My success as a man of science, whatever this may have amounted to, has been determined, as far as I can judge, by complex and diversified mental qualities and conditions. Of these, the most important have been – the love of science – unbounded patience in long reflecting over any subject – industry in observing and collecting facts – and a fair share of invention as well as common sense. With such moderate abilities as I possess, it is truly surprising that I should have influenced to a considerable extent the belief of scientific men on some important points.

– Charles Darwin in The Life and Letters of Charles Darwin, Volume 1

His is a name taught in every elementary textbook on biology and for good reason. Creationists have ever been eager to pounce on the fact that Darwin was never the first to come up with the theory of evolution, and indeed it is well-known that his first public presentation of his ideas was shared with Alfred Russel Wallace who developed the same theory of natural selection independently of Darwin. Yet it was Wallace who wrote:

“We claim for Darwin that he is the Newton of natural history, and that, just so surely as that the discovery and demonstration by Newton of the law of gravitation established order in place of chaos and laid a sure foundation for all future study of the starry heavens, so surely has Darwin, by his discovery of the law of natural selection and his demonstration of the great principle of the preservation of useful variations in the struggle for life, not only thrown a flood of light on the process of development of the whole organic world, but also established a firm foundation for all future study of nature.”

Surprisingly, some form or other of evolutionism had already been theorized by philosophers as early as the ancient Greeks as Prof. H.F. Osborn makes clear in “From the Greeks to Darwin”. As I read from A.C. Seward’s “Darwin and Modern Science“, Empedocles suggested that there were, “four sparks of truth, – first, that the development of life was a gradual process; second, that plants were evolved before animals; third, that imperfect forms were gradually replaced (not succeeded) by perfect forms; fourth, that the natural cause of the production of perfect forms was the extinction of the imperfect.”

Aristotle too apparently leaned towards evolution in his philosophies, as did philosophers like Bacon, Descartes, Leibnitz, Hume, Kant, Lessing, Herder and Schelling. To these names we must add naturalists like Buffon, Erasmus Darwin (his grandfather) and Lamarck. Darwin himself refers to thirty-four authors on evolution in his Historical Sketch (added in later editions of the “Origin of Species”). However, Prof. Osborn writes that, “‘before and after Darwin’ will always be the ante et post urbem conditam of biological history.” Part of the reason for this might be found in a statement by Samuel Butler, one of Darwin’s teachers who became his opponent, written in the preface to his “Evolution, Old and New”, “To the end of time, if the question be asked, ‘Who taught people to believe in Evolution?’ the answer must be that it was Mr. Darwin. This is true, and it is hard to see what palm of higher praise can be awarded to any philosopher.”

A naturalist from the start, Darwin spent much of his time collecting plants and insects as he was growing up and came to develop a taste for solitary walks. Passages from his autobiography portray him as inquisitive and somewhat mischievous but also meticulous and exacting in the pursuit of whatever interested him most at the moment. It also makes clear that he considered himself Christian and took the existence of god as “given”. In fact, at a certain point in his early life, he nearly made the decision to become a clergyman!

The voyage aboard the “Beagle” from 1831 to 1836 is world-famous and Darwin himself attributes to this the start of his scientific career. The purpose of the voyage, originally planned to last two years, was to survey the east and west coasts of South America and then to proceed to the Pacific Islands to establish a string of chronometric stations there. Darwin was brought aboard as an unpaid naturalist upon the recommendation of John Stevens Henslow, a Cambridge botanist.

Though often forced to lie horizontally on his hummock due to his frequent seasickness, his sense of wonder and curiosity in encountering the luxuriant life of the tropics for the first time kept his morale high. Bravely, perhaps even enthusiastically, he faced or witnessed dangers like native Indians, political rebellions, hail storms, earthquakes and tidal waves. His account of the voyage showed that he sympathized greatly with the black slaves and was distressed by the mass extermination of the native Indians.

