Preface XV For reasons that are not entirely clear to me,Darwinism seems more in need of advocacy than similarly established truths in other branches of science.Many of us have no grasp of quantum theory,or Einstein's theories of special and general relativity,but this does not in itself lead us to oppose these theories!Darwinism,unlike 'Einsteinism', seems to be regarded as fair game for critics with any degree of ignorance.I suppose one trouble with Darwinism is that,as Jacques Monod perceptively remarked,everybody thinks he understands it.It is,indeed,a remarkably simple theory;childishly so,one would have thought,in comparison with almost all of physics and mathematics.In essence,it amounts simply to the idea that non-random reproduction, where there is hereditary variation,has consequences that are far-reaching if there is time for them to be cumulative.But we have good grounds for believing that this simplicity is deceptive.Never forget that,simple as the theory may seem,nobody thought of it until Darwin and Wallace in the mid nineteenth century,nearly 200 years after Newton's Principia,and more than 2,000 years after Eratosthenes measured the Earth.How could such a simple idea go so long undiscovered by thinkers of the calibre of Newton,Galileo,Descartes, Leibnitz,Hume and Aristotle?Why did it have to wait for two Victorian naturalists?What was wrong with philosophers and mathematicians that they overlooked it?And how can such a powerful idea go still largely unabsorbed into popular consciousness? It is almost as if the human brain were specifically designed to misunderstand Darwinism,and to find it hard to believe.Take,for instance,the issue of 'chance',often dramatized as blind chance.The great majority of people that attack Darwinism leap with almost unseemly eagerness to the mistaken idea that there is nothing other than random chance in it.Since living complexity embodies the very antithesis of chance,if you think that Darwinism is tantamount to chance you'll obviously find it easy to refute Darwinism!One of my tasks will be to destroy this eagerly believed myth that Darwinism is a theory of 'chance'.Another way in which we seem predisposed to disbelieve Darwinism is that our brains are built to deal with events on radically different timescales from those that characterize evolution- ary change.We are equipped to appreciate processes that take seconds, minutes,years or,at most,decades to complete.Darwinism is a theory of cumulative processes so slow that they take between thousands and millions of decades to complete.All our intuitive judgements of what is probable turn out to be wrong by many orders of magnitude.Our .well-tuned apparatus of scepticism and subjective probability-theory misfires by huge margins,because it is tuned-ironically,by evolution
Preface xv For reasons that are not entirely clear to me, Darwinism seems more in need of advocacy than similarly established truths in other branches of science. Many of us have no grasp of quantum theory, or Einstein's theories of special and general relativity, but this does not in itself lead us to oppose these theories! Darwinism, unlike 'Einsteinism', seems to be regarded as fair game for critics with any degree of ignorance. I suppose one trouble with Darwinism is that, as Jacques Monod perceptively remarked, everybody thinks he understands it. It is, indeed, a remarkably simple theory; childishly so, one would have thought, in comparison with almost all of physics and mathematics. In essence, it amounts simply to the idea that non-random reproduction, where there is hereditary variation, has consequences that are far-reaching if there is time for them to be cumulative. But we have good grounds for believing that this simplicity is deceptive. Never forget that, simple as the theory may seem, nobody thought of it until Darwin and Wallace in the mid nineteenth century, nearly 200 years after Newton's Principia, and more than 2,000 years after Eratosthenes measured the Earth. How could such a simple idea go so long undiscovered by thinkers of the calibre of Newton, Galileo, Descartes, Leibnitz, Hume and Aristotle? Why did it have to wait for two Victorian naturalists? What was wrong with philosophers and mathematicians that they overlooked it? And how can such a powerful idea go still largely unabsorbed into popular consciousness? It is almost as if the human brain were specifically designed to misunderstand Darwinism, and to find it hard to believe. Take, for instance, the issue of 'chance', often dramatized as blind chance. The great majority of people that attack Darwinism leap with almost unseemly eagerness to the mistaken idea that there is nothing other than random chance in it. Since living complexity embodies the very antithesis of chance, if you think that Darwinism is