Richard Dawkins: books: The Blind Watchmaker
The
Blind Watchmaker:
|
- Book and ordering info from the UK publisher Penguin Books Ltd.
- Book info from the US publisher W.W. Norton - Updated Edition with a New Intro by Dawkins (Avail Sep 96)
- Order or the 1996 reissue paperback the from the US online bookstore amazon.com
- Order Dawkins' original Biomorph software the from the US online bookstore amazon.com
- CD-ROM: The Evolution of Life with Richard Dawkins - software based on The Blind Watchmaker
| Book Jacket |
One of the most famous arguments of the creationist theory of the universe is the eighteenth-century theologian William Paley's: Just as a watch is too complicated and too functional to have sprung into existence by accident, so too must all living things, with their far greater complexity, be purposefully designed. But as Richard Dawkins, professor of zoology at Oxford University, demonstrates in this brilliant and eloquent riposte to the Argument from Design, the analogy is false. Natural selection, the unconscious, automatic, blind yet essentially non-random process that Darwin discovered, has no purpose in mind. If it can be said to play the role of watchmaker in nature, it is the blind watchmaker.
Patiently and lucidly, Dr. Dawkins - in this book which has been acclaimed as perhaps the most influential work on evolution written in this century - identifies those aspects of the theory which people find hard to believe and removes the barrier to credibility one by one.
| Reviews |
A
brief review with links from the Page of
Honest Intellectual Inquiry
The New York Times
| Related Links |
Biomorph Resources
- from this site
Almost
like a Whale
The
watchmaker argument
Evolution
and the Myth of Creationism - a similar but more
basic book.
| Endorsements |
"He succeeds admirably in showing how natural
selection allows biologists to dispense with such notions
as purpose and design and he does so in a manner readily
intelligible to the modern reader"
Michael T. Ghiselin, New
York Times
"If you doubt the power of natural selection I
urge you, to save your soul, to reads Dawkins's
book"
Frances Crick
"This just might be the most important evolution
book since Darwin"
John Gribbin
"A lovely book, original and lively, it expounds
the ins and outs of evolution with enthusiastic clarity,
answering at every point, the caveman of
creationism."
Isaac Asimov
"This book is beautifully and superbly written...
It is a completely understandable but has the cadence of
impassioned speech. Every page rings of truth. It is one
of the best science books - one of the best any books - I
have ever read."
Lee Dembart, Los Angesles Times
| Selected Quotes and Excerpts |
Preface
This book is written in the conviction that our own existence once presented the greatest of all mysteries, but that it is a mystery no longer because it is solved. Darwin and Wallace solved it, though we Shall continue to add footnotes to their solution for a while yet, I wrote the book because I was surprised that so many people seemed not only unaware of the elegant and beautiful solution to this deepest of problems but, incredibly, in many cases actually unaware that there was a problem in the first place!
Explaining is a difficult art. You can explain something so that your reader understands the words; and you can explain something so that the reader feels it in the marrow of his bones. To do the latter, it sometimes isn't enough to lay the evidence before the reader in a dispassionate way. You have to become an advocate and use the tricks of the advocate's trade. This book is not a dispassionate scientific treatise. Other books on Darwinism are, and many of them are excellent and informative and should be read in conjunction with this one. Far from being dispassionate, it has to be confessed that in parts this book is written with a passion which, in a professional scientific journal, might excite comment. Certainly it seeks to inform, but it also seeks to persuade and even - one can specify aims without presumption - to inspire. I want to inspire the reader with a vision of our own existence as, on the face of it, a spine-chilling mystery; and simultaneously to convey the full excitement of the fact that it is a mystery with an elegant solution which is within our grasp. More, I want to persuade the reader, not just that the Darwinian world-view happens to be true, but that it is the only known theory that could, in principle, solve the mystery of our existence. This makes it a doubly satisfying theory. A good case can be made that Darwinism is true, not just on this planet but all over the universe, wherever life may be found.
Chapter 1 - Explaining the very Improbable
(Excerpt from William Paley's Natural Theology)
every indication of contrivance, every manifestation of design, which existed in the watch, exists in the works of nature; with the difference, on the side of nature, of being greater or more, and that in a degree which exceeds all computation.
