Boas used his positions at Columbia University and the American Museum of Natural History to train and develop multiple generations of students. His first generation of students included Alfred Kroeber, Robert Lowie, Edward Sapir and Ruth Benedict, who each produced richly detailed studies of indigenous North American cultures. They provided a wealth of details used to attack the theory of a single evolutionary process. Kroeber and Sapir's focus on Native American languages helped establish linguistics as a truly general science and free it from its historical focus on Indo-European languages.