gene

gene, genotype

The fundamental unit of biological inheritance. In sexually reproducing species every individual's genotype is composed of half of each biological parent's genes. This underlying genetic structure combines in complex ways with a wide variety of environmental influences to produce the individual phenotype-or outward appearance. Modern evolutionary theory rests on the premiss of genetic inheritance, but this did not constitute part of Darwin's original formulation. It was not until some thirty years after the publication of the Origin of Species, when the significance of the work of Mendel was recognized, that genes (the actual carriers of genetic information) were first identified. Bio-chemical technology has subsequently advanced to the stage where it is now possible, via genetic engineering techniques, to alter the composition of human genetic material-although the ethical problems involved mean that only limited applications have been permitted.

The implications of these findings for the social science are discussed in Richard Dawkins's The Selfish Gene (1976), a book which did much to popularize the sociobiological vision of Edward O. Wilson. In Dawkins's volume, the unit of natural selection is identified as the gene itself, with the individual organism representing merely a survival machine or carrier for its genetic cargo. If the argument is taken to its logical conclusion then the imperatives of gene survival and reproduction determine all behaviour. The inherent reductionism of this position has been the focus of much criticism. See also chromosomes ; Darwinism ; eugenics ; heredity.