Buck makes the transition from civilization to wilderness, and in the process transforms from obedient dog to wolf-pack leader. Throughout the novel, he becomes less dog-like and more wolf-like; London goes into great detail describing Buck's sharpening of ancient senses and his return to a wild state. The term "retrogression" has slightly negative connotations, but in Buck's case, his adaptations to the wild are a positive, for they enable him to survive and thrive. The sequel to "The Call of the Wild" is the novel "White Fang," in which a wolf becomes domesticated; these make an interesting pair of stories back to back. Could we argue White Fang's journey toward civilization is development "progression?" In either case, each canine is successfully adapting to the environment around him, and comes to a place of prominence within that environment.