A History of Evolution/Chapter 5
CHAPTER V.
DARWIN AND THE TRIUMPH OF EVOLUTION
The outstanding figure of the entire history of evolution is Charles Darwin. Whether or not be deserves all of the prominence that has been given him is a question—a question that probably must be answered in the negative. We are very apt to lionize the victor while we ignore those who made the victory possible, whether it be won in science, politics, or warfare. Among certain circles today there is an undeniable tendency to over-praise Darwin; to talk and think as though he were the first and the last truly great evolutionist. It is becoming with Darwin as Harris found it with Shakespeare: "He is like the Old-Man-of-the-Sea on the shoulders of our youth; he has become an obsession to the critic, a weapon to the pedant, a nuisance to the man of genius." If we substitute 'popularizer' for 'critic,' Harris' sentence will apply to Darwin without further modification. There is a popular misconception that a great and successful scientist must of necessity be a man of great genius; nothing of the sort is true. Take the average "authority" away from his specialty, and he is a very commonplace individual; take him with it, and he is often little more than a remarkably durable and precise human machine.
Neither biographers nor critics have shown us any good reasons for considering Charles Darwin an exceptionally great man. He was a highly successful scientist, but at the same time he was aided to success by the condition of science during the eighteenth and nineteenth centuries, and his personal fortune. In this connection it will be worth our while to examine the opinions of Carlyle, as reported by Frank Harris. The two were discussing notables of the century, and Harris brought up the name of Darwin. Carlyle described the two brothers as "solid, healthy[1] men, not greatly gifted, but honest and careful and hardworking * * *" and speaking of a conversation with Charles Darwin after his return from the "Beagle" voyage, said: "I saw in him then qualities I had hardly done justice to before: a patient clear-mindedness, fairness too, and, above all, an allegiance to facts, just as facts, which was most pathetic to me; it was so instinctive, determined, even desperate, a sort of belief in its way, an English belief, that the facts must lead you right if you only followed them honestly, a poor, groping, blind faith—all that seems possible to us in these days of flatulent unbelief and piggish unconcern for everything except swill and straw."[2]
We need not, like Carlyle, abuse this "allegiance to facts"; it is the foundation-stone of all reliable scientific work, and the scientist who abandons it is sure to bring disaster to himself and his work. And yet, to maintain that fact-hunting is, of necessity, a mark of genius is absurd.
It is largely the qualities that prevent us from ranking Darwin as a genius that establish his eminence as a research scientist. He is great not for his ideas, for they had been worked out before him, but for the clearness with which he stated his conclusions, and the wealth of proof which he brought to their defence. The earliest evolutionists tried to solve their problems by deduction, making the theory first, and searching for the facts afterward. Darwin's method was just the opposite. As he himself says, he searched for fact after fact, at the same time straining to keep all thought of theory from his mind. Finally, when he had ascertained how things actually were, and had arranged his information, he set forth to formulate a theory that might accord fully with what he knew to be the truth. He took the ancient, indefinite idea of evolution and welded it into an organized theory, and armed it with an array of facts that made it irresistible. While some of Darwin's beliefs have failed to show the importance he assigned them, and others of them are very probably errors, there are few indeed who seriously, from the standpoint of science, care to question the conception that all living things have developed from earlier living things of simpler or more primitive character. His careful, painstaking work gained for his ideas a world wide acceptance among thinking men, and made Charles Darwin one of the greatest figures in the history of science.
The story of Darwin's life is a story of long, careful study and preparation, of rapid publication of his discoveries when he set out to write them, and finally of triumph over those who opposed him. He was born on the twelfth of February, 1809, the same day that brought the world Abraham Lincoln. Someone has said that on that day the world's greatest liberators were born—in America the one who would free the bodies of men from bondage; in England the man who would free their minds from a no less real slavery to custom, power, and worn-out dogma.
