil record.' That's what I've devoted my life to. I think that's the most interesting question in the whole universe. Why did dinosaurs rule for 100 million years while mammals existed? That's two-thirds of man's existence. Why did dinosaurs die? Why did the fossils of the Burgess Shale, one quarry in British Columbia 530 million years old, have 20 phyla of organisms that don't exist anymore? Why do you have this pattern of winnowing? Why do we have relays of diversity? That's why we're here. We're not here because from the laws of nature you can predict the evolution of mentality, we're here as a contingency of those events through history. That's interesting. And Richard's telling me that species selection could do that. So I say that's great, I don't want anything else from him.

But then he goes on, he says; 'But it is not a significant force in the evolution of the complex machinery of life. The most it can do is to choose between various alternative complex machineries, given that those complex machineries have already been put together by true Darwinian selection. As I've put it before, species selection may occur but it doesn't seem to do anything much.' Well I don't know, Richard, what can I tell you, to me that's really a lot much, that's the source of my life, it's what interests me.

It's a very hard argument to counter because he's granting the logic of my argument, he just doesn't say it's interesting. All I can do is plead with you that these are fascinating questions. Thank you.

Robyn Williams: Richard Dawkins and Stephen Jay Gould at Oxford in 1987, arguments about the Darwinian heritage still going on, all to wish Charles Darwin a very happy or at least significant 200th birthday.