His centennial tribute to Charles Darwin is offbeat in a characteristically delightful and
affectionate
way.
Richard-Dawkins-The-Devil-s-Chaplain
I agree that natural selection is 'the most revolutionary notion in the history of biology' and I would toy with substituting 'science' for 'biology'.
Childishly simple as it is, nobody thought of it until centuries after far more complicated ideas had become common currency, and it is still the subject of misunderstanding and even apathy among educated people.
A microcosm of this historical enigma is the subject of Gould's first essay.
Just as humankind waited centuries longer than our hindsight deems necessary before discovering natural selection, so Darwin delayed his own publication 20 years after he first thought of the theory in 1838.
Gould's explanation is that Darwin was afraid of the psychological implications of his idea.
He saw what Wallace would never admit, that the human mind itself must be a material product of natural selection.
Darwin, in fact, was a scientific materialist.
In another essay Gould is encouraged by the genetic closeness of humans and chimpanzees to speculate that 'inter-breeding may well be possible'. I doubt it, but it is a pleasing thought and Gould surely exaggerates when he rates it 'the most . . . ethically unacceptable scientific experiment I can imagine'. For my ethics, far less acceptable experiments are conceivable, and actually done in animal physiology laboratories every day, and a chimp/human hybridization would provide exactly the come-uppance that 'human dignity' needs. Gould is, in general, rather good at puncturing human speciesist vanity, and in particular he will have nothing to do with the myth that evolution represents progress towards man. This scepticism informs his valuable account of 'Bushes and ladders in human evolution', and fires his scorn for attempts to rank human races as primitive or advanced.
He returns to the attack on progress in the very different guise of the theory of orthogenesis, the idea that evolutionary trends have their own internal momentum which eventually drives lineages extinct. His telling of the classic Irish Elk story gains freshness from his intimacy with the fossils of the Dublin Museum and gives the lie to the myth that palaeontology is dry and dull. His conclusion that the proverbially topheavy antlers were important in social life is surely right, but he may underestimate the role of within-species competition in driving species extinct. Large antlers could directly have caused the extinction of the Irish Elk while at the same time, right up to the moment of extinction, individuals with relatively large antlers were out-reproducing indivi- duals with relatively small antlers. I would like to see Gould come to terms with the 'orthoselective' impact of 'arms races' both between and
REJOICING IN MULTIFARIOUS NATURE
191
? EVEN THE RANKS OF TUSCANY
within species. He seems to approach this in his essays on the 'Cambrian explosion'.
Natural history can be sold for its intrinsic fascination, but it is much better used to make a point. Gould tells us about a fly that eats its mother from the inside, about 17-year cicadas and 120-year bamboos, and about uncanny fish-decoying mussels. He employs the useful trick of first opening the reader's mind by boggling it, then filling it with the important biological principle. One principle I would have liked to have heard more on is that of the limitation of evolutionary perfection: 'Orchids are Rube Goldberg machines; a perfect engineer would certainly have come up with something better' (Rube Goldberg is the American Heath Robinson). My own favourite example, inherited from an undergraduate tutor, is the recurrent laryngeal nerve. It starts in the head, goes down into the chest, loops round the aorta, then goes straight back into the head again. In a giraffe this detour must be wasteful indeed. The human engineer who first designed the jet engine simply threw the old propeller engine out and started afresh. Imagine the contraption he would have produced if he had been constrained to 'evolve' his jet engine by changing a propeller engine one bit at a time, nut by nut and bolt by bolt!
While on the problem of perfection, I think Gould exaggerates the relevance of 'neutral mutations'. Molecular geneticists are understandably interested in DNA changes as molecular events, and any that have no effect on protein function may reasonably be called neutral mutations. But to a student of whole organism biology they are less than neutral; they are not, in any interesting sense, mutations at all! If the molecular neutralists are right, their kind of neutral mutation will forever be hidden from the field biologist and from natural selection. And if a field biologist actually sees variation in phenotypes, the question of whether that variation could be selectively neutral cannot be settled in the biochemistry laboratory.
Several essays touch on aspects of the relationship of Darwinism to human society and politics. There is much humane good sense here and I agree with most of it. Although 'sociobiology' is inspiring excellent research, Gould is right that it has also led to some second-rate bandwagoneering. 'But was there ever dog that praised his fleas? ' asked Yeats. Perhaps a dog may be held responsible for the fleas he sheds, but only to a small extent. At the AAAS meeting in Washington in 1997, Gould and I witnessed an organized attack on his most distinguished Harvard colleague. * Gould well deserved his ovation for the apt Lenin quote with which he disowned the rabble. But as he watched those
*A glassful of water was thrown sideways at Professor E. O. Wilson (subsequently exaggerated in various accounts to a 'pitcher of iced water, poured over him').
192
? pathetic fleas ineffectually hopping around the stage chanting, of all things, 'genocide', did he wonder with a little itch of conscience on which dog they had been sucking?
The Epilogue is forward-looking and whets our appetite for Volume 2, which I earnestly hope will be forthcoming. * One theme which I know Gould has already carried further in his Natural History column is his dislike for 'the ultimate atomism' of regarding organisms as 'temporary receptacles . . . no more than instruments that genes use to make more
112
genes like themselves'. In describing this as 'metaphorical nonsense'
Gould underestimates the sophistication of the idea, first cogently
113
expressed in its modern form by George C. Williams. The dispute is
largely semantic. Inclusive fitness is defined in such a way that to say 'the individual works so as to maximize its inclusive fitness' is equivalent to saying 'the genes work so as to maximize their survival'. The two forms are each valuable for different purposes. Both contain an element of personification; it is dangerously easier to personify organisms than to personify genes. The gene selection idea is not naively atomistic, as it recognizes that genes are selected for their capacity to interact productively with the other genes with which they are most likely to share 'receptacles'; this means the other genes of the gene pool; and the gene pool may therefore come to resemble a 'homeostatically buffered system' tending to return to (one of) its evolutionarily stable state(s). Irrevocable determination by genes is no part of the idea nor is anything remotely approaching a 'one gene, one trait' mapping from genotype to phenotype. In any case it has nothing to do with 'supreme confidence in universal adaptation', which is as likely to be found among devotees of 'individual selection' or 'species selection'.
'I will rejoice in the multifariousness of nature and leave the chimera of certainty to politicians and preachers': a resounding conclusion to a stimulating book - the work of a free and imaginative scientific mind. The final, sad paradox is this. How can a mind capable of such rejoicing, open enough to contemplate the shifting splendour of three thousand million years, moved by the ancient poetry written in the rocks, how can such a mind not be bored by the drivelling ephemera of juvenile pamphleteers and the cold preaching of spiteful old hardliners? No doubt they are right that science is not politically neutral. But if, to them, that is the most important thing about science, just think what they are missing! Stephen Gould is well qualified, and strategically placed, to strip away even those dark blinkers and dazzle those poor unpractised eyes.
*In fact, ten volumes were eventually published, the last one, / have Landed, at the time of his death.
REJOICING IN MULTIFARIOUS NATURE
193
? '%t0 M mem
The Art of the Developable
The acknowledged master of biological belles lettres has long been Sir Peter Medawar. If there is a younger biologist or an American biologist that bears comparison, it is probably in both cases Stephen Jay Gould. It was therefore with anticipation that I received these two collections of essays, reflections by leading and highly literate biologists on their subject and its history and philosophy.
Pluto's Republic is one of those titles that cannot be mentioned without an immediate explanation, and Sir Peter begins thus:
A good many years ago a neighbour whose sex chivalry forbids me to disclose [it takes a Medawar to get away with this kind of thing nowadays] exclaimed upon learning of my interest in philosophy: 'Don't you just adore Pluto's Republic? ' Pluto's Republic has remained in my mind ever since as a super- latively apt description of that intellectual underworld which so many of the essays in this volume explore. We each populate Pluto's Republic according to our own prejudices . . .
Here I nursed a mischievous half-hope that Stephen Gould might be found among the denizens of Medawar's private underworld - his more sanctimonious cosignatories of a notorious letter to the New York Review of Books about 'sociobiology' (13 November 1975) are prominent in mine. But Gould is several cuts above those former associates of his and he is not among Medawar's targets. Indeed, they share many targets, IQ- metricians for instance.
Most of the essays in Pluto's Republic have appeared twice before, first as book reviews or transcripts of lectures, then in previous anthologies
116
such as The Art of the Soluble and The Hope of Progress, which were
presumably reviewed at the time. Although I shall therefore give Pluto's Republic less than half my space in this joint review, I vigorously repudiate any mutterings about such second order anthologizing being too much of a good thing. The earlier books have long been out of
194
14 Hen's Teeth and Horse's Toes by Stephen Jay Gould
Review of Pluto's Republic by Peter Medawar'
and 11
? print, and I have been scouring the second-hand bookshops ever since my own Art of the Soluble was stolen. I discovered when I reread them here that I had many favourite passages word-perfect in memory. Who indeed could forget the opening sentence of the 1968 Romanes Lecture, 'Science and Literature'? T hope I shall not be thought ungracious if I say at the outset that nothing on earth would have induced me to attend the kind of lecture you may think I am about to give. ' At the time this prompted the apt rejoinder from John Holloway: 'This lecturer can never have been thought ungracious in his life. '
Or listen to Medawar on another great biologist, Sir D'Arcy Thompson:
. . . He was a famous conversationalist and lecturer (the two are often thought to go together, but seldom do), and the author of a work which, considered as literature, is the equal of anything of Pater's or Logan Pearsall Smith's in its complete mastery of the bel canto style. Add to all this that he was over six feet tall, with the build and carriage of a Viking and with the pride of bearing that comes from good looks known to be possessed.
