CHAPTER VIII

BIOLOGY COMES OF AGE

IT IS A FAMOUS TITLE, and one should read it through with a stiff upper lip: On the Origin of Species by Means of Natural Selection; or, The Survival of the Fittest in the Struggle for Life. But is there any “great book” about which one secretly feels so guilty? Is there any fundamental scientific generalization which came into the world in so unassuming a guise? So ordinary is the language that it almost seems as if we could be in the midst of reading a lay sermon on self-help in nature. All the proverbs on profit and loss are there, from pulpit and from counting-house—On many a mickle making a muckle: “Natural selection acts only by the preservation and accumulation of small inherited modifications, each profitable to the preserved being”; On the race being to the swift: “The less fleet ones would be rigidly destroyed”; On progress through competition: “Rejecting those that are bad, preserving and adding up all that are good; silently and insensibly working, whenever and wherever opportunity offers, at the improvement of each organic being”; On success: “But success will often depend on the males having special weapons, or means of defence, or charms; and a slight advantage will lead to victory”; On handsome is as handsome does: “Nature … cares nothing for appearances, except insofar as they are useful to any being”; On saving nine: “I could give many facts showing how anxious bees are to save time;” On reflecting that in the midst of life we are in death: “We behold the face of nature bright with gladness, we often see superabundance of food; we do not see or we forget, that the birds which are idly singing round us mostly live on insects or seeds, and are thus constantly destroying life; or we forget how largely these songsters, or their eggs, or their nestlings, are destroyed by birds and beasts of prey; we do not always bear in mind, that, though food may now be super-abundant, it is not so at all seasons of each recurring year;” On the compensation that all is, nevertheless, for the best: “When we reflect on this struggle, we may console ourselves with the full belief, that the war of nature is not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy, and the happy survive and multiply.”

None but a Victorian Englishman could have written those words. It is, as a German critic said in a remark meant to be scathing, classical political economy applied to biology. Or as Darwin said himself, “This is the doctrine of Malthus applied to the whole animal and vegetable kingdom.” So familiar has the argument become, that its magnitude is not on the face of it apparent. For in this unlikely guise there was clothed nothing less than a new natural philosophy, as new in its domain as Galileo’s in physics. Darwin, in effect, abolished the distinction which had divided first natural history and then biology from physics at least since Newton, and which rested on the supposition (or defense) that the biologist must characteristically study the nature and the wisdom of the whole rather than the structure and arrangement of the parts. Nevertheless, so ordinary are the terms that it requires interpretation to bring out the originality and force of the argument, more so than if Darwin were a Newton or an Einstein abstracting far beyond everyman’s power to follow and to understand. A hero of science should be less accessible.

Darwin never gives his interpreter the benefit of self-dramatization. His style suffers from the damp respectability which spots and kills so many of the lesser flowers of Victorian prose. Nor does his vision of a new science arrest as Galileo’s does. His genius has not the daemonic quality of Newton’s. There hangs over him the shadow of no tragic destiny like Lavoisier’s. There looms, indeed, nothing more ominous than the shadow of Samuel Wilberforce, Bishop of Oxford, and the debate about men and monkeys.

Like T. H. Huxley, his champion and defender, Darwin would face the unknown four-square, taking only science for his guide. And one would find his courage stirring, except for the feeling that the Victorian unknown contained nothing very dreadful. Late in life he wrote a short intellectual autobiography to be circulated among his children. There is a numbing candor in this account of his own mind. He claims for himself not power of abstract thought, but only the worthiest and dullest of intellectual virtues—patience, accuracy, devotion:

I have no great quickness of apprehension or wit which is so remarkable in clever men, for instance Huxley. I am therefore a poor critic: a paper or book, when first read, generally excites my admiration, and it is only after considerable reflection that I perceive the weak points. My power to follow a long and purely abstract train of thought is very limited; I should, moreover, never have succeeded with metaphysics or mathematics. My memory is extensive yet hazy.

He deplores the “curious and lamentable loss” of his youthful taste for music, poetry, and the fine arts:

My mind seems to have become a kind of machine for grinding general laws out of large collections of facts, but why this should have caused the atrophy of that part of the brain alone, on which the higher tastes depend, I cannot conceive. A man with a mind more highly organised or better constituted than mine, would not I suppose have thus suffered; and if I had to live my life again I would have made a rule to read some poetry and listen to some music at least once every week.

And only once does he betray that drive, lacking which no one achieves what he did, and then in what seemly phrases:

My industry has been nearly as great as it could have been in the observation and collection of facts. What is far more important, my love of natural science has been steady and ardent. This pure love has, however, been much aided by the ambition to be esteemed by my fellow naturalists.

Charles Darwin was born in 1809, a younger son in a family whose marriages have drawn it into one of the great ramifications which lend the Victorian intelligentsia an almost hereditary air. By now the Darwins are related to the Wedgwoods, Trevelyans, Macaulays, Huxleys, Arnolds, and Galtons, and number among their connections the names of Keynes and Cornford. Darwin’s grandfathers were Josiah Wedgwood, founder of the pottery firm at Etruria, and Erasmus Darwin, both of whom had been members with Joseph Priestley and James Watt of the Birmingham scientific circle in the 1770’s and ’80’s. Erasmus Darwin, a physician and versifier, had composed one of the numerous evolutionary flights of fancy of the eighteenth century. His Zoonomia reads not unlike Lamarck. Critics of Darwin have sometimes taken him to task for concealing that he owed an intellectual as well as a genetic debt to his grandfather. As far as he could tell, he said, Zoonomia made no impression on his mind at all, any more than did the theories of Lamarck when he later heard tell of them at college. And like most of what Darwin wrote, this was the simple truth.

Nor is it an unimportant truth, for there were two aspects to Darwin’s work, the empirical and the theoretical. The Origin of Species did definitively establish the mutability of animals in their descent out of the past. Nevertheless, it would be difficult—in the face of Erasmus Darwin, Lamarck, Goethe, and Diderot, to name no others—to claim the fact of variability as a Darwinian discovery. What was truly novel was the theory, the concept of natural selection which explained the facts lying all ready to Darwin’s hand in the sciences of paleontology, comparative anatomy, geology, and geography. It may bring out the point to anticipate the two kinds of opposition which Darwinism was to encounter. Religious fundamentalists might deny the fact of evolution. But this reaction was intellectually trivial. Where philosophical offense was taken, it was rather the view of the world implicit in the theory of natural selection which wounded humane sensibilities more deeply, and which was repudiated as inadmissible or meaningless or both, for like the Cartesian and the Leibnizian objections to the Newtonian theory of gravity, the two complaints come down to the same thing, and turn on the eternal question of what a scientific explanation really says.

Darwin’s father, too, was a doctor, a crashing Victorian father, who weighed over three hundred pounds and inspired in his son the kind of unwholesome respect later explained by Freud. Of his mother, he remembered only her deathbed. It is characteristic that he should have married into the same family as his father. His wife, too, was a Wedgwood and his own cousin. Dr. Darwin, indeed, left his son with a neurosis and with adequate means to support it. In later life his chronic indisposition drove him into the shelter of his family, to long days at the baths, long hours upon the sofa and under the shawl. He, too, was intended for medicine as a youth, and at the age of sixteen was entered for that training in the University of Edinburgh. His formal education was a failure. His stomach literally could not support dissection or the horrors of the operating theater. “Dr. Duncan’s lectures on Materia Medica at 8 o’clock on a winter’s morning are something fearful to remember. Dr. Munro made his lectures on human anatomy as dull, as he was himself, and the subject disgusted me.” And he withdrew, to enter Cambridge with a view to becoming a clergyman.

His father had no notion of allowing him to indulge his love of nature as an idle sportsman. “But no pursuit at Cambridge was followed with nearly so much eagerness or gave me so much pleasure as collecting beetles.” Even at Edinburgh he had frequented the naturalists of the Pliny Society, and had read a little paper showing that the so-called ova of Flustra were, in fact, larvae. It was his first discovery. “I gloried in the progress of geology,” he wrote, and was drawn at Cambridge into Sedgwick’s orbit. In 1831 Sedgwick invited Darwin to accompany him on his annual summer expedition into the Cambrian rocks of North Wales. It was the beginning of a scientific life. The next year the vessel Beagle, whose Captain Fitzroy was the nephew of Castlereagh, was outfitting for a voyage of exploration around the world. Darwin was offered the (unpaid) post of naturalist. He accepted, and a kindly uncle, Josiah Wedgwood II, father of his future bride, used his influence to bring his father around.

