Small Items with Big Implications

In the concluding essay of an adventurous collection, Stephen Jay Gould observes that most ‘classic stories’ in science are wrong. There are good reasons why he is right. In their reconstruction of the past, practising scientists have been apt to celebrate the insight of those who anticipated their own ideas, tacitly dismissing those who were blind to where the future would lie. The result has often been sterile histories, distorted by a preoccupation with confirming the present. The apocalyptic aspects of science, with the next breakthrough just around the corner, may add to the distortion by a more general undervaluation of the past. And the distortion is often sealed by an appeal to history for corroboration of fashionable stereotypes of scientific method, the classic discoveries having been made by ‘prepared minds’ whose interrogation of nature was conducted according to the canons of inductivism, hypothetico-deductivism or some transcendent hybrid. Consequently, science carries along a false history which, like a recessive gene, can pass undetected from one generation to the next. Not one of the least justifications for serious scholarship in the history of science is that it can rectify the distorted vision which the textbook traditions enshrine. It is a justification which Gould happily accepts. Whilst the majority of the 30 essays which compose Hen’s Teeth and Horse’s Toes divulge the latest news in natural history, at least a third have the additional merit of bringing a critical history of science to a larger audience. Gould’s iconoclastic remark occurs in a discussion of a 19th-century ‘fact’, the history of which raises interesting questions indeed. This ‘fact’ was the ability of sires to influence subsequent progeny not fathered by them. One example was familiar and acceptable to Charles Darwin: the successive offspring of Lord Morton’s mare. Crossed with a quagga (a now extinct zebra with stripes confined to neck and forequarters), the Arab mare delivered a hybrid with stripes in evidence. Subsequently mated with a black Arab stallion, the mare again produced an offspring resembling the quagga. This curious form of action at a distance was given a name (telegony) and even inspired a major programme of experimental breeding. As a ‘fact’ it was comfortably embedded in most of the genetic theories of the time (including Darwin’s own) and was only rejected when August Weismann made it impossible in theory – the theory he erected on the continuity of the germ plasm and its protection from extraneous influence. Now for the moral. By contrast with the adage that an unquestioned theory may be overthrown by one novel fact, we have the illuminating case of an unquestioned fact being overthrown by one novel theory.

This example epitomises Gould’s predilection for the curious, for seeming trivia in both natural history and its history from which engaging lessons may be drawn. The essays here, with only three exceptions, have already appeared in the author’s monthly column for Natural History Magazine. The one theme which unites them is that they contain ‘small items with big implications’. If Darwin’s path to the validity of evolution was strewn with barnacles and worms, so Gould, in turn, would have us consider the minutiae of the biological world: species of anglerfish in which the male, minute compared with the female, fuses so permanently with her that he becomes dependent upon her for nutrition; ichneumons with their habit of laying eggs in caterpillars and the ensuing grizzly death that so offended Darwin’s sensibilities; true mites, histiostoma murchiei, in which the female is spared the task of finding a husband by laying them – the husband-producing eggs, that is; the spotted hyena in which the female sexual apparatus so closely mimics that of the male that the clitoris is no smaller than the penis; toothless hens whose chick epithelium can still produce enamel and induce dentin in mice; horses with more toes than the statutory hoof. Each of these curiosities, and the many more with which the book abounds, provides the occasion for a homily on what may or may not be inferred about nature and science. His anglerfish shows there is no law in nature which says that females must be smaller and subordinate to males. The ichneumon shows that aesthetic and moral values cannot, in any case, be deduced from the products of natural selection. The mode of sex determination devised by ancient and lonely mites, and its subsequent role in the very different and highly differentiated societies of ants and bees, demonstrate that the current utility of a particular feature may be a poor guide to its evolutionary origin. The genitalia of the female spotted hyena invite explanation in terms of developmental anatomy and not merely adaptive utility. The properties of chick epithelium illustrate the existence of a latent genetic flexibility retained from a distant past; while extra digits in horses suggest that genetic systems may contain hidden capacities for producing large effects from small changes.