tantamount to chance you'll obviously find it easy to refute Darwinism! One of my tasks will be to destroy this eagerly believed myth that Darwinism is a theory of 'chance'. Another way in which we seem predisposed to disbelieve Darwinism is that our brains are built to deal with events on radically different timescales from those that characterize evolutionary change. We are equipped to appreciate processes that take seconds, minutes, years or, at most, decades to complete. Darwinism is a theory of cumulative processes so slow that they take between thousands and millions of decades to complete. All our intuitive judgements of what is probable turn out to be wrong by many orders of magnitude. Our •well-tuned apparatus of scepticism and subjective probability-theory misfires by huge margins, because it is tuned - ironically, by evolution
XVI Preface itself-to work within a lifetime of a few decades.It requires effort of the imagination to escape from the prison of familiar timescale,an effort that I shall try to assist. A third respect in which our brains seem predisposed to resist Darwinism stems from our great success as creative designers.Our world is dominated by feats of engineering and works of art.We are entirely accustomed to the idea that complex elegance is an indicator of premeditated,Grafted design.This is probably the most powerful reason for the belief,held by the vast majority of people that have ever lived,in some kind of supernatural deity.It took a very large leap of the imagination for Darwin and Wallace to see that,contrary to all intuition,there is another way and,once you have understood it,a far more plausible way,for complex 'design'to arise out of primeval simplicity.A leap of the imagination so large that,to this day,many people seem still unwilling to make it.It is the main purpose of this book to help the reader to make this leap. Authors naturally hope that their books will have lasting rather than ephemeral impact.But any advocate,in addition to putting the timeless part of his case,must also respond to contemporary advocates of opposing,or apparently opposing,points of view.There is a risk that some of these arguments,however hotly they may rage today,will seem terribly dated in decades to come.The paradox has often been noted that the first edition of The Origin of Species makes a better case than the sixth.This is because Darwin felt obliged,in his later editions,to respond to contemporary criticisms of the first edition, criticisms which now seem so dated that the replies to them merely get in the way,and in places even mislead.Nevertheless,the temptation to ignore fashionable contemporary criticisms that one suspects of being nine days'wonders is a temptation that should not be indulged,for reasons of courtesy not just to the critics but to their otherwise confused readers.Though I have my own private ideas on which chapters of my book will eventually prove ephemeral for this reason,the reader-and time-must judge. I am distressed to find that some women friends (fortunately not many)treat the use of the impersonal masculine pronoun as if it showed intention to exclude them.If there were any excluding to be done (happily there isn't)I think I would sooner exclude men,but when I once tentatively tried referring to my abstract reader as 'she',a feminist denounced me for patronizing condescension:I ought to say he-or-she',and 'his-or-her'.That is easy to do if you don't care about language,but then if you don't care about language you don't deserve readers of either sex.Here,I have returned to the normal conventions
XVI Preface itself - to work within a lifetime of a few decades. It requires effort of the imagination to escape from the prison of familiar timescale, an effort that I shall try to assist. A third respect in which our brains seem predisposed to resist Darwinism stems from our great success as creative designers. Our world is dominated by feats of engineering and works of art. We are entirely accustomed to the idea that complex elegance is an indicator of premeditated, Grafted design. This is probably the most powerful reason for the belief, held by the vast majority of people that have ever lived, in some kind of supernatural deity. It took a very large leap of the imagination for Darwin and Wallace to see that, contrary to all intuition, there is another way and, once you have understood it, a far more plausible way, for complex 'design' to arise out of primeval simplicity. A leap of the imagination so large that, to this day, many people seem still unwilling to make it. It is the main purpose of this book to help the reader to make this leap. Authors naturally hope that their books will have lasting rather than ephemeral impact. But any advocate, in addition to putting the timeless part of his case, must