Brief Candle in the Dark

by Richard Dawkins

  But Charles has also, during that time, become a really good personal friend to Lalla and me. And a good colleague, for we talk a great deal about science and the world of the mind, and I find myself continually learning from him, and sharpening my arguments in discussion with him.

  I think of Charles as a sort of intellectual James Bond. He lives life to the full, and he won’t mind my saying that he lives it in the fast lane. He loves gadgets and fast cars, pilots his own helicopter and his own jet planes, both the supersonic and the ordinary kind. But the conversation you are likely to have with him in the helicopter or the speedboat is not at all what you would expect from James Bond. It is much more likely to be about the Nature of Consciousness or the Singular Beginning of Time; the Principle of Free Speech, or the hope for a Grand Unified Theory of Everything.

  Charles has now stayed with us in our home four or five times, and it is always a delight to have him. We have visited Seattle slightly less often, mainly because of our relative lack of Lear Jets and Falcons. But we did attend his memorable house-warming party in his unprecedentedly memorable house. Villa Simonyi is one of the most imaginatively planned buildings I have ever seen, the glass walls abutting at unbelievable angles, the ultramodern architecture the perfect backdrop to the Vasarely paintings and the wall to wall computer screen inside.1

  We unfortunately had to miss last year’s party for his fiftieth birthday, but it was possible to imagine what it was like, and attend it in spirit, in the form of a little verse that I composed in honour of the occasion. I should explain that this happened to coincide with the publication of my book Unweaving the Rainbow, which is about Keats and Newton, science and poets.

  Never mind about John Keats,

  Or Newton’s scientific feats.

  Forget your William Butler Yeats,

  William Wordsworth, William Gates.

  Never mind about unweaving:

  Here’s a man beyond believing.

  Here’s a man so smart and swift he

  Penetrates Mach 2 at fifty!

  And that’s not all he’ll penetrate . . .

  (Even Windows 98

  Is not beyond his understanding.)

  Happy take-off. Happy landing.

  See his supersonic plane go –

  Vanishing right through the rainbow!

  UNWEAVING THE THREADS FROM A SCIENTIST’S LOOM

  MY twelve books have punctuated my decades, and their research, composition and revision have dominated my waking thoughts. But, since they are all available to be read, it seems pointless in an autobiography to plod through them one by one, summarizing each and then turning to the next. I’ve already mentioned the titles, more or less chronologically, in the context of my relationships with agents and publishers. If I now descry various themes that recur throughout my books, I don’t mean it to sound grandiose when I hope that these themes taken together might add up to a kind of biologist’s world-view, with an aspiration at least to coherence. Chronology will be only loosely in evidence as I trace each theme through the books in which it is serially developed, and try to look back to its original entry into my life.

  The Taxicab Theory of Evolution

  In An Appetite for Wonder I recalled a visit to Oxford by a Japanese television crew. They turned up, bristling with tripods, lights, umbrella reflectors and camera gear, in a London taxi, and the director was keen to conduct the interview in the moving vehicle. This proved difficult, partly because the official interpreter’s English was unintelligible to me, so ‘interview’ perforce became ‘impromptu monologue’ while the unfortunate interpreter was banished to walk the streets for an hour; and partly because the bemused taxi driver from London didn’t know Oxford, so I had to interrupt my discourse at frequent intervals to bark ‘turn left’ or ‘turn right’ over my shoulder. When we returned to New College, I was curious to know why it had all had to be done in the taxi, so I asked the director, and received the puzzled reply: ‘Hoh! Are you not author of Taxicab Theory of Evolution?’ It was my turn to be puzzled, until I later worked out the probable origin of his phrase. In my writings I have made frequent reference to the body as the ‘survival machine’ or ‘vehicle’ for the genes that ‘ride inside it’. My guess – although I have never checked it – is that a Japanese translator of one of my writings must have rendered ‘vehicle’, with a little poetic licence, as ‘taxicab’. Television being television, that would have been a sufficient reason for conducting the interview in a moving taxi. But never mind about taxicabs in particular: I need to explain the theoretical importance of the ‘vehicle’.