The voyage of the Beagle was the great event of Darwin’s life, the making of him as a scientist, and the end of his prospects as a clergyman. It was. indeed, almost the only event, and the account of it which he published on his return is certainly his most charming book. When Darwin embarked, he was twenty-two years old, and far from being as conversant with the background of evolutionary thought as are the readers of this chapter. In his sea-chest he packed a selection from Milton and Volume I of Lyell’s Principles of Geology. Across the South Atlantic from the Azores to Brazil they went, passed through the Straits of Magellan where they lingered for a bit, and coasted up the Pacific shore to the Equator. The young Darwin was shocked at his brush with slavery in Brazil. In Montevideo he received Volume II of Lyell. In Tierra del Fuego he was horrified at the bestiality of the primitive tribes they encountered, one of which supplemented its diet with old women in severe winters. All these new lands he saw through Lyell’s eyes. In Chile and Peru he made geological forays into the High Andes. And gradually he found his attention more drawn by the flora and fauna, particularly the fauna, than by the structure of these regions. “During the voyage of the Beagle,” he wrote in his Autobiography,

I had been deeply impressed by discovering in the Pampean formation great fossil animals covered with armour like that on the existing armadillos; secondly, by the manner in which closely allied animals replace one another in proceeding southwards over the Continent; and thirdly, by the South American character of most of the productions of the Galápagos Archipelago.

The Galápagos, indeed, were decisive in Darwin’s own development. For the islands were young geologically, differing only slightly in climate from the mainland. No doubt the dramatic character of those far fragments of land was peculiarly impressive. Cones of black lava, they thrust out of the Pacific right on the Equator. It was, he noted, “what we might imagine the cultivated parts of the Infernal regions to be.” Though related to those of South America, most of the species were peculiar to the islands. Reptiles dominated. Everywhere great tortoises lumbered, “so heavy, I could scarcely lift them off the ground. Surrounded by the Black lava, the leafless shrubs, and large cacti, they appeared most old-fashioned antediluvian animals, or rather inhabitants of some other planet.” What was very puzzling to him, the natives could tell by minute variations from which of the islands any particular tortoise had been brought. And from island to island, other species exhibited similar slight variations. The most notable case, which has become a classic of evolutionary studies, is that of the finches. There were several species. The distinctive element seemed to be the beak, some small, some massive, some pointed, some curved. In effect, therefore, these islands were a laboratory readymade in nature, which isolated the problem of species behind 600 miles of ocean. “It was evident,” he wrote later (after he had made it so)

that such facts as these, as well as many others, could only be explained on the supposition that species gradually became modified; and the subject haunted me. But it was equally evident that neither the action of the surrounding conditions [for these did not differ materially from island to island], nor the will of the organisms (especially in the case of plants), could account for the innumerable cases in which organisms of every kind are beautifully adapted to their habitats of life—for instance, a woodpecker or a tree-frog to climb trees, or a seed for dispersal by hooks or plumes. I had always been much struck by such adaptations, and until these could be explained it seemed to me almost useless to endeavour to prove by indirect evidence that species have been modified.

The subject haunted him. He was back in England in October, 1836, having found on his five-year voyage the education that Edinburgh and Cambridge had denied him. He set to work. He wrote, “on true Baconian principles, and without any theory collected facts on a wholesale scale.” He did not long wander undirected in this limbo. In October, 1838, fifteen months after opening his first notebook, he happened to read Malthus on Population—“for amusement,” he says, improbably enough. The argument of that dismal essay is surely known to all. Malthus had first advanced it in 1795 in order to define the limits within which material progress is possible. There is a limiting ratio between a population and its subsistence. Population, he laid down, tends to increase at an exponential rate, while food supply can at best be augmented at a linear rate. Under these circumstances, competition is the law of life. Nor need we pause to consider the validity of these assertions. Their historical importance is independent of that question. For Malthus transformed the subject of political economy from Adam Smith’s mood of optimistic naturalism to the deterministic naturalism of the early industrial apologia for laissez-faire. Eighteenth-century assumptions of harmony gave way before the nineteenth-century conflict of interests.

Like classical physics (and encouraged by its example), classical political economy assumed an atomistic ontology in its universe of discourse, and became in consequence a sort of social kinetics. More subtly, and more deeply in evangelical England, the Malthusian subsistence doctrine became transmuted into the moral foundation of liberal individualism. It gave that tone to the Zeitgeist which identifies an epoch in social history. For the inadequacy of the means of subsistence was the rod of discipline by which Providence, cruel in order to be kind, establishes incentives to thrift, virtue, industry, and continence, and deterrents to their contraries. Only within the rules was progress possible. These would have been the connotations called to Darwin’s mind by the essay he read for amusement, “and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that under these circumstances favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The result of this would be the formation of new species. Here, then, I had at last got a theory by which to work.”

Work he did, for twenty years, collecting facts less on Baconian principles, perhaps, than on Darwinian principles, from whatever might bear on the origin (which is now to say the variation) of species. He studied the accomplishments of stock-breeders and of pigeon-fanciers. (“Few would readily believe in the natural capacity and years of practice requisite to become even a skilful pigeon-fancier.”) He read widely in the literature of geology and paleontology, informing himself in ever more detail on the geographical distribution and the historical succession of animals and plants. He experimented, for Darwin was no mere onlooker, and especially on phenomena of cross-pollination and the hybridization of plants. Here the exchange of old species for new might be demonstrated as explicitly as in Lavoisier’s combinatorial analysis-synthesis applied to chemical species (or reagents). Darwin had a special feeling for botany. “It has always pleased me to exalt plants in the scale of organised beings,” and his last book shows how the power of movement in plants—the root growing toward water, the leaf turning toward the light—accords with the theory of evolution. Botanical experiments were, moreover, peculiarly suited to his retirement in 1842 to a country-house existence.

His state of mind was curious during all this gathering and winnowing of facts. On the one hand, he was urged and driven forward by his theory. It possessed his scientific soul. On the other hand, he was held back from publication, and even from giving himself joyfully to his conclusions, by a fear of seeming premature. This went beyond scientific caution in Darwin. It is, perhaps, a disease of modern scholarship to hold back the great work until it can be counted on to overwhelm by sheer factual mass. Thus has too many a scholar oscillated through a lifetime between creativity and timidity only to succumb to the tension, his ideas secure from criticism and the great work unwritten. Even so did Darwin shiver on the brink of publication—giving occasional hostages to fortune: a travel book on the voyage of the Beagle, a treatise on coral reefs, an immense work on the taxonomy and physiology of Cirripedia (barnacles). In 1842 he ventured to write out a little thirty-five-page abstract of his theory, to try it only on himself. Two years later he expanded this to the dimensions of a small treatise, and had a fair copy made. Only then did he solve a problem which had worried him—that of divergence, which he came to see as a kind of evolutionary momentum pressing the most diverse forms of life into every possible vantage point, and carrying each further from its origins.

Still the notebooks multiplied. Darwin’s two closest scientific friends—J. D. Hooker was to him in botany what Lyell was in geology—began urging him to publish. Not that they were convinced, but they feared lest Darwin never try his wings. Nor was he widely known. In becoming his champion, Huxley was to make of Darwin a symbol of science as evocative in the nineteenth century as Newton had been in the eighteenth. But in 1851, commenting on the eminence of two now forgotten naturalists, Richard Owen and Edward Forbes, Huxley barely alluded to Darwin as one who “might be anything if he had good health.” In 1856 Darwin yielded to Lyell’s exhortations and began writing out his views in detail. The scale on which he worked would have filled many volumes. Then fortune took a hand, or misfortune (as Darwin was bound to feel). In 1858 he received a letter from Malaya, from a little known naturalist called Alfred Russel Wallace, who was working in those far jungles. He enclosed an essay, “On the Tendency of Varieties to Depart Indefinitely from the Original Type.” If Darwin thought well of it, he asked, would he be kind enough to forward it on to Lyell for his opinion? Darwin thought agonizingly well of it. He might have written it himself, and he did send it on to Lyell, under a covering letter:

It seems to me well worth reading. Your words have come true with a vengeance—that I should be forestalled. You said this, when I explained to you here very briefly my views of Natural Selection depending on the struggle for existence. I never saw a more striking coincidence; if Wallace had my manuscript sketch written out in 1842, he could not have made a better short abstract! Even his terms now stand as heads of my chapters. Please return me the manuscript, which he does not say he wishes me to publish, but I shall of course at once write and offer to send to any journal.

So all my originality, whatever it may amount to, will be smashed, though my book, if it will ever have any value, will not be deteriorated; as all the labour consists in the application of theory.

