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
Feathers: The Evolution of a Natural Miracle published by the National Audubon Society. "Feathers" is Hanson's second book, after "The Impenetrable Forest: My Gorilla Years in Uganda" (2008). Following a preface and introduction, "Feathers" is divided into five main parts: "Evolution" discusses the evolutionary history of feathers, "Fluff" explains the role of feathers in regulating body temperature, "Flight" discusses the origin of avian flight as well as its impact on human aviation, "Fancy" discusses the role of feathers in sexual selection and human fashion, and "Function" discusses the continuing evolution of feathers in both nature and human usage. "Feathers" begins with the 1861 discovery of the first