Since the dawn of time man has had a sense of racial differences among people but has not known the extent to human diversity. Five main geographical groups have classified people as being Caucasoid, Mongoloid, Australoid, Congoid, or Capoid. The author seeks to determine how far back in prehistoric antiquity human racial groups can be traced, which he argues are separated by long periods of time due to evidence from comparative ethnology, linguistics, and prehistoric archaeology. He goes on to explain such topics as the problems of human taxonomy, the differentiation of species, balanced polymorphism, the timing of the individual growth cycle, allometry, sexual dimorphism, and the evolution of species.
