Charles Robert Darwin (1809-1882)
EARLY YEARS
Darwin was born in Shrewsbury, England on Feb. 12, 1809, the son of Robert Waring Darwin, a physician, and of Susannah Wedgwood, the daughter of porcelainware manufacturer Josiah WEDGWOOD. He was also the grandson of Erasmus DARWIN, who combined the careers of poet, philosopher, and naturalist. Darwin showed little interest in his early education at Shrewsbury School and in medical studies at Edinburgh University (1825-27). He turned away from becoming a physician after witnessing several operations performed without anesthesia. At the same time he began to be interested in geology and natural history. He was finally sent to study for the holy orders for the Church of England at Christ Church College, Cambridge University (1828), but had no inclination for the ministry.
Instead, he became more and more interested in natural history. After he received his B. A. degree in 1831, a Cambridge professor and friend, John Stevens Henslow, recommended him for an unpaid position as naturalist on a scientific expedition. Darwin embarked on a 5-year voyage on the H. M. S. Beagle, a turning point in his life. The Beagle set sail on Dec. 27, 1831, to study the Pacific coast of South American and some Pacific islands as well as to set up navigational stations in the area. Darwin's duties were to study the geology and biology of these areas.
DARWIN'S RESEARCH
Geology
Although not a trained geologist, Darwin made important discoveries, many of which later provided geological support for some of his ideas on evolution. He noted that sedimentary rock crystallizes when metamorphosed by overlying rock and saw evidence of how volcanoes and earthquakes change the lay of the land, uplifting some areas and sinking others. These and other observations led him to formulate a theory about coral reef formation. Darwin believed the platforms for existing coral reefs were built up from the skeletal remains of coral organisms that died as their home reefs around oceanic mountains gradually sank far below sea level. Darwin's geological observations and theories had one thing in common--the idea that things in nature change with time. He published his observations and conclusions in three books: Coral Reefs (1842), Volcanic Islands (1844), and Geological Observations on South America (1846).
Darwin's Finches
Darwin's biological findings gave him a lasting place in history. The Galapagos Islands were probably the scene of Darwin's most important and best-known research. On these islands, Darwin found a dazzling array of animal life and found that related but different species lived on different islands even though all the islands were very similar in geological, climatic, and other physical conditions. He found, for example, an array of ground finches with beaks ranging from large and powerful to small or fine. He correlated these differences not with physical conditions on the islands but with the birds' feeding habits. Those with powerful beaks ate large seeds; those with smaller beaks ate small seeds; those with fine beaks primarily fed on insects. He postulated that each finch was particularly suited to the food that was available in its environment--an example of what later became known as adaptation. These birds are known today as Darwin's Finches.
Along the Pacific coast of South America, Darwin observed that closely related species often lived in adjacent geographic areas and that species found on isolated oceanic islands often resembled species found on the nearest continent. Established biological thinking held that all species were unchanging and specially created; however, Darwin found that similar species were always present in adjacent geographic areas. When he found, at a given location, fossils of extinct species that were similar to living species, he began to question why similar species existed in successive geologic time periods.
Darwin collected many geologic and biologic specimens, studied many fossils, and made observations of the form, numbers, diversity, and living habits of different forms of life. From his meticulous research he arrived at the idea that species descend, with modifications, from other species, or, in other words, that species evolve from other species.
Darwin's grandfather Erasmus previously had hinted at the idea of evolution, and some geologists contemporary to Darwin had explored the idea that the face of the earth changes over periods of time, but Darwin waited for years after his return to England (1836) to present his conclusions. Even so, he reported on some of the vast amount of data he had accumulated during his trip in the Journal of Researches (1839). He also wrote a brief summary of his ideas on evolution that became known to a few scientists, but for the most part Darwin turned to other work, including detailed study of barnacles.
He married a cousin, Emma Wedgwood, in 1839, and lived in London for a while, at which time he was admitted to the Royal Society. In 1842, he settled in Downe, Kent, plagued by ill health since the Beagle voyage. During his lifetime, with symptoms of fatigue and intestinal trouble, he was dismissed as a hypochondriac. In Argentina, however, he had been frequently bitten by an insect that transmits TRYPANOSOMIASIS, and his illness resembled that of similarly infected people. Other theories about his chronic ill health also exist.
ON THE ORIGIN OF SPECIES
In 1856, Darwin began to write his theory of evolution by natural selection, but before he had finished (1858), he received a paper from naturalist Alfred Russel WALLACE outlining a theory similar to his own. Friends arranged for the two men to present a joint paper before the Linnaean Society of London in 1858. On Nov. 24, 1859, an abstract of Darwin's theory was published under the weighty title of On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life.
Darwinism
In this book, Darwin presented his idea that species evolve from more primitive species through the process of natural selection, which works spontaneously in nature. In his account of how natural selection occurs, known as Darwinism, he pointed out that not all individuals of a species are exactly the same but, rather, that individuals have variations and that some of these variations make their bearers better adapted to particular ecological conditions. He pointed out that most species produce more eggs and offspring than ever reach maturity. He theorized that well-adapted individuals of a species have more chance of surviving and producing young than do the less adapted, and that over the passage of time the latter are slowly weeded out. The accumulation of adaptations to a particular ecological way of life leads--if there is a geographic split of the population--into the development of separate species, each adapted to its own particular ecological living space. It remained for the later science of GENETICS to provide an explanation for this process.
Impact
The effect of On the Origin of Species was immediate and widespread. The book upset many established patterns of thought, contradicted firmly held religious tenets, and brought into focus the concept that humans are one species among many that had evolved from a more primitive one. Controversies and debates on the theory raged all over England, Europe, and the United States. Even as recently as 1925, Darwin's theory of evolution created such furor that it culminated in the famous Scopes trial in Tennessee. Though the evidence Darwin presented was strong, some scientists aligned themselves with orthodox churchmen and others who opposed the theory. Other scientists enthusiastically embraced it.
Darwin himself did not become deeply involved in the defense of his theory, leaving that to others, notably English biologist Thomas Henry HUXLEY. One of the book's greatest effects was the spur it gave biological research. Scientists in all fields of biology pursued research to substantiate or refute Darwin's ideas. Darwin's basic ideas spread to other disciplines, too, although sometimes in a form not true to the original concept, such as the so-called SOCIAL DARWINISM that encouraged a ruthless interpretation of "survival-of-the-fittest" ideas. EUGENICS, a term coined by Darwin's relative Sir Francis GALTON to describe controlled improvement of species, including humans, was also based on Darwin's premises.
Darwin continued to write and do research, expanding on ideas he had presented in On the Origin of Species. In The Descent of Man and Selection in Relation to Sex (1871), Darwin provided evidence for human evolution from more primitive species and discussed the role of sexual selection in evolution. His later studies were devoted to the investigations of plants. Among his botanical works were Insectivorous Plants (1875), in which he described how the sundew traps and digests insects, and The Power of Movement in Plants (1880), in which he wrote how light influences the direction of plant growth. His last work, Formation of Vegetable Mould through the Action of Worms (1881), detailed the manner in which earthworms enrich and aerate soil, benefiting agriculture. Darwin died in Downe on Apr. 19, 1882 and was buried in Westminster Abbey. He has been praised as one of the greatest figures in the history of biology.