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Prof. Fred L. Wilson

Rochester Institute of Technology

Science and Human Values

Charles Darwin and Evolution

Chapter 20 Charles Robert English Darwin (1809-1882)

Darwin was born on the same day that Abraham Lincoln was born four thousand miles away in Kentucky. Darwin was born in no log cabin, however. He was the son of a well-to-do physician and the grandson of the poet-physician, Erasmus Darwin 1260]. His other grandfather was Josiah Wedgwood, famous for his porcelainware.

Darwin showed no particular promise in his youth. At first he studied medicine but found that unlike his father and grandfather he had no aptitude for it. The sight of operations on children (performed without anesthesia) horrified him beyond measure. He thought next that he would make a career in the Church but found he had no aptitude for that either. (His father angrily declared he would disgrace the family.) However, he had made natural history his hobby after reading Humboldt [334] and had grown gradually more interested in the subject during his stay at Cambridge. This was his road to fame.

His first scientific work was participating in a geologic field trip led by Sedgwick recognized the young man's genius, but in later years was to be aggrieved and dismayed by Darwin's theory of evolution.

H.M.S. Beagle : was about to set out for a voyage of scientific exploration in 1831 and Darwin was offered the post of ship's naturalist, after the fashion of Brown a half century before and Banks a quarter century earlier still. The ship's captain hesitated for he was not favorably impressed by Darwin. In addition, Darwin's father, larger in bulk (350 pounds) than in judgment, opposed the project as unfitting a future minister, but Darwin's uncle Josiah intervened and talked the elder Darwin out of his opposition.

Darwin accepted, and off he went on a five-year cruise around the world. He suffered agonies of seasickness and permanently impaired his health. It is possible that he contracted trypanosomiasis on the trip, for his chronic symptoms in late life resemble those of this disease. Since these symptoms are not dramatic Darwin has long been considered a hypochondriac and here he may have been done a great injustice. In any case, the voyage was the making of him, and through him it became the most important voyage in the history of biology.

Darwin had already read some of the works of Lyell. He had been introduced to them by someone who felt Lyell's views were ridiculous and thought Darwin would get a good laugh out of them. Darwin didn't laugh. He was converted to uniformitarianism in geology and to a clear realization of the antiquity of the earth and of the long ages through which life had had time to develop.

Now, during the course of the voyage of the Beagle, his thoughts on the subject had a chance to sharpen. He noticed how species changed, little by little, as he traveled down the coast of South America. Most striking of all were his observations during a five-week stay of the animal life of the Galapagos Islands, a group of a dozen or so islands about six hundred and fifty miles off the coast of Ecuador. The Galapagos Islands contained unusual giant tortoises, but what Darwin mainly noticed was a group of birds now called "Darwin's finches."

These finches were closely similar in many ways but were divided into at least fourteen species. Not one of those species existed on the nearby mainland, or, as far as was known, anywhere else in the world. It seemed unreasonable to different species were created on this small group of islands, fourteen species that existed nowhere else.

Darwin believed that the species of finch on the nearby mainland, a seed-eating variety somewhat similar to the island finches, must have colonized the island eons before and that gradually the descendants of those first finches evolved into different forms. Some came to eat seeds of one sort, some of another; still others came to eat insects. For each way of life a particular species would develop a particular beak, a particular size, a particular scheme of organization. The original finch did not do this on the mainland because a great deal of competition existed in the form of other birds, while on the Galapagos Islands the original finches found a relatively empty land.

But what could cause these evolutionary changes? Lamarck had believed that the inheritance of acquired characteristics was involved and that creatures deliberately tried to change in ways advantageous to themselves. Darwin could not accept that.

He returned to England in 1836 with no answer (though he had come to passionate conclusions regarding Negro slavery, which he had witnessed in the Americas and which he detested with all the fire of a gentle, humanitarian soul). He was elected to the Geological Society and kept busy preparing several books on the voyage and the observations he had made. The first of these, now usually known as A Naturalist's Voyage on the Beagle, published in 1839, was a great success (impressing Humboldt, for one, as Humboldt had once impressed Darwin) and made him famous. (Darwin always strove for a clear, uncluttered style. He believed "in making the style transparently clear and throwing eloquence to the dogs.") He also announced a theory on the slow formation of coral reefs by the gradual accumulation of the skeletons of corals, which was accepted by naturalists with enthusiasm. This theory was in opposition to one held by Lyell, but so pleased or Darwin that the two became close friends.

