Combining the concepts and methods of classical ethology with those of social-cultural anthropology, Navajo Infancy describes the major sources of change and continuity in Navajo infant development as a vehicle for discussing the relationships between human nature and culture. The theoretical framework includes adaptation and natural selection as key background variables, but in the important context of recent advances in evolutionary biology, which argue for a high degree of developmental plasticity in human ontogeny and the unique adaptive value of human epigenetics and socialization.