Naturalism period appeared in 1890s-1950s, its manifest mostly on fiction in United States. Naturalism period is the continuation of Realism period which added determinism and pessimistic. The term of Naturalism first came from Emile Zola-a France artist-and some authors were influenced by his masterpieces, such as Noris and London. While American Literature on Realism period concentrated in literature technique, literature in Naturalism period illustrated the philosophical human science. They were skeptical on the explanation for human behavior in natural science exclusively of the human society. Emile Zola believed that human’s character could be identified by how they act with the others people and how they adapted in a new society. He also researched character of human might be governed by their environment.