One of the greatest accomplishments of Boas and his students was their critique of theories of physical, social, and cultural evolution current at that time. This critique is central to Boas's work in museums, as well as his work in all four fields of anthropology. As historian George Stocking noted, however, Boas's main project was to distinguish between biological and cultural heredity, and to focus on the cultural processes that he believed had the greatest influence over social life.[44]