RICHARD DAWKINS with additional research by YAN WONG WEIDENFELD & NICOLSON John Maynard Smith (1920-2004) He saw a draft and graciously accepted the dedication, which now, sadly, must become In Memoriam 'Never mind the lectures or the "workshops"; be Mowed to the motor coach excursions to local beauty spots; forget your fancy visual aids and radio microphones; the only thing that really matters at a conference is that John Maynard Smith must be in residence and there must be a spacious, convivial bar. If he can't manage the dates you have in mind, you must just reschedule the conference.. .He will charm and amuse the young research workers, listen to their stories, inspire them, rekindle enthusiasms that might be flagging, and send them back to their laboratories or their muddy fields, enlivened and invigorated, eager to try out the new ideas he has generously shared with them.' It isn't only conferences that will never be the same again. ACKNOWLEDGEMENTS I was persuaded to write this book by Anthony Cheetham, founder of Orion Books. The fact that he had moved on before the book was published reflects my unconscionable delay in finishing it. Michael Dover tolerated that delay with humour and fortitude, and always encouraged me by his swift and intelligent understanding of what I was trying to do. The best of his many good decisions was to engage Latha Menon as a freelance editor. As with A Devil's Chaplain, Latha's support has been beyond all estimation. Her grasp of the big picture simultaneously with the details, her encyclopaedic knowledge, her love of science and her selfless devotion to promoting it have benefited me, and this book, in more ways than I can count. Others at the publishers helped greatly, but Jennie Condell and the designer, Ken Wilson, went beyond the call of duty. My research assistant Yan Wong has been intimately involved at every stage of the planning, researching and writing of the book. His resourcefulness and detailed familiarity with modern biology have been matched only by his green fingers with computers. If, here, I have gratefully assumed the role of apprentice, it could be said that he was my apprentice before I was his, for I was his tutor at New College. He then did his doctorate under the supervision of Alan Grafen, once my own graduate student, so I suppose Yan could be called my grandstudent as well as my student. Apprentice or master, Yan's contribution has been so great that, for certain tales, I have insisted on adding his name as joint author. When Yan left to cycle across Patagonia, the book in its final stages benefited greatly from Sam Turvey's extraordinary knowledge of zoology and his conscientious care in deploying it. Advice and help of various kinds were willingly given by Michael Yudkin, Mark Griffith, Steve Simpson, Angela Douglas, George McGavin, Jack Pettigrew, George Barlow, Colin Blakemore, John Mollon, Henry Bennet-Clark, Robin Elisabeth Cornwell, Lindell Bromham, Mark Sutton, Bethia Thomas, Eliza Howlett, Tom Kemp, Malgosia Nowak-Kemp, Richard Fortey, Derek Siveter, Alex Freeman, Nicky Warren, A. V. Grimstone, Alan Cooper, and especially Christine DeBlase-Ballstadt. Others are acknowledged in the Notes at the end. I am deeply grateful to Mark Ridley and Peter Holland, who were engaged by the publishers as critical readers and gave me exactly the right kind of advice. The routine authorial claim of responsibility for the remaining shortcomings is more than usually necessary in my case. As always, I gratefully acknowledge the imaginative generosity of Charles Simonyi. And my wife, Lalla Ward, has once again been my help and strength. RICHARD DAWKINS CONTENTS THE CONCEIT OF HINDSIGHT S T G P 16 HE ENERAL ROLOGUE T HE P B 27 ILGRIMAGE EGINS The Farmer's Tale 28 The Cro-Magnon's Tale 34 A H 36 LL UMANKIND The Tasmanian's Tale 39 Eve's Tale 44 A H 56 RCHAIC OMO SAPIENS The Neanderthal's Tale 58 ERGASTS 59 The Ergast's Tale 63 HABILINES 68 The Handyman's Tale 69 A -M 77 PE EN Little Foot's Tale 80 Epilogue to Little Foot's Tale 84 C 88 HIMPANZEES The Bonobo's Tale 92 G 94 ORILLAS The Gorilla's Tale 95 O U 98 RANG TANS The Orang Utan's Tale 99 G 104 IBBONS The Gibbon's Tale 107 O W M 118 N W M 122 LD ORLD ONKEYS EW ORLD ONKEYS The Howler Monkey's Tale 125 T 134 ARSIERS L , B EMURS USHBABIES K 1 AND THEIR IN The Aye-Aye's Tale 140 T G C C C T S 148 HE REAT RETACEOUS ATASTROPHE OLUGOS AND REE HREWS The Colugo's Tale 150 R R 152 ODENTS AND ABBITKIND The Mouse's Tale 155 The Beaver's Tale 157 L 162 AURASIATHERES The Hippo's Tale 165 Epilogue to the Hippo's Tale 170 The Seal's Tale 171 X 178 ENARTHRANS The Armadillo's Tale 178 A 182 FROTHERES M 188 ARSUPIALS The Marsupial Mole's Tale 191 MONOTREMES 194 The Duckbill's Tale 196 What the Star-Nosed Mole said to the Duckbilled Platypus 204 M -L R 207 AMMAL IKE EPTILES S 214 AUROPSIDS Prologue to the Galapagos Finch's Tale 217 The Galapagos Finch's Tale 220 The Peacock's Tale 222 The Dodo's Tale 231 The Elephant Bird's Tale 235 Epilogue to the Elephant Bird's Tale 242 A 246 MPHIBIANS The Salamander's Tale 252 The Narrowmouth's Tale 261 The Axolotl's Tale 263 LUNGFISH 268 The Lungfish's