Darwin’s Revolution

Scientists are infatuated with the idea of revolution. Even before the publication of Thomas Kuhn’s The Structure of Scientific Revolutions,¹ and with ever increasing frequency after it, would-be Lenins of the laboratory have daydreamed about overthrowing the state of their science and establishing a new intellectual order. After all, who, in a social community that places so high a value on originality, wants to be thought of as a mere epigone, carrying out “normal science” in pursuit of a conventional “paradigm”? Those very terms, introduced by Kuhn, reek of dullness and conventionality. Better, as J.B.S. Haldane used to say, to produce something that is “interesting, even if not true.” As a consequence, new discoveries are characterized as “revolutions” even when they only confirm and extend the power of ideas that already rule.

So, for example, the discovery, by J.D. Watson and Francis Crick, of the structure of DNA, the stuff of the genes, is often regarded as a scientific revolution. Yet, as Watson himself points out, everyone was waiting for the structure; everyone knew that when it was worked out, an immense variety of phenomena could immediately be fitted in.² The model of the organism as a Ford assembly plant was already in place, and the fenders and bumpers were already stockpiled; all that was needed was the key to turn on the assembly line. The discovery of the structure of DNA has been immensely fruitful, for all of present-day molecular biology and genetics was made possible by it, but it has not made us see the biological world in a different way. It has not been upsetting, but fulfilling.

As in politics, so in science, a genuine revolution is not an event but a process. A manifesto may be published, a reigning head may drop into a basket, but the accumulated contradictions of the past do not disappear in an instant. Nor do the supporters of the ancien régime. The new view of nature does indeed resolve many of the old problems, but it creates new ones of its own, new contradictions that are different from, but not necessarily any less deep than, the old. And waiting, just across the border, are the intellectual somocistas, saying, “I told you so. What did you expect?” trying to convince us that the old way of looking at nature was correct after all. Of course, the old view of nature can never return, but rather new revolutions displace the old ones.

There have been only two real revolutions in biology since the Renaissance. The first was the introduction of mechanical biology by William Harvey and René Descartes. While their manifestoes declaring that animals were machines were published early in the seventeenth century,³ it was not for another 250 years that the mechanistic revolution in biology was fully achieved. The difficulties of the reductionist mechanical view of biology has given prolonged life to vitalism and obscurantist holism, relics of an organic view of nature that comes down to us from the Middle Ages and, at the same time, have driven some biologists to search for yet another conceptual revolution to solve the mysteries of mind and of development.⁴

The second biological revolution, to which we attach the name of Darwin, is still being consolidated. Although its manifesto, On the Origin of Species, appeared in 1859, it was not until the 1940s that Darwinism really established a hegemonic hold on such branches of biology as classification, physiology, anatomy, and genetics. It is still under external siege by the restorationist armies of creationism, while at the same time it is undergoing a severe internal struggle to define its own orthodoxy and to resolve its own contradictions. The hundredth anniversary, last year, of Darwin’s death was marked by an enormous production of books, a triumph of the power of modern capitalism to turn ideas into commodities, equaled only by what is being done to commemorate the death of Marx. The year between April 1882 and March 1883 was a bad one for revolutionaries, but a great opportunity for publishers.

Some books, like Darwin for Beginners, are meant to introduce the content and history of Darwinism to the lay person; some, for example Evolution Now: A Century After Darwin, to expose for a professional audience the internal state and modern problems of the theory itself; yet others, such as Evolution Without Evidence, are part of the immense industry of Darwin scholarship that gives employment to large numbers of historians and philosophers of biology and provides the material for their professional journals. Then there are books such as The Monkey Puzzle and The Myths of Human Evolution that are concerned with the quest for that mythic pot of paleontological gold, the Missing Link. Most immediately relevant are works such as Science on Trial and Abusing Science that defend Darwinism against the real besiegers without the walls, or, like Darwinism Defended, that see sinister subversives within the very citadel, conspiring to destroy what the barbarian hordes are unable to shake.