During this time, Darwin also studied Charles Lyell‘s “Principles of Geology” and due to his observations became a convert to Lyell’s then unconventional view that the surface of the Earth was gradually shaped by the cumulative effects of local disturbances, such as eruptions, earthquakes, depositions etc. His observation of coral reefs however, led him to challenge Lyell’s view that they were formed by volcanic action, explaining instead that coral forms a reef by building up on the seafloor as the floor subsides and predicted that if a whole island sank beneath the surface of the ocean, and the coral continued to grow, a reef would turn into an atoll around a lagoon. Lyell in turn became convinced by Darwin’s reinterpretation and 20th-century deep-sea borings have confirmed his prediction.

Perhaps most importantly, during the course of the voyage, he came to handle many rocks and thereby encountered a great quantity of fossils. Remarking that many of the extinct species were very different from existing ones, he came to ask himself: how is it that new species come to replace extinct ones?

The key in the elaboration of his Doctrine of Common Descent was for Darwin reading Thomas Malthus‘ “An Essay on the Principle of Population” in 1838. Independently of the other theorists who postulated evolutionism, Darwin had remarked from his observations that living organisms were beautifully adapted to their environments and that such adaptations could only have been possible through a modification of each of the observed species. For a long time however, he lacked the mechanism to explain how such modification could be brought about until the population pressures noted by Malthus were brought to his attention. As he writes in his autobiography, “…it at once struck me that under these circumstances favorable variations would tend to be preserved, and unfavorable ones to be destroyed. The result of this would be the formation of new species.”

What differentiated Darwin from other naturalists was that while they took note only of the brutality of species against species, Darwin also saw the competition between members of the same species. This essential observation led him to conclude that tiny variations in individuals of the same species, longer beaks, brighter feathers etc., might improve the chances of survival of such individuals and eventually lead their offspring to become predominant within the population. Furthermore, his interest in variation and heredity thus heightened, he actively interviewed animal and plant breeders on how artificial selection worked so as to gain insight into his newfound theory of natural selection.

Knowing how difficult it would be to find acceptance for his idea, he had the caution from refraining to make his thoughts known to the general public and in fact did not begin to put it down in writing until 1842. Lyell, who was initially opposed to this idea and whose conversion was a great source of satisfaction for Darwin, eventually persuaded him to write out his views more fully in 1856. Wallace however took the decision to publish out of his hands by sending Darwin his “On the Tendency of Varieties to depart indefinitely from the Original Type” from the Malay archipelago.

It is a testament to Darwin’s modesty that he at first refrained from publishing his own independently written work, worrying that Wallace might object and that his own writing was of a poorer quality than Wallace’s. But his friends convinced him to agree to a joint publication in the “Journal of the Proceedings of the Linnean Society”. This effort attracted little attention but then in 1859, Darwin completed and published his “Origin of Species” that he himself calls the great work of his life.

It was a great success from the start, selling the 1250 copies of its first edition on the day of publication and its second edition of 3000 copies soon afterwards. In his autobiography, Darwin rightly attributes this success not only to the strength of his arguments, supported by a staggering wealth of data, but also the style of writing and avoidance of technical terms that made the work accessible to the layman. Though Darwin’s letters and autobiography suggested otherwise, the theory of natural selection actually found acceptance in most scientific circles relatively quickly. It is unfortunate however that the opponents, led by the clergy who realized that his theories was inconsistent with a literal interpretation of Genesis, were more vocal than the supporters and this probably gave to Darwin and his circle of close friends the impression that they were being persecuted. In truth, the greatest scientific obstacle to the theory of natural selection was that the then currently accepted theory of blending inheritance would rapidly reduce the variations of individual members of a species to the average of the preexisting population. It was not until 1900 that the masterly experiments of Gregor Mendel, actually published in 1866, became known and the theory of blending inheritance was replaced by Mendelian genetics into which framework Darwin’s ideas fitted very well.

Even if Darwin had stopped producing scientific work after this, he would have already earned his place in science’s Hall of Fame. But his devotion to science pushed him to pursue his work and he continued to publish books and essays on biology, notably on the subject of plants. It is undeniable however that “The Descent of Man” was among all his later works of greatest interest. In his “Origin of Species “, he had made no indication of the ancestry of man except to note that by the work “light would be thrown on the origin of man and his history.” This lack of precision frustrated many of his supporters but as his autobiography made clear, he had never entertained any doubt that man was descended from animals, writing, “as soon as I had become, in the year 1837 or 1838, convinced that species were mutable productions, I could not avoid the belief that man must come under the same law.”