Tale 269 0 272 COELACANTHS R -F F 274 AY INNED ISH The Leafy Sea Dragon's Tale 274 The Pike's Tale 278 The Mudskipper's Tale 279 The Cichlid's Tale 281 The Blind Cave Fish's Tale 288 The Flounder's Tale 290 S K 292 HARKS AND THEIR IN L H 296 AMPREYS AND AGFISH The Lamprey's Tale 299 LANCELETS 302 The Lancelet's Tale 303 S S 306 © EA QUIRTS A 310 MBULACRARIANS P 314 ROTOSTOMES The Ragworm's Tale 322 The Brine Shrimp's Tale 325 The Leaf Cutter's Tale 329 The Grasshopper's Tale 331 The Fruit Fly's Tale 343 The Rotifer's Tale 352 The Barnacle's Tale 359 The Velvet Worm's Tale 362 Epilogue to the Velvet Worm's Tale 373 380 ACOELOMORPH FLATWORMS C 384 NIDARIANS The Jellyfish's Tale 388 The Polypifer's Tale 390 C 396 TENOPHORES P 398 LACOZOANS S 400 PONGES The Sponge's Tale 404 C 406 HOANOFLAGELLATES The Choanoflagellate's Tale 407 DRIPs 410 F 412 UNGI A 416 P 418 MOEBOZOANS LANTS The Cauliflower's Tale 422 The Redwood's Tale 425 U 434 NCERTAIN The Mixotrich's Tale 439 T G HE REAT H R 445 ISTORIC ENDEZVOUS A 448 RCHAEA 450 EUBACTERIA The Rhizobium's Tale 450 Taq's Tale 459 C 464 T ANTERBURY HE H ' R 482 OSTS ETURN F R 507 N 507 B 510 I 516 URTHER EADING OTES IBLIOGRAPHY NDEX THE CONCEIT OF HINDSIGHT 'History doesn't repeat itself, but it rhymes.' MARK TWAIN 'History repeats itself; that's one of the things that's wrong with history.' CLARENCE DARROW History has been described as one damn thing after another. The remark can be seen as a warning against a pair of temptations but, duly warned, I shall cautiously flirt with both. First, the historian is tempted to scour the past for patterns that repeat themselves; or at least, following Mark Twain, to seek reason and rhyme for everything. This appetite for pattern affronts those who insist that, as Mark Twain will also be found to have said, 'History is usually a random, messy affair', going nowhere and following no rules. The second connected temptation is the vanity of the present: of seeing the past as aimed at our own time, as though the characters in history's play had nothing better to do with their lives than foreshadow us. Under names that need not trouble us, these are live issues in human history and they arise with greater force, and no greater agreement, on the longer timescale of evolution. Evolutionary history can be represented as one damn species after another. But many biologists will join me in finding this an impoverished view. Look at evolution that way and you miss most of what matters. Evolution rhymes, patterns recur. And this doesn't just happen to be so. It is so for well understood reasons: Darwinian reasons mostly, for biology, unlike human history or even physics, already has its grand unifying theory, accepted by all informed practitioners, though in varying versions and interpretations. In writing evolutionary history I do not shrink from seeking patterns and principles, but I try to be careful about it. What of the second temptation, the conceit of hindsight, the idea that the past works to deliver our particular present? The late Stephen Jay Gould rightly pointed out that a dominant icon of evolution in popular mythology, a caricature almost as ubiquitous as lemmings jumping over cliffs (and that myth is false too), is a shambling file of simian ancestors, rising progressively in the wake of the erect, striding, majestic figure of Homo sapiens sapiens: man as evolution's last word (and in this context it always is man rather than woman); man as what the whole enterprise is pointing towards; man as a magnet, drawing evolution from the past towards his eminence. There is a physicist's version which is less obviously vainglorious and which I should mention in passing. This is the 'anthropic' notion that the very laws of physics themselves, or the fundamental constants of the universe, are a carefully tuned put-up job, calculated to bring humanity eventually into existence. It is not necessarily founded on vanity. It doesn't have to mean that the universe was deliberately made in order that we should exist. It need mean only that we are here, and we could not be in a universe that lacked the capability of producing us. As physicists have pointed out, it is no accident that we see stars in our sky, for stars are a necessary part of any universe capable of generating us. Again, this does not imply that stars exist in order to make us. It is just that without stars there would be no atoms heavier than lithium in the periodic table, and a chemistry of only three elements is too impoverished to support life. Seeing is the kind of activity that can go on only in the kind of universe where what you see are stars. But there is a little more that needs to be said. Granted the trivial fact that our presence requires physical laws and constants capable of producing us, the existence of such potent ground rules may still seem tantalisingly improbable. Depending upon their assumptions, physicists may reckon that the set of possible universes vastly outnumbers that subset whose laws and constants allowed physics to mature, via stars into chemistry and via planets into biology. To some, this means that the laws and