 Moreover, Boas encouraged his students, by example, to criticize themselves as much as others.For example, Boas originally defended the cephalic index (systematic variations in head form) as a method for describing hereditary traits, but came to reject his earlier research after further study; he similarly came to criticize his own early work in Kwakiutl (Pacific Northwest) language and mythology.Encouraged by this drive to self-criticism, as well as the Boasian commitment to learn from one's informants and to let the findings of one's research shape one's agenda, Boas's students quickly diverged from his own research agenda.