The Call of the Wild is a story of transformation in which the old Buck—the civilized, moral Buck—must adjust to the harsher realities of life in the frosty North, where survival is the only imperative. Kill or be killed is the only morality among the dogs of the Klondike, as Buck realizes from the moment he steps off the boat and watches the violent death of his friend Curly. The wilderness is a cruel, uncaring world, where only the strong prosper. It is, one might say, a perfect Darwinian world, and London’s depiction of it owes much to Charles Darwin, who proposed the theory of evolution to explain the development of life on Earth and envisioned a natural world defined by fierce competition for scarce resources. The term often used to describe Darwin’s theory, although he did not coin it, is “the survival of the fittest,” a phrase that describes Buck’s experience perfectly. In the old, warmer world, he might have sacrificed his life out of moral considerations; now, however, he abandons any such considerations in order to survive.

But London is not content to make the struggle for survival the central theme of his novel; instead, his protagonist struggles toward a higher end, namely mastery. We see this struggle particularly in Buck’s conflict with Spitz, in his determination to become the lead dog on Francois and Perrault’s team, and, at the end of the novel, in the way that he battles his way to the leadership of the wolf pack. Buck does not merely want to survive; he wants to dominate—as do his rivals, dogs like Spitz. In this quest for domination, which is celebrated by London’s narrative, we can observe the influence of Friedrich Nietzsche, a German philosopher of the late nineteenth century. Nietzsche’s worldview held that the world was composed of masters, those who possessed what he called “the will to power,” and slaves, those who did not possess this will. Nietzsche delighted in using animal metaphors, comparing masters to “birds of prey” and “blonde beasts” and comparing slaves to sheep and other herd animals. London’s Buck, with his indomitable strength and fierce desire for mastery, is a canine version of Nietzsche’s masterful men, his Napoleon Bonapartes and Julius Caesars. Buck is a savage creature, in a sense, and hardly a moral one, but London, like Nietzsche, expects us to applaud this ferocity. His novel suggests that there is no higher destiny for man or beast than to struggle, and win, in the battle for mastery.

When Buck enters the wild, he must learn countless lessons in order to survive, and he learns them well. But the novel suggests that his success in the frozen North is not merely a matter of learning the ways of the wild; rather, Buck gradually recovers primitive instincts and memories that his wild ancestors possessed, which have been buried as dogs have become civilized creatures. The technical term for what happens to Buck is atavism—the reappearance in a modern creature of traits that defined its remote forebears. London returns to this theme again and again, constantly reminding us that Buck is “retrogressing,” as the novel puts it, into a wilder way of life that all dogs once shared. “He was older than the days he had seen and the breaths he had drawn,” we are told. “He linked the past with the present, and the eternity behind him throbbed through him in a mighty rhythm to which he swayed as the tides and seasons swayed.” Buck even has occasional visions of this older world, when humans wore animal skins and lived in caves, and when wild dogs hunted their prey in the primeval forests. His connection to his ancestral identity is thus more than instinctual; it is mystical. The civilized world, which seems so strong, turns out to be nothing more than a thin veneer, which is quickly worn away to reveal the ancient instincts lying dormant underneath. Buck hears the call of the wild, and London implies that, in the right circumstances, we might hear it too.

While the two lives that Buck leads stand in stark contrast to each other, this contrast does not go unchallenged throughout the novel. His life with Judge Miller is leisurely, calm, and unchallenging, while his transition to the wilderness shows him a life that is savage, frenetic, and demanding. While it would be tempting to assume that these two lives are polar opposites, events later in the novel show some ways in which both the wild and civilization have underlying social codes, hierarchies, and even laws. For example, the pack that Buck joins is not anarchic; the position of lead dog is coveted and given to the most powerful dog. The lead dog takes responsibility for group decisions and has a distinctive style of leadership; the main factor in the rivalry between Buck and Spitz is that Buck sides with the less popular, marginal dogs instead of the stronger ones. Buck, then, advocates the rights of a minority in the pack—a position that is strikingly similar to that of his original owner, the judge, who is the novel’s most prominent example of civilization.

The rules of the civilized and uncivilized worlds are, of course, extremely different—in the wild, many conflicts are resolved through bloody fights rather than through reasoned mediation. But the novel suggests that what is important in both worlds is to understand and abide by the rules which that world has set up, and it is only when those rules are broken that we see true savagery and disrespect for life. Mercedes, Hal, and Charles enter the wild with little understanding of the rules one must follow to become integrated and survive. Their inability to ration food correctly, their reliance upon their largely useless knife and gun, and their disregard for the dogs’ suffering all attest to laws of the wilderness that they misunderstand or choose to ignore. As a result, the wilderness institutes a natural consequence for their actions. Precisely because they do not heed the warnings that the wild provides via one of its residents, John Thornton, they force the team over unstable ice and fall through to their deaths. The novel seems to say that the wild does not allow chaos or wanton behavior but instead institutes a strict social and natural order different from, but not inferior to, that of the civilized world.

