Anthropologists were more eager to classify races than to define them. Ever since Darwin, the perception of biology as a science that uncovered the mystery of life and deciphered the enigma of evolution had captured the imagination of non-biologists. It was believed that biology held the key to solving social problems. Most of the anthropologists who classified races assumed that biologists had defined the essence of human races, a belief many biologists encouraged. After 1900, enthusiasm for racial classification combined with the hereditarian fervor kindled by the rediscovery of Mendel's Laws brought the popularity of race studies to new heights.

As shown above, anthropologists, and especially physical anthropologists, had no means of evaluating competing methodologies, and their commitment to the study of race was based on a blind faith that their important subject enjoyed fundamental scientific support, even if the details were not all clear. Elucidation was left finally in the hands of biologists who, with the growth of experimental genetics, were becoming more skeptical of their ability to deliver a methodology for racial classification. This inability of biology to supply satisfactory answers to social questions allowed social scientists to carve for themselves a growing space. Cultural and social anthropology largely replaced both physical anthropology and the old ethnology which was based on biological explanation as the frontier of the discipline.