constants must have been deliberately premeditated from the start (although it baffles me why anybody regards this as an explanation for anything, given that the problem so swiftly regresses to the larger one of explaining the existence of the equally fine-tuned and improbable Premeditator). Other physicists are less confident that the laws and constants were free to vary in the first place. When I was little it was not obvious to me why five times eight had to give the same result as eight times five. I accepted it as one of those facts that grownups assert. Only later did I understand, perhaps through visualising rectangles, why such pairs of multiplications are not free to vary independently of one another. We understand that the circumference and the diameter of a circle are not independent, otherwise we might feel tempted to postulate a plethora of possible universes, each with a different value of n. Perhaps, argue some physicists such as the Nobel Prize-winning theorist Steven Weinberg, the fundamental constants of the universe, which at present we treat as independent of one another, will in some Grand Unified fullness of time be understood to have fewer degrees of freedom than we now imagine. Maybe there is only one way for a universe to be. That would undermine the appearance of anthropic coincidence. Other physicists, including Sir Martin Rees, the present Astronomer Royal, accept that there is a real coincidence in need of explanation, and explain it by postulating many actual universes existing in parallel, mutually incommunicado, each with its own set of laws and constants.* Obviously we, who find ourselves reflecting upon such things, must be in one of those universes, however rare, whose laws and constants are capable of evolving us. The theoretical physicist Lee Smolin added an ingenious Darwinian spin which reduces the apparent statistical improbability of our existence. In Smolin's model, universes give birth to daughter universes, which vary in their laws and constants. Daughter universes are born in black holes produced by a parent universe, and they inherit its laws and constants but with some possibility of small random change — 'mutation'. Those daughter universes that have what it takes to reproduce (last long enough to make black holes, for This "many universes' idea is not to be confused (though it often is) with Hugh Everett's 'many worlds" interpretation of quantum theory, brilliantly advocated by David Deutsch in The Fabric of Reality. The resemblance between the two theories is superficial and meaningless. Both theories could be true, or neither, or one. or the other. They were proposed to answer completely different problems. In the Everett theory, the different universes don"t differ in their fundamental constants. But it is the entire point of the theory we are here considering that the different universes have different fundamental constants. The laws of zoological nomenclature follow strict precedence, and I fear there is no hope of changing the name Australopithecus to something less confusing to the contemporary majority who lack a classical education. It has nothing to do with Australia. No member of the genus has ever been found outside Africa. Australo simply means southern. Australia is the great southern continent, the Aurora australis is the southern equivalent of the Aurora borealis (boreal means northern), and Australopithecus was first found in south Africa, in the person of the Taung child. instance) are, of course, the universes that pass on their laws and constants to their daughters. Stars are precursors to black holes which, in the Smolin model, are the birth events. So universes that have what it takes to make stars are favoured in this cosmic Darwinism. The properties of a universe that furnish this gift to the future are the self-same properties that incidentally lead to the manufacture of large atoms, including vital carbon atoms. Not only do we live in a universe that is capable of producing life. Successive generations of universes progressively evolve to become increasingly the sort of universe that, as a by- product, is capable of producing life. The logic of the Smolin theory is bound to appeal to a Darwinian, indeed to anyone of imagination, but as for the physics I am not qualified to judge. I cannot find a physicist to condemn the theory as definitely wrong — the most negative thing they will say is that it is superfluous. Some, as we saw, dream of a final theory in whose light the alleged fine-tuning of the universe will turn out to be a delusion anyway. Nothing we know rules out Smolin's theory, and he claims for it the merit — which scientists rate more highly than many laymen appreciate — of testability. His book is The Life of the Cosmos and I recommend it. But that was a digression about the physicist's version of the conceit of hindsight. The biologist's version is easier to dismiss since Darwin, though harder before him, and it is our concern here. Biological evolution has no privileged line of descent and no designated end. Evolution has reached many millions of interim ends (the number of surviving