The Eclipse of Darwinism - End of The Eclipse

End of The Eclipse

See also: Modern evolutionary synthesis, Population genetics, and History of evolutionary thought Biston betularia f. carbonaria is the black-bodied form of the peppered moth. In 1924 J.B.S. Haldane published a statistical analysis of the evolution of industrial melanism in peppered moths as an example of natural selection in a real world population.

During the period 1916-1932, the discipline of population genetics developed largely through the work of the geneticists Ronald Fisher, J.B.S. Haldane, and Sewall Wright. Their work recognized that the vast majority of mutations produced small effects that served to increase the genetic variability of a population rather than creating new species in a single step as the saltationists assumed, and they were able to produce statistical models of population genetics that included Darwin's concept of natural selection as the driving force of evolution.

Developments in the field of genetics made many field naturalists such as Bernhard Rensch and Ernst Mayr abandon neo-Lamarckian ideas about evolution in the early 1930s. By the late 1930s biologists like Mayr and Theodosius Dobzhansky had synthesized the ideas of population genetics with the knowledge of field naturalists about the amount of genetic diversity in wild populations, and the importance of genetically distinct sub populations (especially sub populations partially or fully isolated from one another by geographical barriers) to begin the modern evolutionary synthesis. In 1944 George Gaylord Simpson integrated paleontology into the synthesis by statistically analyzing the fossil record to show that it was consistent with the branching non-directional form of evolution predicted by the modern synthesis, and in particular that the linear trends cited by earlier paleontologists in support of Lamarckism and orthogenesis did not stand up to careful analysis. Mayr wrote that by the end of the synthesis natural selection together with chance mechanisms like genetic drift had become the universal explanation for evolutionary change.