The big implications may begin to sound familiar. They point towards a critique of neo-Darwinian gradualism for which the author enjoys renown or notoriety depending on one’s point of view. Certain themes therefore recur. The ‘fact’ of evolution is ‘proved’ from those imperfections in living organisms which betray a history of descent. The self-styled ‘scientific creationists’ have no leg to stand on and are simply playing politics. Natural selection must not be construed as a perfecting principle in any strong sense of perfection. Neo-Darwinists who look to adaptive utility as the key to every explanation are as myopic as the natural theologians of the early 19th century who saw in the utility of every organ the stamp of its divine origin. It is intriguing that Gould should make that comparison because it is the basis on which historians of science have asserted continuity between the natural theology tradition and Darwin’s own theorising. Another recurrent theme is the extent to which the course of evolution has been constrained by the simple fact that organisms inherit a body structure and style of embryonic development which impose limits on the scope of transformation: ‘in many cases, evolutionary pathways reflect inherited patterns more than current environmental demands.’ The relevance of the structural constraints is brought home with an entertaining digression on wheels and why nature failed to invent them. The same concern with structural constraint underlies his complaint that unity of design has been neglected as a regulative principle in the practice of research. As for the dynamics of evolutionary change, Gould reaffirms his model of punctuated equilibrium: the changes are episodic, the pace of change jerky.

These are the issues on which many discussions of Gould’s work have already been focused. There are, however, other contentions in these essays which raise questions of wide philosophical interest. In clarifying the distinction between the selfish gene hypothesis of Richard Dawkins and the selfish DNA hypothesis of Francis Crick, he is led into an enlightening discussion of biological reductionism. The Darwinism of Dawkins is thoroughly reductionist, in the sense that bodies are merely temporary containers for their selfish genes: the genes themselves increase in frequency because they have effects upon bodies which facilitate survival. On the Crick hypothesis, middle-repetitive DNA increases in frequency for the opposite reason: it has no initial effect on bodies and is therefore not suppressed at the higher level of organisation until, eventually, the cost in wasted energy enters the equation. As the distinction is articulated, Gould moves towards the assertion that selection operates on several levels from gene up to body, with the levels connected by complex ties of feedback. Consequently, his own sympathies lie with a hierarchical rather than a crude reductionist model. His antipathy towards reductionist schema finds expression, too, in a lively critique of sociobiologists, who, in his estimation, rush headlong into the zoocentric fallacy of reducing human behaviour to sets of traits ostensibly discernible in other animals but frequently projected upon them with the eventual reduction in mind. He is equally critical of the anthropocentric fallacy which makes of man the measure of the universe and the goal of the evolutionary process. He therefore parts company with those architects of theistic evolution, such as Teilhard de Chardin, for whom the branches of the evolutionary tree point in the same direction. Teilhard suffers, too, in a historical reconstruction which sensitively and without malice implicates him in the Piltdown conspiracy as one who had been privy to a joke which disastrously backfired. The one essay which has not been published before constitutes a reasoned reply to critics of that reconstruction who, in Gould’s opinion, have yet to offer a more persuasive account of Teilhard’s embarrassed silence.

The role of ‘chance’ or randomness in evolution is the other philosophical issue on which the author may be read with profit. Randomness, he suggests, is challenging the determinism of natural selection on three fronts. Some, perhaps even many, genes may be neutral, ‘invisible’ to natural selection and therefore preserved or increased as a result of chance alone. Where there is an exclusive harem structure of kin breeding, with a chromosomal mutation in the dominant male, the new chromosome may establish itself irrespective of whether it confers advantage or not. And looking at the overall pattern of rise and fall in the history of life, when as many as 96 per cent of existing species could perish at the end of the Permian, one might think that some species have been more fortunate than others and survived for ‘no particular reason at all’. In suggesting that these chance elements are analogous to the effects of free will, he is, however, begging some large questions.

