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
Alternatives to evolution by natural selection Alternatives to evolution by natural selection Alternatives to evolution by natural selection, also described as non-Darwinian mechanisms of evolution, have been proposed by scholars investigating biology since classical times to explain signs of evolution and the relatedness of different groups of living things. The alternatives in question do not encompass religious points of view such as young or old earth creationism or intelligent design, but are limited to explanations proposed by biologists, though one was confusingly named 'theistic evolution' by Asa Gray. Where the fact of evolutionary change was accepted but the mechanism proposed by Charles Darwin, natural selection, was