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 Feathers: The Evolution of a Natural Miracle Feathers: The Evolution of a Natural Miracle is a 2011 natural history book by American conservation biologist Thor Hanson. Published by Basic Books and written for general audiences, the book discusses the significance of feathers, their evolution, and their history both in nature and in use by humans. "Feathers" is divided into five parts. In "Evolution", Hanson discusses the scientific debate over how feathers evolved, interviewing ornithologists Richard Prum and Alan Feduccia, as well as paleontologist Xing Xu. In "Fluff", Hanson discusses how feathers play a role in regulating a bird's body temperature