Darwin, Charles Robert (1809–82)

4. Human origins

From the start, Darwin accepted that the human species would have to be included within the evolutionary worldview. If humans were to be treated as merely advanced animals, the mental and moral faculties traditionally seen as products of the soul would have to be explained as extensions of those faculties already possessed by animals. In his Descent of Man (1871) and Expression of the Emotions in Man and the Animals (1872), Darwin tried to justify this proposition and to explain how the human mind had developed so much further than those of our closest animal relatives. He did not believe that the mind was a tabula rasa or blank slate capable of indefinite modification by experience. Many mental activities are governed by instincts imprinted by evolution. He showed that many aspects of human behaviour, especially the way we express emotions, are relics of our animal ancestry. He also took seriously many stories that interpreted animal behaviour in anthropomorphic terms, thus providing apparent evidence that animals possess rudiments of even the highest mental and moral faculties.

Darwin accepted that the mental faculties were produced by the brain, and that the increased brain size of the ’higher’ animals is reponsible for their increased intelligence and more complex behaviour. Many of his contemporaries assumed that evolution would inevitably produce a steady increase in the level of animal intelligence. In The Descent of Man, however, Darwin anticipated the modern position in which (since evolution is not inherently progressive) it is necessary to explain why the branch leading to humans has experienced a much greater expansion in intelligence than that leading to our closest cousins, the great apes. He argued that the distant ancestors of humans had stood upright as a means of walking on the open plains, while the apes had stayed in the trees. Human intellengence was a by-product of this change of habitat, produced as a means of exploiting the hand’s ability to manipulate the environment.

Darwin argued that the higher animals exhibit social behaviour which provides the foundation for human moral values. Social behaviour is governed by instincts, and natural selection can act upon the variations in such instincts to promote useful behaviour patterns. Since our distant ancestors lived in social groups, we have inherited their social instincts, and our moral values are rationalizations of behavioural tendencies which we feel automatically. Modern efforts to explain some aspects of human behaviour in terms of biologically implanted instincts make use of the same argument (see Sociobiology).

Although Darwin anticipated some modern ideas on human evolution, he shared the prejudices of his own time and was convinced that Europeans were superior to other races and that modern industrial civilization is the highest expression of social evolution. His ideas were taken up by some social evolutionists who argued that here, as in the biological realm, progress would only result if individuals or races were left to struggle among themselves to determine which was fit enough to survive. This social philosophy came to be known as ’social Darwinism’ – although one of its leading proponents, Herbert Spencer, was more a Lamarckian than a Darwinian. The claim that struggle was a spur to progress was developed in many other forms besides Darwin’s theory of natural selection.