Charles Darwin is widely regarded as the founder of modern evolutionism. Although not the first to propose a theory of the transmutation of species, his Origin of Species (1859) sparked the debate which converted the scientific community to evolutionism. This book not only provided the basic argument for evolution, but also proposed a new mechanism of change: natural selection. Although this mechanism remained controversial until synthesized with Mendelian genetics in the twentieth century, it has now become the basis for most biologists’ approach to the question. Darwin also confronted the human implications of evolutionism in his Descent of Man (1871) exploring the link between humans and their ape-like ancestors and the implications of such a link for the nature of society.
Charles Robert Darwin was born in Shrewsbury, England. His father was a wealthy doctor. His grandfather, Erasmus Darwin, also a successful physician, had proposed an evolutionary theory in the 1790s. During an abortive attempt to study medicine at Edinburgh, Darwin met the Lamarckian evolutionist R.E.Grant, who aroused his interest in fundamental biological problems. Darwin then went to Cambridge, where he studied for a BA in the expectation of becoming an Anglican clergyman, but also came into contact with the botanist John Henslow and the geologist Adam Sedgwick. After taking his degree he spent five years as ship’s naturalist aboard the survey vessel HMS Beagle (1831–6). On the voyage he studied both the geology and zoology of South America. He soon accepted the uniformitarian geology of Charles Lyell, in which all change was supposed to be slow and gradual. He proposed important geological theories, especially on the formation of coral reefs. The fauna of the Galapagos islands (off the Pacific coast of South America) forced him to reassess his belief in the fixity of species. It was clear that closely related forms on separate islands had diverged from a common ancestor when the populations were isolated from each other.
On his return to England, Darwin spent the years 1836–42 as an active member of the scientific community in London. Family support enabled him to marry and then to set up as a country gentleman at Down in Kent. Darwin had already turned his attention to the problem of the evolutionary mechanism. He realized that evolution adapted each population to its local environment, but did not think that the Lamarckian explanation of the inheritance of acquired characteristics was adequate. He studied the techniques of artificial selection used by animal breeders and then encountered the principle of population expansion proposed in T.R.Malthus’s Essay on the Principle of Population. This led to his theory of natural selection: population pressure created a struggle for existence in which the best adapted individuals would survive and breed, while the least adapted would die out. The extent to which the selection theory embodies the competitive ethos of capitalism remains controversial. Darwin wrote outlines of his theory in 1842 and 1844, but had no intention of publishing at this time. Although now affected by a chronic illness, he continued his researches. He studied barnacles, in part to throw light on evolutionary problems, and also worked on biogeography. A few naturalists were informed of the evolutionary project lying behind these studies, especially the botanist J.D.Hooker. In the mid-1850s he realized the significance of divergence and specialization in evolution and began to write an account of his theory for publication. This was interrupted by the arrival in 1858 of A.R.Wallace’s paper on natural selection, which prompted Darwin to write the ‘abstract’ which became the Origin of Species.
The Origin aroused much controversy, but Darwin had primed a group of sympathetic naturalists, including J.D.Hooker and T.H.Huxley, who ensured that his theory would not be dismissed. By 1870 the general idea of evolution was widely accepted, although natural selection remained controversial. Both scientists and non-scientists found natural selection too harsh a mechanism to square with their religious and philosophical beliefs. Darwin himself accepted a role for Lamarckism, and this mechanism became widely popular in the late nineteenth century. Much evolutionary research was based on an attempt to reconstruct the tree of life from anatomical and paleontological evidence, but Darwin’s own later work concentrated on botany, explaining the origin of various structures in plants in terms of natural selection. He also studied the effects of earthworms upon the soil.
Darwin had become aware of the human implications of evolutionism in the 1830s, but avoided this topic in the Origin to minimize controversy. His Descent of Man of 1871 was the first detailed attempt to explain the origin of the human race in evolutionary terms and to explore the implications of this approach for human affairs. Darwin used T.H.Huxley’s work as evidence that the human species was closely related to the great apes. Much of his book took it for granted that mental and social evolution were progressive. Darwin was convinced that the white race was the most advanced, while darker races were closer to the ancestral ape. Yet he also pioneered ideas about human origins that would not be taken seriously until the mid-twentieth century. He identified Africa rather than Asia as the most probable centre of human evolution and proposed that the key breakthrough separating the ape and human families was the latter’s adoption of bipedalism. This freed the hands for making weapons and tools, introducing a selection for intelligence and a consequent increase in the size of the brain. He explained the moral faculties as rationalizations of the instinctive behaviour patterns that had been programmed into our ancestors because of their social life. His Expression of the Emotions in Man and the Animals (1872) explained many aspects of human behaviour as relics of our animal ancestry.
Peter J.Bowler
Queen’s University Belfast
References
Darwin, C.R. (1859) On the Origin of Species by Means of Natural Selection: or the Preservation of Favoured Races in the Struggle for Life London.
——(1871) The Descent of Man and Selection in Relation to Sex, London.
——(1872) The Expression of the Emotions in Man and the Animals, London.
Further reading
Bowler, P.J. (1990) Charles Darwin: The Man and his Influence, Oxford.