The reader may be hazy about Logan Pearsall Smith and Pater, but he is left with the overwhelming impression (since he probably is familiar with the idiom of P. G. Wodehouse) of a style that is undoubtedly bel, and may very well be canto. And there is more of Medawar in the passage quoted than Medawar himself realized.
Medawar continually flatters his readers, implying in them an erudition beyond them, but doing it so that they almost come to believe in it themselves:
'Mill,' said John Venn in 1907, has 'dominated the thought and study of intelligent students to an extent which many will find it hard to realise at the present day'; yet he could still take a general familiarity with Mill's views for granted . . .
The reader scarcely notices that Medawar himself is still taking a general familiarity with Mill's views for granted, although in the reader's own case it may be far from justified. 'Even George Henry Lewes found him- self unable to propound his fairly sensible views on hypotheses without prevarication and pursing of the lips. ' The reader's knowing chuckle is out before he realizes that actually he is in no position to respond knowingly to that 'even'.
Medawar has become a sort of chief spokesman for 'The Scientist' in the modern world. He takes a less doleful view of the human predica- ment than is fashionable, believing that hands are for solving problems rather than for wringing. He regards the scientific method - in the right
THE ART OF THE DEVELOPABLE
195
? EVEN THE RANKS OF TUSCANY
hands - as our most powerful tool for 'finding out what is wrong with [the world] and then taking steps to put it right'. As for the scientific method itself, Medawar has a good deal to tell us, and he is well qualified to do so. Not that being a Nobel Prize winner and a close associate of Karl Popper is in itself an indication that one will talk sense: far from it when you think of others in that category. But Medawar not only is a Nobel Prize winner, he seems like a Nobel Prize winner; he is everything we think a Nobel Prize winner ought to be. If you have never understood why scientists like Popper, try Medawar's exposition of the philosophy of his 'personal guru'.
He read Zoology at Oxford, and early in his career made important contributions to classical Zoology, but was soon drawn into the highly populated and highly financed world of medical research. Inevitably, his associates have been molecular and cell biologists, but he seldom had any truck with the molecular chauvinism which plagued biology for two decades. Medawar has a good appreciation of biology at all levels.
He has also inevitably associated with doctors, and the preoccupa- tions and sympathies of a doctor pervade several of these essays, for example his sensitive reviews of books on cancer and psychosomatic heart disease. I especially enjoyed his blistering contempt for psycho- analysis: not a lofty, detached contempt for any ordinary pretentious drivel, but a committed contempt, fired by a doctor's concern. Psychoanalysts have even had their say over the puzzle of Darwin's long illness, and Medawar is at his withering best in telling us about it.
For Good, there is a wealth of evidence that unmistakably points to the idea that Darwin's illness was 'a distorted expression of the aggression, hate and resentment felt, at an unconscious level, by Darwin towards his tyrannical father'. These deep and terrible feelings found outward expression in Darwin's touching reverence towards his father and his father's memory, and in his describing his father as the kindest and wisest man he ever knew: clear evidence, if evidence were needed, of how deeply his true inner sentiments had been repressed.
Medawar, when he smells pretentious pseudoscience, is a dangerous man. His famous annihilation of Teilhard de Chardin's The Phenomenon of Man might have been thought an unfair attack on the dead, but for the extraordinary influence Teilhard exerted (and still exerts: Stephen Gould tells us that two journals established to discuss his ideas still flourish) over legions of the gullible including, I am afraid, my juvenile self. I would love to quote huge chunks of what is surely one of the great destructive book reviews of all time, but must content myself with
196
? two sentences from Medawar's typically barbed explanation of the popular appeal of Teilhard.
Just as compulsory primary education created a market catered for by cheap dailies and weeklies, so the spread of secondary and latterly of tertiary education has created a large population of people, often with well-developed literary and scholarly tastes who have been educated far beyond their capacity to undertake analytical thought . . . [The Phenomenon of Man] is written in an all but totally unintelligible style, and this is construed as prima-facie evidence of profundity.
Medawar's Herbert Spencer Lecture, and his review of Arthur Koestler's Act of Creation, are more respectful of his victims, but pretty punchy nevertheless. His review of Ronald Clark's Life of J. B. S. Haldane is enlivened by personal reminiscence, and reveals a sort of affection for the old brute which seems to have been reciprocated.
I remember Haldane's once going back on a firm promise to chair a lecture given by a distinguished American scientist on the grounds that it would be too embarrassing for the lecturer: he had once been the victim of a sexual assault by the lecturer's wife. The accusation was utterly ridiculous and Haldane did not in the least resent my saying so. He didn't want to be bothered with the chairmanship, and could not bring himself to say so in the usual way.
But if Haldane did not in the least resent Medawar's saying so, one cannot help wondering whether this was only because Medawar must have been one of the very few people Haldane ever met who could look him levelly in the eye, on equal terms intellectually. Peter Medawar is a giant among scientists and a wicked genius with English prose. Even if it annoys you, you will not regret reading Pluto's Republic.
In 1978 the Reviews Editor of a famous scientific journal, whose nature prudence forbids me to disclose, invited me to review Stephen
Jay Gould's Ever Since Darwin, remarking that I could 'get my own back' on opponents of 'genetic determinism'. I don't know which annoyed me more: the suggestion that I favoured genetic 'determinism' (it is one of those words like sin and reductionism: if you use it at all you are against it) or the suggestion that I might review a book for motives of revenge. The story warns my readers that Dr Gould and I are supposed to be on opposites sides of some fence or other. In the event, I accepted the commission and gave the book what could fairly be described as a rave review, even, I think, going so far as to praise Gould's style as a creditable second best to Peter Medawar's. *
*See 'Rejoicing in Multifarious Nature' (pp. 190-3).
THE ART OF THE DEVELOP ABLE
197
? EVEN THE RANKS OF TUSCANY
I feel inclined to do the same for Hen's Teeth and Horse's Toes. It is another collection of essays reprinted from Gould's column in Natural Histor)'. When you have to turn these pieces out once a month you must pick up some of the habits of the professional working to a deadline - this is not a criticism, Mozart did the same. Gould's writing has some- thing of the predictability that we enjoy in Mozart, or in a good meal. His volumes of collected essays, of which this is the third, are put together to a recipe: one part biological history, one part biological politics (less if we are lucky), and one part (more if we are lucky) vignettes of biological wonder, the modern equivalent of a mediaeval bestiary but with interesting scientific morals instead of boring pious ones. The essays themselves, too, often seem to follow a formula or menu. As appetizer there is the quotation from light opera or the classics, or sometimes its place is taken by a piece of reassuring nostalgia; a reminiscence from a normal, happy, very American childhood world of baseball stars and Hershey bars and Bar Mitzvahs - Gould, we learn, is not just one of your pointy-headed intellectuals but a regular guy. This homely informality softens the conspicuous erudition of the main course - the fluency in several languages, the almost Medawarian familiarity with literature and humanities - and even gives it a certain (un-Medawarian) charm (compare Gould himself on Louis Agassiz: '. . . the erudition that has so charmed American rustics . . . ').
Gould's own respect for Medawar is evident. The idea of science as 'the art of the soluble' provides the punchline for at least four of the essays: 'We may wallow forever in the thinkable; science traffics in the doable', '. . . science deals in the workable and soluble'; and two essays end with explicit quotations of the phrase. His view of Teilhard de Chardin's style is similar to Medawar's: '. . . difficult, convoluted writing may simply be fuzzy, not deep'. If he gives Teilhard's philosophy a slightly more sympathetic hearing, he is probably just making amends for his delightfully mischievous thesis that the young Teilhard connived in the Piltdown hoax. For Medawar, Teilhard's accepted role as one of the principal victims of the joke is just more evidence that he was
in no serious sense a thinker. He has about him that innocence which makes it easy to understand why the forger of the Piltdown skull should have chosen Teilhard to be the discoverer of its canine tooth.
Gould's case for the prosecution is a fascinating piece of detective work which I will not spoil by attempting to summarize it. My own verdict is a Scottish 'non-proven'.
198
? In whatever underworld the Piltdown forger languishes, he has a lot to answer for. Only last month an acquaintance, whose sex the grammar of English pronouns will probably force me to disclose, exclaimed upon learning of my interest in evolution: 'But I thought Darwin had been disproved. ' My mind started placing bets with itself: which particular second-hand, distorted half-truth has she misunderstood? I had just put my money on garbled Stephen Gould with a small side bet on (no need to garble) Fred Hoyle, when my companion revealed the winner as an older favourite: T heard that the missing link had now been shown to be a hoax. ' Piltdown, by God, still raising his ugly cranium after all these years!
Incidents like this reveal the extreme flimsiness of the straws that will be clutched by those with a strong desire to believe something silly. There are between 3 and 30 million species alive today, and as many as a billion have probably existed since life began. Just one fossil of just one of those millions of species turns out to be a hoax. Yet of all the volumes and volumes of facts about evolution, the only thing that stuck in my companion's head was Piltdown. A parallel case is the extra- ordinary popular aggrandizement of Eldredge and Gould's theory of 'punctuated equilibrium'. A minor dispute among experts (about whether evolution is smoothly continuous or interrupted by periods of stagnation when no evolutionary change occurs in a given lineage) has been blown up to give the impression that Darwinism's foundations are quivering. It is as if the discovery that the Earth is not a perfect sphere but an oblate spheroid cast sensational doubt on the whole Copernican world view, and reinstated flat-earthism. The anti-Darwinian sounding rhetoric of the punctuated equilibrists was a regrettable gift to creationists. Dr Gould regrets this as strongly as anyone, but I fear his protestations that his words have been misinterpreted will be to little avail. *
Whether Gould really has anything to answer for, he certainly has fought the good fight in the bizarre tragicomedy or tragifarce of modern American evolution politics. He travelled to Arkansas in 1981 to lend his formidable voice to the right side in the 'Scopes Trial IP. His obsession with history even took him on a visit to Dayton, Tennessee, scene of that previous Southern farce, and the subject of one of the
*'Since we proposed punctuated equilibria to explain trends, it is infuriating to be quoted again and again by creationists - whether by design or stupidity, I do not know - as admitting that the fossil record includes no transitional forms. Transitional groups are generally lacking at the species level but they are abundant between larger groups. ' From the essay, 'Evolution as Fact and Theory', p. 260 of Hen's Teeth and Horse's Toes.