When he was sixteen years old, Darwin went to Edinburgh to study medicine. But he was already a rebel against dryness and dead academic thought, and wrote home that the lectures in anatomy were quite as dry as was the lecturer himself. After two years of medicine he gave up his work at Edinburgh, and went to Cambridge to become a preacher. But while studying for the ministry the young Darwin spent a great deal of his time with nature, and acquired something of a reputation as a naturalist. When, in 1831, he was offered the chance to make a five years' trip around the world as naturalist on the exploring ship "Beagle" he did not delay long in accepting. The things seen, and the facts learned on that long voyage probably had more to do with making Darwin a great naturalist than any other single phase of his life. On his return to England the young man set about writing up the results of his studies while on his trip, and put into this book most of the arguments which he had to give in favor of evolution. In 1856 he sent this report to Sir Joseph Hooker, then the leading authority on plants in England, and finally in 1859 published his great book, "The Origin of Species." This was the first concise statement of a theory of evolution, backed up by actual evidence, and it created a furore both in Europe and America. Some scientists eagerly took up with Darwin's ideas, seeing in them the explanation of facts that they. had long been unable to understand. Others, lacking in breadth of knowledge, or unwilling to give up old beliefs, fought bitterly against evolution. The controversy involved not only scientists, but the churchmen, and was a leading feature in newspapers, magazines, and books. "The Origin of Species" ran into many editions, and was translated into several languages. Darwin found himself a center of interest for the world, and his theory a cause of heated argument for all who cared to talk or write about it.
How revolutionary Darwin's work was, and how unwillingly he himself came to the conclusion that organic evolution was an undeniable truth, it is hard for us to understand. For most of us, some at least, of the essential facts of evolution are every-day knowledge; we look upon the anti-evolutionist as a strange anachronism—a hang-over from a past age. But in Darwin's day conditions were very different. Thus we find him, in a letter written in 1844 to the great botanist Hooker, saying:
"I have been … engaged in a very presumptuous work, and I know no one individual who would not say a very foolish one. I was so struck with the distribution of the Galapagos organisms, etc., and with the character of the American fossil mammifers[3], etc., that I determined to collect, blindly, every sort of fact, which could bear in any way on what are species. … At last, gleams of light have come, and I am almost convinced (quite contrary to the opinion that I started with) that species are not (it is like confessing a murder) immutable. Heaven forfend me from Lamarck nonsense[4] of a 'tendency to progression,' 'adaptations from the slow willing of animals', etc.! But the conclusions I am led to are not widely different from his; though the means of change are wholly so." This last statement, as we shall see by reference to the "Origin of Species" was not wholly true.
Another glimpse at the state of affairs in 1859 and the immediately succeeding years may be found in Darwin's anxiety to convince Hooker, Lyell, and Huxley that species were variable and changeable, and his rejoicing when Huxley wrote out his very guarded acceptance of the Darwinian version of organic evolution. We find it hard to conceive of Huxley, the "war-horse of Darwinism" reluctantly agreeing to most of Darwin's points, but at the same time voicing strong objections to others. And yet these very objections of Huxley's, made in 1859, were in 1921 paraded before an audience at one of the country's most famous universities as evidence against the truth of organic evolution!
In France, even more than in England, the "Origin of Species" was held in disapproval. A translation of the book was offered to a noted publisher of Paris, and was unceremoniously refused. The country which had praised Cuvier, and ridiculed Lamarck and St.-Hilaire was not going to receive willingly the contributions of an iconoclastic Englishman. We are not surprised to find Darwin depressed by the European reception of his theories, and writing to Huxley: "Do you know of any good and speculative foreigners to whom it would be worth while to send my book?"
But what was this "new" theory of evolution that so aroused the world? What were its characteristics, and how did if differ from the theories of Aristotle, Kant, Buffon, and Charles Darwin's own grandfather, Dr. Erasmus Darwin?
The theory of evolution set forth in the "Origin of Species" contained three principal factors: (1) the constant variation of animals and plants, (2) the struggle for existence, and (3) the natural selection of those organisms which possess variations which are of value to them in their attempt to keep alive.
