Sociocultural evolution justify new policies such as eugenics. Most 19th-century and some 20th-century approaches aimed to provide models for the evolution of humankind as a single entity. However, most 20th-century approaches, such as multilineal evolution, focused on changes specific to individual societies. Moreover, they rejected directional change (i.e. orthogenetic, teleological or progressive change). Most archaeologists work within the framework of multilineal evolution. Other contemporary approaches to social change include neoevolutionism, sociobiology, dual inheritance theory, modernisation theory and postindustrial theory. In his seminal 1976 book "The Selfish Gene", Richard Dawkins wrote that "there are some examples of cultural evolution in birds and monkeys,
Group Selection (book) of Sex" (pp 163–175), containing ideas on evolution of sex later developed by Maynard Smith; see especially his 1978 book "The Evolution of Sex". Group Selection (book) Group Selection is a 1971 book edited by George C. Williams, containing papers written by biologists arguing against the view of group selection as a major force in evolution. The group of biologists writing on a single unified (if somewhat broad) theme contrasts with Williams' earlier seminal 1966 book "Adaptation and Natural Selection", whose arguments Williams suspected to be his alone. In particular it contains a reprint, with an erratum, of W.D. Hamilton's