THE ART OF THE DEVELOPABLE
199
? EVEN THE RANKS OF TUSCANY
most sympathetic and charming of the essays in the present book. His analysis of the appeal of creationism is wise and should be read by intolerant Darwin-freaks like me.
Gould's tolerance is his greatest virtue as a historian: that and his warmth towards his subjects.
His centennial tribute to Charles Darwin is offbeat in a characteristically delightful and affectionate way. Where others loftily pontificate, Gould goes down to earth and celebrates Darwin's last treatise, on worms. Darwin's worm book is not a 'harmless work of little importance by a great naturalist in his dotage'. It exemplifies his entire world view, based on the power of small causes, working together in large numbers and over long time spans, to wreak great changes:
We who lack an appreciation of history and have so little feel for the aggregated importance of small but continuous change scarcely realize that the very ground is being swept from beneath our feet; it is alive and constantly churning . . . Was Darwin really conscious of what he had done as he wrote his last professional lines, or did he proceed intuitively, as men of his genius some- times do? Then I came to the last paragraph and I shook with the joy of insight. Clever old man; he knew full well. In his last words, he looked back to the beginning, compared those worms with his first corals and completed his life's work in both the large and the small . . .
And the quotation of Darwin's last sentences follows.
Hen's Teeth and Horse's Toes is as enigmatic a title as Pluto's Republic,
and it requires more explanation. If the present volume could be said to exercise a bee in Gould's bonnet, to distinguish it from its two pre- decessors, it is epitomized in the essay of the same name. I will explain the point rather fully, because it is one with which I strongly agree although I am supposed, apparently by Gould himself among others, to hold opposing views. I can sum the point up by giving a new twist to a phrase already twisted by Peter Medawar. If science is the art of the soluble, evolution is the art of the developable.
Development is change within an individual organism, from single cell to adult. Evolution is also change, but change of a type that requires subtler understanding. Each adult form in an evolutionary series will appear to 'change' into the next, but it is change only in the sense that each frame on a movie film 'changes' into the next. In reality, of course, each adult in the succession begins as a single cell and develops anew. Evolutionary change is change in genetically controlled processes of embryonic development, not literal change from adult form to adult form.
200
? Gould fears that many evolutionists lose sight of development, and this leads them into error. There is firstly the error of genetic atomism, the fallacious belief in a one-to-one mapping between single genes and bits of body. Embryonic development doesn't work like that. The genome is not a 'blueprint'. Gould regards me as an arch genetic
117
atomist, wrongly, as I have explained at length elsewhere. It is one of
those cases where you will misunderstand an author unless you interpret his words in the context of the position he was arguing against.
Consider the following, from Gould himself:
Evolution is mosaic in character, proceeding at different rates in different structures. An animal's parts are largely dissociable, thus permitting historical change to proceed.
This appears to be rampant, and very un-Gouldian, atomism! Until you realize what Gould was arguing against: Cuvier's belief that evolution is impossible because change in any part is useless unless immediately accompanied by change in all other parts. * Similarly, the apparent genetic atomism that Gould criticizes in some other authors makes sense when you realize what those authors were arguing against: 'group selection' theories of evolution in which animals are supposed to act for the good of the species or some other large group. An atomistic inter- pretation of the role of genes in development is an error. An atomistic interpretation of the role of genetic differences in evolution is not an error, and is the basis of a telling argument against errors of the 'group selection' kind.
Atomism is just one of the errors that Gould sees as flowing from evolutionists' cavalier treatment of development. There are two others which are, on the face of it, opposite to each other: the error of assuming that evolution is too powerful, and the error of assuming that it is not powerful enough. The naive perfectionist believes that living material is infinitely ductile, ready to be shaped into whatever form natural selection dictates. This ignores the possibility that developmental processes are incapable of producing the desired form. The extreme 'gradualist' believes that all evolutionary changes are tiny, forgetting, according to Gould, that developmental processes can change in very large and complex ways, in single mutational steps. The general point, that we have to understand development before we can speculate constructively about evolution, is correct.
This must be what Medawar meant when he complained about 'the
*A doctrine recently revived as 'irreducible complexity' under the mistaken impression that it is new.
THE ART OF THE DEVELOPABLE
201
? EVEN THE RANKS OF TUSCANY
real weakness of modern evolutionary theory, namely its lack of a complete theory of variation, of the origin of candidature for evolution'. And this is why Gould is interested in hens' teeth and horses' toes. He makes the point that atavistic 'throwbacks', like hens with teeth and horses with three toes rather than one, are interesting because they tell us about the magnitude of evolutionary change that development allows. For the same reason he is interested in (and very interesting on) the development of zebras' stripes, and macromutations like insects with supernumerary thoraxes and wings.
I said that Gould and I were supposed to be professional adversaries and I would be disingenuous to pretend to like everything in this book. Why, for instance, does he find it necessary, after the phrase 'A strict Darwinian', to add '- I am not one -'? Of course Gould is a strict Darwinian, or if he isn't, nobody is; if you interpret 'strict' strictly enough, nobody is a strict anything. It is a pity, too, that Gould is still preaching against innocuous phrases like 'adultery in mountain bluebirds' and 'slavery in ants'. His rhetorical question about his own disapproval of such harmless anthropomorphisms, 'Is this not mere pedantic grousing', should be answered with a resounding 'Yes'. Gould himself made unselfconscious use of 'slavery of ants' in his own account
of the phenomenon (Ever Since Darwin; presumably this was written in the days before some pompous comrade spotted the dangerous ideological implications of the phrase). Since our language grew in a human setting, if biologists tried to ban human imagery they would almost have to stop communicating. Gould is an expert communicator, and of course he in practice treats his own puritanical strictures with the contempt that he secretly knows they deserve. The very first essay
of the present book tells us how two angler fish (anglerfish? )are caught 'in flagrante delicto' and discover 'for themselves what, according to Shakespeare, "every wise man's son doth know" - "journeys end in lovers meeting"'.
This is indeed a beautiful book, the pages glowing with a naturalist's love of life and a historian's respect and affection for his subjects, the vision extended and clarified by a geologist's familiarity with 'deep time'. To borrow a Medawarian phrase and like Peter Medawar himself, Stephen Gould is an aristocrat of learning. These are both extra- ordinarily gifted men, with some of the arrogance natural to aristocrats and those who have always been top of every class of which they have been members, but big enough to get away with it and generous enough to rise above arrogance too. Read their books if you are a scientist and, especially, read them if you are not.
202
? So
Hallucigenia, Wiwaxia and Friends1
Review of Wonderful Life by S. J. Gould
Wonderful Life is a beautifully written and deeply muddled book. To make unputdownable an intricate, technical account of the anatomies of worms, and other inconspicuous denizens of a half-billion-year-old sea, is a literary tour de force. But the theory that Stephen Gould wrings out of his fossils is a sorry mess.
The Burgess Shale, a Canadian rock formation dating from the Cambrian, the earliest of the great fossil eras, is a zoological treasury. Freak conditions preserved whole animals, soft parts and all, in full 3-D. You can literally dissect your way through a 530-million-year-old animal. C. D. Walcott, the eminent palaeontologist who discovered the Burgess fossils in 1909, classified them according to the fashion of his time: he 'shoehorned' them all into modern groups. 'Shoehorn' is Gould's own excellent coining. It recalls to me my undergraduate impatience with a tutor who asked whether the vertebrates were descended from this invertebrate group or that. 'Can't you see,' I almost shouted, 'that our categories are all modern? Back in the Precambrian, we wouldn't have recognized those invertebrate groups anyway. You are asking a non- question. ' My tutor agreed, and then went right on tracing modern animals back to other modern groups.
That was shoehorning, and that is what Walcott did to the Burgess animals. In the 1970s and 80s, a group of Cambridge palaeontologists returned to Walcott's museum specimens (with some newer collections from the Burgess site), dissected their 3-dimensional structure and overturned his classifications. These revisionists, principally Harry Whittington, Derek Briggs and Simon Conway Morris, are the heroes of Gould's tale. He milks every ounce of drama from their rebellion against the shoehorn, and at times he goes right over the top: T believe that Whittington's reconstruction of Opabinia in 1975 will stand as one of the great documents in the history of human knowledge. '
Whittington and his colleagues realized that most of their specimens
203
? EVEN THE RANKS OF TUSCANY
were far less like modern animals than Walcott had alleged. By the end of their epic series of monographs they thought nothing of coining a new phylum for a single specimen ('phylum' is the highest unit of zoological classification; even the vertebrates constitute only a sub- category of the Phylum Chordata). These brilliant revisions are almost certainly broadly correct, and they delight me beyond my under- graduate dreams. What is wrong is Gould's usage of them. He concludes that the Burgess fauna was demonstrably more diverse than that of the entire planet today, he alleges that his conclusion is deeply shocking to other evolutionists, and he thinks that he has upset our established view of history. He is unconvincing on the first count, clearly wrong on the second two.
