Final answer:
Historical plasticity of human development, proposed by Franz Boas, suggests that cultures do not develop in isolation and each has its own unique historical trajectory. Boas used ethnographic data to challenge racist theories and emphasize the role of environment and culture in human development.
Step-by-step explanation:
Historical Plasticity of Human Development (Boas)
Historical plasticity of human development, as proposed by Franz Boas, is the idea that cultures do not develop in isolation along a common trajectory towards 'civilization.' Boas argued that each culture has its own unique historical trajectory and constantly changes through the sharing of new ideas and practices. He used ethnographic data to challenge ethnocentric and racist theories prevalent in the late 19th and early 20th centuries. Boas played a significant role in disproving race theory and highlighting the role of environment and cultural factors in human development.