There is, I believe, one philosophical issue to which he fails to do justice, despite a valiant attempt. His object is to establish criteria whereby ‘sturdy facts’ can be distinguished from ‘flimsy facts’ – a necessary undertaking if one wishes to affirm the fact of evolution against creationists who distressingly seize any critique (Gould’s own included) of neo-Darwinian theory as evidence against the fact. The issue is whether such a complex ‘fact’ as organic evolution can be as conveniently separated from the theories which describe the mechanism as Gould’s rejoinder requires. The ‘fact’ is surely theory-dependent to the extent that every mechanism that has ever been proposed has had a different set of implications for the precise course which evolution has followed. No more than Gould himself would I wish to imply that the case for evolution is any less than overwhelming, but by his own admission ‘ “facts” cannot be divorced from cultural contexts.’ And this makes it all the more difficult to establish criteria whereby the inverted commas may be removed. Gould’s proposal is that ‘sturdy facts are pervasive patterns in nature’ whilst flimsy facts are individual peculiarities. But this barely succeeds in relegating his own example (the 19th-century fact of telegony) to the flimsy category in which it apparently ought to go. During the seventy years when it was accepted it surely was part of a wider pattern which included Darwin’s theory of pangenesis. It meshed – a word Gould cannot avoid: ‘telegony meshed well with pangenesis because gemmules included with the quagga’s sperm would have remained in the body of Lord Morton’s mare and extended their influence to her subsequent offspring.’ Perhaps what the history of science really shows is that the sturdy and the flimsy can only be fully differentiated with the privilege of hindsight. Which is why so many of the classic ‘crucial experiments’ in science were not crucial at the time they were made.

So we are back again with the classic stories being wrong. Some of them Gould himself puts right. Take the case of the late-18th-century thinker James Hutton, whose Theory of the Earth was a milestone in the emergence of modern geology because of the systematic manner in which he interpreted earth history in terms of causes which could be seen to be acting in the present. Cyclic processes of elevation, erosion, deposition and consolidation had been at work for so long that there was neither vestige of a beginning nor prospect of an end. In the textbook traditions this apparent blow against theological and teleological reasoning is still attributed, as it was by Sir Andrew Geikie, to Hutton’s scrupulous inductivism: ‘He made no assumptions. Every step in his deductions was based upon actual fact.’ As Gould correctly points out, the very opposite was the case. Hutton’s radical conclusions were actually based on a form of teleological reasoning. A solid body of land, Hutton explained, ‘could not have answered the purpose of a habitable world’. The answer, in fact, lay in the soil, so necessary for the growth of plants. But the same processes of erosion which produced soil from mountains would in time destroy the land. Accordingly, if the world was the work of ‘infinite power and wisdom’ there had to be restorative forces, which he went on to locate in the earth’s central fire. The Huttonian cycles, in other words, were grounded in teleological reasoning which presupposed that nature purposed the maintenance of plants and animals. The classic story that mechanical philosophies of nature eliminated final causes simply will not do. Hutton’s reasoning offers a striking parallel with that of Joseph Priestley, the 250th anniversary of whose birth has just been celebrated. Priestley’s discovery of photosynthesis was the result of a long inquiry sustained by the conviction that if nature was the work of benevolence there must be a restorative process. Air rendered noxious by breathing had to be restored somehow to its former salubrious condition.