In 1958 the palaeontologist James Brough published the following remarkable argument: evolution must have been qualitatively different in the earliest geological eras, because then new phyla were coming into existence; today only new species arise! The fallacy is glaring: every new phylum has to start as a new species. Brough was wielding the other end of Walcott's shoehorn, viewing ancient animals with the misplaced hindsight of a modern zoologist: animals that in truth were probably close cousins were dragooned into separate phyla because they shared key diagnostic features with their more divergent modern descendants. Gould too, even if he is not exactly reviving Brough's claim, is hoist with his own shoehorn.
How should Gould properly back up his claim that the Burgess fauna is super-diverse? He should - it would be the work of many years and might never be made convincing - take his ruler to the animals them- selves, unprejudiced by modern preconceptions about 'fundamental body plans' and classification. The true index of how unalike two animals are is how unalike they actually are. Gould prefers to ask whether they are members of known phyla. But known phyla are modern constructions. Relative resemblance to modern animals is not a sensible way of judging how far Cambrian animals resemble one another.
The five-eyed, nozzle-toting Opabinia cannot be assimilated to any textbook phylum. But, since textbooks are written with modern animals in mind, this does not mean that Opabinia was, in fact, as different from its contemporaries as the status 'separate phylum' would suggest. Gould makes a token attempt to counter this criticism, but he is hamstrung by dyed-in-the-wool essentialism and Platonic ideal forms. He really seems unable to comprehend that animals are continuously variable functional machines. It is as though he sees the great phyla not diverging from early blood brothers but springing into existence fully differentiated.
204
? Gould, then, singularly fails to establish his super-diversity thesis. Even if he were right, what would this tell us about 'the nature of history'? Since, for Gould, the Cambrian was peopled with a greater cast of phyla than now exist, we must be wonderfully lucky survivors. It could have been our ancestors who went extinct; instead it was Conway Morris's 'weird wonders', Hallucigenia, Wiwaxia and their friends. We came 'that close' to not being here.
Gould expects us to be surprised. Why? The view that he is attacking
- that evolution marches inexorably towards a pinnacle such as man -
has not been believed for years. But his quixotic strawmandering, his
shameless windmill-tilting, seem almost designed to encourage mis-
understanding (not for the first time: on a previous occasion he went so
far as to write that the neo-Darwinian synthesis was 'effectively dead').
The following is typical of the publicity surrounding Wonderful Life
(incidentally, I suspect that the lead sentence was added without the
knowledge of the credited journalist): 'The human race did not result
from the "survival of the fittest", according to the eminent American
professor, Stephen Jay Gould. It was a happy accident that created
119
Mankind. ' Such twaddle, of course, is nowhere to be found in Gould,
but whether or not he seeks that kind of publicity, he all too frequently attracts it. Readers regularly gain the impression that he is saying something far more radical and surprising than he actually is.
Survival of the fittest means individual survival, not survival of major lineages. Any orthodox Darwinian would be entirely happy with major extinctions being largely a matter of luck. Admittedly there is a minority of evolutionists who think that Darwinian selection chooses between higher-level groupings. They are the only Darwinians likely to be disconcerted by Gould's 'contingent extinction'. And who is the most prominent advocate of higher-level selection today? You've guessed it. Hoist again!
HALLUCIGENIA, WIWAXIA AND FRIENDS
205
? 5. 4
Human Chauvinism and
Evolutionary Progress120 Review of Full House by S. J. Gould
I
This pleasantly written book has two related themes. The first is a statistical argument which Gould believes has great generality, uniting baseball, a moving personal response to the serious illness from which, thankfully, the author has now recovered, and his second theme: that of whether evolution is progressive. The argument about evolution and progress is interesting - though flawed as I shall show - and will occupy most of this review. The general statistical argument is correct and mildly interesting, but no more so than several other homilies of routine methodology about which one could sensibly get a bee in one's bonnet.
Gould's modest and uncontroversial statistical point is simply this. An apparent trend in some measurement may signify nothing more than a change in variance, often coupled with a ceiling or floor effect. Modern baseball players no longer hit a 0. 400 (whatever that might be - evidently it is something pretty good). But this doesn't mean they are getting worse. Actually everything about the game is getting better and the variance is getting less. The extremes are being squeezed and 0. 400 hitting, being an extreme, is a casualty. The apparent decrease in batting success is a statistical artefact, and similar artefacts dog generalizations in less frivolous fields.
That didn't take long to explain, but baseball occupies 55 jargon- ridden pages of this otherwise lucid book and I must enter a mild protest on behalf of those readers who live in that obscure and little known region called the rest of the world. I invite Americans to imagine that I spun out a whole chapter in the following vein:
The home keeper was on a pair, vulnerable to anything from a yorker to a chinaman, when he fell to a googly given plenty of air. Silly mid on appealed for leg before, Dicky Bird's finger shot up and the tail collapsed. Not surprisingly, the skipper took the light. Next morning the night watchman, defiantly out of his popping crease, snicked a cover drive off a no ball straight through the gullies and on a fast outfield third man failed to stop the boundary . . . etc. etc.
206
? HUMAN CHAUVINISM AND EVOLUTIONARY PROGRESS
Readers in England, the West Indies, Australia, New Zealand, India, Pakistan, Sri Lanka and anglophone Africa would understand every word, but Americans, after enduring a page or two, would rightly protest.
Gould's obsession with baseball is harmless and, in the small doses to which we have hitherto been accustomed, slightly endearing. But this hubristic presumption to sustain readers' attention through six chapters of solid baseball chatter amounts to American chauvinism (and I suspect American male chauvinism at that). It is the sort of self-indulgence from which an author should have been saved by editor and friends before publication - and for all I know they tried. Gould is normally so civilized in his cosmopolitan urbanity, so genial in wit, so deft in style. This book has a delightfully cultivated yet unpretentious 'Epilog on Human Culture' which I gratefully recommend to anyone, of any nation. He is so good at explaining science without jargon yet without talking down, so courteous in his judgement of when to spell out, when to flatter the reader by leaving just a little unsaid. Why does his gracious instinct desert him when baseball is in the air?
Another minor plaint from over the water, this time something which is surely not Dr Gould's fault: may I deplore the growing publishers' habit of gratuitously renaming books when they cross the Atlantic (both ways)? Two of my colleagues are at risk of having their (excellent, and already well-named) books retitled, respectively, 'The Pelican's Breast' and 'The Pony Fish's Glow' (now what, I wonder, can have inspired such flights of derivative imagination? ) As one embattled author wrote to me, 'Changing the title is something big and important they can do to justify their salaries, and it does not require reading the book, so that's why they like it so much. ' In the case of the book under review, if the author's own title, Full House, is good enough for the American market, why is the British edition masquerading under the alias of Life's Grandeur? Are we supposed to need protection from the argot of the card table?
At the best of times such title changes are confusing and mess up our literature citations. This particular change is doubly unfortunate because Life's Grandeur (the title, not the book) is tailor-made for confusion with Wonderful Life, and nothing about the difference between the titles conveys the difference between the contents. The two books are not Tweedledum and Tweedledee, and it is unfair on their author to label them as if they were. More generally, may I suggest that authors of the world unite and assert their right to name their own books.
Enough of carping. To evolution: is it progressive? Gould's definition of progress is a human-chauvinistic one which makes it all too easy to
207
? EVEN THE RANKS OF TUSCANY
deny progress in evolution. I shall show that if we use a less anthro- pocentric, more biologically sensible, more 'adaptationist' definition, evolution turns out to be clearly and importantly progressive in the short to medium term. In another sense it is probably progressive in the long term too.
Gould's definition of progress, calculated to deliver a negative answer to the question whether evolution is progressive, is
a tendency for life to increase in anatomical complexity, or neurological elaboration, or size and flexibility of behavioral repertoire, or any criterion obviously concocted (if we would only be honest and introspective enough about our motives) to place Homo sapiens atop a supposed heap.
My alternative, 'adaptationist' definition of progress is
a tendency for lineages to improve cumulatively their adaptive fit to their particular way of life, by increasing the numbers of features which combine together in adaptive complexes.
I'll defend this definition and my consequent, limited, progressivist conclusion, later.
Gould is certainly right that human chauvinism, as an unspoken
motif, runs through a great deal of evolutionary writing. He'll find even
better examples if he looks at the comparative psychology literature,
which is awash with snobbish and downright silly phrases like
'subhuman primates', 'subprimate mammals' and 'submammalian
vertebrates', implying an unquestioned ladder of life denned so as to
perch us smugly on the top rung. Uncritical authors regularly move 'up'
or 'down' the 'evolutionary scale' (bear in mind that they are in fact
moving sideways among modern animals, contemporary twigs dotted
all around the tree of life). Students of comparative mentality
unabashedly and ludicrously ask, 'How far down the animal kingdom
does learning extend? ' Volume 1 of Hyman's celebrated treatise on the
invertebrates is entitled 'Protozoa through Ctenophora' (my emphasis) -
as if the phyla exist along an ordinal scale such that everybody knows
which groups sit 'between' Protozoa and Ctenophora. Unfortunately,
all zoology students do know - we've all been taught the same
121 groundless myth.
This is bad stuff, and Gould could afford to attack it even more severely than he attacks his normal targets. Whereas I would do so on logical grounds, Gould prefers an empirical assault. He looks at the actual course of evolution and argues that such apparent progress as can in general be detected is artefactual (like the baseball statistic). Cope's
208
? HUMAN CHAUVINISM AND EVOLUTIONARY PROGRESS
rule of increased body size, for example, follows from a simple 'drunkard's walk' model. The distribution of possible sizes is confined by a left wall, a minimal size. A random walk from a beginning near the left wall has nowhere to go but up the size distribution. The mean size has pretty well got to increase, and it doesn't imply a driven evolutionary trend towards larger size.