Darwin surely was a revolutionary, but there is a certain confusion about what constituted his epistemological break with the past. Clearly it was not the idea of evolution itself. Darwin was rather the inheritor than the creator of the view that life evolved. Indeed, the nineteenth century was a period in which rampant evolutionism became a general world view, one not restricted to the history of life. Evolutionary cosmology began in 1796 with Laplace’s nebular hypothesis for the origin of the solar system. Charles Darwin’s grandfather, Erasmus, had postulated the evolution of all organisms from “rudiments of form and sense” in his epic poem The Temple of Nature. Chartism and the discoveries of geology conspired to popularize the view that change and instability were universal. Not even nature could be counted on to hold the line:

“So careful of type?” but no.
   From scarpéd cliff and quarried stone
She cries, “A thousand types are gone;
I care for nothing, all shall go.”

(Tennyson, In Memoriam, 1844)

Change, ceaseless change, “a beneficent necessity,” as Herbert Spencer called it, preoccupied the scientific, literary, philosophical, and political consciousness of European culture from the suppression of the Encyclopédie in 1759 to the instantaneous bookshop success of The Origin of Species in 1859. For a revolutionizing bourgeoisie, the only constant was the process of change itself. Their battle cry was already formulated 100 years before Darwin by Diderot in Le Rêve de d’Alembert: “Tout change, tout passe. Il n’y a que le tout qui reste.”

Although Darwin did not invent the idea of evolution, he certainly was responsible for its widespread acceptance. The Origin of Species not only precipitated the intense popular debate on evolution, but was in itself a convincing argument. Its persuasiveness arose only partly from the assemblage of evidence from natural history and paleontology that evolution had occurred, but largely from the construction of a plausible theory of how it occurred. When we speak of the “theory of evolution,” a constant confusion arises between the fact of the historical transformation of organisms over the last three billion years and a detailed and coherent theory of the dynamics of that historical process. There is no disagreement in science about whether evolution has occurred. There is bloody warfare on the question of how it has occurred.

It is this confusion between fact and theory that is exploited by creationists, who use the struggle among scientists about the process to claim that the phenomenon itself is in question. Science on Trial and Abusing Science both deal with the structure of evolutionary fact and theory as it is confronted by creationist attacks. In Science on Trial, Futuyma, a biologist, makes “The Case for Evolution” by a lucid exposition of what is known about the history of organisms and about the processes of inheritance and natural selection, devoting only a single chapter to refuting creationist arguments directly. Kitcher, a philosopher, argues “The Case Against Creationism” by exposing point by point the epistemological errors and willful intellectual dishonesty that characterize creationist claims. Anyone seriously interested in understanding the scientific and philosophical content of the struggle over evolution and creation must read both of these books, Futuyma first and Kitcher second. Anyone who is still confused after doing so has just not been paying attention.

For all their lucidity in dealing with the content of evolutionary theory and the creationist attack upon it, Futuyma and Kitcher give us only academic logic and natural history. They leave us mystified about the origins of the struggle and why people care all that much about it. Why only in America? Why now? Why the passion, commitment, expenditure of time and money by fundamentalists?

Creationism can only be understood as part of the history of southern and southwestern American populism. Earlier in this century, tenants, small holders, and miners shared the perception that their lives were controlled by rich bankers, merchants, and distant absentee corporations who were their creditors and their employers. The same regions of America that were strongest in fundamentalist Christianity were strongest in socialism. Eugene Debs received more votes in 1912 from the poorest counties in Oklahoma, Texas, and Arkansas than in northern urban centers. The best-selling weekly magazine in the United States in 1913, surpassing even the Saturday Evening Post, was the socialist Appeal to Reason published in Gerard, Kansas. Farmers rode to summer socialist camp meetings in buckboards with red flags flying.⁵ If the poor could have no control over their economic and political lives, at least they could control their cultural and religious life and what went into the heads of their children. And so they did. As late as 1956, my children in North Carolina learned that “God made the flowers out of sunshine.” Evolution was taught barely at all in the classroom; it was not in the school texts.