Thus occurred one of the famous cases of independent discovery—Wallace, too, had been put onto the theory of natural selection by recalling a passage from Malthus as he wrestled mentally with the puzzle of species during a bout of malaria. One can only sympathize with Darwin, whose priority was incontestable, caught between the code of an English gentleman and a scientist’s feeling about his intellectual property in discovery. It is a commentary on the excessively Baconian cast of Victorian notions of science, reinforced by the gospel of work, that Darwin should always have felt obliged to think that the real merit of his work lay in empirically piling Pelions of fact on Ossas of evidence. For all the while his own feelings as an innovator belied this labor theory of value in science. What hurt was to lose priority in his theory. Nor was there consolation in his pile of notebooks. Yet these were “trumpery feelings,” and he must clearly now refrain from publication, lest he seem to be forestalling Wallace. “It seems hard on me that I should be compelled to lose my priority of many years standing, but I cannot feel at all sure that this alters the justice of the case.”

Fortunately for Darwin, Lyell and Hooker took over the management of his interests, and those of science. Hooker asked for all the manuscripts and letters. The Wallace memoir was communicated to the Linnaean Society to be published in 1858, side by side with extracts from Darwin’s sketch of 1844. Lyell and Hooker explained the circumstances as friends of the court. This was England, and everyone behaved extremely well. Ever after, Darwin and Wallace were meticulous and truthful in their appreciation of the other’s qualities. Posterity may feel that Darwin got the better of all this equity. But after all, seniority (and all those facts) did count, and should have counted. It is not likely that Wallace alone would have prevailed, or even won attention. The two papers were little noticed in 1858. Nor is it likely that Darwin without Wallace would have written On the Origin of Species. For he undertook as part of the settlement to prepare an “abstract” of the great work of compilation. He began in September 1858, and “though often interrupted by ill-health, and short visits to Dr. Lane’s delightful hydropathic establishment,” he completed the Origin of Species in thirteen months, and it was published in November, 1859.

It does not read like a profound book. “Some of my critics have said,” wrote Darwin in his Autobiography, “‘Oh, he is a good observer, but he has no power of reasoning.’” This he did think a little hard: “For the Origin of Species is one long argument from the beginning to the end, and it has convinced not a few able men. No one could have written it without some power of reasoning.” The argument is easier, perhaps, to summarize than to appreciate in its true scope and depth. Chapter I passes in review the familiar varieties that occur in domesticated species. It points out the ambiguity of species. And it adduces many illustrations to show how man has adapted species to his uses, differentiating by selective breeding the dray horse and the racehorse, the whippet and the dachshund. “The key is man’s power of accumulative selection: nature gives successive variations; man adds them up in certain directions useful to him…. Breeders habitually speak of an animal’s organisation as something plastic, which they can model almost as they please.” Chapter II transfers the scene to nature, and diminishes the distinction between species and varieties from the status of a boundary to that of a convenience for the naturalist. Chapter III comes to the crux of the argument, which assigns to the struggle for existence the role in nature that the stockbreeder plays in the barnyard. Variations arise by chance in particular animals. “Owing to this struggle, variations, however slight and from whatever cause proceeding, if they be in any degree profitable to the individuals of a species, in their infinitely complex relations to other organic beings and to their physical conditions of life, will tend to the preservation of such individuals, and will generally be inherited by the offspring.”

In later editions Darwin was forced by criticism to develop what he understood by the concept of natural selection. And it is in this more than in any other passage that the real assurance of his scientific grasp appears:

Several writers have misapprehended or objected to the term Natural Selection. Some have even imagined that natural selection induces variability, whereas it implies only the preservation of such variations as arise and are beneficial to the being under its conditions of life…. Others have objected that the term selection implies conscious choice in the animals which become modified; and it has even been urged that, as plants have no volition, natural selection is not applicable to them! In the literal sense of the word, no doubt, natural selection is a false term; but who ever objected to chemists speaking of the elective affinities of the various elements?—and yet an acid cannot strictly be said to elect the base with which it in preference combines. It has been said that I speak of natural selection as an active power or Deity; but who objects to an author speaking of the attraction of gravity as ruling the movements of the planets? Every one knows what is meant and is implied by such metaphorical expressions; and they are almost necessary for brevity. So again it is difficult to avoid personifying the word Nature; but I mean by Nature, only the aggregate action and product of many natural laws, and by laws the sequence of events as ascertained by us. With a little familiarity such superficial objections will be forgotten.

The authentic voice of science speaks out of the Victorian smog in that last sentence, stiff with hauteur. No biologist had yet thought or dared to write like this, not just about the structure and functioning of some organism or set of organs in his laboratory, but about the whole course of nature. And now it begins to be clear, the sense in which Darwin settled the crucial problem of adaptation. Crucial it was, because the case in favor of purpose, the conception of biology as the science of the goal-directed, rested precisely there, on the ancient and reasonable observation that animals seem to be made in order to fit their circumstances and in order to lead the lives they do lead, with the right equipment, the right instincts, and the right habits. Darwin did better than solve the problem of adaptation. He abolished it. He turned it from a cause, in the sense of final cause or evidence of a designing purpose, into an effect, in the Newtonian or physical sense of effect, which is to say that adaptation became a fact or phenomenon to be analyzed, rather than a mystery to be plumbed.

He himself suggests the comparison to “an author speaking of the attraction of gravity as ruling the movements of the planets.” And the turn of the discussion bears out the analogy. For the next chapter deals with the laws of variation. It is full of acute observations on use and disuse, climate, the greater variability of specific than generic characters, and the like. Most of this is either obvious or obsolete in the light of modern genetics, and Darwin himself recognized his limitations here. For the burden of the discussion is that the causal mechanism of variation is precisely what we do not know. But also (to continue the comparison with Newton and the cause of gravity), it is what we do not need to know. All we need is the evidence (which he and geology and comparative anatomy and all of foregoing natural history provided) that variations do occur, and that they are inherited. The theory of natural selection never depended on Darwin’s trying to specify the cause of the variations that are selected by circumstance. Indeed, its success hinged precisely on dropping that question. Of Darwin, too, it might be said, “Hypotheses non fingo,” and in the same sense in which it is true of Newton—not as a sterile assertion of empiricism, but as a statement that theories (speculations are another matter) must just embrace the evidence.

The final chapters of the Origin of Species anticipate and meet the difficulties of the argument. “Some of them are so serious that to this day I can hardly reflect on them without being in some degree staggered.” But for all his professed Baconianism, Darwin never failed to maintain his composure as a theorist. He deals with instinct, and with extreme specialization. He handles the (normal) sterility of hybrids, as against the fertility of varieties within a species. He grapples with the apparent absence of transitional forms between species. He discusses the extravagant beauty of the male in certain birds, so difficult to reconcile with the humdrum operation of natural selection. Some accounts have interpreted his emphasis on “sexual selection” in such cases as a partial abandonment of his claims. His language here is a little vague, but it does seem more consonant with his single-mindedness to interpret sexual selection as a special case of natural selection rather than an auxiliary. He made great play with the imperfection of the geological record, emphasized the incompleteness of our knowledge, and reviewed from his experience of the Beagle the geographical distribution of variations, and particularly in the isolated populations of the great oceanic islands. Without summarizing all this material, let it simply be said that contemporary evolutionists bear him out on all essential points: they have vindicated him as Laplace did Newton. All these apparent difficulties are like the planetary anomalies observed in the eighteenth century. Once they are explained as instances rather than violations of natural selection or of gravity, they sophisticate the theory, instead of serving as escape hatches. Nor does contemporary science offer any handle to dissent from the concluding paragraph of what he knew to be “the chief work of my life.” In it Darwin rose on rudimentary wings of prose as high as ever he could flutter toward lyricism

It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the conditions of life, and from use and disuse: a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.

EIGHTEENTH-CENTURY PHYSICS had required about fifty years from the publication of the Principia to assume with ease the Newtonian posture. Biology has had to traverse even wider confusions before orienting itself cleanly around the Darwinian theory of evolution. Indeed, it has clarified its outlook through the instrumentality of modern genetics only since the 1930’s. In 1929 Erik Nordenskiold’s History of Biology, still the foremost text, closed with a reference to “the dissolution of Darwinism.” That natural selection “does not operate in the form imagined by Darwin must certainly be taken as proved,” wrote Nordenskiold. Exactly the contrary is now thought to be true. Since such shifts of scientific opinion were still to occur in the twentieth century, it is not surprising that the import of Darwin’s theory for the whole science was not mastered at the time. Claude Bernard, perhaps the greatest of experimentalists in his skill and sobriety, saw the future of biology as lying in its reduction in physiology to laws of chemistry and physics. There was nothing for him in Darwin, whose work he did not distinguish from Naturphilosophie. “We must doubtless admire,” he writes in his fine manifesto on Experimental Medicine, “those great horizons dimly seen by the genius of a Goethe, an Oken, a Carus, a Geoffroy Saint-Hilaire, a Darwin, in which a general conception shows us all living beings as the expression of types ceaselessly transformed in the evolution of organisms and species,—types in which every living being individually disappears like a reflection of the whole to which it belongs.” But he did not admire them. He never thought this science. In the critical tradition of French learning, Darwin’s mind and language seemed simply slack.

