How will life change for Buck and the other dogs now that their lead dog, Spitz, is gone?

Significantly, it is Buck's imagination, not his greater instinct, which allows him to kill Buck. This idea is different than that advanced thus far in the novel. Before London emphasized the importance of instinct over reason, and the greater happiness of the dog that harkens back to instinct. Now London suggests that Buck is superior to the other dogs because of a combination of instinct and human-like intelligence. The fact that he is on more of a human wavelength gives him an advantage over most other dogs.

While London suggests there is an advantage for dogs in learning from humans, London also implies that humans are less different from animals than they might like to admit. London suggests that the human desire for the hunt and their instinct to kill is inseparable from an animal's. Human's do not kill out of reason and thought any more than dogs do, but are similarly caught up in bloodlust and thrill of the chase. In the world of the gold rush, men and dogs grow more alike. Their wilder natures are awakened, and they are bound together by 'animal' desires to survive and conquer the 'inhuman' landscape.