Then came the challenge of Soviet science and the world was turned upside down. The National Science Foundation supported scores of professors from eastern establishment universities to rewrite the biology textbooks to bring them up to date, and then saw to it that the school curricula were everywhere revised. Suddenly the intellectual culture of the well-to-do had invaded the homes of ordinary folk in Texas, Oklahoma, and Arkansas, and of the descendants of Okies and Arkies in California. In response, the forces of Christian fundamentalism began to assemble, to prepare the campaign that has only reached full force in the last few years. Though Futuyma and Kitcher speak with the tongues of biologists and philosophers, if they have no historical understanding, their arguments are as sounding brass or a tinkling cymbal. As an implacable but compassionate enemy of religion pointed out:

The abolition of religion as people’s illusory happiness is the demand for their real happiness. The demand to abandon their illusions about their condition is a demand to abandon a condition that requires illusions. The criticism of religion is, then, in embryo, a criticism of the vale of tears whose halo is religion.⁶

A second difficulty of both Futuyma’s analysis and the Kitchers’ is that they lose courage on the question of materialist explanations of the world. In the last chapter of Abusing Science, the Kitchers offer a Newtonian first cause as a form of religious belief that is not in necessary conflict with natural science. God, according to this view, set the world rolling according to laws of His own invention and has since kept His hands off. The job of natural sciences is then to explicate the divine order. But that analysis misses the essential differences between a God who has not intervened (except perhaps to produce an occasional incarnation or resurrection) and a god who cannot intervene. Nature is at constant risk before an all-powerful God who at any moment can rupture natural relations. For sufficient reason, He may just decide to stop the sun, even if He hasn’t done so yet. Science cannot coexist with such a God. If, on the other hand, god cannot intervene, he is not God; he is an irrelevancy. By failing to confront this problem, biologists and philosophers may make Unitarians and agnostics feel that ontological pluralism is a happy solution, but they haven’t fooled any fundamentalists, who know better.

If Darwin’s revolution was not in proclaiming evolution as a fact, then it must have been in his theory of its mechanism. And what was that theory? Why, “natural selection,” of course, which then makes the theory of natural selection the very essence of Darwinism and any doubt about the universal efficacy of natural selection anti-Darwinian. There is a form of vulgar Darwinism, characteristic of the late nineteenth century and rejuvenated in the last ten years, which sees all aspects of the shape, function, and behavior of all organisms as having been molded in exquisite detail by natural selection—the greater survival and reproduction of those organisms whose traits make them “adapted” for the struggle for existence. This Panglossian view is held largely by functional anatomists and comparative physiologists who, after all, make a living by explaining what everything is good for, and by sociobiologists who are self-consciously trying to win immortality by making their own small revolution. Evolutionary geneticists, on the other hand, who have spent the last sixty years in detailed experimental and theoretical analysis of the actual process of evolutionary change, and most epistemologists, take a more pluralistic view of the forces driving evolution.

An occasional philosopher has allied himself or herself with the “adaptionists,” who give exclusive emphasis to natural selection, and, one such, Michael Ruse, makes a characteristic presentation in Darwinism Defended. Darwinism, the representative of objective modern science, is under ideologically motivated attack. Professor Ruse is alarmed: “‘Darwinism,’ as I shall refer to Darwin-inspired evolutionary thought, is threatened from almost every quarter.” Well, not from every quarter, just the right and left flanks, it seems. First, the fundamentalists, supported by Ronald Reagan, make a know-nothing assault from the right. No sooner have real evolutionists wheeled to face this attack than they are fallen upon by subversive elements from the left, “biologists with Marxist sympathies” and their “fellow travelers” among philosophers who argue “that any evolutionary theory based on Darwinian principles—particularly any theory that sees natural selection as the key to evolutionary change—is misleadingly incomplete.”

On to the field, mounted upon his charger perfectly adapted for the purpose, with weapons carefully shaped by selection to spread maximum confusion among the enemy, not to mention innocent civilians, comes Professor Ruse, “trying to rescue…from the morass into which so many seem determined to drag them,” “Darwin’s life and achievements.” In all fairness to Professor Ruse, he did not invent this version of events. The theory that evolutionary science is being brutally beaten and cut with crosses, hammers, and sickles made its first appearance in E.O. Wilson’s On Human Nature as the only plausible explanation he could imagine for the failure of sociobiology to achieve instant, universal, and lasting adherence. The situation of evolutionary theory, however, is rather more complex and more interesting than Professor Ruse’s Manichaean analysis suggests.

