Our culture pays a high price for scientific specialisation. As individual researchers have come to know more and more about less and less, so they have increasingly distanced themselves – from one another, from interested amateurs and from the general public. This distancing has created a demand for yet more specialists – professional popularisers such as science journalists, science writers, television producers and presenters, and so forth – whose task it is to mediate between scientists and everybody else. What these mediators offer is, for the most part, second or even thirdhand reporting; and all too often this either sensationalises or (which is much worse) sanitises the work it purports to describe.
The extent of our loss in the transition to professional popularisation is revealed most clearly by the relatively few exceptions to the rule. For quite against the general trend, one or two active scientists continue to speak about their work to audiences far beyond the circle of their professional colleagues. One such is the evolutionary biologist Richard Dawkins. Significantly, Dawkins’s books defy classification in terms of our specialist categories: professional monograph, student text, popular book, etc. The Selfish Gene (1976) was at once a key document of the so-called ‘sociobiological revolution’ of the Seventies, a major student text, and a successful popular book. The Extended Phenotype (1981) was in some respects harder-going, but still it combined novel evolutionary ideas with accessibility to a general readership.
Now we have The Blind Watchmaker. This, Dawkins’s best book to date, contrives once again to convey original scientific insights excitingly and readably. It is a self-confessedly passionate exposition and defence of Darwinian evolutionary theory against all-comers. Avoiding the awful condescension of so much popular science-writing, which simply assumes that non-specialists cannot be entrusted with the assessment of scientific arguments, Dawkins sets out to win the general reader over to the Darwinian point of view by sheer force of reason. His aim is to explain Darwin’s view of life, not just so that we understand the words, but so that we ‘feel it in the marrow of [our] bones’.
Sensibly enough, Dawkins begins his task with the problem which Darwin’s theory of evolution by natural selection is intended to solve. Living things are not just fairly well-built: they are amazingly, awesomely, staggeringly well-built, to the point where only a fool or an idiot would suppose that they happended ‘just by chance’. Bringing conceptual clarity to the notion of being well-built, Dawkins points out what surgeons and undertakers know best: namely, that there are vastly more ways of being dead than there are of being alive. In formal terms, the problem is to understand how so many objects on the surface of the earth have come to be organised in one or another of the vastly improbable ways that are consistent with life.
It was not evolutionary biologists who first clearly saw that this was the problem, but natural theologians: and Dawkins (like Darwin before him) respects them for it. Taking his title from the famous ‘watchmaker’ version of the argument from design for the existence of God, Dawkins tries to out-do even that most tireless and tiresome of natural theologians. William Paley, in the sheer quality (if not, thank heaven, the quantity) of his illustrations of good design in the living world. Bats are Dawkins’s chosen animals, and echolocation is his chosen example of good design; with material like this, Paley would have filled a shelf-ful of volumes.
He would not, though, have drawn Darwin’s or Dawkins’s conclusion. For where Paley followed the natural theological tradition in concluding that good design requires a good designer, Dawkins follows the Darwinian tradition in arguing that an altogether more prosaic explanation will suffice. ‘Cumulative selection’, the building-up of large effects in many small stages, is the key to the problem of good design. Small, advantageous genetic changes, each in isolation highly probable, are preserved as they arise, and gradually accumulate to the point where they constitute vastly improbable combinations of inherited characteristics.
There is nothing new here, of course. What is new is the elegance of Dawkins’s exposition, and the ingenuity with which he demonstrates the power of cumulative selection. Dawkins introduces us to a series of computer programs which provide increasingly close approximations of Darwinian evolution. By far the most engaging of these programs features charming mythical creatures called ‘biomorphs’. Biomorphs are actually nothing more than branching-tree structures based on simple mathematical rules, the details of which are specified by nine hypothetical ‘genes’. From any chosen starting-point, the program breeds a population of biomorphs based upon small random genetic variations, or mutations. The operator then selects a particular individual as the ancestor of the next generation, and the process is repeated. Thus, biomorphs evolve through an indefinite number of generations by what is really a form of artificial selection.
This may sound an unpromising basis for exploring Darwinian evolution. However, partly because they mimic both the genetic and the developmental characteristics of organisms, biomorphs turn out to be spectacularly successful evolutionary material. Quite rapidly, the most rudimentary ancestors give way to all sorts of fantastic and often lifelike descendants – particular examples we are shown are named ‘swallowtail’, ‘caddis’, ‘scorpion’, ‘tree frog’ and ‘fox’. Dawkins has clearly fallen in love with Biomorph Land; and having played with the program, I can testify that it is enormous fun. Unfortunately, British readers of The Blind Watchmaker must satisfy their curiosity with printed illustrations only. American readers are, I understand, luckier: their edition of the book includes a copy of the software in the form of a floppy disc.
Biomorphs are not merely good fun. Precisely because they are so simple, they are useful aids to the Darwinian imagination. In two pivotal chapters, Dawkins demonstrates both the power and the limitations of cumulative selection with the help of his mythical creatures. Central to this demonstration is the notion of ‘genetic space’. Given that there are nine hypothetical genes controlling the development of a biomorph, all possible biomorphs can be seen as located in a nine-dimensional space. In this space immediate neighbours are separated by single mutations, and it is therefore possible to ‘travel’ by cumulative selection between any two biomorphs in a series of single mutational steps. In the same way, there is a real genetic space in which all the animals that either have existed or could exist are located. By exploiting the imaginative potential of Biomorph Land, Dawkins exposes some fundamental features of Darwinian evolution: that it is gradual, that it is irreversible, that it is constrained by local advantage (as opposed to long-term benefit).