Darwin married his cousin Emma Wedgwood in 1839, and he joined the Geological Society of London, serving as secretary from 1838 to 1844. In this way he had an opportunity for close association with Lyell and discussed with him the problem of evolution -- for suddenly he had the key.

In 1838 he read a famous book entitled An Essay on the Principle of Population, written by Malthus forty years earlier. Malthus had maintained that human population always increased faster than the food supply and that eventually population had to be cut down by starvation, disease, or war.

Darwin thought at once that this must hold for all other forms of life as well and that those of the excess population that were first cut down would be those who were at a disadvantage in the competition for food.

For instance those first finches on the Galapagos Islands must have multiplied unchecked to begin with and would surely have outstripped the supply of the seeds they lived on. Some would have had to starve, the weaker ones first, or those less adept at finding seeds. But what if some could turn to eating bigger seeds or tougher seeds or, better still, turn from the eating of seeds to the eating of insects? Those that could not make the change would be held in check by starvation, while those that could would find a new untapped food supply and could then multiply rapidly until, in turn, their food supply began to dwindle.

In other words, creatures would adapt themselves to different ways of life under the stress of environmental pressure. Every once in a while a change that would allow a better fit to a particular niche in the environment would permit one group of creatures to swamp another group and to replace them. Thus Nature would select one group over another and by such "natural selection" life would branch out into infinite variety, more efficient groups always replacing less efficient ones in each particular environmental niche. (To be sure, Darwin had hen thinking of natural selection before reading Malthus' book, but Malthus had made him aware of just what a powerful force natural selection could be. It made Darwin realize that natural selection was sufficient to explain evolution.)

But how did these changes come about? How could a seed-eating finch suddenly learn to eat larger seeds which others could not, or learn to eat insects? Here Darwin was on rough ground. There was no doubt that changes did take place. For one thing, Darwin, a country gentleman, kept pigeons as a hobby and had personal experience with the breeding of odd varieties of domesticated animals.

He could see that in any group of young there were variations from one to another -- random variations in size, coloring, abilities. Darwin reasoned that it was through taking advantage of such variations, by deliberately breeding one and suppressing others, that over the generations man had developed larger, stronger, faster horses; cattle to give more milk and beef, sheep to give more wool; hens more eggs; and cats and dogs of odd and amusing shapes.

Could not Nature substitute for man and make the same selection for its own purposes, much more slowly and over a much longer period, fitting animals to their environment rather than to man's tastes and demands?

By Darwinian notions the giraffe got its long neck not because it tried for one (as Lamarck had it) but because some giraffes were born with naturally longer necks and these got more leaves, lived better, and left more descendants, which inherited the naturally longer necks. A combination of natural variation and natural selection saw to it that the neck continued to get longer very slowly.

This view explained the giraffe's blotched coat just as well. Even Lamarck couldn't have made a case in favor of the giraffe trying to be blotched. However, a giraffe that happened to be blotchier by random variation would better blend in with a blotched forest background and would the more likely escape the eyes of prowling predators. It would leave more descendants to inherit its blotchiness.

The chief difficulty about all this was that it was hard to see how the random variations would carry over from generation to generation. There would be matings among creatures that varied differently and for all Darwin knew these variations should then level out into an undistinguished average.

Darwin never was completely satisfied on this point, but he went on. Some creatures, among whom the male had very conspicuous coloring, did offer a way out, at least with respect to certain prominent characteristics. The female of the species must deliberately select the most flamboyant male she could find as her mate. There it was no question of averaging out. The development of the peacock would be driven constantly in the direction of flamboyance as the result of "sexual selection."

Darwin also collected data on vestiges, that is, the useless remnants of tissues that bespoke full-scale useful organs eons before. For instance whales and snakes have useless scraps of bones that might once have formed parts of hip girdles and hind legs, showing that they were descendants of creatures that had walked on all fours. A horse has a single line of bones down its leg ending in a single hoof, but on either side are two thin splints that come to a dead end, but show that the horse might once have been a three-hooved creature.

Darwin was a painstaking perfectionist, collecting and classifying his information endlessly. In 1844 he started a book on the subject but so ardently did he continue to multiply his examples and tighten his reasoning that in 1858 he was still working at it. Fortunately he was a man of independent means and could work on such a nonremunerative project as slowly and as thoroughly as he liked.

His friends knew what he was doing and Lyell in particular was constantly urging him to publish or face being anticipated, for evolutionary notions were in the air.