“The Descent of Man” was published in 1871 and in his arguments Darwin was supported by the paleontologist T. H. Huxley, the botanist J.D. Hooker and the geologist Lyell. Wallace however found himself unable to accept the ultimate consequences of the body of work to which he had himself contributed, and maintained that something else of a spiritual nature must have been added to what man inherited from his animal ancestors.

As for Darwin’s religious views, Schwalbe in “Darwin and Modern Science” maintained that he had long since abandoned his former Christian orthodoxy. Schwalbe writes, “He describes how, though he was still quite orthodox during his voyage round the world on board the ‘Beagle’, he came gradually to see, shortly afterwards (1836-1839) that the Old Testament was no more to be trusted than the Sacred Books of the Hindoos; the miracles by which Christianity is supported, the discrepancies between the accounts in the different Gospels, gradually led him to disbelieve in Christianity as a divine revelation.”

A year later in 1872, Darwin published “The Expression of the Emotions in Man and Animals“. Originally meant to be a chapter in “The Descent of Man”, this book demonstrated that the expression of emotions was not unique to man. Again, Darwin aroused the ire of the clergy, for in doing so, he proposed that mental development was subservient to physiological evolution. The difference between man and animal became then a matter not of kind but merely of degree. What place is there then for the soul? It is significant that this book, though less famous than the “Origin of Species”, laid the groundwork for the study of ethology, neurobiology and communication theory in psychology.

Many of his later books, concentrated largely in the field of botany, also contributed greatly to science. For example, he noted that cross-pollinated plants tended to be healthier than self-pollinated ones and thereby established a selective advantage in organisms to develop sexual rather than asexual reproductive methods. He observed that climbing plants were responsive to external stimuli and altered their growth as a result, thereby bringing the plant kingdom much closer to the animal kingdom. By studying the actions of worms in digesting leaves and recirculating organic matter, he founded the field of quantitative ecology.

It cannot be denied that great as his intellect was, it could not have been brought to full fruition if not for the extremely fortunate circumstances into which he was born. He never had to worry about money and the freedom of an independent scientist allowed him to work on whatever he wished. Furthermore, it has been argued that the fear of being ostracized from the upper-middle class formed at least part of his initial reluctance to making his views known to his general public. His own letters and autobiography made it clear that he was never able to directly confront his detractors in public debate. More recently, some writers have theorized that Darwin’s lifelong struggle with illness (he was a semi-invalid before his 40th year) had more to do with psychological rather than physiological factors, due perhaps to the pain he felt in the realization of what his findings would mean to the society he was so much a part of. His treatment of women too, including his wife and daughters, as intellectual inferiors (using his theory of sexual selection to justify his opinion) have also earned him much criticism. Nevertheless, his character has in most respects been exemplary as H. Hoffding writes in “Darwin and Modern Science”:

“His deep love of truth, his indefatigable inquiry, his wide horizon, and his steady self-criticism make him a scientific model, even if his results and theories should eventually come to possess mainly an historical interest. In the intellectual domain the primary object is to reach high summits from which wide surveys are possible, to reach them toiling honestly upwards by way of experience, and then not to turn dizzy when a summit is gained. Darwinians have sometimes turned dizzy, but Darwin never. He saw from the first the great importance of his hypothesis, not only because of its solution of the old problem as to the value of the concept of species, not only because of the grand picture of natural evolution which it unrolls, but also because of the life and inspiration its method would impart to the study of comparative anatomy, of instinct and of heredity, and finally because of the influence it would exert on the whole conception of existence.”

Charles Darwin died in 1882 and a parliamentary petition won him burial in Westminster Abbey, a few feet from the grave of Sir Isaac Newton. A fitting resting place for the man, who, as the opening of this essay noted, did for all the natural sciences what Newton did for physics.