Answer:
Anthropologists of the early twentieth-century took an interest in cultural change. They still shared the same interest in the cultural practices of native peoples around the world, but instead of focusing exlusively on the current practices, they began to study the changes that brought the culture to the current point.
For example, a nineteenth century anthropologist would have noticed that Native Peoples in the Peruvian Mountains grow potatoes and domesticated the llama, and an early twentieth-century anthropologist would have tried to find how the people began to grow potatoes, and how they went about domesticating the llama.