There are two basic dynamic forms for evolving systems. One is transformational, in which the collection of objects evolves because every individual element in the collection undergoes a similar transformation. Stellar evolution is an example. The universe of stars is evolving because every star undergoes the same general set of transformations of mass and temperature during its life cycle from birth to its eventual winking out. The Harvard class of 1950 is getting grayer and flabbier, because each of its members is doing so. Most physical systems and social institutions evolve transformationally, and it was characteristic of pre-Darwinian evolutionary theories that they, too, were transformational. Lamarck held that a species evolved because its individual members, through inner will and striving, changed to meet the demands of the environment.

The alternative evolutionary dynamic, unique as far as we know to the organic world, and uniquely understood by Darwin, is variational evolution. In a variational scheme, there is variation of properties among individuals in the ensemble, variation that arises from causes independent of any effect it may have on the individual who possesses it. That is, the variation arises at random with respect to its effect. The collection of individuals evolves by a sorting process in which some variant types persist and reproduce, while others die out. Variational evolution occurs by the change of frequency of different variants, rather than by a set of developmental transformations of every individual. Houseflies, for example, have become resistant to DDT. Because of random mutations of genes that affect the sensitivity of flies to insecticide, some flies were more resistant and some less. When DDT was widely applied, the sensitive flies were killed and their genes were lost, while the resistant forms survived and reproduced, so their genes were passed on to future generations. Thus, the species as a whole became resistant to DDT.

Darwin’s problem, and that of anyone trying to produce a theory of evolution, was to explain two apparently distinct features of the organic world, diversity and fit.

In considering the Origin of Species, it is quite conceivable that a naturalist…might come to the conclusion that species had not been independently created, but had descended like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how the innumerable species inhabiting this world have been modified, so as to acquire that perfection of structure and coadaptation which justly excites our admiration.⁷

The observations of diversity were strong support for evolution, for the immense variety of species alone seemed to make special creation unreasonable. Once, when J.B.S. Haldane was asked what he could deduce about the Creator from the nature of Creation, he replied, “He must have been inordinately fond of beetles.” The marvelous fit of organisms to their environments, however, seemed evidence of a deliberate design. What was so attractive about Darwin’s theory was that it explained both diversity and “that perfection…which so justly excites our admiration” by a single coherent mechanism.

Darwin claimed that it was the sorting process among variants that produced the fit of organisms to the environment. In the “struggle for existence,” some variants, because of their particular shapes, behaviors, and physiologies, were more efficient at using resources in short supply, or in escaping predators or other vicissitudes of nature. Thus, the differential survival and reproduction of different variants would be directed by the circumstances of the external world; and so the outcome of the sorting process would bear a close correspondence to that world and its demands. That is, adaptation of the species occurs by sorting among individuals. What vulgar Darwinists fail to understand, however, is that there is an asymmetry in Darwin’s scheme. When adaptation is observed, it can be explained by the differential survival and reproduction of variant types being guided and biased by their differential efficiency or resistance to environmental stresses and dangers. But any cause of differential survival and reproduction, even when it has nothing to do with the struggle for existence, will result in some evolution, just not adaptive evolution.

The Panglossians have confused Darwin’s discovery that all adaptation is a consequence of variational evolution with the claim that all variation evolution leads to adaptation. Even if biologists cannot, philosophers are supposed to be able to distinguish between the assertion that “all x is y” and the assertion that “all y is x,” and most have. This is not simply a logical question but an empirical one. What evolutionary geneticists and developmental biologists have been doing for the last sixty years is to accumulate a knowledge of a variety of forces that cause the frequency of variant types to change, and that do not fall under the rubric of adaptation by natural selection. These include, to name a few: random fixation even of antiadaptive traits because of limitations of population size and the colonization of new areas by small numbers of founders; the acquisition of traits because the genes influencing them are dragged along on the same chromosome as some totally unrelated gene that is being selected; and developmental side effects of genes that have been selected for some quite different reason.

An example of the last is the redness of our blood. Presumably we have hemoglobin because natural selection favored the acquisition of a molecule that would carry oxygen from our lungs to the rest of our body, and carbon dioxide along the reverse route. That our blood is red, as opposed to, say, green, is an accidental epiphenomenon of hemoglobin’s molecular structure, and a few animals, like lobsters, have green blood. This has not stopped adaptationist ideologues from inventing stories about why blood ought to be red, but they are not taken seriously by most biologists.

