The book might have ended as Slim and George walked toward the highway. Instead, Steinbeck added a coda with Carlson saying, "What the hell ya suppose is eatin' them two guys." Why do you think this was added?

Carlson's remark demonstrates the lack of empathy that these men have developed after only taking care of themselves for so long. This adds further tragedy to the death of Lennie. The men can't understand why George and Slim might be sad.