As Gould convincingly argues, the effect is compounded by a human tendency to give undue weight to new arrivals on the geological scene. Textbook biological histories emphasize a progression of grades of organization. As each new grade arrives, there is temptation to forget that the previous grades haven't gone away. Illustrators abet the fallacy when they draw, as representative of each era, only the newcomers. Before a certain date there were no eucaryotes. The arrival of eucaryotes looks more progressive than it really was because of the failure to depict the persisting hordes of procaryotes.
In another essay Gould is encouraged by the genetic closeness of humans and chimpanzees to speculate that 'inter-breeding may well be possible'. I doubt it, but it is a pleasing thought and Gould surely exaggerates when he rates it 'the most . . . ethically unacceptable scientific experiment I can imagine'. For my ethics, far less acceptable experiments are conceivable, and actually done in animal physiology laboratories every day, and a chimp/human hybridization would provide exactly the come-uppance that 'human dignity' needs. Gould is, in general, rather good at puncturing human speciesist vanity, and in particular he will have nothing to do with the myth that evolution represents progress towards man. This scepticism informs his valuable account of 'Bushes and ladders in human evolution', and fires his scorn for attempts to rank human races as primitive or advanced.
He returns to the attack on progress in the very different guise of the theory of orthogenesis, the idea that evolutionary trends have their own internal momentum which eventually drives lineages extinct. His telling of the classic Irish Elk story gains freshness from his intimacy with the fossils of the Dublin Museum and gives the lie to the myth that palaeontology is dry and dull. His conclusion that the proverbially topheavy antlers were important in social life is surely right, but he may underestimate the role of within-species competition in driving species extinct. Large antlers could directly have caused the extinction of the Irish Elk while at the same time, right up to the moment of extinction, individuals with relatively large antlers were out-reproducing indivi- duals with relatively small antlers. I would like to see Gould come to terms with the 'orthoselective' impact of 'arms races' both between and
REJOICING IN MULTIFARIOUS NATURE
191
? EVEN THE RANKS OF TUSCANY
within species. He seems to approach this in his essays on the 'Cambrian explosion'.
Natural history can be sold for its intrinsic fascination, but it is much better used to make a point. Gould tells us about a fly that eats its mother from the inside, about 17-year cicadas and 120-year bamboos, and about uncanny fish-decoying mussels. He employs the useful trick of first opening the reader's mind by boggling it, then filling it with the important biological principle. One principle I would have liked to have heard more on is that of the limitation of evolutionary perfection: 'Orchids are Rube Goldberg machines; a perfect engineer would certainly have come up with something better' (Rube Goldberg is the American Heath Robinson). My own favourite example, inherited from an undergraduate tutor, is the recurrent laryngeal nerve. It starts in the head, goes down into the chest, loops round the aorta, then goes straight back into the head again. In a giraffe this detour must be wasteful indeed. The human engineer who first designed the jet engine simply threw the old propeller engine out and started afresh. Imagine the contraption he would have produced if he had been constrained to 'evolve' his jet engine by changing a propeller engine one bit at a time, nut by nut and bolt by bolt!
While on the problem of perfection, I think Gould exaggerates the relevance of 'neutral mutations'. Molecular geneticists are understandably interested in DNA changes as molecular events, and any that have no effect on protein function may reasonably be called neutral mutations. But to a student of whole organism biology they are less than neutral; they are not, in any interesting sense, mutations at all! If the molecular neutralists are right, their kind of neutral mutation will forever be hidden from the field biologist and from natural selection. And if a field biologist actually sees variation in phenotypes, the question of whether that variation could be selectively neutral cannot be settled in the biochemistry laboratory.
Several essays touch on aspects of the relationship of Darwinism to human society and politics. There is much humane good sense here and I agree with most of it. Although 'sociobiology' is inspiring excellent research, Gould is right that it has also led to some second-rate bandwagoneering. 'But was there ever dog that praised his fleas? ' asked Yeats. Perhaps a dog may be held responsible for the fleas he sheds, but only to a small extent. At the AAAS meeting in Washington in 1997, Gould and I witnessed an organized attack on his most distinguished Harvard colleague. * Gould well deserved his ovation for the apt Lenin quote with which he disowned the rabble. But as he watched those
*A glassful of water was thrown sideways at Professor E. O. Wilson (subsequently exaggerated in various accounts to a 'pitcher of iced water, poured over him').
192
? pathetic fleas ineffectually hopping around the stage chanting, of all things, 'genocide', did he wonder with a little itch of conscience on which dog they had been sucking?
The Epilogue is forward-looking and whets our appetite for Volume 2, which I earnestly hope will be forthcoming. * One theme which I know Gould has already carried further in his Natural History column is his dislike for 'the ultimate atomism' of regarding organisms as 'temporary receptacles . . . no more than instruments that genes use to make more
112
genes like themselves'. In describing this as 'metaphorical nonsense'
Gould underestimates the sophistication of the idea, first cogently
113
expressed in its modern form by George C. Williams. The dispute is
largely semantic. Inclusive fitness is defined in such a way that to say 'the individual works so as to maximize its inclusive fitness' is equivalent to saying 'the genes work so as to maximize their survival'. The two forms are each valuable for different purposes. Both contain an element of personification; it is dangerously easier to personify organisms than to personify genes. The gene selection idea is not naively atomistic, as it recognizes that genes are selected for their capacity to interact productively with the other genes with which they are most likely to share 'receptacles'; this means the other genes of the gene pool; and the gene pool may therefore come to resemble a 'homeostatically buffered system' tending to return to (one of) its evolutionarily stable state(s). Irrevocable determination by genes is no part of the idea nor is anything remotely approaching a 'one gene, one trait' mapping from genotype to phenotype. In any case it has nothing to do with 'supreme confidence in universal adaptation', which is as likely to be found among devotees of 'individual selection' or 'species selection'.
'I will rejoice in the multifariousness of nature and leave the chimera of certainty to politicians and preachers': a resounding conclusion to a stimulating book - the work of a free and imaginative scientific mind. The final, sad paradox is this. How can a mind capable of such rejoicing, open enough to contemplate the shifting splendour of three thousand million years, moved by the ancient poetry written in the rocks, how can such a mind not be bored by the drivelling ephemera of juvenile pamphleteers and the cold preaching of spiteful old hardliners? No doubt they are right that science is not politically neutral. But if, to them, that is the most important thing about science, just think what they are missing! Stephen Gould is well qualified, and strategically placed, to strip away even those dark blinkers and dazzle those poor unpractised eyes.
*In fact, ten volumes were eventually published, the last one, / have Landed, at the time of his death.
REJOICING IN MULTIFARIOUS NATURE
193
? '%t0 M mem
The Art of the Developable
The acknowledged master of biological belles lettres has long been Sir Peter Medawar. If there is a younger biologist or an American biologist that bears comparison, it is probably in both cases Stephen Jay Gould. It was therefore with anticipation that I received these two collections of essays, reflections by leading and highly literate biologists on their subject and its history and philosophy.
Pluto's Republic is one of those titles that cannot be mentioned without an immediate explanation, and Sir Peter begins thus:
A good many years ago a neighbour whose sex chivalry forbids me to disclose [it takes a Medawar to get away with this kind of thing nowadays] exclaimed upon learning of my interest in philosophy: 'Don't you just adore Pluto's Republic? ' Pluto's Republic has remained in my mind ever since as a super- latively apt description of that intellectual underworld which so many of the essays in this volume explore. We each populate Pluto's Republic according to our own prejudices . . .
Here I nursed a mischievous half-hope that Stephen Gould might be found among the denizens of Medawar's private underworld - his more sanctimonious cosignatories of a notorious letter to the New York Review of Books about 'sociobiology' (13 November 1975) are prominent in mine. But Gould is several cuts above those former associates of his and he is not among Medawar's targets. Indeed, they share many targets, IQ- metricians for instance.
Most of the essays in Pluto's Republic have appeared twice before, first as book reviews or transcripts of lectures, then in previous anthologies
116
such as The Art of the Soluble and The Hope of Progress, which were
presumably reviewed at the time. Although I shall therefore give Pluto's Republic less than half my space in this joint review, I vigorously repudiate any mutterings about such second order anthologizing being too much of a good thing. The earlier books have long been out of
194
14 Hen's Teeth and Horse's Toes by Stephen Jay Gould
Review of Pluto's Republic by Peter Medawar'
and 11
? print, and I have been scouring the second-hand bookshops ever since my own Art of the Soluble was stolen. I discovered when I reread them here that I had many favourite passages word-perfect in memory. Who indeed could forget the opening sentence of the 1968 Romanes Lecture, 'Science and Literature'? T hope I shall not be thought ungracious if I say at the outset that nothing on earth would have induced me to attend the kind of lecture you may think I am about to give. ' At the time this prompted the apt rejoinder from John Holloway: 'This lecturer can never have been thought ungracious in his life. '
Or listen to Medawar on another great biologist, Sir D'Arcy Thompson:
. . . He was a famous conversationalist and lecturer (the two are often thought to go together, but seldom do), and the author of a work which, considered as literature, is the equal of anything of Pater's or Logan Pearsall Smith's in its complete mastery of the bel canto style. Add to all this that he was over six feet tall, with the build and carriage of a Viking and with the pride of bearing that comes from good looks known to be possessed.
The reader may be hazy about Logan Pearsall Smith and Pater, but he is left with the overwhelming impression (since he probably is familiar with the idiom of P. G. Wodehouse) of a style that is undoubtedly bel, and may very well be canto. And there is more of Medawar in the passage quoted than Medawar himself realized.
Medawar continually flatters his readers, implying in them an erudition beyond them, but doing it so that they almost come to believe in it themselves:
'Mill,' said John Venn in 1907, has 'dominated the thought and study of intelligent students to an extent which many will find it hard to realise at the present day'; yet he could still take a general familiarity with Mill's views for granted . . .