Paley's argument is made with passionate sincerity and is informed by the best biological scholarship of his day, but it is wrong, gloriously and utterly wrong. The analogy between telescope and eye, between watch and living organism, is false. All appearances to the contrary, the only watchmaker in nature is the blind forces of physics, albeit deployed in a very special way. A true watchmaker has foresight: he designs his cogs and springs, and plans their interconnections, with a future purpose in his mind's eye. Natural selection, the blind, unconscious, automatic process which Darwin discovered, and which we now know is the explanation for the existence and apparently purposeful form of all life, has no purpose in mind. It has no mind and no mind's eye. It does not plan for the future. It has no vision, no foresight, no sight at all. If it can be said to play the role of watchmaker in nature, it is the blind watchmaker.
But, however many ways there may be of being alive, it is certain that there are vastly more ways of being dead, or rather not alive.
For those that like '-ism' sorts of names, the aptest name for my approach to understanding how things work is probably 'hierarchical reductionism'. If you read trendy intellectual magazines, you may have noticed that 'reductionism' is one of those things, like sin, that is only mentioned by people who are against it. To call oneself a reductionist will sound, in some circles, a bit like admitting to eating babies. But, just as nobody actually eats babies, so nobody is really a reductionist in any sense worth being against.
...We concluded that the behaviour of a complicated thing should be explained in terms Of interactions between its component parts, considered as successive layers of an orderly hierarchy.
The physicist's problem is the problem of ultimate origins and ultimate natural laws. The biologist's problem is the problem of complexity.
Chapter 2 - Good Design
Natural selection is the blind watchmaker, blind because it does not see ahead, does not plan consequences, has no purpose in view. Yet the living results of natural selection overwhelmingly impress us with the appearance of design as if by a master watchmaker, impress us with the illusion of design and planning. The purpose of this book is to resolve this paradox to the satisfaction of the reader, and the purpose of this chapter is further to impress the reader with the power of the illusion of design. We shall look at a particular example and shall conclude that, when it comes to complexity and beauty of design, Paley hardly even began to state the case.
Nowadays theologians aren't quite so straightforward as Paley. They don't point to complex living mechanisms and say that they are self-evidently designed by a creator, just like a watch. But there is a tendency to point to them and say 'It is impossible to believe' that such complexity, or such perfection, could have evolved by natural selection. Whenever I read such a remark, I always feel like writing 'Speak for yourself' in the margin.
...There are two things wrong with the argument put by Raven. First, there is the familiar, and I have to say rather irritating, confusion of natural selection with 'randomness'. Mutation is random; natural selection is the very opposite of random. Second, it just isn't true that 'each by itself is useless'. It isn't true that the whole perfect work must have been achieved simultaneously. It isn't true that each part is essential for the success of the whole.
Chapter 3 - Accumulating small change
We have seen that living things are too improbable and too beautifully 'designed' to have come into existence by chance. How, then, did they come into existence? The answer, Darwin's answer, is by gradual, step- by-step transformations from simple beginnings, from primordial entities sufficiently simple to have come into existence by chance. Each successive change in the gradual evolutionary process was simple enough, relative to its predecessor, to have arisen by chance. But the whole sequence of cumulative steps constitutes anything but a chance process, when you consider the complexity of the final end-product relative to the original starting point. The cumulative process is directed by nonrandom survival. The purpose of this chapter is to demonstrate the power of this cumulative selection as a fundamentally nonrandom process.
Evolution has no long-term goal. There is no long-distance target, no final perfection to serve as a criterion for selection, although human vanity cherishes the absurd notion that our species is the final goal of evolution.
If you don't know anything about computers, just remember that they are machines that do exactly what you tell them but often surprise you in the result.
Biomorph is the name coined by Desmond Morris for the vaguely animal-like shapes in his surrealist paintings.
In true natural selection, if a body has what it takes to survive, its genes automatically survive because they are inside it. So the genes that survive tend to be, automatically, those genes that confer on bodies the qualities that assist them to survive.
