ethnology, the scientific study of the origin and functioning of human cultures. It is usually considered one of the major branches of cultural anthropology, the other two being anthropological archaeology and anthropological linguistics. In the 19th cent. ethnology was historically oriented and offered explanations for extant cultures, languages, and races in terms of diffusion, migration, and other historical processes. In the 20th cent. ethnology has focused on the comparative study of past and contemporary cultures. Since cultural phenomena can seldom be studied under conditions of experiment or control, comparative data from the total range of human behavior helps the ethnologist to avoid those assumptions about human nature that may be implicit in the dictates of any single culture.