At the other extreme from Gallic indifference burgeoned the enthusiasm which made a religion of science, mistook nature for God, and adopted Darwin as the prophet. The German for this “ism,” Darwinismus, best conveys its spirit, always most at home in Germany. There Ernst Haeckel and his like, deploying all the rich capacity of their language for blurring distinctions, worked a syncretism between the Goethean sense of unity in nature and the Darwinian proof of organic evolution. Haeckel’s were the voice of Jacob and the hands of Esau, the historicist spirit of romantic idealism and the hairy philosophy of monistic materialism. All biology would be made over into evolution. Thus (to take only one example) embryology was henceforth to be ruled by the doctrine of recapitulation, by which every individual traverses in embryo the evolution of the race, from the single-celled through the invertebrate stage, the gill-breathing, the reptilean, and so on. Everyone, to adapt a saying of Huxley’s, climbs his own family tree out of the womb. But all truth, too, was evolution. In Haeckel’s words, “Darwin’s theory of the natural origin of species at once gives us the solution of the mystic ‘problem of creation,’ the great ‘question of all questions,’—the problem of the true character and origin of man himself.” Two chapters in Haecke’s Riddle of the Universe handle the “embryology” and the “phytogeny” of the soul, making use of recapitulation. And though enthusiasm is the most forgivable of excesses, in this lavishness evolutionary theory explained too much. Haeckel gave little thought to what precise problems might connect evolutionary theory to the technical reaches of biology, or what positive route through the whole science its reduction to evolutionary terms might take. His fault in judgment was the reverse of Bernard’s, and of parochial specialization.

In retrospect it seems obvious that in pushing analysis beyond the point where Darwin left it, the critical question was the mechanism of inheritance. Darwin here confused the clarity of his original admission of ignorance by vague and contradictory speculations about pangenesis in certain later writings. To meet the criticism that Darwinian evolution does not explain inheritance, certain other biologists leafed back the pages to Lamarck. From among all his principles, they chose the inheritance of acquired characters, and in their own extremity made it into the main point of Lamarck’s philosophy and the essential supplement to Darwin’s. German biological romanticism gave neo-Lamarckism a hospitable climate. Nor was it unreasonable. In the trivial sense, the inheritance of acquired characters is not so much wrong as tautological. Morphological changes in species must be cumulative, and therefore in some sense heritable, or there would be no evolution. The serious question is rather how these characters are inherited, and the relationship of acquisition to inheritance. Indeed, a general failure to distinguish these questions was what kept biological thought moving in widening circles for the rest of the nineteenth century.

Nor were mechanists notably more successful than vitalists in breaking out of these circles. Once again it appears that the real problem was to achieve biological objectivity rather than to choose between vitalism and mechanism, idealism and realism. If one takes the standpoint of modern genetics and compares the work of the foremost idealist, Karl von Nägeli, with that of the foremost mechanist, August Weismann, the structure of their theories seems not dissimilar, and their differences come down to matters of temperament. Nägeli was a botanist and cytologist who had studied philosophy under Hegel in Berlin, and who taught in Munich. His researches on pollen grains and unicellular algae, and upon sexuality in cryptogams, were fundamental. The conception of natural selection held for him no meaning whatever. And his own speculation (or as he thought theory) on evolution illustrates how romanticism in biology carried on a kind of Cartesian search for an ideal mechanism to serve in explanations.

Nägeli’s idioplasm ramifies through time like some webbed vortex. It bears all the characteristics of the imaginary mechanism—a texture too fine and plastic to be detectable by instruments, films through which influences pass, tensions in the Protean ineffable. Idioplasm was born of the tactical necessity for making a physical distinction between ontogeny and phylogeny, the history of the individual and the history of the race. There are in every being two kinds of substance, tropoplasm and idioplasm. Tropoplasm builds up the gross structure of parts and organs, and all tropocells die with the organism. Idioplasm is immortal. It is itself cellular in structure, a filament of “micelles” which crystallize out of primitive albuminoid matter in the ooze where life begins. They arrange themselves in parallel. They are like fibers twisted and tensed into thread, whereas tropocells flocculate in depth like layers of felted serge.

Or perhaps idioplasm might better be understood as an evolutionary counterpart of the Stoic pneuma. On the one hand, it is the principle of unity in evolution. But on the other hand, it differentiates the stream of living substance into phyla, species, individuals, organs, and cells. For idioplasm is the bearer of determinants. Every filament fixes some quality upon the organ it penetrates: its color, chemical composition, physical state, physiological function, or whatever. Nothing is left out. Idioplasm branches all through the organism like an undetectable nervous system. All parts of the body are traversed by the whole of the idioplasm. The reproductive organs are no exception, and generation consists in the mingling in the fertilized ovum of idioplasm from both parents. That strain of idioplasm, therefore, which runs through (say) the species horse is nothing less than identical with the nature of horse. Differences between individual horses are caused, not by any change in the substance of idioplasm, but by differential tensions which may develop here and there between particular micelles, or perhaps by accidents which occur in the lifetime of the animal.

Now this is obviously the purest latter-day Lamarckism, and it would be an ungrateful task to follow Nägeli into his hundreds of pages of imaginary detail. What is significant historically is the way in which the romantic mind had still to explain evolution in the decades after Darwin. We are here concerned with the strand of life: “I shall proceed from the primitive, unorganized condition of matter and endeavor to show how organized micellar substance has arisen in it, and how, from this micellar substance, organisms with their manifold properties have arisen.” Evolution is the expression of the “automatic perfecting process or progression of the idioplasm, and entropy of organic matter.” Any adaptive variations caused by external conditions are of the most trivial importance. The environment only provides the organism with food and matter for its life processes. It causes no permanent variation and has only ontogenetic significance. Reproduction represents no break in continuity. Parents continue in the offspring as the “stem continues its specific life in the branch.” Finally, what he, the biologist, must study is the nature of the organism as displayed in evolution, the fundamental biological process of the world. It is not a problem which can be broken up into its parts, any more than may the organism itself:

If heredity and variation are defined according to the true nature of organisms, they are only apparent opposites. Since idioplasm alone is transmitted from one ontogeny to the next following, the phylogenetic development consists solely in the continual progress of the idioplasm; and the whole genealogical tree from the primordial drop of plasma up to the organism of the present day (plant or animal) is, strictly speaking, nothing else than an individual consisting of idioplasm, which at each ontogeny forms a new individual body, corresponding to its advance.

Weismann, on the other hand, is usually introduced by historians of biology as the one who imported Darwinian natural selection into the study of heredity. His postulation of the germ plasm (Keimplasm—these things lose their magic outside the language of their birth) still figures in the textbooks. There it is taken to be the historical foundation of the case against evolution by inheritance of acquired characters. Weismann coined his germ plasm in 1882, two years before Nägeli’s idioplasm. Both were expressions of the tactic, quite generally adopted in theoretical biology of the 1880’s, to contemplate the hereditary patrimony apart from the incidents of ontogeny. To the latter, anatomists, physiologists, and pathologists might address themselves, and to the former, evolutionists. Thus, Weismann distinguished between germ-cells and soma-cells, the germ-cells immortal in the sense in which unicellular organisms are that multiply by division. The distinction no longer obtains in all sharpness, but it still serves to dramatize the important difference between gametes and differentiated body cells, and to emphasize that the latter have nothing to do with heredity. That is to say, the body cells of an organism derive from its germ cells, but not vice versa. The line of reproductive cells is indeed direct from generation to generation. But in any one generation they lead a sequestered, one might say a monastic life, if the figure did not seem anti-clerical.

Nägeli was a profound idealist and a Lamarckian; Weismann a profound mechanist and a Darwinian, and his construction of the germ-plasm presented conceptual advantages over Nägeli’s idioplasm. He imagined it to be the locus of natural selection, not of an indwelling drive toward progress, man, and beyond. He imagined it, further, to be a particulate plasma continuing from one organism to the next, not an undetectable network ramifying everywhere in life and time. Weismann’s temper was more sober, his mind open as well as ingenious. He proved very agile in expedients for adapting his germ plasm to the discoveries that occurred in his lifetime. Of these the most relevant was Roux’s identification by staining of the chromosomes, and the extraordinary and beautiful behavior of those structures in cell division or mitosis (to use the later term). Weismann correctly predicted how meiosis would involve first a halving and then a mingling of the hereditary substance. And since Weismann enthusiastically adopted the chromosomes as the containers of germ-plasm, it is not surprising that he is usually credited with having announced the program of contemporary genetics.

