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,
Selfish genetic element successful selfish genetic elements. The discovery of transposable elements led to her being awarded the Nobel Prize in Medicine or Physiology in 1983. The empirical study of selfish genetic elements benefited greatly from the emergence of the so-called gene-centred view of evolution in the nineteen sixties and seventies. In contrast with Darwin's original formulation of the theory of evolution by natural selection that focused on individual organisms, the gene's-eye view takes the gene to be the central unit of selection in evolution. It conceives evolution by natural selection as a process involving two separate entities: replicators (entities that produce faithful