neo-Darwinism

n. Neo-Darwinism is the synthesis during the early decades of the 20th century of Darwin's original theory of natural selection, Mendelian genetics, and mathematical population genetics. Darwin's theory lacked a modern theory of genetics, which was provided around 1900, when Mendel's work entered the scientific mainstream. Mendel's work showed that genes were transmitted discretely between generations rather than as a result of blending the genes from the male and female. For example, a recessive gene transmitted from parent to child retains its characteristics in the offspring apart from mutations. The details of how Mendelian genetics could be integrated with natural selection and the inheritance of continuous traits were provided by the field of mathematical population genetics, beginning with the work of Ronald Fisher in 1918. Fisher developed a model in which continuous traits such as height or intelligence are influenced by many discrete genes, each with small effects which result in genetically based correlations between parents and offspring. This work revolutionized evolutionary science and led to a number of landmark publications: Fisher's The Genetical Theory of Natural Selection(1930), Sewall Wright's Evolution in Mendelian Populations(1931), and J. B. S. Haldane's The Causes of Evolution (1932). Later work, notably Theodosius Dobzhansky's Genetics and the Origin of Species (1937), Ernst Mayr's Systematics and the Origin of Species (1942), G. G. Simpson's Tempo and Mode in Evolution (1944), and G. Ledyard Stebbins's Variation and Evolution in Plants (1950), applied neo-Darwinism to natural populations of plants and animals, resulting in what is often termed “the modern synthetic theory of evolution,” or the modern synthesis. – KM