  One of the most persistent – and annoying – criticisms of The Selfish Gene is that it mistakes the level at which natural selection acts. Characteristically, the error was most articulately expressed by Stephen Gould, whose genius for getting things wrong matched the eloquence with which he did so:

  Challenges to Darwin’s focus on individuals have sparked some lively debates among evolutionists. These challenges have come from above and from below. From above, Scottish biologist V. C. Wynne-Edwards raised orthodox hackles fifteen years ago by arguing that groups, not individuals, are units of selection, at least for the evolution of social behavior. 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.1

  Gould was right that Darwin focused on the individual organism as the unit of natural selection, and right about Wynne-Edwards arguing for group selection as an alternative. Right, too, that I regard individuals as temporary receptacles for genes. But wrong wrong wrong to see that as a challenge to Darwin’s focus on the individual. That whole ‘above/below’ rhetoric is as misconceived as it is seductive. The gene, the individual and the group are not rungs on the same ladder. If we must talk ladders, the gene is off to one side, more like a single rung all on its own. The gene and the individual are both units of natural selection, but in two different senses of ‘unit’: as replicator and as vehicle. Replicators (on this planet they are usually stretches of DNA code, occasionally RNA) are the units that actually survive – potentially for millions of years – or fail to survive. The world becomes full of successful replicators and empty of unsuccessful ones, where ‘successful’ means literally good at surviving as copies through very many generations, even through geological deep time.

  What makes a replicator successful is its talent for influencing the world to promote its own survival (exactly how it does so varies massively from species to species, but it typically involves influencing the development of vehicles to make them good at reproducing). And if it succeeds in surviving it potentially survives again, and again, and again . . . into the indefinite future. So the difference between success and failure really matters. Really matters for a replicator, that is. The same is not true of vehicles: no matter how successful or unsuccessful an organism may be, it will last only a single generation. Success, for an organism, means passing genes on to the distant future before inevitably dying in the comparatively near future. Not even asexually reproducing animals like aphids or stick insects are replicators, as you can tell if you pull one leg off (there’s no need to do anything so sadistic: you know what the result would be). That kind of ‘mutation’ is not inherited. Remove, or change, a bit of DNA, however, and the change – a true mutation – may survive for a million generations.

  The word ‘phenotype’ denotes the outward and physical levers used by replicators to promote their own survival (whether successfully or not). In practice, phenotypes normally consist of features of individual organisms. And organisms are built by embryological processes influenced by the replicators that ride inside them. Organisms, especially animals (plants less so), are coherent, unified bodies that either survive as a whole or die as a whole. And when an animal dies, all its replicators die with it, except those that have previously been handed on to another organism in the process of reproduction. Do you begin to see how ap
t the word ‘vehicle’ is? And ‘throwaway survival machine’?

  Most animals reproduce sexually, which means that the replicators inside them are continually changing partners, sharing new bodies with new combinations of replicators – serving yet again to emphasize the temporary nature of the individual ‘survival machine’, the mortal vehicle for immortal genes. This is not a way of thinking that would have occurred to most biologists a few decades ago. Genes would have been seen as tools used by organisms, rather than the other way around, as we now see things.

