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
Natural selection 1900. With the early 20th century integration of evolution with Mendel's laws of inheritance, the so-called modern synthesis, scientists generally came to accept natural selection. The synthesis grew from advances in different fields. Ronald Fisher developed the required mathematical language and wrote "The Genetical Theory of Natural Selection" (1930). J. B. S. Haldane introduced the concept of the "cost" of natural selection. Sewall Wright elucidated the nature of selection and adaptation. In his book "Genetics and the Origin of Species" (1937), Theodosius Dobzhansky established the idea that mutation, once seen as a rival to selection, actually supplied the raw material