The idea of variation was based upon simple observation. Dr. Herbert Walter has said that "variation is the most constant thing in nature," and paradoxical as that may seem, it is nevertheless true. No man looks exactly like another man, no tree exactly like another tree, no shell exactly like another shell. The Japanese artists appreciate this variation, and make use of their knowledge in painting, which is one of the reasons why their art is not readily appreciated by the occidental who is much inclined to "lump" things. No Japanese artist would think of painting two dogs, or two streams, or two houses that resembled each other in every respect, for he knows that every thing in the universe, whether it be alive or dead, organic or inorganic, differs from every other thing in the universe. Sometimes the difference is easily seen, as that between a shark and a goldfish, or a Negro and a Scandinavian or Teuton. At others it is almost indistinguishable, and can be discovered only by the most accurate micrometer, or the most precise chemical analysis. But always the difference exists, the variation is present, and this fact is the basis for Darwin's belief in the inborn necessity for all living things to vary.
The second factor, that of a struggle for existence, was suggested to Darwin by a reading of Malthus' classic paper on population. All creatures normally tend to increase in numbers. Mating fish produce millions of eggs in a season; chickens rear nestfulls of young; rabbits and guinea-pigs produce litter after litter of young from the matings of two parents—everywhere, both in nature and in domestication, living things seem to be on the increase. And yet we have no evidence that (excluding the rather doubtful influence of man) there are more animals on earth today than there were half a million years ago; the probabilities are that there are fewer. Clearly, therefore, some process is at work which prevents the seeming increase from taking place. In order to understand something of the complexity of this process, let us select a specific example. Among marine animals, the oysters are remarkable for the immense numbers of eggs which they produce—the average for the American oyster is probably about 16,000,000. If all the progeny of a single oyster were to live and reproduce, and their progeny were to do likewise, and so on until there were great-great-grandchildren, the total number of oysters that were descendants of the original pair would be about 66,000,000,000,000,000,000,000,000,000,000,000 and their shells would make a mass eight times as great as the earth.
Now it is quite obvious that the earth cannot hold, and cover with water, a mass of oyster shells eight times as great as itself; the oceans, if they were spread evenly over the surface (which they never were, and never can be), would accommodate but a few of the great horde. Neither do those same oceans contain enough food to satisfy, or begin to satisfy, the needs of these theoretical descendants of a single oyster. Clearly, therefore, space and food alone are enough to prevent the undue multiplication of creatures upon the earth.
But there are factors other than space and food which aid in accomplishing the result. There are water conditions, animal enemies such as the starfish, and a host of other means by which the population of oysters is kept down. And even if it were to increase greatly, the numbers of starfish would at the same time increase, and simultaneously set about decreasing the numbers of the oysters, which decrease would in turn cut down the numbers of the starfish, and so on. Thus we see that the maximum abundance of an organism is arbitrarily set by the conditions under which that organism lives. It may attain the limit set for it, but beyond that it may go only temporarily. Then the surplus dies from starvation, crowding, animal and plant enemies, and a thousand other of the factors which constantly work in the constant warfare of nature, the never-ending "struggle for existence."
The third factor of Darwinian evolution, that of natural selection, is based upon the other two. Darwin supposed that the individuals of a species, or variety, exhibited variations for two reasons: because it was part of their very nature to do so, and because the conditions of their environment forced them. In the course of this constant change there would, of necessity, be some modifications that were of value to their possessors, while others would appear which were of more or less definite harm. In the course of the struggle for existence, those creatures which possessed helpful variations would naturally possess a certain advantage over those which lacked it or which exhibited variations which were of harmful nature. Thus in a cold, snowy climate, that animal which developed a white coat would be much safer from detection than his companions which might have fur of a dark hue, either in approaching his prey, or in escaping his pursuers. The ultimate outcome of this would be that the white animal would populate the region, while his colored brethren would soon become extinct. The same principle, Darwin thought, applied to mental advantages; the more skillful mind triumphed over the less; the quick-witted animal lived at the expense of the clumsy-witted one. Throughout the earth, those animals most capable of living lived, brought forth young, and thus perpetuated their capabilities, both mental and physical. This process quite plainly helped in the development of man, and in his progress, but singularly enough, within this ranks today it does not operate. Great mental capacity is not today the most important survival factor among humanity. As the archeologist Keith has pointed out a great philosopher or artist may lead a life of misery, want, and despair, and leave no descendants, while a thoughtless, happy Burman will live out his days believing that the earth is flat and Buddha an all-powerful god, but will leave behind him a large and rapidly multiplying family.