  Do you see, too, how persuasive – yet in very different ways – are the unitary qualities of both the gene (replicator) and the individual (vehicle)? And do you see that both are units of natural selection but in their two different senses? I tried, and signally failed, to explain this to Steve Gould when we had a much publicized debate in Oxford’s Sheldonian Theatre in the late 1980s. The event was sponsored by Gould’s publishers, W. W. Norton, and chaired by John Durant, then of Oxford’s Department of Continuing Education. John hosted dinner for the three of us beforehand, in the Randolph Hotel where Steve was staying. I remember it as a rather frosty occasion, perhaps because Steve was not particularly friendly, perhaps because I was intimidated by the looming thought of Oxford’s largest and most hallowed theatre, despite rehearsing and expert prepping with my closest friend at the time, Helena Cronin. My nervousness persisted into the debate itself, although I think I performed well enough, especially in the public conversation that followed our two prepared speeches. An audiotape of the two formal speeches was preserved, and later broadcast by Robyn Williams, star science journalist of the Australian Broadcasting Corporation. Unfortunately, no recording seems to have survived of the cut and thrust after the speeches, when most of the interesting points were made. The loss of this part of the tape is a matter of great regret to me because I believe it would show – well, I would say that, wouldn’t I, and Steve, alas, is no longer here to dissent – that I was right and he simply couldn’t get it.

  Two images add colour to ‘this view of life’ (the Darwinian phrase borrowed by Steve Gould to head his column in Natural History, but here I am re-borrowing it from Darwin for my own view of life). The first is from The Blind Watchmaker: a willow tree at the bottom of my garden, pumping out downy seeds to cover the ground in all directions, and down the Oxford Canal as far as my binoculars could reach.

  It is raining DNA outside . . . The whole performance, cotton wool, catkins, tree and all is in aid of one thing and one thing only, the spreading of DNA around the countryside . . . Those fluffy specks are, literally, spreading instructions for making themselves. They are there because their ancestors succeeded in doing the same. It is raining instructions out there; it’s raining programs; it’s raining tree-growing, fluff-spreading algorithms. That is not a metaphor, it is the plain truth. It couldn’t be any plainer if it were raining floppy discs.

  Floppy discs – that dates it. But the ‘plain truth’ is timeless and deep, its truth undiminished by Moore’s Law chipping away at the superficial imagery. Here, from January 2015, is a heartwarming illustration of what Twitter does well (there’s a lot that it does badly). A woman quoted the above passage and added her own delightful reaction:

  It’s winter outside, but spring inside. Suddenly, I’m lying on the grass under a willow tree.1

  The second image is from Climbing Mount Improbable, ten years later. I made a strong analogy between computer viruses and biological viruses. Both are programs that say ‘Duplicate me’ and little else besides. What, then, of a large animal like an elephant? Elephant DNA instructions

  are also saying ‘Duplicate me’, but they are saying it in a much more roundabout way. The DNA of an elephant constitutes a gigantic program, analogous to a computer program. Like the virus DNA it is fundamentally a Duplicate Me program but it contains an almost fantastically large digression as an essential part of the efficient execution of its fundamental message. That digression is an elephant. The program says: ‘Duplicate me by the roundabout route of building an elephant first.’

  It is because an individual organism like an elephant is such a unitary and coherent entity, such a plausible and persuasive vehicle, that the great majority of evolutionary biologists have followed Darwin in treating the organism as the main agent of biological adaptation. Ethologists follow Darwin in seeing animal behaviour as a striving, by individual animals, to survive and reproduce. This is correct, but you have to take a sophisticated view of the quantity that this agent is striving to maximize. Population geneticists call it ‘fitness’, which is (or is proportional to) a kind of weighted sum of children, grandchildren and other descendants.

  Parental care, and self-sacrifice in the interests of offspring, are obviously easily accommodated in this formulation, as is ‘Darwin’s other theory’ of sexual selection. But R. A. Fisher, J. B. S. Haldane and above all W. D. Hamilton realized that natural selection could also favour individuals who care for collateral kin who have a statistical probability of sharing the genes that mediate the caring.

