Given the long line of evolutionists, from Anaximander to Charles's own grandfather Erasmus, wherein lies Darwin's greatness, the originality of his contribution? In picking up, one might say, the disjointed threads, plaiting them into a braid, and then weaving an enormous carpet around it. The main thread was the evolutionist's credo that the various species in the animal and vegetable kingdom 'had not been independently created, but had descended, like varieties, from other species'. [17] Now this doctrine disposed of the idea of the Creator putting down separately the first serpent, giraffe and walrus as ready-made products on the earth; but it gave no explanation of the reasons which caused the common ancestor to transform itself gradually into serpents, walruses, and giraffes. Only Lamarck had attempted to provide a comprehensive reason for evolution in his four 'laws'. They said, in essence, that an animal's physical characteristics and particularities of behaviour are shaped by its needs, that is, by adaptation to its natural environment; that specialized organs grow and decline in proportion to their use or disuse; and that these adaptive changes which the animal acquires in its lifetime are inherited by its offspring.
Contrary to popular belief, Darwin had no objection against the last point, the 'inheritance of acquired characteristics' -- decried as a mortal heresy by neo-Darwinians. On the contrary, in his Variations of Animals and Plants under Domestication, and in the later editions of the Origin, he gave a series of examples of what he believed to be inherited characteristics in the offspring, due to adaptive changes in their ancestors. But he refused to accept such direct adaptations as the only, or even the main cause of evolution, because the evidence seemed to speak against it. Evidence showed that a great variety of species lived under identical environmental conditions; and vice versa, that the same species could be found under widely varying conditions. If species evolved, as Lamarck's theory proposed, by direct adaptations to the environment, then their variety remained unexplained. Evolution was a fact; but what caused it? What was the nature of the force which transformed animals and plants into new shapes?
The second thread that he picked up was of almost as trivial a nature for a country-bred English gentleman as Archimedes's daily bath: domestic Breeding. The improvement of domestic breeds is achieved by the selective mating of favourable variations:
It seemed to me probable that a careful study of domesticated animals and of cultivated plants would offer the best chance of making out this complicated problem. Nor have I been disappointed; in this and in all other perplexing cases I have invariably found that our knowledge, imperfect though it be, of variation under domestication, afforded the best and safest clue. I may venture to express my conviction of the high value of such studies, although they have been very commonly neglected by naturalists. [18] (my italics)
We might say that Darwin had discovered 'evolution through artificial selection'. Incidentally the discovery is again not quite as original as the last sentence might suggest. Darwin's notebooks of that period show that he had been reading and pondering Lamarck; and twenty years earlier, in his Philosophie Zoologique, Lamarck had written:
What nature does in the course of long periods we do every day when we suddenly change the environment in which some species of living plants is situated . . . Where in nature do we find our cabbages, lettuces, etc., in the same state as in our kitchen gardens? And is not the case the same with regard to many animals which have been altered or gready modified by domestication? [19]
Whether Darwin read this passage from Lamarck, or similar passages, we do not know. But the question is irrelevant except for historians who specialize in priority claims. At any rate, Darwin now set out to collect facts about domestic breeding 'patiently and indiscrimnately', not only from technical journals but from 'skilful breeders and gardeners'. A great number of the 'facts' were spurious, and some of his theorizings were as wild and fantastic as Kepler's speculations on the broom-like sweeping force emanating from the sun:
The cat had its tail cut off at Shrewsbury and its kittens had all short tails; but one a little longer than the rest; they all died. She had kittens before and afterwards with tails. My father says on authority of Mr. Wynne, the bitch's offspring is affected by previous marriages with impure breed . . . Dr. Smith says he is certain that when white men and Hottentots or Negroes cross at Cape of Good Hope, the children cannot be made intermediate. The first children partake more of the mother, the later ones of the father.