If this be altogether correct, however, it is difficult to see why that science should have had to await the twentieth century to learn its business. For a critical scrutiny will leave Weismann closer, perhaps, to Nägeli than to the modern synthesis. Weismann could have saved mechanism simply enough, by making one particle in the germ-plasm the physical basis of every variable quality expressed in the cell. But this would have been to fall into infinite regression. It was, therefore, by an intellectual necessity that the germ-plasm consisted of bundles of organic molecules or “biophores”—“They must exist, for the phenomena of life must be bound to an entity of matter.” Each type of biophore governs some part of the cell, and the biophores are, therefore, “the bearers of the characters or qualities of cells.” But cells are differentiated by histological function, too, and this aspect of organization is governed by the second order of units within the germ-plasm, the “determinants” into which biophores cluster. Finally, the determinant “knows” to what cell it must migrate in the course of ontogeny because of its position in the third order of plasmic units, the “ids,” out of which is fashioned the “inherited and perfectly definite architecture” of the germ-plasm. In this word Weismann acknowledged his debt to idioplasm. His “ids” are to be thought of, perhaps, as functioning like the harness of a draw loom, each of the lashes (or ids) raising a characteristic combination of warp threads (or determinants) to make the design. And all this weaves on below the level of sense inside the rodlike chromosomes.

But what of natural selection? And only now does the full measure of Weismann’s ingenuity first appear, and then betray itself. For it is Darwinism he would seat in all these intragerminal entities. Since this is where the stream of living water flows, why it is there that the struggle for existence must obtain, there among the biophores and ids. Each is the root of variations or complexes of variation which appear in ontogeny, but are selected in phylogeny. It is in the germ-plasm that one id wins out over another, as a consequence of its suiting the organism wherein it prevails to changes in climate, habitat, diet, or other external conditions. In such case, the selected germ-plasm will run in greater volume in the widening channel provided by the increased numbers of favored individuals and races, gradually becoming new species.

The notion of germinal selection is what reveals the measure of the gap between Weismann’s thinking and that of modern genetics. For the germ-plasm remains a qualitative hypostasis, after all, an imaginary physical agent (even like the idioplasm) which bears properties through historic time. Germ-plasm is nothing but a word for a stream of rudiments within the chromosomes. It never became, it was logically incapable of becoming, that programmer of biological events, that item of organizational information, which is the gene. In effect, therefore, Weismann’s isolation of the germ-plasm turned evolution into a process indwelling in the chromosomes. Instead of objectifying evolution in the relation of structure to circumstance, he internalized it in the organism. For Weismann, too, we are beads strung on a rope. Even though it is a rope of sand, evolutionists would still study the rope. Germ-plasm, therefore, was another of those proto-scientific constructions which failed by explaining too much. Weismann would solve both heredity and development by germ-plasm, “on the changes of which development depends, while heredity rests on its continuity.”

AND ALL THE WHILE the right answer had blossomed unregarded in the form of Mendel’s garden peas. Mendel published his now famous paper, “Experiments in Plant Hybridization,” in 1866. But because biologists were busy asking all these wrong questions, it was ignored until 1900. For what is often said is not true, that Mendel’s results remained unknown because of the obscurity of the Brünn Society for the Study of Natural Science, whose Proceedings printed them. One of the supreme ironies of the history of science is the correspondence between Mendel and Nägeli—the modest Sudeten monk in his kitchen garden, the Geheimrat Professor Doktor in the University of Munich. Mendel described his findings in an early letter. Were they not, replied Nägeli (a good Hegel student), “empirical rather than rational?”—and passed on, intending no discussion, to put Mendel onto doing experiments for him on hawkweed, thus treating him like an unpaid laboratory assistant. And it is indeed curious that the two concepts on which biological objectivity rests historically, natural selection and the discreteness of hereditary characters, should have been the work of the last two naturalists, not to say amateurs, to figure importantly in the history of science—Darwin, an English country gentleman, and Gregor Mendel, an Austrian monk.

No more in Mendel’s case than in Darwin’s, however, did science have to do with a lucky strike. To read “Experiments in Plant Hybridization” is to experience the company of a fine biological intelligence. There is that instinct for the detail of a situation which distinguishes the biologist from the physicist. There is a quality of patience, which the physicist is not called upon to exercise, with the conditions imposed by the organism, and a willingness to set up the experiment and wait and watch while the organism performs it. Mendel’s experiment lasted through generation after generation for eight years. There is displayed throughout a gentleness of handling which argues a manual temperament different from the mechanically precise, but no less delicate. He worked with statistically significant numbers of plants, and had to pollinate each one himself before nature in the form of some busy bee should forestall him with uncontrolled pollen: “Artificial fertilization is certainly a somewhat elaborate process, but nearly always succeeds. For this purpose the bud is opened before it is perfectly developed, the keel is removed, and each stamen carefully extracted by means of forceps, after which the stigma can at once be dusted over with the foreign pollen.” Then he would tie a little bag over the plant’s head, to protect what was left of its chastity from its own kind. There is evident, finally, in Mendel’s mind the clearest perception of what precise problem would have what general significance, and of how to pose it.

For the critical mystery of biology was the relationship of the persistence of organic form to the variation of species. In retrospect we can see how neatly Mendel took up this problem from the pole opposite to Darwin’s, to whose solution his was the necessary complement. That is to say, Darwin would study variation in species apparently fixed. Mendel would study fixity amid the apparent variation of hybrids, where the problem of persistence and change appears with peculiar urgency. He had at hand the great body of botanical experience in producing novel flowering plants by artificial insemination. What struck his attention was the regularity with which the same hybrid forms recur, and he proposed to find “a generally applicable law governing the formation and development of hybrids.” No experiment had ever “been carried out to such an extent and in such a way as to make it possible to determine the different forms under which the offspring of hybrids appear, or to arrange these forms with certainty according to their separate generations, or definitely to ascertain their statistical relations.” These were the right questions. To their cogency Mendel owed his success. But neither was he (as is sometimes implied) lost to the large issues: “It requires, indeed, some courage to undertake a labour of such far-reaching extent; this appears, however, to be the only right way by which we can finally reach the solution of a question the importance of which cannot be overestimated in connection with the history of the evolution of organic forms.” (Mendel’s library contained a heavily annotated copy of On the Origin of Species).

Nor was it luck he hit on peas for his experiments. His conception of the problem required plants which should show constant differentiating features, and among which the differences should be marked. The hybrid offspring of two varieties must be either tall or short, not taller or shorter. After many trials, Mendel selected thirty-four varieties of the genus Pisum, and bred them to observe the inheritance of seven pairs of contrasting characters: smooth versus wrinkled seeds; yellowish versus green cotyledon; white versus colored seed-coat and flower; plump versus emaciated pods; green versus yellow pods in the unripe state; axial versus terminal arrangement of flowers along the stem; tall plants (six to seven feet) versus short ones (about one foot).

The results are known to the student in the most elementary course in general science, who easily bandies the words dominant and recessive once he is taught by those famous genealogical diagrams:

How simple it looks, and how pat those ratios! Like rigid models of atoms, such pictures support the student’s memory and destroy his appreciation of the thought the information once required. Mendel had had first to conceive of dominant and recessive characters amid the medley of tall and short plants, or smooth and wrinkled seeds, which succeeded each other generation after generation. Then, in an age when probability was still an occasional instrument of scientific demonstration, he had to resign himself to the search for a statistical order. For the progeny of any one set of parents will not usually exhibit Mendelian ratios.

As an example, he gives the results for offspring of the first ten plants (F-1) in his initial two experiments:

In Experiment 1 the extreme cases were 43 round, 2 angular; and 14 round, 15 angular. It will, perhaps, suggest the magnitude of his labors, and the firmness of his control, to tabulate simply the amount of information he needed in order to establish the dominant-recessive ratio in each of the seven characters he studied:

Character	Number of plants (F-1)	Dominant-Recessive Ratio
Smooth vs. Wrinkled seed	7,324	2.96
Yellow vs. Green cotyledon	8,023	3.01
White vs. Colored flower	929	3.15
Plump vs. Emaciated pod	1,181	2.95
Green vs. Yellow pod	580	2.82
Axial vs. Terminal flower	858	3.14
Tall vs. Short plant	1,064	2.84 —— 2.98 or 3 to 1

And this was only the F-1 generation. In later generations he had to keep his mind firmly fixed on the succession of ratios to make the second order distinction between the true breeders (one-third) and the two-thirds which breed hybrid, once again in the three-to-one proportion among themselves.