Despite the fact that mechanisms of nonadaptive evolution are firmly entrenched as part of modern evolutionary explanation and are discussed at some length in Futuyma’s book, they are dismissed by Ruse as only “background noise against the main evolutionary tune.” It may be, however, that Professor Ruse’s ear is not accustomed to counterpoint.

A more realistic and less ideological view of the current problems and controversies in evolutionary theory can be seen in Evolution Now, although the lay reader will find it hard going. It includes chapters on the evolution of the structure of genes themselves and how they are grouped together on the chromosome partly as a consequence of adaptive forces and partly as a trace of purely historical accident. One section concerns the speed of evolution, and whether most evolutionary change may occur during short periods at the time that new species are formed. An ultra-adaptationist section deals with the evolution of behavior and an antiadaptationist section with parasitic DNA. Most of the ideas in this book will turn out to be false alarms, but they illustrate the richness of evolutionary phenomenology as opposed to the poverty of a mindless adaptationist program.

Nothing produced more resistance to Darwin and his supporters than the claim that human beings had themselves evolved from “lower” forms of life. By an ironic inversion, nothing has titillated public interest in evolution in our own time so much as the search for the bones of human ancestors. The surest way to intense, if fleeting, fame and glory is to announce that some tooth, jaw, skullcap, or entire head has just been dug up that is “probably a human ancestor.” If it is a half-million years older than the oldest “probable human ancestor” already known, fame and controversy are guaranteed.

There is a problem, however. The only way to be sure that a fossil is really a human ancestor is to find one that is already indubitably human, but then it has no interest. The farther back in time one goes and the greater the differences from us, the more likely it is that the bones belong to some twenty-second cousin twelve times removed. During the last hundred years, there has been a gradual change in the understanding of paleontologists about the shape of evolutionary trees. At one time it was thought that a group of related fossils of increasing ages could be aligned in a single ancestral order or, at most, two or three branches joining the main stem at a few points. It is now reasonably clear that most fossils of different ages cannot be connected in a linear sequence, but represent a small sample from a lot of parallel lines. Evolutionary trees have become bushes. Since fossils, especially of vertebrates, are few and far apart there are big gaps in the fossil record, and any temptation to arrange fossils in a linear order is likely to be overturned when the next bone is dug up. Often a supposed ancestor will turn out to be contemporaneous or even later than the species to which it supposedly gave rise. Between two million and one million years ago there were four known coeval “apemen,” including three that probably used tools.

What makes the situation all the more confused is that the shapes of organisms do not change uniformly in time. There are periods of rapid change and periods of relative stasis. That observation has led to the theory of “punctuated equilibrium,” which exaggerates and universalizes that temporal irregularity. According to punctuationists, gaps in the fossil record are real and are the consequence of long periods of absolutely no change in organisms followed by a paltry few thousand years of very rapid evolution. Gradualists, who scornfully refer to this theory as “punc. eq.,” say that it is just hard to find the intermediates because suitable fossil-bearing strata are so seldom exposed, so what appears as “punc. eq.” is just punk rock.

The theory of punctuated equilibrium is applied to the human fossil record in Eldredge and Tattersall’s The Myths of Human Evolution. The authors are judicious but biased, minimizing the observed differences between fossils so that they can claim that species show no significant change over a million years or more. There just is not enough material evidence to make a convincing case for punctuated equilibrium from human fossils, but one thing is clear from their analysis. The search for the missing link, the oldest form that is clearly in the direct line of human ancestry, is a delusion. No one knows, or ever will know with the sort of evidence upon which we now depend, whether any fossils is a direct ancestor of the people who dig them up and write books about them. That will not stop the claims. One doesn’t get many column inches with the announcement that yet another bit of yet another relative of unknown degree has been found in the deserts of East Africa.

Despite the myth of song and story, we did not descend from monkeys or apes, at least not from any forms of them now alive. But we did have common ancestors with chimpanzees and gorillas, not all that long ago. Just how long ago, and who among the living apes is our nearest relative, is not known for certain.

