This article focuses on the concept of « type » in Franz Boas’ work. Based on a close examination of his main anthropometrical texts, it sheds light onthe way Boas used statistical methods in order to criticize the taxonomic approach of physical anthropology. Instead, he developed a perspective where relations between types are put forward and emphasized the importance of variability and correlation phenomena. By using the plural “types”, Boas was able to consider human plasticity as a scene for borrowing and intermixture.