Or take the case of Hutton’s contemporary Georges Cuvier, whose opposition to theories of evolution has commonly led to the judgment that, whatever the merits of his comparative anatomy and paleontology, his conclusions were compromised by a theological mentality. Gould points out, again correctly, that the very doctrines for which he stands condemned – creationism and catastrophism – regulated research strategies which established the foundations of modern geology: the successive extinctions of the fossil record and the long chronology for earth history. Affirming that organisms, past and present, were created as integrated wholes, he could not bring himself to countenance evolution since any incipient transformation would be detrimental to the organism. This same view, with its emphasis on parts indissolubly correlated, also regulated his reconstruction of fossil species which diverged so significantly from extant forms that there was no way of avoiding a long and involved history of creation and extinction. Creationism did once serve a useful scientific function in establishing (against Lamarck, for example) that extinction had occurred and in a pattern which demanded aeons of time. The classic story that catastrophism with its paroxysms and floods was generally a device to compress earth history is not itself watertight. As Gould himself writes, ‘a claim that paroxysms sometimes engulf the earth dictates no conclusion about its age.’

A sympathetic account of Cuvier makes an ideal introduction to Rupke’s reappraisal of William Buckland and the English School of Geology. For Rupke, too, is doing battle with the story that modern geology had its roots in the uniformitarianism of Hutton and Charles Lyell to the exclusion of the catastrophism of Cuvier and his English disciples, the clerical geologists of Oxbridge. The conventional line used to be that Buckland, Conybeare, Sedgwick and Whewell so twisted their geological columns to accommodate a Biblical flood, or an interventionist God, that it required the secular insights of Lyell to sort out the mess. This story, disseminated by Gillispie in Genesis and Geology, has already been much qualified. It has become clear, for example, that one must distinguish two components in Lyell’s uniformitarianism – that the forces which shaped the earth’s surface in the past were of the same kind and the same intensity as those acting in the present. The conventional antithesis between catastrophism and uniformitarianism then fails, for the alleged catastrophists did not doubt that the same kind of forces were at work. The issue was their intensity, on which, from the perspective of Buckland, Sedgwick and Whewell, Lyell was taking an unwarranted a-priori stand. Similarly, it has been argued that the synthesis against which Lyell reacted can best be described as ‘directionalist’ rather than ‘catastrophist’ because the essence of the progressive creationist position was that the fossil record did indicate advances in complexity. In denying progression Lyell, as others have observed, was out on a limb. Nor will it do to extol Lyell’s geology as a triumph for secularism, because Lyell himself considered it one of the best arguments for design that Providence had inserted new species during earth history in perfect co-ordination with the receptivity of the physical environment.

One of my minor complaints about Rupke’s otherwise challenging revision is that he tends to conceal the hefty qualifications that already exist in the literature. His rescue act on Buck-land is, however, new in the sense that it incorporates useful manuscript material in a resolute attempt to locate the extension of historical geology in the work of an English school which deliberately distanced itself from a rival Scottish system which, as represented by Hutton and later Lyell, was profoundly unhistorical in its dependence on recurring cycles. Against the view that it was Lyell’s Principles of Geology that persuaded Buckland and Sedgwick to abandon the Biblical deluge as a geological agent, Rupke notes that the real determinant of their renunciation was the absence of antediluvian human remains in the diluvial gravel. This is typical of a thesis which maximises the radicalism of Buckland and minimises the relevance of Lyell.

It takes a little readjustment to think of Buckland as a radical. He had once implied that geology spoke so forcibly of Noah’s flood that it would have been a necessary postulate even were it not known from Scripture. When the British Association for the Advancement of Science came to Oxford in 1832 he gripped an overcrowded Holywell Music Room, almost till midnight, with the wondrous design of the giant sloth, so perfectly equipped for excavating his diet of roots that he ‘would drain all Lincolnshire in the ordinary process of digging for his daily food’. Much of his radicalism, as Rupke contends, consisted in the simple fact of his preaching the gospel of geology within a university steeped in the Classics for its conceptions of history. It was geology not Scripture that had to be vindicated. And there was the rub: for Buckland, despite his theocentric perspective, dug some dangerous things from the ground. The diversity of bones in a Kirkdale cave suggested it had once been a hyena den. One could then argue for a catastrophic torrent which caught the last hyena generation on the hop, there being no remains of the hyenas themselves. But, as Rupke shows, the theory was more subversive than it appears. The cave fossils were not themselves relics of the deluge, but of the feeding habits of hyenas accumulating over a long antediluvian period. If the fossils had arisen in situ (rather than being swept there by a global flood) the universality of the Biblical deluge was possibly impugned. So, too, was the prevailing theory of how the deluge had been caused. The straight interchange of land and sea was an option now closed by the fact that the Kirkdale hyenas could not have munched at the bottom of the sea. For Buckland this was all good clean fun, even when he turned his attention to fossil excrement. There he was able to show that ichthyosaurs had been eating each other long before Adam fell – which to those feeding on their Milton and St Paul was decidedly unfunny.