The Monkey Puzzle by Gribbin and Cherfas makes a convincing, if breezy argument, accessible to a lay reader not frightened by an occasional number, that we are as closely related to the sulky gorilla as to the lovable chimp, and that our genes parted company from theirs only about four to five million years ago. The evidence comes from a form of nonadaptive evolution that has turned out to be one of the most powerful tools biologists have in reconstructing ancestry. It appears that some of the building blocks, the amino acids, of which some of our proteins are made, can be replaced with blocks of slightly different molecular form without affecting the function of the proteins. As the generations succeed one another, this replacement occurs at a clocklike rate, independent of natural selection for specific adaptation. If this clock can be calibrated, by counting the number of replacements that separate two species whose time of evolutionary divergence is known form the fossil record, even approximately, then for other species without a fossil record a time of divergence can be estimated. It is this technique that has shown us to be a mere five million years separated from Mr. Jiggs.

Unfortunately, Gribbin and Cherfas seem to think that this information tells us something important about the human condition. After all, they say, our proteins are only I percent different from those of apes. But this is a spurious comparison. The authors have forgotten, in their anxiety to say something profound, that the very method they describe with such clarity depends critically on protein differences that have no functional significance in the first place. If calibration of the molecular clock uses nonadaptive evolutionary change as its basis, then how can they expect to draw adaptive meaning from the amount of that change? More generally, how do we convert the percentage difference in molecular composition into a percentage difference in shape, size, or the ability to do biochemistry? I would turn the comparison upside down and remark how little difference in protein structure can correspond to such profound differences in organism. It is a sign of the foolishness into which an unreflective reductionism can lead us that we seriously argue from protein similarity to political similarity.

While they are more relevant to proteins than to politics, Darwin’s writings have a great deal more in common with those other grand theorists of the nineteenth century, Marx and Freud, than with, say, Newton. Darwin’s work is filled with ambiguities, contradictions, and theoretical revisions. The early Darwin of the Beagle in 1836 is neither the middle Darwin of the preliminary sketch of 1844 nor the mature Darwin of The Origin in 1859. Indeed, successive editions of The Origin contain important changes, and at one point Darwin seriously flirted with the inheritance of acquired characteristics, a notion that is logically fatal to his entire enterprise.

So, like the other Victorian radicals, Darwin has become the subject of a major historical industry. His letters, his diaries, his notebooks, his successive sketches, editions, and papers are the fossil bones to be used by the paleontologist of history in building a true picture of the beast. Unlike the remains of long-dead animals, however, the Darwinian fossil record is very unlikely to become fuller. Barring the discovery of a dusty bundle in some unlit corner of the Royal Society’s attic, we have it all, and historians must be content to find the real Darwin by rereading and reinterpreting the same words. For me at least, the reconstruction has remained something of a cardboard cutout of a Great Man, eccentrically hypochondriacal, but indubitably a great man, unlike any practicing scientist I have ever known.

Barry Gale has changed all that. I do not know whether his thesis in Evolution Without Evidence that Darwin published The Origin of Species without confidence in his evidence, and well before he intended to, is right or wrong. Certainly Gale has produced an abundance of quotations that support this view. As late as February 1858, Darwin wrote to Hooker, “I must come to some definite conclusion whether or not entirely to give up the ghost [of my theory],” and six months later wrote to Asa Gray at Harvard, “I cannot give you facts and I must write dogmatically, though I do not feel so on any point.” But in a corpus as rich as the Darwin letters and notebooks, there are quotations to prove anything. What is appealing in Gale’s work is a picture of a life in the social community of science that corresponds to our everyday experience of how careers are built.

Darwin returned from the voyage of the Beagle in 1836 to become a rising young star in geology. He was ambitious, courted success and successful men, and cared for their approval. He wrote in his autobiography (a genre not usually entered into by the self-effacing) that he wanted a “fair place among scientific men.” When, after ten years, he had exhausted the career possibilities of geology, he turned his full attention to biology, including, among other questions, what was universally acknowledged to be the problem of the time. For twenty years he successfully exploited his relationships with the community of biologists to acquire information and specimens and to stake out a long-term claim on the species problem.

