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] In fact, Boas supported Darwinian theory, although he did not assume that it automatically applied to cultural and historical phenomena (and indeed was a lifelong opponent of 19th-century theories of cultural evolution, such as those of Lewis H. Morgan and Edward Burnett Tylor).[45] The notion of evolution that the Boasians ridiculed and rejected was the then dominant belief in orthogenesis—a determinate or teleological process of evolution in which change occurs progressively regardless of natural selection. Boas rejected the prevalent theories of social evolution developed by Edward Burnett Tylor, Lewis Henry Morgan, and Herbert Spencer not because he rejected the notion of "evolution" per se, but because he rejected orthogenetic notions of evolution in favor of Darwinian evolution.