The gene-centered view of evolution, also known as the selfish gene theory, holds that adaptive evolution occurs through the differential survival of competing genes, increasing the allele frequency of those alleles whose phenotypic trait effects successfully promote their own propagation. The proponents of this viewpoint argue that, since heritable information is passed from generation to generation almost exclusively by DNA, natural selection and evolution are best considered from the perspective of genes.
Proponents of the gene-centered viewpoint argue that it permits understanding of diverse phenomena such as altruism and intragenomic conflict that are otherwise difficult to explain from an organism-centered viewpoint. Some proponents claim that the gene-centered view is the aspect of evolutionary theory that is the most empirically validated, has the greatest predictive power, and has the broadest applicability.
The gene-centered view of evolution is a synthesis of the theory of evolution by natural selection, the particulate inheritance theory, and the rejection of transmission of acquired characters. It states that those alleles whose phenotypic effects successfully promote their own propagation will be favorably selected relative to their competitor alleles within the population. This process produces adaptations for the benefit of alleles that promote the reproductive success of the organism, or of other organisms containing the same allele (kin altruism and green-beard effects), or even its own propagation relative to the other genes within the same organism (selfish genes and intragenomic conflict).
Opponents of the gene-centered view argue that it is too narrowly focused on adaptation as the only important mechanism of evolution. Thus, it ignores the possibility that traits might be neutral and fixed by random genetic drift. It also ignores the possibility that some fixed traits might even be deleterious. Critics argue that proponents of the gene-centered view often favor an adaptationist perspective that assumes a role for natural selection as the null hypothesis.
Overview
The gene-centered view of evolution is a model for the evolution of social characteristics such as selfishness and altruism, with gene defined as "not just one single physical bit of DNA [but] all replicas of a particular bit of DNA distributed throughout the world".
Acquired characteristics
thumb|upright|John Maynard Smith
The formulation of the central dogma of molecular biology was summarized by Maynard Smith:
The rejection of the inheritance of acquired characters, combined with Ronald Fisher the statistician, giving the subject a mathematical footing, and showing how Mendelian genetics was compatible with natural selection in his 1930 book The Genetical Theory of Natural Selection. J. B. S. Haldane, and Sewall Wright, paved the way to the formulation of the selfish-gene theory. For cases where environment can influence heredity, see epigenetics.
The gene as the unit of selection
thumb|upright|Richard Dawkins
The view of the gene as the unit of selection was developed mainly in the works of Richard Dawkins, W. D. Hamilton, Colin Pittendrigh and George C. Williams. It was popularized by Dawkins in his book The Selfish Gene (1976).
According to Williams' 1966 book Adaptation and Natural Selection,