That is why it was to him that Alfred Russel Wallace wrote in 1858 with the news of his own independent invention of the theory of natural selection. Darwin was already a member of the British scientific establishment (he had received the Royal Medal of the Royal Society two years before), so it was to other establishment figures that he turned for tactical advice on how to save his scientific priority while saving his soul. He rather hoped the problem might go away since Wallace had not actually said he was hoping for publication, but Darwin’s friends did not take the hint, and the solution agreed upon was a joint publication. So, it appears, Darwin was hustled into publication before he was really ready, for otherwise, as he put it, “all my originality, whatever it may amount to, will be smashed,” and “it seems hard on me that I should be thus compelled to lose my priority of many years standing.”⁸

It is not only ambiguity, contradiction, and long intellectual development that Darwin shared with other nineteenth-century revolutionaries. They are all dimly perceived through slogans. Survival of the fittest, like penis envy, is the opium of the people, To understand Darwinism simultaneously as a social phenomenon arising out of the remaking of the British social structure and as an extraordinary insight into the operation of natural forces, requires considerable knowledge and subtlety of mind. To explain all that clearly, correctly, wittily, but without condescension, to a lay public demands a high expository art. What one obviously needs for the job is to put together a physician-director-actor-comedian-TV star with the illustrator of Swamp Comix. It has been tried, and it works. While the illustrations are at times a bit swampier than the text demands, Darwin for Beginners is a superb introduction to a very tricky subject. It puts all the emphasis in the right place, is historically correct, scientifically impeccable, and contains as a postscript the best 250 word piece on reductionist social explanation yet written. Anyone who reads and understands Jonathan Miller’s text will know a good deal more about Darwinism than most biologists and historians, while the pictures will be a constant reminder not to take the life of the mind more seriously than it deserves.

What is the revolution that Darwin made? It was not the idea of evolution. Nor was it the invention of natural selection as an explanation. Although undoubtedly ingenious, and certainly a correct characterization of a great deal of evolution it is, in the end, only a completion of the unfinished Cartesian revolution that demanded a mechanical model for all living processes. Nor was it even the variational model for a historical process in place of the usual transformational scheme. The invention of the variational model was indeed a considerable intellectual feat and represented a real epistemological break, for it changed the locus of historical action from the individual to the ensemble. Collectivities, the species, changed even though each individual within them was constant through its lifetime. What the variational model does is to convert one quality of variation, the static variation among objects in space, into another quality the dynamic variation in time. As extraordinary as that insight may be, it can hardly be said to revolutionize, by itself, our way of seeing nature. It remains, again, a mechanism.

Darwin’s real revolution consisted in the epistemological reorientation that had to occur before the variational mechanism could even be formulated. It was a change in the object of study from the average or modal properties of groups to the variation between individuals within them. That is, variation itself is the proper object of biological study, for it is the ground of biological being. Without it, there would have been no evolution and therefore no living biological world, for the earliest proto-life would have long since made the world uninhabitable for its own kind.

Before Darwin, the central issue for science was to discover the Platonic form that lay behind the imperfect reality, as Newton in the first book of the Principia treated ideal bodies moving in perfect voids, and only later considered the disturbing effects of friction and viscosity. Variation among organisms was thought to be ontologically distinct from the causes of their similarity, a similarity that we glimpse but dimly. If only we could eliminate the noisy confusion of the material objects themselves, the true relation would be seen. Darwin revolutionized our study of nature by taking the actual variation among actual things as central to the reality, not as an annoying and irrelevant disturbance to be wished away.

That revolution is not yet completed. Biology remains in many ways obdurately Platonic. Developmental biologists are so fascinated with how an egg turns into a chicken that they have ignored the critical fact that every egg turns into a different chicken and that each chicken’s right side is different in an unpredictable way from its left. Neurobiologists want to know how the brain works, but they don’t say whose brain. Presumably when you have seen one brain you have seen them all. Given the extraordinary complexity of connections in a brain, it is at least conceivable, if not likely, that two people may organize their memories of the same event differently, or, God forbid, differently on different days of the week. Even my $100 home computer reorganizes and moves its memory storage around as I add more input. Geneticists, who are supposed to know better, will sometimes talk about a gene’s determining a particular shape, size, or behavior instead of reminding themselves that if genes determine anything, it is the pattern of variation of a developing organism in response to variation in the environment.

This error of geneticists is particularly ironic, because it was Gregor Mendel who, unknown to the rest of the scientific world, had, contemporaneously with Darwin, solved the other leading problem of biology by making variation his object of study. Mendel solved the problem of why offspring look like their parents by studying the pattern of differences between them. He discovered, as Darwin had, that similarity and variation are inextricably intertwined aspects of the same reality.