In his book on Variations of Animals and Plants under Domestication we are further informed that a cow having lost its horn owing to an infected wound, gave birth 'to three calves, each with a small bony lump in place of a horn'.
A contemporary biologist has commented on Darwin's 'amiable credulity'. [20] It is a character trait which he shared with Tycho, Kepler, Freud, Pasteur, and a large number of other great scientists. Ernest Jones [21] remarked in an essay about Freud that creative genius seems to be a mixture of scepticism and naïveté scepticism regarding the dogmas implied in traditional modes of thought, combined with the willingness of a wide-open mind to consider far-fetched theories. Darwin himself, as one of his biographers remarked, 'was able to give ultimate answers because he asked ultimate questions. His colleagues, the systematizers, knew more than he about particular species and varieties, comparative anatomy and morphology. But they had deliberately eschewed such ultimate questions as the pattern of creation, or the reasons for any particular form, on the grounds that these were not the proper subjects of science. Darwin, uninhibited by these restrictions, could range more widely and deeply into the mysteries of Nature. . . . It was with the sharp eyes of the primitive, the open mind of the innocent, that he looked at his subject, daring to ask questions that his more learned and sophisticated colleagues could not have thought to ask' (Himmelfarb). [22]
However, the study of domestic breeding led into another cul-de-sac; for, in the case of domestic animals, man acts as the agent of selection; but who or what selects the favourable variations for breeding in the case of undomesticated animals or plants? 'How selection could be applied to organisms living in a state of nature remained for some time a mystery to me.'
The deadlock lasted a year and three months. He tried a number of hypotheses, but none of them worked. He toyed with the idea of some universal law, according to which species were born, matured, and died, just as individuals do. 'There is nothing stranger in the death of a species than in the death of individuals.' Then he assumed, by a perverse analogy, that since nothing is preserved of an individual who dies without leaving offspring, so a species too will die out unless it gives rise to another species. But they were wrong guesses, and his thoughts kept running in circles in the blocked matrix -- as Sultan's did until his eyes fell on the stick.
In Darwin's case the stick was Malthus's "An Essay on the Principle of Population." It had been published in 1797 -- more than forty years earlier. When Darwin read the essay -- among other books which he read 'for amusement', as he said -- he saw in a flash the 'natural selector', the causative agent of evolution, for which he had been searching:
As many more individuals of each species are born than can possibly survive; and as consequently there is a frequently recurring struggle for existence, it follows that any being, if it vary ever so slightly in a manner profitable to itself . . . will have a better chance of survival, and thus be naturally selected (Darwin's italics). Thus favourable variations would tend to be preserved, and unfavourable ones to be destroyed. Here, then, I had at last got a theory by which to work. [23]
He had found the third thread. Now the pattern of the theory was complete: what remained to be done was its elaboration -- the weaving of the huge carpet which took him most of the rest of his life.
The odd thing about the story is -- as others have pointed out -- that Darwin had completely misunderstood Malthus. The struggle for existence, in which Darwin discovered the causative mechanism of evolutionary improvement, Malthus himself had regarded as a cause of misery, frustrat
ion, and decline. The increase of population was for Malthus an unmitigated evil and an obstacle to progress. The essay had actually been written as a polemic against Condorcet and Godwin, who had argued the perfectability of the human species. Domestic breeding, Malthus retorted, could improve animals and plants only to a very limited degree; but a carnation could never be made to reach the size of a cabbage, and similar limits were set to human progress. Thus the struggle for existence was for Malthus not the whiphand of evolution, but a scourge. What Darwin found in Malthus's essay he had read into it himself -- as Kepler had read his brooms and planetary lodestones into the skies.
