Though best known for a series of best-selling books on human and animal nature, Ardrey's early career was as a novelist and playwright. In the 1950s he became deeply interested in R. A. Dart's discoveries of fossil hominids in Kenya, and their possible implications for our view of human nature. In a series of books (African Genesis, 1961, The Territorial Imperative, 1966, and The Social Contract, 1970) Ardrey combined his view of humans as descended from ‘a race of terrestrial, flesh-eating, killer apes’, with generalizations on territoriality, dominance, aggression and so on in non-human animals, to draw conclusions about the instinctual basis of nature. On his own account, the egalitarian and socialist assumptions of his youth were refuted by this ‘revolution in natural science’. The popular reception of Ardrey's work was undoubtedly connected with its politically conservative response to the challenges and conflicts of the 1960s, and it remains an exemplar of the biological reductionism to which many sociologists object.