Final answer:
Franz Boas and his predecessors' primary task in American anthropology was to document Native American cultures, with a focus on their unique developments and rejection of ethnocentric theories of the time.
Step-by-step explanation:
According to Bourguignon, Franz Boas and his predecessors felt that the primary task of American anthropology was to study Native American cultures and to document their way of life, languages, customs, and history. Boas, a leading figure in anthropology, advocated for a holistic and respectful approach, collecting ethnographic data through direct contact and emphasizing the unique and constantly evolving nature of each culture. Rejecting the ethnocentric and racist theories of his time, Boas focused on the Native peoples of the Northwest coast of North America, especially the Kwakiutl peoples, recording their myths, songs, and cultural practices.
His work profoundly influenced the discipline, advocating for cultural relativism and challenging prevailing theories of racial superiority. Boas's ethnographic standards became the foundation for modern anthropology, supporting the view that biological differences do not determine culture, language, or achievement, and that environmental factors like nutrition and medical care can significantly influence physical development.