also respond to contemporary advocates of opposing, or apparently opposing, points of view. There is a risk that some of these arguments, however hotly they may rage today, will seem terribly dated in decades to come. The paradox has often been noted that the first edition of The Origin of Species makes a better case than the sixth. This is because Darwin felt obliged, in his later editions, to respond to contemporary criticisms of the first edition, criticisms which now seem so dated that the replies to them merely get in the way, and in places even mislead. Nevertheless, the temptation to ignore fashionable contemporary criticisms that one suspects of being nine days' wonders is a temptation that should not be indulged, for reasons of courtesy not just to the critics but to their otherwise confused readers. Though I have my own private ideas on which chapters of my book will eventually prove ephemeral for this reason, the reader - and time - must judge. I am distressed to find that some women friends (fortunately not many) treat the use of the impersonal masculine pronoun as if it showed intention to exclude them. If there were any excluding to be done (happily there isn't) I think I would sooner exclude men, but when I once tentatively tried referring to my abstract reader as 'she', a feminist denounced me for patronizing condescension: I ought to say 'he-or-she', and 'his-or-her'. That is easy to do if you don't care about language, but then if you don't care about language you don't deserve readers of either sex. Here, I have returned to the normal conventions
Preface xvii of English pronouns.I may refer to the 'reader'as 'he',but I no more think of my readers as specifically male than a French speaker thinks of a table as female.As a matter of fact I believe I do,more often than not,think of my readers as female,but that is my personal affair and I'd hate to think that such considerations impinged on how I use my native language. Personal,too,are some of my reasons for gratitude.Those to whom I cannot do justice will understand.My publishers saw no reason to keep from me the identities of their referees (not 'reviewers'-true reviewers,pace many Americans under 40,criticize books only after they are published,when it is too late for the author to do anything about it),and I have benefited greatly from the suggestions of John Krebs (again),John Durant,Graham Cairns-Smith,leffrey Levinton, Michael Ruse,Anthony Hallam and David Pye.Richard Gregory kindly criticized Chapter 12,and the final version has benefited from its complete excision.Mark Ridley and Alan Grafen,now no longer even officially my students,are,together with Bill Hamilton,the leading lights of the group of colleagues with whom I discuss evolution and from whose ideas I benefit almost daily.They,Pamela Wells,Peter Atkins and John Dawkins have helpfully criticized various chapters for me.Sarah Bunney made numerous improvements,and John Cribbin corrected a major error.Alan Grafen and Will Atkinson advised on computing problems,and the Apple Macintosh Syndicate of the Zoology Department kindly allowed their laser printer to draw biomorphs. Once again I have benefited from the relentless dynamism with which Michael Rodgers,now of Longman,carries all before him.He, and Mary Cunnane of Norton,skilfully applied the accelerator (to my morale)and the brake(to my sense of humour)when each was needed. Part of the book was written during a sabbatical leave kindly granted by the Department of Zoology and New College.Finally-a debt I should have acknowledged in both my previous books-the Oxford tutorial system and my many tutorial pupils in zoology over the years have helped me to practise what few skills I may have in the difficult art of explaining. Richard Dawkins Oxford.1986
Preface xvii of English pronouns. I may refer to the 'reader' as 'he', but I no more think of my readers as specifically male than a French speaker thinks of a table as female. As a matter of fact I believe I do, more often than not, think of my readers as female, but that is my personal affair and I'd hate to think that such considerations impinged on how I use my native language. Personal, too, are some of my reasons for gratitude. Those to whom I cannot do justice will understand. My publishers saw no reason to keep from me the identities of their referees (not 'reviewers' - true reviewers, pace many Americans under 40, criticize books only after they are published, when it is too late for the author to do anything about it), and I have benefited greatly from the suggestions of John Krebs (again), John Durant, Graham Cairns-Smith, leffrey Levinton, Michael Ruse, Anthony Hallam and David Pye. Richard Gregory kindly criticized Chapter 12, and the final version has benefited from its complete excision. Mark Ridley