The Evolution of Cooperation insects, where the workers – which are sterile, and therefore incapable of passing on their genes – benefit the queen, who is essentially passing on copies of "their" genes. This is further elaborated in the "selfish gene" theory of Richard Dawkins, that the unit of evolution is not the individual organism, but the gene. (As stated by Wilson: "the organism is only DNA's way of making more DNA.") However, kinship selection works only where the individuals involved are closely related; it fails to explain the presence of altruism and cooperation between unrelated individuals, particularly across species. In a 1971 paper
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