species at the time of observation), and there is no reason other than vanity — human vanity as it happens, since we are doing the talking — to designate any one as more privileged or climactic than any other. This doesn't mean, as I shall continue to argue, that there is a total dearth of reasons or rhymes in evolutionary history. I believe there are recurring patterns. I also believe, though this is more controversial today than it once was, that there are senses in which evolution may be said to be directional, progressive and even predictable. But progress is emphatically not the same thing as progress towards humanity, and we must live with a weak and unflattering sense of the predictable. The historian must beware of stringing together a narrative that seems, even to the smallest degree, to be homing in on a human climax. A book in my possession (in the main a good book, so I shall not name and shame it) provides an example. It is comparing Homo habilis (a human species, probably ancestral to us) with its predecessors the australopithecines." What the book says is that Homo habilis was 'considerably more evolved than the Australopithecines'. More evolved? What can this mean but that evolution is moving in some pre-specified direction? The book leaves us in no doubt of what the presumed direction is. "The first signs of a chin are apparent." 'First' encourages us to expect second and third signs, towards a 'complete' human chin. 'The teeth start to resemble ours ...' As if those teeth were the way they were, not because it suited the habiline diet but because they were embarking upon the road towards becoming our teeth. The passage ends with a telltale remark about a later species of extinct human, Homo erectus: Although their faces are still different from ours, they have a much more human look in their eyes. They are like sculptures in the making, 'unfinished' works. In the making? Unfinished? Only with the unwisdom of hindsight. In excuse of that book it is probably true that, were we to meet a Homo erectus face to face, it might well look to our eyes like an unfinished sculpture in the making. But that is only because we are looking with human hindsight. A living creature is always in the business of surviving in its own environment. It is never unfinished — or, in another sense, it is always unfinished. So, presumably, are we. The conceit of hindsight tempts us at other stages in our history. From our human point of view, the emergence of our remote fish ancestors from water to land was a momentous step, an evolutionary rite of passage. It was undertaken in the Devonian Period by lobe-finned fish a bit like modern lungfish. We look at fossils of the period with a pardonable yearning to gaze upon our forebears, and are seduced by a knowledge of what came later: drawn into seeing these Devonian fish as 'halfway' towards becoming land animals; everything about them earnestly transitional, bound into an epic quest to invade the land and initiate the next big phase of evolution. That is not the way it was at the time. Those Devonian fish had a living to earn. They were not on a mission to evolve, not on a quest towards the distant future. An otherwise excellent book about vertebrate evolution contains the following sentence about fish which ventured out of the water on to the land at the end of the Devonian Period and jumped the gap, so to speak, from one vertebrate class to another to become the first amphibians... The 'gap' comes from hindsight. There was nothing resembling a gap at the time, and the 'classes' that we now recognise were no more separate, in those days, than two species. As we shall see again, jumping gaps is not what evolution does. It makes no more sense (and no less) to aim our historical narrative towards Homo sapiens than towards any other modern species — Octopus vulgaris, say, or Panthera leo or Sequoia sempervirens. A historically minded swift, understandably proud of flight as self-evidently the premier accomplishment of life, will regard swiftkind — those spectacular flying machines with their swept- back wings, who stay aloft for a year at a time and even copulate in free flight — as the acme of evolutionary progress. To build on a fancy of Steven Pinker, if elephants could write history they might portray tapirs, elephant shrews, elephant seals and proboscis monkeys as tentative beginners along the main trunk road of evolution, taking the first fumbling steps but each — for some reason — never quite making it: so near yet so far. Elephant astronomers might wonder whether, on some other world, there exist alien life forms that have crossed the nasal rubicon and taken the final leap to full proboscitude. We are not swifts nor elephants, we are people. As we wander in imagination through some long-dead epoch, it is humanly natural to reserve a special warmth and curiosity for whichever otherwise ordinary species in that ancient I am grateful to Nicky Warren for suggesting this word. landscape is our ancestor (it is an intriguingly unfamiliar thought that there is always one such species). It is hard to deny our human temptation to see this