Anthropology grew increasingly distinct from natural history and by the end of the nineteenth century the discipline began to crystallize into its modern form—by 1935, for example, it was possible for T.K. Penniman to write a history of the discipline entitled "A Hundred Years of Anthropology". At the time, the field was dominated by 'the comparative method'. It was assumed that all societies passed through a single evolutionary process from the most primitive to most advanced. Non-European societies were thus seen as evolutionary 'living fossils' that could be studied in order to understand the European past. Scholars wrote histories of prehistoric migrations which were sometimes valuable but often also fanciful. It was during this time that Europeans first accurately traced Polynesian migrations across the Pacific Ocean for instance—although some of them believed it originated in Egypt. Finally, the concept of race was actively discussed as a way to classify—and rank—human beings based on difference.