This arithmetical maze did not, perhaps, invite mathematical thought at a high level of abstraction. Nevertheless, the assertion may be ventured that Mendel’s was the first significant application of mathematics to biology. And notwithstanding his other great merits, this may well be taken as Mendel’s cardinal contribution to his science: that its quantification goes back to his experiments. With even greater admiration must one follow the strong thread of his reasoning through the labyrinth of inheritance when several variable characters were united by crossing—tallness or shortness, for example, combined with white or colored flowers. Without following into detail, it will illustrate the point to give the expression by which he represents his results:

AB+Ab+aB+ab+2ABb+2aBb
+2AaB+2aab+4AaBb …,

where each term represents a class for every possible combination of the four characters, and the coefficients the relative occurrence of that class in the offspring.

The identity of particular characters persists in discrete form from generation to generation, and this was Mendel’s basic discovery: that heredity comes, not in blendings, but in packets. It comes in jumps like those which the physicists, when they got down to comparable fundamentals, would call quanta, which too would require statistical ordering. His own interpretation of his results is atomistic in its structure, though he no more offered an hypothesis of wherein the units of heredity consist than did Newton of the cause of gravity:

Since the various constant forms are produced in one plant, or even in one flower of a plant, the conclusion appears logical that in the ovaries of the hybrids there are formed as many sorts of egg cells, and in the anthers as many sorts of pollen cells, as there are possible constant combination forms, and that these egg and pollen cells agree in their internal composition with those of the separate forms.

Precisely because Mendel did distinguish the problem of heredity from that of variation, these “cells” were logically capable of reduction to the genes of contemporary genetics. Such was not the case with the blending inheritance of Nägeli’s and Weismann’s theories, nor with the constructions of the other eminent and puzzled biologists of the late nineteenth century, who had to grapple with Darwin’s legacy. Their idioplasms and germ-plasms put them in a position like that in which Fontenelle and the Cartesians had once confronted Newton, trying to explain the cause and describe the operation of gravity by a single concept. The historian of science may, therefore, be pardoned for wondering what might have been the influence on biology had these scientists known the history of science, and whether they might then have noticed the interest of Mendel’s work? Suppose they had thought to compare the simple whole numbers of his ratios to Dalton’s, by which the chemical revolution was reduced to numerical terms. Suppose they had known of the relationship of the corpuscular philosophy of the seventeenth century to the Newtonian synthesis. Might they not have saved themselves much unprofitable reasoning, and advanced the progress of their science by several decades?

This was not to be, however, and Mendel’s paper was stillborn. It lay in a state of suspended animation until 1900, when it was quickened to life, less by the logic of science than the illogic of its history. Several biologists at the end of the century were addressing themselves to an objection frequently advanced against Darwinism: that it was difficult to see how a variation too slight to be detected from one generation to the next could confer enough advantage to be selected and perpetuated. It is now known that this is a false problem, since the significant mutations occur in the gene. Nevertheless, it directed attention to the possibility of gross mutation rather than gradualism. Perhaps evolution was a staircase rather than a slope. The most notable to explore this avenue was Hugo de Vries of Amsterdam, who observed what he took to be brusque transformations into new species in certain offshoots of the evening primrose. As a botanist, moreover, he found unsatisfactory the implication of Weismann’s germ-plasm, that the color (say) of the flower is determined by a genetic substructure governing just that organ. Rather, the whiteness of a flower involves other manifestations in leaf or stem, and must be governed by what De Vries called “pangens,” discrete but immanent constituents of the entire organism: “The whole character of a plant is built up out of definite units…. To each character there corresponds a particular form of material carrier”—not (be it emphasized) to each organ or each soma cell, but to each character. “There are no transitions between these elements, any more than there are between the molecules of the chemist.… We have to recognize that the general image of the species passes into the background, and that the idea of the composition of the species out of independent factors comes to the front…. The units of the characters of a species are … to be regarded as sharply separated magnitudes.”

When De Vries wrote that, he had already discovered Mendel’s paper. So almost simultaneously had two colleagues, Carl Correns in Tübingen and Erich Tschermak in Vienna, who were working quite independently on problems of discontinuous heredity. The triple coincidence arrested attention, the more so as it involved the pathos of a wrong righted too late to benefit the injured party. De Vries’s unsettled primroses were not in fact true mutations. Nevertheless, they served to impress upon the scientific world the proposition that heredity might be discontinuous in its basis. Only the prefix had to be dropped from De Vries’s “pangens,” and biology would be left with the word and the Mendelian structure of interpretation waiting to accommodate the right evidence. That appeared in the year 1906 in the laboratory of Columbia University, where T. H. Morgan, breeding generation after generation of pink-eyed fruit flies, found one whose eyes were white. A disproportionate share of the explosive new science of genetics is born on the wings of that tiny insect, which is to the geneticist what the mouse was to Boyle and Priestley. And with this the historian must hand over to the biologist the threads he has gathered up. Suffice it to point out how Mendel-cum-Morgan occupy the place in the historic strategy of the biological revolution that Dalton did in chemistry. The geneticist will separate out or combine characters from generation to generation—short-wings, grey bodies, white eyes—as wilfully as the chemist with his reagents. His test of the objective significance of the material units of heredity is the same as Lavoisier’s: analysis followed by synthesis. Nor is the point clouded by gathering doubt whether the gene is a real particle or a configuration in the giant molecules of the hereditary patrimony—either hypothesis (as Lavoisier observed in a similar situation) will permit expression of the quantities involved in an abstract and mathematical manner, and perhaps they are complementary truths.

MUTATIONS occur in the gene, either at random or as a consequence of radiation or some other positive injury. But they are selected for preservation according as they confer on the animal advantages in objective circumstance. And such is the movement of evolution against time. Darwin himself closed The Origin of Species with a passage which compared the generality of evolution in respect to time with that of gravity in respect to space. Certainly the nineteenth-century awareness of science was conditioned by the theory of evolution as that of the eighteenth century had been by the Newtonian theory. And now the vindication of Darwin’s theory of natural selection in the science of genetics puts scholarship in a position to specify what were the elements in its success, to push further a structural comparison between the Newtonian and Darwinian theories, and thus to exhibit the justice of the judgment which attributes to Darwin the importance for biology which Newton has had in physics. For the concept of natural selection, quantified in genetics, has put an end to the opposition between mechanism and organism through which the humane view of nature, ultimately the Greek view, had found refuge from Newton in biology. Lamarck’s theory, on the other hand, had originated as the transfer to biology of that old view of flux and process, since become romanticism, for which Lavoisier had made chemistry, the science of matter, uninhabitable. It is for this reason that Darwin was the orderer of biological science, as Newton had been of physics and Galileo of kinematics. Perhaps it will be apropos to push the earlier term of the comparison back to Galileo. For the objectification and quantification of motion were the germs of metrical science. And in the over-arching structure of the history of science, Darwinian evolutionary theory stands in the same relation to Lamarckian or neo-Lamarckian as does Galilean kinematics to that of the impetus school.

In mechanics, Galileo achieved objectivity by accepting motion as natural, and considering its quantity as something to be measured independently of the moving body. This he accomplished by treating time as a dimension, after which translational motion is no longer taken as metaphysical change. In Darwin—to draw out the parallel—natural selection treats in the same way that sort of change which expresses itself in organic variation (the motion of species, so to say, through historic time). Instead of explaining variation (or motion), he begins with it as a fundamental fact of nature. Variations are assumed to occur—in the gene they do occur—at random, requiring from Darwin no further explanation and presupposing in his theory no causative agent for science to seek out. This is what opened the breach through which biology could follow physics into objectivity. It introduced the distinction, which Darwin was the first to make, between the origin of variations and their preservation. Variations arise by chance. But they are preserved according as they work more or less effectively in objective circumstance.

Darwinian evolutionary change is analytically analogous to Galilean motion in another and even more impressive respect. There is direction in it, whereas in Lamarck’s formulation life simply circles endlessly through nature. H. F. Blum has recently considered evolution as a problem in entropy, and advanced the interesting argument that time as it enters into thermodynamic processes may be considered as a coordinate of evolution. This amounts to saying, on the one hand, that evolution is capable of vectorial description, and on the other, that biological time is a dimensional component of a physical situation and ceases thereby to be a refuge of becoming or a locus of flux. Quite generally, in fact, Darwin’s work, though not numerical in expression, was, nevertheless, quantitative in method and matter of thought. As to this, the relationship of Mendel to Darwin repeats that of Dalton to Lavoisier—the one attaching numbers to the other’s quantities. Thus, that Darwin began with the Malthusian ratio was of far more significance for his success than was the question of its validity. It was, indeed, of utmost significance. What selection does in Darwin’s theory is to determine the quantity of living beings which can survive in any given set of objective circumstances. This aspect of the approach is more evident, perhaps, in Wallace’s essay than in Darwin’s more diffuse account. For example:

Wild cats are prolific and have few enemies: why then are they never as abundant as rabbits?