Even odder is the fact that Wallace arrived at the same discovery also by way of Malthus. Alfred Russell Wallace was even more gullible, and at the beginning of his career even more of a dilettante than the young Darwin. He was fourteen years younger than Darwin; he had been educated at an indifferent grammar school and learned the trade of land-surveying. Before he took up that occupation, he had shown no interest in nature, and 'it took another four years for him to advance beyond the recognition of rose and buttercup, and to learn, from a shilling booklet published by the Society for the Diffusion of Useful Knowledge, the elementary classifications of botany'. [24]
At twenty-one he became a schoolteacher of sorts. In that year he read, among other books, Darwin's Journal of a Naturalist's Voyage on the Beagle and Malthus's "Essay on Population." But his mind did not click. He struck up a friendship with the entymologist Henry Walter Bates and became an expert collector of beetles. This led him to speculate about 'the almost infinite number of specific forms [among beetles], the endless modifications of structure, shape, colour, and surface-markings . . . and their innumerable adaptations to diverse environments'; he was 'bitten by the passion for species' [25] and the secret of their origin. Like Darwin he became an evolutionist by an act of faith; like Darwin he was searching for its cause; like Darwin he embarked -- with his friend Bates -- on a naturalist expedition to collect insects, shells, birds, and animals; like Darwin he wrote a book about it (Travels on the Amazon and Rio Negro).
The expedition lasted four years; two years later, in 1854, he published an article in a scientific journal in which he postulated that 'every species has come into existence coincident both in space and time with a pre-existing, closely allied species'; all species together thus formed a 'branching tree'. But, like Darwin earlier on, he did not know what made the tree grow: 'the question of how changes of species could have been brought about was rarely out of my mind'. Darwin read the paper and wrote to Wallace that he agreed with 'almost every word' in it; he added that he himself had been working for twenty years on the problem and had a 'distinct and tangible idea of its solution'.
One year later the same 'distinct and tangible idea' came to Wallace. In his autobiography Wallace described how he was 'lying muffled in blankets in the cold fit of a severe attack of intermittent fever at Ternate' (an island near New Guinea) when he suddenly remembered Malthus's essay on population which he had read 'twelve or more years earlier'. [26]
The effect was analogous to that of friction upon the specially prepared match, producing that flash of insight which led immediately to the simple but universal law of the 'survival of the fittest' . . . 'It suddenly flashed upon me that this self-action process [i.e. the struggle for existence] would necessarily improve the race, because in every generation the inferior would inevitably be killed off and the superior would remain -- that is, the fittest would survive. The more I thought over it the more I became convinced that I had at length found the long-sought-for law of nature that solved the problem of the origin of the species.' [27] In the course of the next two evenings, 'in a few feverish hours', he put his theory into a paper of four thousand words and sent it off to Darwin, in the pleasant belief that it would be a surprise to him -- since Darwin had not yet published his own theory, although he had put it on paper years earlier in several versions and shown it to his friends.
'I never saw a more striking coincidence', Darwin wrote. 'If Wallace had my manuscript sketch written out in 1843, he could not have made a better short abstract.'
Luckily, both Wallace and Darwin acted with a generosity and reasonableness rare in the annals of science; the result was the presentation on 1 July 1848 of a joint memoir by Darwin and Wallace to the Linnean Society, under the title 'On the Tendency of species to form Varieties; and on the Perpetuation of Varieties and species by Natural Means of Selection'. Neither author was present; Wallace was overseas, Darwin ill in bed. When the paper was read out there was no discussion and no sign of interest. At the end of the year the President of the society said in his annual report: 'The year which has passed . . . has not, indeed, been marked by any of those striking discoveries which at once revolutionize, so to speak, the department of science on which they bear.' [28] In November next year The Origin of Species was published, and only then did the storm break.
Though both men were constantly ailing from real and perhaps also from imaginary diseases, Darwin lived to be seventy-three, and Wallace ninety. Though they differed on some points of theory and though their opponents tried to play them out against each other, they managed to remain life-long friends; towards the end of his life Darwin obtained a pension for Wallace from Mr. Gladstone, and Wallace was one of Darwin's pall-bearers. At the fiftieth anniversary, in 1909, commemorating the joint publication of the Darwin-Wallace papers, Wallace modestly declared that their relative contributions 'could be justly estimated as the proportion of twenty years to one week' [29] -- which was an exaggeration, as Wallace's later works, particularly the 'Contributions' and 'Darwinism' were of considerable importance.