When I wrote the program [Biomorph], I never thought that it would evolve anything more than a variety of tree-like shapes. I had hoped for weeping willows, cedars of Lebanon, Lombardy poplars, seaweeds, perhaps deer antlers. Nothing in my biologist's intuition, nothing in my 20 years' experience of programming computers, and nothing in my wildest dreams, prepared me for what actually emerged on the screen.
Chapter 4 - Making tracks through animal space
As we saw in Chapter 2, many people find it hard to believe that something like the eye, Paley's favourite example, so complex and well designed, with so many interlocking working parts, could have arisen from small beginnings by a gradual series of step-by-step changes. Let's return to the problem in the light of such new intuitions as the biomorphs may have given us. Answer the following two questions:
1. Could the human eye have arisen directly from no eye at all, in a single step ?
2. Could the human eye have arisen directly from something slightly different from itself, something that we may call X ?
The answer to Question 1 is clearly a decisive no. The odds against a 'yes' answer for questions like Question 1 are many billions of times greater than the number of atoms in the universe. ... The answer to Question 2 is equally clearly yes, provided only that the difference between the modern eye and its immediate predecessor X is sufficiently small.
What use is half a wing? How did wings get their start? Many animals leap from bough to bough, and sometimes fall to the ground. Especially in a small animal, the whole body surface catches the air and assists the leap, or breaks the fall, by acting as a crude aerofoil.
...There are animals alive today that beautifully illustrate every stage in the continuum. There are frogs that glide with big webs between their toes, tree-snakes with flattened bodies that catch the air, lizards with flaps along their bodies, and several different kinds of mammals that glide with membranes stretched between their limbs, showing us the kind of way bats must have got their start. Contrary to the creationist literature, not only are animals with 'half a wing' common, so are animals with a quarter of a wing, three quarters of a wing, and so on.
The idea of tiny changes cumulated over many steps is an immensely powerful idea, capable of explaining an enormous range of things that would be otherwise inexplicable.
Sometimes the history of gradual, intermediate stages is clearly written into the shape of modern animals, even taking the form of outright imperfections in the final design. Stephen Jay Gould, in his excellent essay on The Panda's Thumb, has made the point that evolution can be more strongly supported by evidence of telling imperfections than by evidence of perfection.
...the timeseale on which continents have drifted about is the same slow timescale on which animal lineages have evolved, and we cannot ignore continental drift if we are to understand the patterns of animal evolution on those continents.
Anti-evolution propaganda is full of alleged examples of complex systems that 'could not possibly' have passed through a gradual series of intermediates. This is often just another case of the rather pathetic 'Argument from Personal Incredulity' that we met in Chapter 2. Immediately after the section on the eye, for example, The Neck of the Giraffe goes on to discuss the bombardier beetle, which
"squirts a lethal mixture of hydroquinone and hydrogen peroxide into the face of its enemy. These two chemicals, when mixed together, literally explode. So in order to store them inside its body, the Bombardier Beetle has evolved a chemical inhibitor to make them harmless. At the moment the beetle squirts the liquid out of its tail, an anti-inhibitor is added to make the mixture explosive once again. The chain of events that could have led to the evolution of such a complex, coordinated and subtle process is beyond biological explanation on a simple step-by-step basis. The slightest alteration in the chemical balance would result immediately in a race of exploded beetles."
A biochemist colleague has kindly provided me with a bottle of hydrogen peroxide, and enough hydroquinone for 50 bombardier beetles. I am now about to mix the two together. According to the above, they will explode in my face. Here goes...
Well, I'm still here. I poured the hydrogen peroxide into the hydroquinone, and absolutely nothing happened. It didn't even get warm. Of course I knew it wouldn't: I'm not that foolhardy! The statement that 'these two chemicals, when mixed together, literally explode', is, quite simply, false, although it is regularly repeated throughout creationist literature. If you are curious about the bombardier beetle, by the way, what actually happens is as follows. It is true that it squirts a scaldingly hot mixture of hydrogen peroxide and hydroquinone at enemies. But hydrogen peroxide and hydroquinone don't react violently together unless a catalyst is added. This is what the bombardier beetle does. As for the evolutionary precursors of the system, both hydrogen peroxide and various kinds of quinones are used for other purposes in body chemistry. The bombardier beetle's ancestors simply pressed into different service chemicals that already happened to be around. That's often how evolution works.