The only intelligible answer is, that their supply of food is more precarious. It appears evident, therefore, that so long as a country remains physically unchanged, the numbers of its animal population cannot materially increase. If one species does so, some others requiring the same kind of food must diminish in proportion.… It is, as we commenced by remarking, “a struggle for existence,” in which the weakest and least perfectly organized must always succumb.

And even more striking is Wallace’s passage on natural selection as accounting

… for that balance so often observed in nature—a deficiency in one set of organs always being compensated by an increased development of some others—powerful wings accompanying weak feet, or great velocity making up for the absence of defensive weapons; for it has been shown that all varieties in which an unbalanced deficiency occurred could not long continue their existence. The action of this principle is exactly like that of the centrifugal governor of the steam engine, which checks and corrects any irregularities almost before they become evident; and in like manner no unbalanced deficiency in the animal kingdom can ever reach any conspicuous magnitude, because it would make itself felt at the very first step, by rendering existence difficult and extinction almost sure to follow.

No longer need it appear as a paradox, therefore, that it should have been Darwin, Wallace, and Mendel, the old-fashioned naturalists, and not the embryologists and physiologists of the continental laboratories, who brought the revolution in biology. The reason is clear. Nor does it lie only in the nature of their empirical contributions. It lies in the nature of their reasoning, which was concerned with quantity and circumstance. This is why it was they who liberated biology from its limiting dependence on classification and dissection, with the gulf between bridged insubstantially by that metaphor of goal-directed organism which the evidence never could control. For nothing is more arresting in the comparison of the biological to the Newtonian revolution than the reduction of the concept of natural selection to material atomism in the hybrid science of genetics, produced by the crossing of Darwinism and Mendelism. Just as the discontinuity of matter in atoms-and-the-void liberates motion from subjectivity, or indwelling qualities, so biological objectivity was firmly seated in the discontinuity of the hereditary patrimony, where inheritance might be comprised in number. In this perspective, it may appear as a kind of wisdom in Darwin, rather than as a failing, that his theoretical work began as an application to biology of the individualistic assumptions of classical political economy. He had, after all, no other basis for atomism. And the outcome is a conception of biological order no different from the order assumed by contemporary atomic physics—an order of chance to be analyzed by the techniques appropriate to mathematical probability.

Darwin and the Lamarckians speak their parts, therefore, in that endless debate between atoms and the continuum, the multiplicity of events and the unity of nature, which is what has given the history of science its dialectic since its start in Greece. For the continuum of life as the program of nature goes back to that aspect of classical philosophy which was a prolongation of cosmogony, back through the Stoics and Heraclitus to fire and the world as flux and process. But it is cosmology, the opposite of this, from which science derives, rather from the contemplation of being in the light of reason than of becoming in the light of process. And this resolves, perhaps, a final apparent paradox, which is that providentialism and belief in fixity and divine design have in effect been more conducive to positive scientific work—in Newton, for example, in Linnaeus, or in Cuvier—than has belief in process—in Diderot, in Goethe, or in Nägeli. As a constituent of theory, providentialism ends in self-defeat—but only after establishing structure for science to find. It posits the existence of specific entities which may serve as the term of analysis. But in becoming, everything blends into everything, and nothing may ever be defined. And though Darwin certainly did invest science with historical depth, his is the nominalist history of the true historian, and not the immanent process of the Marxian or Hegelian historicist philosopher. It is a mistake to say, as often is said, as even the great Cassirer said, that Darwin brought this Hegelian sense of becoming within the pale of science. What he did was to treat that whole range of nature which had been relegated to becoming rather as a problem of being, an infinite set of objective situations reaching back through time. He treated scientifically the historical evidence for evolution, which had been marshalled often enough before him, but more as a travesty than an extension of science. Rightly understood, therefore, the Darwinian theory of evolution by natural selection turned the problem of becoming into a problem of being, and permitted the eventual mathematicization of that vast area of living nature which until Darwin had been protected from logos in the wrappings of process.

IF THIS BE SO, a further word is needed on the significance of evolutionary thought. Science and religion, evolution and ethics, social Darwinism—these topics form a considerable portion of the nineteenth-century stock-in-trade of the historian of ideas. Will all this, too, appear as a variation on the theme of the Enlightenment and science, transposing the essential misunderstanding of the one for the other into the keys of history and time? And the answer, on the whole, is yes. No doubt Darwinism was more directly translatable into political and social terms than Newtonianism. Rugged individualists, Marxists, militarists, racists, they all found in the cruelty of nature ideological comfort comparable to that which their eighteenth-century forebears had discovered in its harmony. And if the influence of Darwinism was not deeper, its lessons seemed more plausible, however contradictory. For Darwin took the form of his ideas, not like Newton from classical geometry, but from the constructs of English liberalism. We are concerned not with a translation after all, but only with a retranslation.

This, indeed, is the only point that needs to be made about the validity of social Darwinism (as apart from the real and different question of its influence). Consider words in the title alone: “Origin”—it is a theological problem; “Selection”—it implies an act of choice; “Survival”—who can be indifferent? “Favoured Races”—the phrase which Darwin substituted for “Survival of the Fittest” in later editions evokes shadows of Gobineau and Hitler falling before; “Fittest”—but who is to judge of the fit? Is nature harmony or is it conflict? Is the law of the jungle or the law of love the rule of life? Must dog eat dog with relish? And the trouble was, not that Darwin meant to pronounce on all this, but that in the relatively inexact state of biology, he borrowed from common language terms which have human connotations quite different from the meaning they assume in the scientific theory of evolution. Just so does a word like force mean one thing in physics and quite other things in life. Nor could Darwin stop at every paragraph to explain himself. When he did, it is clear that he was capable of thinking clearly even in loose language. The measure of “success,” for example, he defines as the amount of progeny, and this is obviously the particular animal’s contribution to evolution. But that is not what Andrew Carnegie meant by success, much less Malthus. And we for our part may define social Darwinism as the re-exportation into social science of a language quite speciously fortified with the deterministic vigor of natural science—opinions converted into truths through having traversed science.

In a sense the critics of Darwin saw the point more correctly than did the epigones who associated evolution with some social gospel. For the romantics criticized the theory of natural selection precisely because it denied the history of nature any meaning for man as a social or moral being. The concept of fitness in the organism was simply a tautology, said the romantic biologists, of whom Driesch was the most important. (Just so had Fontenelle objected to Newtonian geometric proofs that they come out exactly even.) What is causation in Darwin, and what in Newton?—only a formless sequence of results extending backward or outward endlessly into a metaphysical limbo. For the romantics of the nineteenth century, like the Cartesians of the eighteenth (in this way, too, their successors), wanted a science which would account at once for the behavior and the cause of phenomena, which would see nature steadily and see it whole. They wanted a science which would seize on the unity of nature, instead of fragmenting it into discrete events connected only by chance and circumstance, and never by reason or purpose or will or the good of man. In the case of Driesch, the heart of the position is that Darwin simply impoverishes biology, that he gives no rational insight into events, that he is simply a recorder posing as a philosopher, a chronicler rather than a historian of nature—and all this because he will not see that the laws of life are different from those of physics, and that in the organism purpose is everything. And this, of course, is why, once Darwin had established the facts of evolution, the Nägelis and Driesches and Bergsons repudiated the very theory of natural selection which carried those facts home to the scientific consciousness of the age, substituted for it an idioplasm or an entelechy or an élan vital, and reached back to Lamarck—in the case of George Bernard Shaw back to Methuselah—as to a humane alternative.

Biological romanticism never made much impression in the world of English letters, where Samuel Butler and Shaw have been the most widely read of Darwin’s critics. In their case, too, a comparison with certain themes of the eighteenth-century Enlightenment is instructive, for it makes clear that the question is no biological discussion, but simply the continuing expression of a moral resentment which wants more out of nature than science finds there. To read Diderot and Butler together is a curious experience, itself almost a vindication of Butler’s Unconscious Memory. For one has the impression that this and Butler’s other writings upon nature were products of his own rather painful and labored reflection, and yet how unoriginal they are! These, for example, are the four principles of Butler’s Life and Habit: “The oneness of personality between parents and offspring; memory on the part of offspring of certain actions which it did when in the persons of its forefathers; the latency of that memory until it is rekindled by a recurrence of the associated ideas; and the unconsciousness with which habitual actions come to be performed.” Butler follows Diderot’s route out of atomistic materialism: “It is more coherent with our other ideas, and therefore more acceptable, to start with every molecule as a living thing, and then deduce death as the breaking up of an association or corporation, than to start with inanimate molecules and smuggle life into them; and,… therefore, what we call the inorganic world must be regarded as up to a certain point living, and instinct, within certain limits, with consciousness, volition, and power of concerted action.”