The psychologically fascinating aspect of the story is that the same bisociative process was triggered off in Darwin's case by reading Malthus, in Wallace's by the buried memory of Malthus, whom he had read many years earlier, popping into consciousness at a feverish moment. Thus Darwin's discovery strikes one as more rational, Wallace's as more dramatic and bizarre, and this is in keeping with the character of the two men. If Darwin had more patience and clarity of mind, Wallace had more fantasy and perhaps even more depth. His remark that selection through survival of the fittest was a 'self-acting process' anticipated the concept of negative feed-back. His conviction that the rise of organic life, the rise of consciousness, and the rise of man represent 'jumps' in the evolutionary series, due to some 'unknown reality' which has to be added to the mechanical operation of natural selection, had a religious flavour; yet his conclusion that 'man and his rise now appear short in time -- explosively short' has been confirmed by contemporary anthropology. If Darwin had an 'amiable credulity', Wallace believed, among other things, in phrenology and in the cruder forms of mesmerism and spiritualism. No wonder he had to dive into the depths of his unconscious mind to bring up the same trophy which Darwin spied drifting on the surface, and secured with a boathook.
That both read Malthus is not much of a coincidence as his essay was well known and discussed at the time; and had it not been Malthus, they could have extracted the same idea from other sources -- from Erasmus Darwin, for instance, or from certain passages in Lamarck. The time was ripe; 'it was not the coincidence of discovery that is surprising but rather the fact that the coincidence was so long delayed'. [30] This remark by one of Darwin's biographer's is not based on hind-sight, but on the opinion of Darwin's friends and contempotaries:
'How extremely stupid not to have thought of that,' was Huxley's first reaction, reflecting that 'Columbus' companions had probably felt the same way when he made the egg stand on end'. The same thought suggested itself to the ornithologist Alfred Newton, who did not know whether to be 'more vexed at the solution not having occurred to me, than pleased that it had been found at all', particularly since it was 'a perfectly simple solution' of the problem that had been plaguing him for months. . . . Many of Darwin's friends must have felt as Huxley did . . . and many of his enemies must have agreed with Samuel Butler: 'Buffon plan
ted, Erasmus Darwin and Lamarck watered, but it was Mr. Darwin who said "that fruit is ripe", and shook it into his lap.' [31]
VII
THINKING ASIDE
Limits of Logic
In an old Alchemist's Rosarium, whose author I have forgotten, I once saw two pieces of advice for finding the Philosopher's Stone I printed side by side:
The Stone can only be found when the search lies heavily on the searcher. -- Thou seekest hard and findest not. Seek not and thou wilst find.
The introspective reports of artists and scientists on their sources of inspiration and methods of work often display the same contradiction. 'Saturate yourself through and through with your subject . . . and wait' was Lloyd Morgan's advice. 'Chance only favours invention for minds which are prepared for discoveries by patent study and persevering efforts.' This was said by Pasteur, and his meaning goes here beyond what I have called the factor of 'ripeness': he seems to regard chance as a kind of legitimate reward, causally related to the effort -- an almost mystic conception. Souriau's famous 'to invent you must think aside' -- pour inventer il faut penser à côté quoted with approval by Poincaré, points in the same direction. The consensus, at least among mathematicians, seems to be that if you strive hard enough to get to India you are bound to get to some America or other. 'One sometimes finds,' Fleming once said, 'what one is not looking for. For instance, the technician who set out to find a way to synchronize the rate of fire of a machine-gun with the revolutions of an air-screw discovered an excellent way of imitating the lowing of a cow.'
The Act of Creation Page 15