Buckland’s contribution, Rupke suggests, has to be assessed, not against the background of European geology, but against the foreground of educational reform at Oxford. One is made a little anxious by this because there is a danger of confusing understanding with evaluation. That Buckland was radical by Oxford standards does not automatically bring him to the forefront of geological research, which is where Rupke wants him to be. But one’s anxiety is partially quelled by the subsequent discussion, which succeeds in conveying the achievements of the English geologists with Buckland at their eccentric point. In their study of comparative stratigraphy, their reconstruction of reptilian fossils and their directionalist interpretation of the fossil record, they did more than merely embellish a new historical science. Buckland himself was into footprints, from which he created the most vivid pictures of reptilian ecology. He was also the first, and the least incredulous, English convert to Agassiz’s theory of glaciation, his conversion rendered all the more explicable by his having formerly been a diluvialist. In Buckland’s world, epochs had come and gone and so had God’s creatures. But it was not evolution. Literary critics who have seen in Tennyson’s poetry glimpses of Darwin’s world or glimpses of Lyell’s geology are severely rebuked by Rupke, who indicates, persuasively, that In Memoriam was informed not by Lyell but by the progressive creationism of Buckland and his school.

One of the welcome features of Rupke’s work is his recognition that the directionalist synthesis was developed with a sense of urgency and excitement, not because it shattered the arguments of natural theology, but because it enhanced them. Against the old atheism, which had species existing from eternity, the fossil record was decisive: each species had a beginning, albeit a different one, in time. And, as Rupke also insists, it was vital for Buckland to wrap his fossils in the vocabulary of natural theology if the new science was to enter Oxford safely. The irony is that the Tractarians soon spotted the trick and duly advertised the inadequacies of natural theology as a Christian apologia. Rupke’s analysis is in line with that of other historians who have been stressing that the form and fortunes of natural theology have to be related to the wider social context in which the arguments were struck. Appeals to design were a useful (and no doubt sincere) gambit in promoting science against clerical opposition and were also useful in mediating between different doctrinal traditions. In Buckland’s case, the providential direction to which they referred was underlined by Britain’s industrial expansion. God was an Anglophile who had ensured that coal, iron ore and limestone were in the right place at the right time.

If it is one of the strengths of Rupke’s analysis that he places the arguments of natural theology in their social and economic context, it is arguably a weakness of Gould’s that, when he reflects on their demise, he finds the impact of Darwin a sufficient explanation. It is one of the truly classic stories of science that Darwin showed how natural selection could counterfeit design, with dire consequences for the Designer. For all Gould’s iconoclasm, this is one story he is not prepared to question. Buckland’s theologising, already vulnerable to the ichneumon fly, was smashed by a biological hammer. But was it that simple? During the course of the 19th century, with the emergence of a self-consciously ‘professional’ scientific élite, the clerical scientists, of whom Buckland was the type, were fast becoming an extinct breed. By the 1860s and 1870s there were fewer pressures for men of science to placate clerical practitioners or clerical opponents of their craft. And there were fewer social penalties to pay for religious deviation. The several mediating functions which design arguments had fulfilled were becoming increasingly redundant, irrespective of their intellectual status. Darwin’s science had a profound and enduring impact to be sure, but that must not be allowed to be the whole story.