The reader scarcely notices that Medawar himself is still taking a general familiarity with Mill's views for granted, although in the reader's own case it may be far from justified. 'Even George Henry Lewes found him- self unable to propound his fairly sensible views on hypotheses without prevarication and pursing of the lips. ' The reader's knowing chuckle is out before he realizes that actually he is in no position to respond knowingly to that 'even'.
Medawar has become a sort of chief spokesman for 'The Scientist' in the modern world. He takes a less doleful view of the human predica- ment than is fashionable, believing that hands are for solving problems rather than for wringing. He regards the scientific method - in the right
THE ART OF THE DEVELOPABLE
195
? EVEN THE RANKS OF TUSCANY
hands - as our most powerful tool for 'finding out what is wrong with [the world] and then taking steps to put it right'. As for the scientific method itself, Medawar has a good deal to tell us, and he is well qualified to do so. Not that being a Nobel Prize winner and a close associate of Karl Popper is in itself an indication that one will talk sense: far from it when you think of others in that category. But Medawar not only is a Nobel Prize winner, he seems like a Nobel Prize winner; he is everything we think a Nobel Prize winner ought to be. If you have never understood why scientists like Popper, try Medawar's exposition of the philosophy of his 'personal guru'.
He read Zoology at Oxford, and early in his career made important contributions to classical Zoology, but was soon drawn into the highly populated and highly financed world of medical research. Inevitably, his associates have been molecular and cell biologists, but he seldom had any truck with the molecular chauvinism which plagued biology for two decades. Medawar has a good appreciation of biology at all levels.
He has also inevitably associated with doctors, and the preoccupa- tions and sympathies of a doctor pervade several of these essays, for example his sensitive reviews of books on cancer and psychosomatic heart disease. I especially enjoyed his blistering contempt for psycho- analysis: not a lofty, detached contempt for any ordinary pretentious drivel, but a committed contempt, fired by a doctor's concern. Psychoanalysts have even had their say over the puzzle of Darwin's long illness, and Medawar is at his withering best in telling us about it.
For Good, there is a wealth of evidence that unmistakably points to the idea that Darwin's illness was 'a distorted expression of the aggression, hate and resentment felt, at an unconscious level, by Darwin towards his tyrannical father'. These deep and terrible feelings found outward expression in Darwin's touching reverence towards his father and his father's memory, and in his describing his father as the kindest and wisest man he ever knew: clear evidence, if evidence were needed, of how deeply his true inner sentiments had been repressed.
Medawar, when he smells pretentious pseudoscience, is a dangerous man. His famous annihilation of Teilhard de Chardin's The Phenomenon of Man might have been thought an unfair attack on the dead, but for the extraordinary influence Teilhard exerted (and still exerts: Stephen Gould tells us that two journals established to discuss his ideas still flourish) over legions of the gullible including, I am afraid, my juvenile self. I would love to quote huge chunks of what is surely one of the great destructive book reviews of all time, but must content myself with
196
? two sentences from Medawar's typically barbed explanation of the popular appeal of Teilhard.
Just as compulsory primary education created a market catered for by cheap dailies and weeklies, so the spread of secondary and latterly of tertiary education has created a large population of people, often with well-developed literary and scholarly tastes who have been educated far beyond their capacity to undertake analytical thought . . . [The Phenomenon of Man] is written in an all but totally unintelligible style, and this is construed as prima-facie evidence of profundity.
Medawar's Herbert Spencer Lecture, and his review of Arthur Koestler's Act of Creation, are more respectful of his victims, but pretty punchy nevertheless. His review of Ronald Clark's Life of J. B. S. Haldane is enlivened by personal reminiscence, and reveals a sort of affection for the old brute which seems to have been reciprocated.
I remember Haldane's once going back on a firm promise to chair a lecture given by a distinguished American scientist on the grounds that it would be too embarrassing for the lecturer: he had once been the victim of a sexual assault by the lecturer's wife. The accusation was utterly ridiculous and Haldane did not in the least resent my saying so. He didn't want to be bothered with the chairmanship, and could not bring himself to say so in the usual way.
But if Haldane did not in the least resent Medawar's saying so, one cannot help wondering whether this was only because Medawar must have been one of the very few people Haldane ever met who could look him levelly in the eye, on equal terms intellectually. Peter Medawar is a giant among scientists and a wicked genius with English prose. Even if it annoys you, you will not regret reading Pluto's Republic.
In 1978 the Reviews Editor of a famous scientific journal, whose nature prudence forbids me to disclose, invited me to review Stephen
Jay Gould's Ever Since Darwin, remarking that I could 'get my own back' on opponents of 'genetic determinism'. I don't know which annoyed me more: the suggestion that I favoured genetic 'determinism' (it is one of those words like sin and reductionism: if you use it at all you are against it) or the suggestion that I might review a book for motives of revenge. The story warns my readers that Dr Gould and I are supposed to be on opposites sides of some fence or other. In the event, I accepted the commission and gave the book what could fairly be described as a rave review, even, I think, going so far as to praise Gould's style as a creditable second best to Peter Medawar's. *
*See 'Rejoicing in Multifarious Nature' (pp. 190-3).
THE ART OF THE DEVELOP ABLE
197
? EVEN THE RANKS OF TUSCANY
I feel inclined to do the same for Hen's Teeth and Horse's Toes. It is another collection of essays reprinted from Gould's column in Natural Histor)'. When you have to turn these pieces out once a month you must pick up some of the habits of the professional working to a deadline - this is not a criticism, Mozart did the same. Gould's writing has some- thing of the predictability that we enjoy in Mozart, or in a good meal. His volumes of collected essays, of which this is the third, are put together to a recipe: one part biological history, one part biological politics (less if we are lucky), and one part (more if we are lucky) vignettes of biological wonder, the modern equivalent of a mediaeval bestiary but with interesting scientific morals instead of boring pious ones. The essays themselves, too, often seem to follow a formula or menu. As appetizer there is the quotation from light opera or the classics, or sometimes its place is taken by a piece of reassuring nostalgia; a reminiscence from a normal, happy, very American childhood world of baseball stars and Hershey bars and Bar Mitzvahs - Gould, we learn, is not just one of your pointy-headed intellectuals but a regular guy. This homely informality softens the conspicuous erudition of the main course - the fluency in several languages, the almost Medawarian familiarity with literature and humanities - and even gives it a certain (un-Medawarian) charm (compare Gould himself on Louis Agassiz: '. . . the erudition that has so charmed American rustics . . . ').
Gould's own respect for Medawar is evident. The idea of science as 'the art of the soluble' provides the punchline for at least four of the essays: 'We may wallow forever in the thinkable; science traffics in the doable', '. . . science deals in the workable and soluble'; and two essays end with explicit quotations of the phrase. His view of Teilhard de Chardin's style is similar to Medawar's: '. . . difficult, convoluted writing may simply be fuzzy, not deep'. If he gives Teilhard's philosophy a slightly more sympathetic hearing, he is probably just making amends for his delightfully mischievous thesis that the young Teilhard connived in the Piltdown hoax. For Medawar, Teilhard's accepted role as one of the principal victims of the joke is just more evidence that he was
in no serious sense a thinker. He has about him that innocence which makes it easy to understand why the forger of the Piltdown skull should have chosen Teilhard to be the discoverer of its canine tooth.
Gould's case for the prosecution is a fascinating piece of detective work which I will not spoil by attempting to summarize it. My own verdict is a Scottish 'non-proven'.
198
? In whatever underworld the Piltdown forger languishes, he has a lot to answer for. Only last month an acquaintance, whose sex the grammar of English pronouns will probably force me to disclose, exclaimed upon learning of my interest in evolution: 'But I thought Darwin had been disproved. ' My mind started placing bets with itself: which particular second-hand, distorted half-truth has she misunderstood? I had just put my money on garbled Stephen Gould with a small side bet on (no need to garble) Fred Hoyle, when my companion revealed the winner as an older favourite: T heard that the missing link had now been shown to be a hoax. ' Piltdown, by God, still raising his ugly cranium after all these years!
Incidents like this reveal the extreme flimsiness of the straws that will be clutched by those with a strong desire to believe something silly. There are between 3 and 30 million species alive today, and as many as a billion have probably existed since life began. Just one fossil of just one of those millions of species turns out to be a hoax. Yet of all the volumes and volumes of facts about evolution, the only thing that stuck in my companion's head was Piltdown. A parallel case is the extra- ordinary popular aggrandizement of Eldredge and Gould's theory of 'punctuated equilibrium'. A minor dispute among experts (about whether evolution is smoothly continuous or interrupted by periods of stagnation when no evolutionary change occurs in a given lineage) has been blown up to give the impression that Darwinism's foundations are quivering. It is as if the discovery that the Earth is not a perfect sphere but an oblate spheroid cast sensational doubt on the whole Copernican world view, and reinstated flat-earthism. The anti-Darwinian sounding rhetoric of the punctuated equilibrists was a regrettable gift to creationists. Dr Gould regrets this as strongly as anyone, but I fear his protestations that his words have been misinterpreted will be to little avail. *
Whether Gould really has anything to answer for, he certainly has fought the good fight in the bizarre tragicomedy or tragifarce of modern American evolution politics. He travelled to Arkansas in 1981 to lend his formidable voice to the right side in the 'Scopes Trial IP. His obsession with history even took him on a visit to Dayton, Tennessee, scene of that previous Southern farce, and the subject of one of the
*'Since we proposed punctuated equilibria to explain trends, it is infuriating to be quoted again and again by creationists - whether by design or stupidity, I do not know - as admitting that the fossil record includes no transitional forms. Transitional groups are generally lacking at the species level but they are abundant between larger groups. ' From the essay, 'Evolution as Fact and Theory', p. 260 of Hen's Teeth and Horse's Toes.