During the years just prior to the appearance of the "Origin," Darwin had an almost complete confidence in the power of natural selection to account for all the phenomena of evolution. Even in the year when that work appeared, he wrote Lyell: "Grant a simple archetypal creature, like the Mud-fish or Lepidosiren, with five senses and some vestige of mind, and I believe Natural Selection will account for the production of every vertebrate animal." In publication, however, he was more cautious, saying, "I am convinced that Natural Selection has been the main, but not the exclusive means of modification."
From his extreme position on the effective ability of natural selection to seize upon a variation and so foster it that a new species would appear, Darwin slowly but not unwillingly receded. Ten years after the first publication of the Darwinian theory[5], he admitted that variations might not have been so supremely important as he supposed; in 1878 he believed in the direct action of environment in producing variations, as did Buffon; in 1880 he adopted Lamarck's theory of the use and disuse of parts. In 1881, in the "Descent of Man," Darwin lays much stress upon sexual selection, the idea that members of one sex rendered themselves particularly attractive in order to capture the attentions of their would-be mates. This, however, is really a subdivision of the natural selection idea—in the general reliability of which the famous evolutionist still believed.
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As we have said, in the estimate of Darwin's general environment, the world of the middle nineteenth century did not welcome the new prophet of natural law in the natural world. Many scientists accepted Darwinism, or at least, the principle of evolution, without reserve; others made reservations; most of the "intelligentsia" declared it to be without the slightest element of truth. The public in general, and especially the church, clung to the old, valueless doctrine of a multitude of special creations by an omnipotent deity, apparently forgetting that the greatest of the church fathers, Aquinas and Augustine, had been prominent evolutionists in their day. There arose about Darwin's theories a storm of argument that lasted for many years, and involved scientists, theologians, philosophers, and laymen thorughout the world.
Darwin, although an excellent and self-confident scientist, was modest, retiring, and greatly hampered by ill-health contracted during his "Beagle" voyage. He was forced to leave the work of publicly defending his theories to other men, the most noted of whom was Thomas Henry Huxley, the "Bull dog of Evolution." Huxley was an accomplished scientist, a powerful speaker, and one of the finest of European writers of science for the every-day man. He wrote, taught, and lectured in defense of the evolution theory; after a long, hard day at the university, he would spend the evening lecturing before crowds of workingmen from London's factories, telling them how one species came from another, and how a single-celled creature developed into a complex animal with hundreds of millions of cells in its body, at the same time reconstructing during its growth the entire evolutionary history of its kind. It was largely because of the lectures and magazine articles of this tireless scientist, who believed in the truth of evolution, and enjoyed the task of fighting for his beliefs, that Darwin achieved so early an almost complete victory over the scientists who opposed him. Of course, the triumph was not all-embracing; there are still a few people who follow the natural sciences and yet refuse to believe that one species can arise, either by natural selection or by some other means, from another species without the interference of a deity. And the public at large, particularly that portion of it which lives far away from museums, zoological gardens, and centers where illustrated talks on natural science are regularly given, still believes in the theory of special creation. But that belief neither signifies defeat for Darwin and his followers, nor casts doubt upon the essential truth of their ideas; it simply means that he theory of evolution is still relatively young, and that popular education is in its infancy.
- ↑ This was not true of the naturalist in later life, when he was for years a semi-invalid.
- ↑ "Contemporary Portraits," pp. 12–13.
- ↑ "Mammifers" = mammals; that is, animals which suckle their young.
- ↑ Darwin seemed unable to speak of Lamarck without contempt or derision. Certainly he was not familiar with Lamarck's writings in the French, and attributed to that naturalist certain erroneous ideas for which he was not responsible. Also, it would seem that Darwin failed to make allowances for Lamarck's insuperable handicaps, and his position as a pioneer, and therefore adopted an attitude of unjustified antagonism.
- ↑ "Darwinism," or "The Darwinian Theory" refers to the theory of natural selection, and the sub-theory of sexual selection, not to the theory or concept of organic evolution.