When Buck arrives in the wild, his primordial instincts do not awaken immediately, and he requires a great deal of external help before he is suited to life there. Help arrives in realizations about the very different rules that govern the world outside of civilization, but also in the support of the pack of which he becomes a part. Two dogs in particular, Dave and Sol-leks, after having established their seniority, instruct Buck in the intricacies of sled pulling. Furthermore, the group members take pride in their work, even though they are serving men. When they make trips in good time, they congratulate themselves—they all participate in a common enterprise.

At the same time, however, one of the most valued traits in the wilderness is individualism. If The Call of the Wild is a story about ultimately achieving mastery over a foreign, primal world, that mastery is achieved only through separation from the group and independent survival. Throughout much of the story, Buck is serving a master or a pack; even as a leader he is carrying out someone else’s commands and is responsible for the well-being of the group. In many ways, then, when John Thornton cuts Buck free from his harness, he is also beginning the process of Buck’s separation from a pack mentality. Although Buck continues to serve Thornton, his yearnings for a solitary life in the wild eventually overcome him.

The balance between individual and group is disrupted once more, however, toward the end of the novel, when Buck becomes the leader of a wolf pack. Although the pack is much different from the dog pack whose responsibility was to serve humans by pulling sleds, the message seems to be that, while encouraging the skills to survive on one’s own, the wild ultimately requires the cooperation of a group in order to ensure individual survival.

Life-and-death battles punctuate The Call of the Wild’s narrative, serving as reminders of the dangers of life in the Klondike, but more importantly as markers of Buck’s gradual integration into his new environment. When Buck first arrives in the north, he watches a friendly dog named Curly brutally killed by a husky. Soon, he finds himself in a rivalry with Spitz that ends with the two of them locked in single combat, a battle from which only Buck emerges alive. Having established himself as a dominant dog with this victory, Buck must continue to prove himself in battles with other creatures—with a bear, with a moose, and, finally, with humans. When Buck kills the Yeehat Indians who have killed John Thornton, he is fighting for his life against mankind for the first time, a sure sign of his final assimilation into the wild.

One of the themes of The Call of the Wild is “atavism,” or an animal’s (in this case, Buck’s) recovery of the instincts of his wild ancestors. For Buck, this recovery involves repeated visions of his primitive past, which usually occur late at night when he is lying alongside a campfire. He sees the men around him as primitive men, draped in furs and wary of the prehistoric dark around them, and then he has visions of himself as a primitive, wild creature, hunting his prey in the primeval forests. Each of these visions brings him closer to his destiny, which is the return to his ancestors’ ways and becoming a wild animal himself.

Mercedes loads the sled up with so many of her things that the dogs cannot possibly pull it; later, she herself gets on the sled, making the load even heavier. Her insistence on having all of her possessions with her emphasizes the difference between the wild, where the value of an object lies in its immediate usefulness, and civilization, where the value of an object lies in its ability to symbolize the wealth of its possessor. Material possessions and consumerism have no place in the wild, and it is at least partly Mercedes’ inability to recognize this fact that leads to her death when the overburdened sled falls through the ice.

The significance of Buck’s traces—the straps that bind him to the rest of the team—changes as the plot develops. The novel initially charts his descent from his position as the monarch of Judge Miller’s place in civilization to a servile status in which it is his duty to pull the sled for humans. But as he becomes more a part of the wild, Buck begins to understand the hierarchy of the pack that pulls the sled, and he begins to gain authority over the pack. After his duel with Spitz, he is harnessed into the lead dog’s position; his harness now represents not servitude to the humans but leadership over the dogs. Finally, however, John Thornton cuts Buck free from his traces, an act that symbolizes his freedom from a world in which he serves humans. Now a companion to Thornton rather than a servant, Buck gradually begins to enter a world of individual survival in the wild.

When Buck is kidnapped, he attempts to attack one of the men who has seized him, only to be beaten repeatedly with a club. This moment, when his fighting spirit is temporarily broken, along with the brutal killing of Curly by a group of vicious sled dogs, symbolizes Buck’s departure from the old, comfortable life of a pet in a warm climate, and his entrance into a new world where the only law is “the law of club and fang.”

In the closing chapters of the novel, Buck feels the call of life in the wild drawing him away from mankind, away from campfires and towns, and into the forest. The only thing that prevents him from going, that keeps him tied to the world of men, is his love for John Thornton. When the Yeehat Indians kill Thornton, Buck’s last tie to humanity is cut, and he becomes free to attack the Yeehats, killing a number of them. To attack a human being would once have been unthinkable for Buck, and his willingness to do so now symbolizes the fact that his transformation is complete—that he has truly embraced his wild nature.