Huxley coined the phrase, the ‘modern synthesis’ to refer to the acceptance by a vast majority of biologists in the mid-twentieth century of a ‘synthetic’ view of evolution. According to its main chroniclers, Mayr and Provine, the ‘synthesis’ consisted in the acceptance of natural selection acting on minor hereditary variation as the primary cause of both adaptive change within populations and major changes, such as speciation, and the evolution of higher taxa (e.g. families and genera). However, the dating and substance of the synthesis is controversial. The evolutionary synthesis may be broken down into two periods, the ‘early’ synthesis from 1918 to 1932, and the later, ‘modern synthesis’ from 1936 to 1947. The authors most commonly associated with the early synthesis are J. B. S. Haldane, R. A. Fisher, and S. Wright. These three authored a number of important advances; first, they demonstrated the compatibility of a Mendelian theory of inheritance with the results of Biometry, a study of the correlations of measures of traits between relatives. Second, they developed the theoretical framework for evolutionary biology, classical population genetics. This is a family of mathematical models representing evolution as change in genotype frequencies, from one generation to the next, as a product of selection, mutation, migration, and drift, or chance. Third, there was a broader synthesis of population genetics with cytology (cell biology), genetics, and biochemistry, as well as both empirical and mathematical demonstrations to the effect that very small selective forces acting over a relatively long time were able to generate substantial evolutionary change. The later ‘modern’ synthesis is most often identified with the work of Mayr, Dobzhansky and Simpson. There was a major institutional change in biology at this stage, insofar as different subdisciplines formerly housed in different departments, and using different methods, were united under the institutional umbrella of ‘evolutionary biology’. Mayr played an important role as a community architect, in founding the Society for the Study of Evolution, and the journal Evolution, which drew together work in systematics, biogeography, paleontology, and theoretical population genetics. The synthesis presents an occasion for addressing a number of important philosophical questions about the nature of theories, explanation, progress in science, theory unification, and reduction.
Sewall Wright, 21 December 1889 - 3 March 1988