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,
The Evolution of God of God. Among other things, Wright discusses the role of evolutionary biology in the development of religion. Geneticist Dean Hamer hypothesized that some people have a specific gene that makes them prone to religious belief, which he calls the God gene, and that over time natural selection has favored these people because their spirituality leads to optimism. Wright, however, thinks the tendency towards religious belief is not an adaptive trait influenced by natural selection, but rather a spandrel - a trait that happens to be supported by adaptations originally selected for other purposes. Wright states that the human brain approaches