and Alan Grafen, now no longer even officially my students, are, together with Bill Hamilton, the leading lights of the group of colleagues with whom I discuss evolution and from whose ideas I benefit almost daily. They, Pamela Wells, Peter Atkins and John Dawkins have helpfully criticized various chapters for me. Sarah Bunney made numerous improvements, and John Cribbin corrected a major error. Alan Grafen and Will Atkinson advised on computing problems, and the Apple Macintosh Syndicate of the Zoology Department kindly allowed their laser printer to draw biomorphs. Once again I have benefited from the relentless dynamism with which Michael Rodgers, now of Longman, carries all before him. He, and Mary Cunnane of Norton, skilfully applied the accelerator (to my morale) and the brake (to my sense of humour) when each was needed. Part of the book was written during a sabbatical leave kindly granted by the Department of Zoology and New College. Finally - a debt I should have acknowledged in both my previous books - the Oxford tutorial system and my many tutorial pupils in zoology over the years have helped me to practise what few skills I may have in the difficult art of explaining. Richard Dawkins Oxford, 1986
CHAPTER 1 EXPLAINING THE VERY IMPROBABLE We animals are the most complicated things in the known universe. The universe that we know,of course,is a tiny fragment of the actual universe.There may be yet more complicated objects than us on other planets,and some of them may already know about us.But this doesn't alter the point that I want to make.Complicated things,everywhere, deserve a very special kind of explanation.We want to know how they came into existence and why they are so complicated.The ex- planation,as I shall argue,is likely to be broadly the same for com- plicated things everywhere in the universe;the same for us,for chimpanzees,worms,oak trees and monsters from outer space.On the other hand,it will not be the same for what I shall call 'simple'things, such as rocks,clouds,rivers,galaxies and quarks.These are the stuff of physics.Chimps and dogs and bats and cockroaches and people and worms and dandelions and bacteria and galactic aliens are the stuff of biology. The difference is one of complexity of design.Biology is the study of complicated things that give the appearance of having been designed for a purpose.Physics is the study of simple things that do not tempt us to invoke design.At first sight,man-made artefacts like computers and cars will seem to provide exceptions.They are complicated and obviously designed for a purpose,yet they are not alive,and they are made of metal and plastic rather than of flesh and blood.In this book they will be firmly treated as biological objects. The reader's reaction to this may be to ask,'Yes,but are they really biological objects?'Words are our servants,not our masters.For different purposes we find it convenient to use words in different senses.Most cookery books class lobsters as fish.Zoologists can
CHAPTER 1 EXPLAINING THE VERY IMPROBABLE We animals are the most complicated things in the known universe. The universe that we know, of course, is a tiny fragment of the actual universe. There may be yet more complicated objects than us on other planets, and some of them may already know about us. But this doesn't alter the point that I want to make. Complicated things, everywhere, deserve a very special kind of explanation. We want to know how they came into existence and why they are so complicated. The explanation, as I shall argue, is likely to be broadly the same for complicated things everywhere in the universe; the same for us, for chimpanzees, worms, oak trees and monsters from outer space. On the other hand, it will not be the same for what I shall call 'simple' things, such as rocks, clouds, rivers, galaxies and quarks. These are the stuff of physics. Chimps and dogs and bats and cockroaches and people and worms and dandelions and bacteria and galactic aliens are the stuff of biology. The difference is one of complexity of design. Biology is the study of complicated things that give the appearance of having been designed for a purpose. Physics is the study of simple things that do not tempt us to invoke design. At first sight, man-made artefacts like computers and cars will seem to provide exceptions. They are complicated and obviously designed for a purpose, yet they are not alive, and they are made of metal and plastic rather than of flesh and blood. In this book they will be firmly treated as biological objects. The reader's reaction to this may be to ask, 'Yes, but are they really biological objects?' Words are our servants, not our masters. For different purposes we find it convenient to use words in different senses. Most cookery books class lobsters as fish. Zoologists can