The books describes the historical development of evolutionary genetics, starting from early ideas on evolution and ending with the modern synthesis. It provides an extensive coverage of the history of both evolution and heredity, and gives detailed descriptions of the works of Lamarck, Darwin, Mendel, Näageli, Weismann, de Vries, Galton, Pearson, Bateson, Johannsen, Morgan, Fisher, Wright and Haldane, amongst many others. The book does not deal only with a description of historical work: it also analyses and critiques existing theories and evolutionary beliefs throughout history, and discusses several controversies between biologists.