THE ART OF THE DEVELOPABLE
199
? EVEN THE RANKS OF TUSCANY
most sympathetic and charming of the essays in the present book. His analysis of the appeal of creationism is wise and should be read by intolerant Darwin-freaks like me.
Gould's tolerance is his greatest virtue as a historian: that and his warmth towards his subjects.
His centennial tribute to Charles Darwin is offbeat in a characteristically delightful and affectionate way. Where others loftily pontificate, Gould goes down to earth and celebrates Darwin's last treatise, on worms. Darwin's worm book is not a 'harmless work of little importance by a great naturalist in his dotage'. It exemplifies his entire world view, based on the power of small causes, working together in large numbers and over long time spans, to wreak great changes:
We who lack an appreciation of history and have so little feel for the aggregated importance of small but continuous change scarcely realize that the very ground is being swept from beneath our feet; it is alive and constantly churning . . . Was Darwin really conscious of what he had done as he wrote his last professional lines, or did he proceed intuitively, as men of his genius some- times do? Then I came to the last paragraph and I shook with the joy of insight. Clever old man; he knew full well. In his last words, he looked back to the beginning, compared those worms with his first corals and completed his life's work in both the large and the small . . .
And the quotation of Darwin's last sentences follows.
Hen's Teeth and Horse's Toes is as enigmatic a title as Pluto's Republic,
and it requires more explanation. If the present volume could be said to exercise a bee in Gould's bonnet, to distinguish it from its two pre- decessors, it is epitomized in the essay of the same name. I will explain the point rather fully, because it is one with which I strongly agree although I am supposed, apparently by Gould himself among others, to hold opposing views. I can sum the point up by giving a new twist to a phrase already twisted by Peter Medawar. If science is the art of the soluble, evolution is the art of the developable.
Development is change within an individual organism, from single cell to adult. Evolution is also change, but change of a type that requires subtler understanding. Each adult form in an evolutionary series will appear to 'change' into the next, but it is change only in the sense that each frame on a movie film 'changes' into the next. In reality, of course, each adult in the succession begins as a single cell and develops anew. Evolutionary change is change in genetically controlled processes of embryonic development, not literal change from adult form to adult form.
200
? Gould fears that many evolutionists lose sight of development, and this leads them into error. There is firstly the error of genetic atomism, the fallacious belief in a one-to-one mapping between single genes and bits of body. Embryonic development doesn't work like that. The genome is not a 'blueprint'. Gould regards me as an arch genetic
117
atomist, wrongly, as I have explained at length elsewhere. It is one of
those cases where you will misunderstand an author unless you interpret his words in the context of the position he was arguing against.
Consider the following, from Gould himself:
Evolution is mosaic in character, proceeding at different rates in different structures. An animal's parts are largely dissociable, thus permitting historical change to proceed.
This appears to be rampant, and very un-Gouldian, atomism! Until you realize what Gould was arguing against: Cuvier's belief that evolution is impossible because change in any part is useless unless immediately accompanied by change in all other parts. * Similarly, the apparent genetic atomism that Gould criticizes in some other authors makes sense when you realize what those authors were arguing against: 'group selection' theories of evolution in which animals are supposed to act for the good of the species or some other large group. An atomistic inter- pretation of the role of genes in development is an error. An atomistic interpretation of the role of genetic differences in evolution is not an error, and is the basis of a telling argument against errors of the 'group selection' kind.
Atomism is just one of the errors that Gould sees as flowing from evolutionists' cavalier treatment of development. There are two others which are, on the face of it, opposite to each other: the error of assuming that evolution is too powerful, and the error of assuming that it is not powerful enough. The naive perfectionist believes that living material is infinitely ductile, ready to be shaped into whatever form natural selection dictates. This ignores the possibility that developmental processes are incapable of producing the desired form. The extreme 'gradualist' believes that all evolutionary changes are tiny, forgetting, according to Gould, that developmental processes can change in very large and complex ways, in single mutational steps. The general point, that we have to understand development before we can speculate constructively about evolution, is correct.
This must be what Medawar meant when he complained about 'the
*A doctrine recently revived as 'irreducible complexity' under the mistaken impression that it is new.
THE ART OF THE DEVELOPABLE
201
? EVEN THE RANKS OF TUSCANY
real weakness of modern evolutionary theory, namely its lack of a complete theory of variation, of the origin of candidature for evolution'. And this is why Gould is interested in hens' teeth and horses' toes. He makes the point that atavistic 'throwbacks', like hens with teeth and horses with three toes rather than one, are interesting because they tell us about the magnitude of evolutionary change that development allows. For the same reason he is interested in (and very interesting on) the development of zebras' stripes, and macromutations like insects with supernumerary thoraxes and wings.
I said that Gould and I were supposed to be professional adversaries and I would be disingenuous to pretend to like everything in this book. Why, for instance, does he find it necessary, after the phrase 'A strict Darwinian', to add '- I am not one -'? Of course Gould is a strict Darwinian, or if he isn't, nobody is; if you interpret 'strict' strictly enough, nobody is a strict anything. It is a pity, too, that Gould is still preaching against innocuous phrases like 'adultery in mountain bluebirds' and 'slavery in ants'. His rhetorical question about his own disapproval of such harmless anthropomorphisms, 'Is this not mere pedantic grousing', should be answered with a resounding 'Yes'. Gould himself made unselfconscious use of 'slavery of ants' in his own account
of the phenomenon (Ever Since Darwin; presumably this was written in the days before some pompous comrade spotted the dangerous ideological implications of the phrase). Since our language grew in a human setting, if biologists tried to ban human imagery they would almost have to stop communicating. Gould is an expert communicator, and of course he in practice treats his own puritanical strictures with the contempt that he secretly knows they deserve. The very first essay
of the present book tells us how two angler fish (anglerfish? )are caught 'in flagrante delicto' and discover 'for themselves what, according to Shakespeare, "every wise man's son doth know" - "journeys end in lovers meeting"'.
This is indeed a beautiful book, the pages glowing with a naturalist's love of life and a historian's respect and affection for his subjects, the vision extended and clarified by a geologist's familiarity with 'deep time'. To borrow a Medawarian phrase and like Peter Medawar himself, Stephen Gould is an aristocrat of learning. These are both extra- ordinarily gifted men, with some of the arrogance natural to aristocrats and those who have always been top of every class of which they have been members, but big enough to get away with it and generous enough to rise above arrogance too. Read their books if you are a scientist and, especially, read them if you are not.
202
? So
Hallucigenia, Wiwaxia and Friends1
Review of Wonderful Life by S. J. Gould
Wonderful Life is a beautifully written and deeply muddled book. To make unputdownable an intricate, technical account of the anatomies of worms, and other inconspicuous denizens of a half-billion-year-old sea, is a literary tour de force. But the theory that Stephen Gould wrings out of his fossils is a sorry mess.
The Burgess Shale, a Canadian rock formation dating from the Cambrian, the earliest of the great fossil eras, is a zoological treasury. Freak conditions preserved whole animals, soft parts and all, in full 3-D. You can literally dissect your way through a 530-million-year-old animal. C. D. Walcott, the eminent palaeontologist who discovered the Burgess fossils in 1909, classified them according to the fashion of his time: he 'shoehorned' them all into modern groups. 'Shoehorn' is Gould's own excellent coining. It recalls to me my undergraduate impatience with a tutor who asked whether the vertebrates were descended from this invertebrate group or that. 'Can't you see,' I almost shouted, 'that our categories are all modern? Back in the Precambrian, we wouldn't have recognized those invertebrate groups anyway. You are asking a non- question. ' My tutor agreed, and then went right on tracing modern animals back to other modern groups.
That was shoehorning, and that is what Walcott did to the Burgess animals. In the 1970s and 80s, a group of Cambridge palaeontologists returned to Walcott's museum specimens (with some newer collections from the Burgess site), dissected their 3-dimensional structure and overturned his classifications. These revisionists, principally Harry Whittington, Derek Briggs and Simon Conway Morris, are the heroes of Gould's tale. He milks every ounce of drama from their rebellion against the shoehorn, and at times he goes right over the top: T believe that Whittington's reconstruction of Opabinia in 1975 will stand as one of the great documents in the history of human knowledge. '
Whittington and his colleagues realized that most of their specimens
203
? EVEN THE RANKS OF TUSCANY
were far less like modern animals than Walcott had alleged. By the end of their epic series of monographs they thought nothing of coining a new phylum for a single specimen ('phylum' is the highest unit of zoological classification; even the vertebrates constitute only a sub- category of the Phylum Chordata). These brilliant revisions are almost certainly broadly correct, and they delight me beyond my under- graduate dreams. What is wrong is Gould's usage of them. He concludes that the Burgess fauna was demonstrably more diverse than that of the entire planet today, he alleges that his conclusion is deeply shocking to other evolutionists, and he thinks that he has upset our established view of history. He is unconvincing on the first count, clearly wrong on the second two.
In 1958 the palaeontologist James Brough published the following remarkable argument: evolution must have been qualitatively different in the earliest geological eras, because then new phyla were coming into existence; today only new species arise! The fallacy is glaring: every new phylum has to start as a new species. Brough was wielding the other end of Walcott's shoehorn, viewing ancient animals with the misplaced hindsight of a modern zoologist: animals that in truth were probably close cousins were dragooned into separate phyla because they shared key diagnostic features with their more divergent modern descendants. Gould too, even if he is not exactly reviving Brough's claim, is hoist with his own shoehorn.