But from the point of view of one who admires the intellectual achievements of science, it is Shaw rather than Butler who, by contrast to his pretensions, seems drastically diminished in stature by his ventures into scientific criticism. The famous preface to Back to Methuselah presents clichés with the air of lordly malice that Shaw knew how to assume as the right of a superior intelligence which did not mind pointing to its own perversity. But it was an intelligence which, far from transcending science, had never given itself the trouble to understand the force or limitations of scientific demonstrations, and in the perspective of history, Shaw on Darwin will surely find a place side by side with Bellarmine and the papal jury setting the astronomers right about natural philosophy. It does not appear that Shaw ever thought to ask the biologists whether natural selection was true. It was simply “a blasphemy, possible to many for whom Nature is nothing but a casual aggregation of inert and dead matter, but eternally impossible to the spirits and souls of the righteous.” Darwin is forbidden to banish mind from the universe: “For ‘Natural Selection’ has no moral significance: it deals with that part of evolution which has no purpose, no intelligence, and might more appropriately be called accidental selection, or better still, Unnatural Selection, since nothing is more unnatural than an accident. If it could be proved that the whole universe had been produced by such Selection, only fools and rascals could bear to live.” And the Shavian word on evolution, therefore, is in fact only a diatribe, another expression of the antivivisectionism—and in a certain sense the vegetarianism—of a personality whose Rousseauist attitude to nature involved more of sentimental hostility to intellect (as to any aristocracy) than is generally appreciated.

With this background in mind, one might have predicted that the latest thrust back to Lamarckism would have occurred in a Marxist context. And this episode should stand as a warning that ideas have consequences, and that to succumb to the very natural and often well-intentioned temptation to bend science to the socializing or the moralizing of nature is to invite its subjection to social authority, which is to say to politics. For the moralist knows what kind of nature he wants science to give him, and if it does not, he will either, like Shaw, repudiate it; or if, like Lysenko, he has the power, he will change it. Once again, as in Diderot, as in Goethe, as in Lamarck, resentment of mathematics (which expresses quantity and not the good) reveals the moralist beneath the natural philosopher—the Michurin school rejects in principle the mathematicization of biology in favor of the autonomy of organism. Lysenko’s purported findings may, therefore, be taken as the nadir of the history of Lamarckism, and (one hopes) the end of the story. For in his demagoguery the humane view of nature is vulgarized by way of a humanitarian naturalism into the careerist’s opportunity. But there is nothing new about it. It is only the most recent expression of that pattern of resistance to science which has attended its entire history in reaction against the objectification of nature.

There was nothing of Christianity in all this, either in Shaw or in the Marxian belief that man does regenerate himself in the revolutionary moment of truth. And surely if one thinks about it, there was never a more unnecessary battle than that between science and theology in the nineteenth century, nor any set of findings more irrelevant to the latter than those of evolutionary theory. In retrospect, it appears that the issue between a naturalistic and providential historiography of nature had been largely worked out on the plane of geology, and needed only to be settled by the culmination of natural history in The Origin of Species. This is not to deny the growth of agnosticism in the nineteenth century, and particularly in the world of Anglo-Saxon Protestantism, still living in the aftermath of the Methodist revival. But surely science, as epitomized by the theory of evolution, was at most the emblem or the scapegoat of this movement. It was not the cause.

Darwin’s own experience, as he tells about it in his Autobiography, was typical of the Victorian intelligentsia. His family background was intermingled with the radical nonconformity of the midlands, where puritanism slowly evolved through Unitarianism to agnosticism. Nor did he lose his little faith as a consequence of the theory of evolution. He became unconvinced for historical and, above all, for moral reasons. Gradually, he saw “that the Old Testament from its manifestly false history of the world, with the Tower of Babel, the rainbow as a sign, etc. etc., and from its attributing to God the feelings of a revengeful tyrant, was no more to be trusted than the sacred books of the Hindoos, or the beliefs of any barbarians.” But the ground of the New Testament was no more solid. Discrepancies abound in the Gospels. Those four books are in any case hearsay, whereas “the clearest evidence would be requisite to make any sane man believe in the miracles by which Christianity is supported.”

Thus disbelief crept over me at a very slow rate, but was at last complete. The rate was so slow that I felt no distress, and have never since doubted even for a single second that my conclusion was correct. I can indeed hardly see how anyone ought to wish Christianity to be true; for if so the plain language of the text seems to show that the men who do not believe, and this would include my Father, Brother and almost all my best friends, will be everlastingly punished.

And this is a damnable doctrine.

These meditations were much in Darwin’s mind in the years from October 1836 to January 1839. Thus, when he read Malthus and formulated the theory of natural selection in October 1838, he was already far gone in free thought. This is not to argue that Darwin’s eminence in biology makes his religious experience—or inexperience—decisive for historical interpretation. Nevertheless, it is interesting that even Darwin’s disbelief substantiates a pattern of agnosticism which may equally be exhibited in the repudiation of Christianity by other eminent Victorians—Francis Newman (to name some notable names), James Anthony Froude, George Eliot, John Stuart Mill, and Leslie Stephen. In no one of these cases was the decisive factor the findings of science. In every case it was an ethical revulsion from doctrines of the atonement, everlasting damnation, original sin, and an omnipotent God who permits evil.

We did not, therefore, need Darwin’s allusion to “almost all my best friends” to suspect that the decay of theology had left many intelligent Victorians faced with a dangerous choice. Upright, unblinking, committed to truth—TRUTH, come what may—they must repudiate their religion in the name of its ethic. Huxley, it turns out, is the spokesman for Darwin on religion as on science. And Darwin is as vulnerable as Huxley to the very pertinent criticism in A. J. Balfour’s Foundations of Belief: “Their spiritual life is parasitic: it is sheltered by convictions which belong, not to them, but to the society of which they form a part: it is nourished by processes in which they take no share. And when those convictions decay, and those processes come to an end, the alien life which they have maintained can scarce be expected to outlast them.” But science was not the worm in the apple: that worm was manliness, it was honor, it was decency—the Victorian virtues, left defenseless by a theology which Methodism had drowned in rivers of vulgar Evangelical piety, or which the Oxford Movement had blown away on the high, ecclesiastical winds of Tractarian romance.

The Origin of Species did cause distress. After all, Christianity does say that man, the possessor of an immortal soul, was specially created in the image of God. Evolutionary theory says that he was evolved by natural processes from other animals. Was it necessary, therefore, to choose between Christianity and science? It was the kind of dilemma which the Victorians loved to face. “’Tis the crown and glory of organic science,” wrote Darwin’s old teacher, Sedgwick, acknowledging his presentation copy, “that it does, through final cause, link material to moral.… You have ignored this link; and, if I do not mistake your meaning, you have done your best in one or two pregnant cases to break it. Were it possible (which, thank God, it is not) to break it, humanity, in my mind, would suffer a damage that might brutalize it, and sink the human race into a lower grade of degradation than any into which it has fallen since its written records tell us of its history.” In less pensive vein, Gladstone and the Bishop of Oxford made fools of themselves debating the issue with Huxley. One exchange turned on the question whether the destruction of livestock in the miracle of the Gadarene swine had not been a divine invasion of property rights.

Despite all this triviality, it is curious, one hundred years later, that it is the theologians who have learned to live with the theory of evolution. Whereas the ones who have not so learned, and cannot, are those atheists who would substitute nature for God as the source of morality and ethics, private or public. The Scopes Trial was a piece of intellectual buffoonery, after all—the Victorian age expiring in Tennessee. Shaw’s preface to Back to Methuselah was not. Neither was the Lysenko affair, nor the tedious effusions of Samuel Butler. It is not the intellectual conflict between science and religion which has proved fundamental. It is the conflict between science and naturalistic social or moral philosophy.

If one be clear about the nature of science as a description of the world, declarative but never normative, may not the choice between science and religion be refused? Is it not simply a false problem, arising from a confusion—an ancient confusion going back to the beginning of science—between objects and persons? Science is about nature, after all, not about duties. It is about objects. Christianity is about persons, the relation of the persons of men to the person of God. Biology has found that the human animal is the product of evolution. It has not found—in principle, science (not being omniscience) cannot find—that man is nothing but the product of evolution. Historically speaking, it is precisely those who have said he is nothing but that, nothing but natural, who have found intolerable the meaningless chance which operates under the name of natural selection.