The story of the development of the synthetic theory of evolution, named from Julian Huxley 's contribution, Evolution The Modern Synthesis (1942), has been told many times, notably in Mayr (1982) and in the collective work, Mayr and Provine (1980). As Mayr has frequently emphasised, population thinking - seeing anagenesis as the establishment of new forms in interbreeding populations - plus the biological species concept, traceable to John Ray in the seventeenth century (Ray 1686; see Chapter 14), were necessary before the theory could be developed. Theoretical population genetics - the mathematical modelling of genes in populations – was developed with different emphases by Fisher, Haldane, and Sewall Wright. Contemporary with them, Chetverikov and his colleagues in Russia were not only developing parallel ideas but testing them on wild populations of the fruit-fly Drosophila, Morgan 's choice of experimental animal. Dobzhansky, not a member of Chetverikov 's group but strongly influenced by them, continued his work in the United States in a series of papers on D. pseudoobscura from 1938 to 1976 and also produced what is usually considered the first great book of the synthesis, Genetics and the Origin of Species, in 1937. The others usually recognized are Huxley 's; Mayr 's Systematics and the Origin of Species (1942); Rensch (1947), translated in its second edition as Evolution Above the Species Level (1959); and Simpson 's Tempo and Mode in volution (1944), considerably changed (Gould 1980c) and reissued as The Major Features of Evolution (Simpson 1953).