Unit of selection and Confirmation of Evolutionary Theory" provides a basic "philosophical" introduction to the debate. Below, cases of selection at the genic, cellular, individual and group level from within the multi-level selection perspective are presented and discussed. George C. Williams in his influential book "Adaptation and Natural Selection" was one of the first to present a gene-centered view of evolution with the gene as the unit of selection, arguing that a unit of selection should exhibit a high degree of permanence. Richard Dawkins has written several books popularizing and expanding the idea. According to Dawkins, genes cause phenotypes and a gene is
Richard Dawkins: How a Scientist Changed the Way We Think Ridley. () The reviews of the book have been mixed, but the controversial title phrase, "How a Scientist Changed the Way We Think" has been explained by considering Dawkins to have worked as an influential educator and concise author, of "The Selfish Gene", who promoted the key ideas of others about evolutionary biology, also including some controversial ideas which are not as widely accepted. As the author of a popular science book, Dawkins had popularized ideas by George Williams about group selection, William Hamilton on the theory of kin selection in evolution, biologist/geneticist John Maynard Smith on evolutionarily stable strategies,