It is a book on evolution by ethologist Richard Dawkins that promotes the gene-centred view of evolution, as opposed to views focused on the organism and the group. The book builds upon the thesis of George C. Williams's Adaptation and Natural Selection (1966); it also popularized ideas developed during the 1960s by W. D. Hamilton and others. From the gene-centred view, it follows that the more two individuals are genetically related, the more sense (at the level of the genes) it makes for them to behave cooperatively with each other.