Sinclair and Garland

Most literature scholars would put Upton Sinclair and Hamlin Garland in the camp of Naturalism. In light of what you read this week, why do you suppose these two authors are classified as naturalists? What do you see in their works that strikes you as naturalistic thinking? Looking back at the assigned readings over the last few weeks, are there other authors whose works seem to qualify as Naturalism, too? Please read ; Hamlin garland " under the lion's paw" and uptown Sinclair "from the jungle"