Darwin could not be hurried and Lyell was proved right; Darwin was anticipated. Another naturalist, Wallace, wrote a paper embodying Darwin's notions almost to the letter and then sent a copy to none other than Darwin himself for his opinion. When Darwin received the manuscript he was thunderstruck. However, he proceeded to behave like the ideal scientist. He made no attempt to publish quickly in order to reserve the credit for himself. Magnanimously he passed on Wallace's work to other important scientists and might have abandoned his own priority, had not Lyell insisted that he offer to collaborate with Wallace on papers summarizing their combined conclusions. Wallace was equally generous and cheerfully agreed, in view of Darwin's prior claim. The collaboration was carried through and work by both men appeared in the Journal of the Linnaean Society in 1858. (How Linnaeus would have turned in his grave if he knew that the society named for him bore so intimate a connection with the Darwinian theory.)

But it was no longer possible to delay. The next year Darwin published his book. It was quite a long one, but it was only a fifth as long as he had been planning and for the rest of his life he referred to it disparagingly as an abstract. The full title of the book (one of the most world-shaking ever published) is On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. It is usually known simply as The Origin of Species.

The learned world was waiting for the book. Only 1250 copies were printed and every one was snapped up on the first day of publication. It went through printing after printing, and it is still being reprinted now, a century later. It is one of the classics of science.

(Ironically, within a decade of the publication of the book Mendel was to carry through a course of research that shored up the weakest point in the theory, the manner in which random variations were inherited. Darwin, however, was never to know of this work, nor did the world of science generally until De Vries rediscovered Mendel and his conclusions a generation later. )

Darwin's book started a violent controversy that lasted for generations. It was viewed as contrary to the statements of the Bible by some and many sincerely believed that the Darwinian theory of evolution was destructive of religion. Even among scientists the fight was bitter.

In England, for instance, Richard Owen was a die-hard opponent and in 1865, when Darwin received the Copley medal of the Royal Society, it was for his other achievements, and not for his theory of evolution.

Darwin himself was not temperamentally suited to enter the lists of controversy. For one thing, he was too gentle. He was the kindest of men and incapable of the hurly-burly of polemical warfare. (One of the reasons he spent so many years gathering evidence was in a vain effort to make the case so ironclad as to avoid controversy. ) Fortunately, fighting for him was Huxley, who called himself "Darwin's bulldog."

In Germany, Haeckel took up the Darwinian struggle against the opposition of Virchow, and in America, Asa Gray fought for Darwin against the opposition of Agassiz

Naturally one of the touchiest points about Darwinian evolution was its possible application to man himself. Darwin had skirted that point in The Origin of Species, but Lyell, whose geological views had so influenced Darwin a generation before, now returned the compiiment. In a book entitled The Antiquity of Man, published in 1863, Lyell came out strongly in favor of Darwinism and discussed the many thousands of years during which man, or manlike creatures, must have existed on the earth. He used as his evidence stone tools found in ancient strata by men such as Boucher de Perthes.

Wallace doubted that evolution could apply to man, but Darwin did not. He took his stand at Lyell's side and in 1871 published The Descent of Man, in which he discussed evidence showing man to have descended from subhuman forms of life. For one thing, man contains many vestigial organs. There are traces of points on the incurved flaps of the outer ear, dating back to a time when the ear was upright and pointed, and there are tiny, useless muscles still present that were once designed to move those ears. (Some people still can.) There are four bones at the bottom of the spine which are remnants of a tail, and so on.

The world of science, at least, was won over before long and by the time of Darwin's death the notion of evolution by natural selection had scored a clear victory. The opponents that remained were not scientists but were for the most part members of the more literal word-of-the-Bible sects. These fought a rear-guard action that made newspaper headlines on occasion but did not affect the progress of biological science.

Darwin was rated above controversy at his death and buried in Westminster Abbey, among England's heroes and near Newton and Faraday, as well as his friend Lyell. However, this burial in Westminster Abbey was the only honor ever granted him by the ultrarespectable government of Great Britain under Queen Victoria. The great British prime ministers William Gladstone and Benjamin Disraeli were both strongly opposed to Darwinism. Disraeli, indeed, coined a famous phrase when he said that, if asked to choose between apes and angels as the forebears of man, "I am on the side of the angels."

Some have never given up the fight against Darwin and evolution. In the 1980s a court case in Arkansas ruled against those who argue for requireing "Creation Science" to be taught in the public schools. It is important to read the judges decision, not only to see the arguments why he decided the way he did, but also to see some very good work in defining just what science is. Please read the article on Creationism

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