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
The Genetical Theory of Natural Selection Charles Darwin, "In gratitude for the encouragement, given to the author, during the last fifteen years, by discussing many of the problems dealt with in this book." The book was reviewed by Charles Galton Darwin, who sent Fisher his copy of the book, with notes in the margin, starting a correspondence which lasted several years. The book also had a major influence on W. D. Hamilton's theories on the genetic basis of kin selection. John Henry Bennett gave an account of the writing and reception of the book. Sewall Wright, who had many disagreements with Fisher, reviewed the book and