For Dawkins, it is no coincidence that computer programs offer useful insights into evolution. Glorying in what is arguably the central and most powerful metaphor of 20th-century biology, The Blind Watchmaker takes its readers on a guided tour of life seen as a form of sophisticated information technology. On this view, genes and gene-complexes are sequences of digital information which constitute programs (or sets of instructions) for the building of organisms in the course of development. Commenting on a seeding willow tree at the bottom of his garden. Dawkins writes: ‘It is raining instructions out there; it’s raining tree-growing, fluff-spreading, algorithms. This is not a metaphor, it is the plain truth. It couldn’t be any plainer if it were raining floppy discs.’
This part of the book has already caused offence to some biologists who regard the terms of information technology, for all their usefulness in genetics, as woefully inadequate in the context of organic development. Certainly, there are real problems here. For example, it appears from the above passage that we are being invited to view development as analogous to the running of a program in a computer. But we must be careful here. If genes are the biological equivalent of ‘software’, what is the biological equivalent of the ‘hardware’ on which they run? Notice that the answer to this question cannot possibly be bodies, since bodies are themselves products of developmental processes which, in the analogy with information technology, are equivalent to the running of software: and by definition, software cannot be run on itself.
Faced with this problem, we may be tempted to look for some more elementary structures, common to all organisms, which constitute the necessary hardware for the running of genetic programs (obvious candidates here are fertilised eggs, or the protein-sythesising machinery within fertilised eggs). But again, the objection arises that eggs – and anything else we may care to put in their place – are also products of developmental processes; and these we have already agreed to analogise, not with hardware, but with the running of programs. What this argument appears to show is that the elementary distinction between software and hardware is difficult to sustain when the objects being dealt with happen to be alive: and this difficulty, it seems to me, lies close to the heart of most objections to the idea of defining the developmental relationship between genes and bodies in terms of information technology.
These objections, however, hardly constitute a major criticism of Dawkins’s enterprise. For The Blind Watchmaker is concerned not so much with a particular view of development as with a particular view of evolution: and there, the analogy with information technology works extremely well for most purposes. Dawkins’s fondness for computers is one of the great charms of this book: above all, it enables him to set a new standard in the exposition and defence of Darwinism. It is difficult to see how anyone could do more to explain what natural selection is, how it works, and what it can reasonably be called upon to explain. I strongly suspect that anyone who finishes the first two thirds of this book unpersuaded of the cogency of Darwin’s theory is simply not open to rational argument on the subject at all.
The last third of The Blind Watchmaker deals with a number of fashionable criticisms of Darwinism. An incisive analysis of the much-discussed notion that evolution occurs in fits and starts (in ‘punctuated equilibria’) suggests controversially that the considerable scientific and public interest in this idea over the past ten years amounts to a storm in a scientific tea-cup; an even sharper discussion of the obscure (and, Dawkins argues, obscurantist) school of ‘transformed cladism’ leads to the unpleasant conclusion that, on behalf of a rather technical point in the study of classification, some scientists have been led to ‘debauch language and betray truth’; and a wide-ranging final chapter smites sundry supposed alternatives to Darwinism – Lamarckism, neutralism, mutationism, molecular drive, and – last but by no means least – the oldest alternative of the lot, special creation by conscious (usually divine) design.
Dawkins’s rebuttal of supposed alternatives to Darwinism is extremely sure-footed – his critique of Lamarckism, in particular, is superb, and deserves to lay to rest this venerable doctrine once and for all. Characteristically, Dawkins avoids the obvious tack of trying to assemble empirical evidence against the different anti-Darwinian theories. Instead, he shows how these theories are in principle incapable of standing as alternatives to cumulative selection. Thus, even if it were to be shown that acquired characteristics are heritable, this would not constitute a plausible basis for an alternative theory of the evolution of well-built organisms. It is to be hoped that this basic point will be remembered by the next biologist who embarks on the attempt to demonstrate so-called Lamarckian inheritance.
Inevitably, Dawkins’s attempt to clear away a lot of contemporary evolutionary confusions and heresies takes him off the highway of Darwinian theory and into a number of often poorly lit by-ways. General readers may find some of these by-ways relatively uninteresting – anyone, for example, could be forgiven for finding tedious the ins and outs of cladistic terminology. Yet at least one important point emerges from this exercise: namely, that cumulative selection is the only even half-way plausible theory of the evolution of organic complexity that has ever been proposed. Of course, it is conceivable (however much it may be unlikely) that the theory will turn out in due course to be wrong: but if it does, then we shall have to replace it with something that has not hitherto even been dreamt of.
It is not particularly fashionable to defend what might be termed a metaphysically ambitious view of the scientific world-picture. Even among those who are not tempted by any of the anti-scientific world-views which prosper in our culture, it is commonplace to find the attitude that science should be kept firmly ‘in its place’. I suspect that Dawkins is not much impressed with this sort of caution. Interestingly, he shares with Stephen Jay Gould, the other leading public representative of Darwinism in the English-speaking world today, the conviction that evolution matters, not just intellectually and philosophically, but personally and even socially. It is partly because Dawkins and Gould both write as evolutionary philosophers of nature on the grand scale that each has won such large audiences for his subject. Intriguingly, for both are passionate Darwinists, the two men appear to have rather different evolutionary philosophies, and this is something that I hope they will explore when they meet in a ‘Darwinian Dialogue’ at the Sheldonian in Oxford on 9 April.