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
The Genetical Theory of Natural Selection chapter, Fisher considers the nature of inheritance, rejecting blending inheritance, because it would eliminate genetic variance, in favour of particulate inheritance. The second chapter introduces Fisher's fundamental theorem of natural selection. The third considers the evolution of dominance, which Fisher believed was strongly influenced by modifiers. Other chapters discuss parental investment, Fisher's geometric model, concerning how spontaneous mutations affect biological fitness, Fisher's principle which explains why the sex ratio between males and females is almost always 1:1, reproductive value, examining the demography of having girl children. Using his knowledge of statistics, the Fisherian runaway, which explores how sexual selection can