Chapter 5 - The power and the archives
It is raining DNA outside. On the bank of the Oxford canal at the bottom of my garden is a large willow tree, and it is pumping downy seeds into the air. ... 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. Not just any DNA, but DNA whose coded characters spell out specific instructions for building willow trees that will shed a new generation of downy seeds. 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.
If you want to understand life, don't think about vibrant, throbbing gels and oozes, think about information technology.
The particular polymers used by living cells are called polynucleotides. There are two main families of polynucleotides in living cells, called DNA and RNA for short. Both are chains of small molecules called nucleotides. Both DNA and RNA are heterogeneous chains, with four different kinds of nucleotides. This, of course, is where the opportunity for information storage lies. Instead of just the two states 1 and 0, the information technology of living cells uses four states, which we may conventionally represent as A, T, C and G. There is very little difference, in principle, between a two-state binary information technology like ours, and a four-state information technology like that of the living cell.
DNA is ROM. It can be read millions of times over, but only written to once - when it is first assembled the birth of the cell in which it resides.
The thing that defines a species is that all members have the same addressing system for their DNA.
...Instead, what we find is that natural selection exerts a braking effect on evolution. ... This isn't really paradoxical. When we think about it carefully, we see that it couldn't be otherwise. Evolution by natural selection could not be faster than the mutation rate, for mutation is, ultimately, the only way in which new variation enters the species. All that natural selection can do is accept certain new variations, and reject others. The mutation rate is bound to place an upper limit on the rate at which evolution can proceed. As a matter of fact, most of natural selection is concerned with preventing evolutionary change rather than with driving it. This doesn't mean, I hasten to insist, that natural selection is a purely destructive process. It can construct too, in ways that Chapter 7 will explain.
Where are these facts leading us? They are leading us in the direction of a central truth about life on Earth, ... This is that living organisms exist for the benefit of DNA rather than the other way around. This won't be obvious yet, but I hope to persuade you of it. The messages that DNA molecules contain are all but eternal when seen against the time scale of individual lifetimes. The lifetimes of DNA messages (give or take a few mutations) are measured in units ranging from millions of years to hundreds of millions of years; or, in other words, ranging from 10,000 individual lifetimes to a trillion individual lifetimes. Each individual organism should be seen as a temporary vehicle, in which DNA messages spend a tiny fraction of their geological lifetimes.
Chapter 6 - Origins and miracles
Chance, luck, coincidence, miracle. One of the main topics of this chapter is miracles and what we mean by them. My thesis will be that events that we commonly call miracles are not supernatural, but are part of a spectrum of more-or-less improbable natural events. A miracle, in other words, if it occurs at all, is a tremendous stroke of luck. Events don't fall neatly into natural events versus miracles.
Cumulative selection is the key but it had to get started, and we cannot escape the need to postulate a single-step chance event in the origin of cumulative selection itself.
Cairns-Smith believes that the original life on this planet was based on self-replicating inorganic crystals such as silicates. If this is true, organic replicators, and eventually DNA, must later have taken over or usurped the role.
Cultural evolution is many orders of magnitude faster than DNA-based evolution, which sets one even more to thinking of the idea of 'takeover'. And if a new kind of replicator takeover is beginning, it is conceivable that it will take off so far as to leave its parent DNA (and its grandparent clay if Cairns-Smith is right) far behind. If so, we may be sure that computers will be in the van.
Just as our eyes can see only that narrow band of electromagnetic frequencies that natural selection equipped our ancestors to see, so our brains are built to cope with narrow bands of sizes and times.
It is often pointed out that chemists have failed in their attempts to duplicate the spontaneous origin of life in the laboratory. This fact is used as if it constituted evidence against the theories that those chemists are trying to test. But actually one can argue that we should be worried if it turned out to be very easy for chemists to obtain life spontaneously in the test-tube. This is because chemists' experiments last for years not thousands of millions of years, and because only a handful of chemists, not thousands of millions of chemists, are engaged in doing these experiments. If the spontaneous origin of life turned out to be a probable enough event to have occurred during the few man-decades in which chemists have done their experiments, then life should have arisen many times on Earth, and many times on planets within radio range of Earth.