How should Gould properly back up his claim that the Burgess fauna is super-diverse? He should - it would be the work of many years and might never be made convincing - take his ruler to the animals them- selves, unprejudiced by modern preconceptions about 'fundamental body plans' and classification. The true index of how unalike two animals are is how unalike they actually are. Gould prefers to ask whether they are members of known phyla. But known phyla are modern constructions. Relative resemblance to modern animals is not a sensible way of judging how far Cambrian animals resemble one another.
The five-eyed, nozzle-toting Opabinia cannot be assimilated to any textbook phylum. But, since textbooks are written with modern animals in mind, this does not mean that Opabinia was, in fact, as different from its contemporaries as the status 'separate phylum' would suggest. Gould makes a token attempt to counter this criticism, but he is hamstrung by dyed-in-the-wool essentialism and Platonic ideal forms. He really seems unable to comprehend that animals are continuously variable functional machines. It is as though he sees the great phyla not diverging from early blood brothers but springing into existence fully differentiated.
204
? Gould, then, singularly fails to establish his super-diversity thesis. Even if he were right, what would this tell us about 'the nature of history'? Since, for Gould, the Cambrian was peopled with a greater cast of phyla than now exist, we must be wonderfully lucky survivors. It could have been our ancestors who went extinct; instead it was Conway Morris's 'weird wonders', Hallucigenia, Wiwaxia and their friends. We came 'that close' to not being here.
Gould expects us to be surprised. Why? The view that he is attacking
- that evolution marches inexorably towards a pinnacle such as man -
has not been believed for years. But his quixotic strawmandering, his
shameless windmill-tilting, seem almost designed to encourage mis-
understanding (not for the first time: on a previous occasion he went so
far as to write that the neo-Darwinian synthesis was 'effectively dead').
The following is typical of the publicity surrounding Wonderful Life
(incidentally, I suspect that the lead sentence was added without the
knowledge of the credited journalist): 'The human race did not result
from the "survival of the fittest", according to the eminent American
professor, Stephen Jay Gould. It was a happy accident that created
119
Mankind. ' Such twaddle, of course, is nowhere to be found in Gould,
but whether or not he seeks that kind of publicity, he all too frequently attracts it. Readers regularly gain the impression that he is saying something far more radical and surprising than he actually is.
Survival of the fittest means individual survival, not survival of major lineages. Any orthodox Darwinian would be entirely happy with major extinctions being largely a matter of luck. Admittedly there is a minority of evolutionists who think that Darwinian selection chooses between higher-level groupings. They are the only Darwinians likely to be disconcerted by Gould's 'contingent extinction'. And who is the most prominent advocate of higher-level selection today? You've guessed it. Hoist again!
HALLUCIGENIA, WIWAXIA AND FRIENDS
205
? 5. 4
Human Chauvinism and
Evolutionary Progress120 Review of Full House by S. J. Gould
I
This pleasantly written book has two related themes. The first is a statistical argument which Gould believes has great generality, uniting baseball, a moving personal response to the serious illness from which, thankfully, the author has now recovered, and his second theme: that of whether evolution is progressive. The argument about evolution and progress is interesting - though flawed as I shall show - and will occupy most of this review. The general statistical argument is correct and mildly interesting, but no more so than several other homilies of routine methodology about which one could sensibly get a bee in one's bonnet.
Gould's modest and uncontroversial statistical point is simply this. An apparent trend in some measurement may signify nothing more than a change in variance, often coupled with a ceiling or floor effect. Modern baseball players no longer hit a 0. 400 (whatever that might be - evidently it is something pretty good). But this doesn't mean they are getting worse. Actually everything about the game is getting better and the variance is getting less. The extremes are being squeezed and 0. 400 hitting, being an extreme, is a casualty. The apparent decrease in batting success is a statistical artefact, and similar artefacts dog generalizations in less frivolous fields.
That didn't take long to explain, but baseball occupies 55 jargon- ridden pages of this otherwise lucid book and I must enter a mild protest on behalf of those readers who live in that obscure and little known region called the rest of the world. I invite Americans to imagine that I spun out a whole chapter in the following vein:
The home keeper was on a pair, vulnerable to anything from a yorker to a chinaman, when he fell to a googly given plenty of air. Silly mid on appealed for leg before, Dicky Bird's finger shot up and the tail collapsed. Not surprisingly, the skipper took the light. Next morning the night watchman, defiantly out of his popping crease, snicked a cover drive off a no ball straight through the gullies and on a fast outfield third man failed to stop the boundary . . . etc. etc.
206
? HUMAN CHAUVINISM AND EVOLUTIONARY PROGRESS
Readers in England, the West Indies, Australia, New Zealand, India, Pakistan, Sri Lanka and anglophone Africa would understand every word, but Americans, after enduring a page or two, would rightly protest.
Gould's obsession with baseball is harmless and, in the small doses to which we have hitherto been accustomed, slightly endearing. But this hubristic presumption to sustain readers' attention through six chapters of solid baseball chatter amounts to American chauvinism (and I suspect American male chauvinism at that). It is the sort of self-indulgence from which an author should have been saved by editor and friends before publication - and for all I know they tried. Gould is normally so civilized in his cosmopolitan urbanity, so genial in wit, so deft in style. This book has a delightfully cultivated yet unpretentious 'Epilog on Human Culture' which I gratefully recommend to anyone, of any nation. He is so good at explaining science without jargon yet without talking down, so courteous in his judgement of when to spell out, when to flatter the reader by leaving just a little unsaid. Why does his gracious instinct desert him when baseball is in the air?
Another minor plaint from over the water, this time something which is surely not Dr Gould's fault: may I deplore the growing publishers' habit of gratuitously renaming books when they cross the Atlantic (both ways)? Two of my colleagues are at risk of having their (excellent, and already well-named) books retitled, respectively, 'The Pelican's Breast' and 'The Pony Fish's Glow' (now what, I wonder, can have inspired such flights of derivative imagination? ) As one embattled author wrote to me, 'Changing the title is something big and important they can do to justify their salaries, and it does not require reading the book, so that's why they like it so much. ' In the case of the book under review, if the author's own title, Full House, is good enough for the American market, why is the British edition masquerading under the alias of Life's Grandeur? Are we supposed to need protection from the argot of the card table?
At the best of times such title changes are confusing and mess up our literature citations. This particular change is doubly unfortunate because Life's Grandeur (the title, not the book) is tailor-made for confusion with Wonderful Life, and nothing about the difference between the titles conveys the difference between the contents. The two books are not Tweedledum and Tweedledee, and it is unfair on their author to label them as if they were. More generally, may I suggest that authors of the world unite and assert their right to name their own books.
Enough of carping. To evolution: is it progressive? Gould's definition of progress is a human-chauvinistic one which makes it all too easy to
207
? EVEN THE RANKS OF TUSCANY
deny progress in evolution. I shall show that if we use a less anthro- pocentric, more biologically sensible, more 'adaptationist' definition, evolution turns out to be clearly and importantly progressive in the short to medium term. In another sense it is probably progressive in the long term too.
Gould's definition of progress, calculated to deliver a negative answer to the question whether evolution is progressive, is
a tendency for life to increase in anatomical complexity, or neurological elaboration, or size and flexibility of behavioral repertoire, or any criterion obviously concocted (if we would only be honest and introspective enough about our motives) to place Homo sapiens atop a supposed heap.
My alternative, 'adaptationist' definition of progress is
a tendency for lineages to improve cumulatively their adaptive fit to their particular way of life, by increasing the numbers of features which combine together in adaptive complexes.
I'll defend this definition and my consequent, limited, progressivist conclusion, later.
Gould is certainly right that human chauvinism, as an unspoken
motif, runs through a great deal of evolutionary writing. He'll find even
better examples if he looks at the comparative psychology literature,
which is awash with snobbish and downright silly phrases like
'subhuman primates', 'subprimate mammals' and 'submammalian
vertebrates', implying an unquestioned ladder of life denned so as to
perch us smugly on the top rung. Uncritical authors regularly move 'up'
or 'down' the 'evolutionary scale' (bear in mind that they are in fact
moving sideways among modern animals, contemporary twigs dotted
all around the tree of life). Students of comparative mentality
unabashedly and ludicrously ask, 'How far down the animal kingdom
does learning extend? ' Volume 1 of Hyman's celebrated treatise on the
invertebrates is entitled 'Protozoa through Ctenophora' (my emphasis) -
as if the phyla exist along an ordinal scale such that everybody knows
which groups sit 'between' Protozoa and Ctenophora. Unfortunately,
all zoology students do know - we've all been taught the same
121 groundless myth.
This is bad stuff, and Gould could afford to attack it even more severely than he attacks his normal targets. Whereas I would do so on logical grounds, Gould prefers an empirical assault. He looks at the actual course of evolution and argues that such apparent progress as can in general be detected is artefactual (like the baseball statistic). Cope's
208
? HUMAN CHAUVINISM AND EVOLUTIONARY PROGRESS
rule of increased body size, for example, follows from a simple 'drunkard's walk' model. The distribution of possible sizes is confined by a left wall, a minimal size. A random walk from a beginning near the left wall has nowhere to go but up the size distribution. The mean size has pretty well got to increase, and it doesn't imply a driven evolutionary trend towards larger size.
As Gould convincingly argues, the effect is compounded by a human tendency to give undue weight to new arrivals on the geological scene. Textbook biological histories emphasize a progression of grades of organization. As each new grade arrives, there is temptation to forget that the previous grades haven't gone away. Illustrators abet the fallacy when they draw, as representative of each era, only the newcomers. Before a certain date there were no eucaryotes. The arrival of eucaryotes looks more progressive than it really was because of the failure to depict the persisting hordes of procaryotes.