  One way to approach the argument is a thought experiment which, in The Selfish Gene, I dubbed the ‘Green Beard’. Most new mutations have more than one effect on bodies (the phenomenon is called pleiotropy). Imagine a gene which gives individuals a conspicuous label like a green beard and simultaneously confers benign feelings towards green beards, and a tendency to help green-bearded individuals to survive and reproduce. The contingency is a remote one, Sir, as Jeeves would say, but it makes the point. Such a gene would spread through the population. The idea caught on (a Google search for ‘Green Beard Effect’ achieves lots of hits and even some photos), but my purpose was only to pave the way for an explanation of kin selection. Pleiotropic coincidences of bodily peculiarities coupled with altruistic tendencies towards those peculiarities are improbable (although several suggestive examples have since appeared in the scientific literature). What is not at all improbable, however, is a statistical equivalent of the Green Beard Effect – a statistical watering down of it. If you ‘know’ who your brother is, you don’t have to specify a particular gene like a green beard gene. You can calculate the probability that he will share any particular gene with you.1 Such a gene could plausibly be a hypothetical gene for being nice to brothers. Or, more practically, a hypothetical gene for being nice to individuals with whom you shared a childhood nest; or individuals who smell like you – a practical rule of thumb for identifying siblings – could easily be favoured in practice, for the same reason as a green-beard gene would be favoured in theory. Kinship – or in practice nest-sharing, or smelling like me – is a realistic statistical proxy for the unrealistic green beard.

  Hamilton in 1964 published a mathematical way to redefine ‘fitness’ to take account of kinship from the individual organism’s point of view. He came up with the concept of inclusive fitness. I informally (perhaps too informally, but Hamilton himself gave his blessing) redefined inclusive fitness as ‘that quantity which an individual will appear to be maximizing, when what is really being maximized is gene survival’. The table below summarizes the two ideas of ‘replicator’ and ‘vehicle’ and explains how both are units of selection but in different senses.

  Unit of selection Role Quantity maximized

  Gene Replicator Survival

  Individual organism Vehicle Inclusive fitness

  In The Extended Phenotype, I used the analogy of the Necker Cube (see below) to argue that both these ways of looking at natural selection amount to the same thing, just as both views of the Necker Cube are equally compatible with the information flowing in from the eyes. I shall return to the Necker Cube in a later section of this chapter.

  In The Selfish Gene I claimed to follow Hamilton, but Hamilton himself switched between two ways of expressing himself, the gene-centred way and the individual-centred, inclusive fitness way. Here’s how he put the gene-centred view:

  A gene is being favoured in natural selection if the aggregate of its re
plicas form an increasing fraction of the total gene pool. We are going to be concerned with genes supposed to affect the social behaviour of their bearers, so let us try to make the argument more vivid by attributing to the genes, temporarily, intelligence, and a certain freedom of choice. Imagine that a gene is considering the problem of increasing the number of its replicas . . .

  He wrote those words some eight years after his ‘inclusive fitness’ paper, but it’s entirely clear that the same gene-centred view undergirded the epic 1964 tour de force as well. In The Selfish Gene I too switched pretty freely between the gene itself as metaphorical agent or decision-maker, and a kind of informal inclusive fitness approach in which I allowed individual organisms to soliloquize about what would be best for their genes. Neither of these kinds of subjective soliloquy, needless to say, is intended to be taken literally. The ‘agents’ in both cases should be thought of as behaving as if calculating optimal courses of action. But only ‘as if’.

  Although Hamilton based his idea on the gene’s-eye view, inclusive fitness is nevertheless a way of preserving the traditional focus on the individual organism, the vehicle. Indeed, I see it as a regrettably cumbersome bending over backwards to rescue the individual as the focus of our Darwinian attention instead of the gene. But why is the organism such a salient and discrete vehicle at all? Why do we take the organism for granted? Just as we ask why wings and eyes, antlers and penises exist, and expect to get a gene-centred answer, shouldn’t the gene’s-eye view lead us to ask why organisms themselves exist? Genes survive by pulling phenotypic levers of power. But why are those phenotypic levers bundled into discrete vehicles which we call organisms, and why do the immortal replicators ‘choose’ to gang up with other genes to share vehicles? This was the point at which I went beyond Hamilton, while never really going against anything he said. I did so in my second book, The Extended Phenotype. After interviewing me for his own book A Reason for Everything, subtitled Natural Selection and the English Imagination, Marek Kohn put the point well.