So we have arrived at the following paradox. If a theory of the origin of life is sufficiently 'plausible' to satisfy our subjective judgement of plausibility, it is then too 'plausible' to account for the paucity of life in the universe as we observe it. According to this argument, the theory we are looking for has got to be the kind of theory that seems implausible to our limited, Earth-bound, decade-bound imaginations. Seen in this light, both Cairns-Smith's theory and the primeval-soup theory seem if anything in danger of erring on the side of being too plausible! Having said all this I must confess that, because there is so much uncertainty in the calculations, if a chemist did succeed in creating spontaneous life I would not actually be disconcerted!
Chapter 9 - Puncturing Punctuationism
From Darwin onwards evolutionists have realized that, if we arrange all our available fossils in chronological order, they do not form a smooth sequence of scarcely perceptible change. ... the trends as seen in the fossil record are usually jerky, not smooth. Darwin, and most others following him, have assumed that this is mainly because the fossil record is imperfect. [229]
What the 'punctuationists' did, when they first proposed their theory, was to ask themselves: Given that, like most neo-Darwinians, we accept the orthodox theory that speciation starts with geographical isolation, what should we expect to see in the fossil record? [239]
The 'gaps', far from being annoying imperfections or awkward embarrassments, turn out to be what we should positively expect, if we take seriously our orthodox neo-Darwinian theory of speciation. ... The point that Eldredge and Gould were making, then, could have been modestly presented as a helpful rescuing of Darwin and his successors from what had seemed to them an awkward difficulty. Indeed that is, at least in part, how it was presented - initially. ... Eldredge and Gould could have made this their main message: Don't worry Darwin, even if the fossil record were perfect you shouldn't expect to see a finely graduated progression if you only dig in one place, for the simple reason that most of the evolutionary change took place somewhere else. ... But no, instead they chose, especially in their later writings in which they were eagerly followed by journalists, to sell their ideas as being radically opposed to Darwin's and opposed to the neo-Darwinian synthesis. [240-241]
The fact is that, in the fullest and most serious sense, Eldredge and Gould are really just as gradualist as Darwin or any of his followers. It is just that they would compress all the gradual change into brief bursts, rather than having it go on all the time; and they emphasise that most of the gradual change goes on in geographical areas away from the areas where most fossils are dug up.
So it is not really the gradualism of Darwin that the punctuationists oppose: gradualism means that each generation is only slightly different from the previous generation; you would have to be a saltationist to oppose that, and Eldredge and Gould are not saltationists. Rather, it turns out to be Darwin's alleged belief in the constancy of rates of evolution that they and other punctuationists object to. [241]
... it is all too easy to confuse gradualism (the belief, held by modern punctuationists as well as Darwin, that there are no sudden leaps between one generation and the next) with 'constant evolutionary speedism' (opposed by punctuationists and allegedly, though not actually, held by Darwin). They are not the same thing at all. [242-243]
It isn't true that Darwin believed that evolution proceeded at a constant rate. He certainly didn't believe it in the ludicrously extreme that I satirized [in a parable that since it took the Israelistes 40 years to get to Palestine, they were only doing 24 yards a day]..., and I don't think he really believed it in any important sense. [243-244]
The theory of punctuated equilibrium is a minor gloss on Darwinism, one which Darwin himself might well have approved if the issue had been discussed in his day. As a minor gloss, it does not deserve a particularly large measure of publicity. .. the theory has been sold - oversold by some journalists - as if it were radically opposed to the views of Darwin and his successors. [250]
What needs to be said now, loud and clear, is the truth: that the theory of punctuated equilibrium lies firmly within the neo-Darwinian synthesis. It always did. It will take time to undo the damage wrought by overblown rhetoric, but it will be undone. The theory of punctuated equilibrium will come to be seen in proportion, as an interesting but minor wrinkle on the surface of neo-Darwinian theory. [251]"
(sorry, but this section will not be continued)