Because The Call of the Wild focuses upon Buck’s experience, the human Characters are of secondary importance. Buck is a magnificent dog, part shepherd and part St. Bernard. His superior strength enables him to adapt readily to the northern climate and the harsh demands of his labors. But he possesses one additional quality-imagination. Buck fights with his head as well as his brawn.
Adaptability is a dominant theme in The Call of the Wild. In order to survive in the Yukon, Buck must learn “the law of club and fang.” Buck is first taught this law by the club-wielding sled drivers Francois and Perrault, who show him that the strongest individuals are the ones who rule. Buck also learns this primitive law from the other team dogs, such as Dave, Sol-leks, and the vicious team leader, Spitz. From them, Buck learns that he must either bite or be bitten, master or be mastered.
The theme of adaptability, or “survival of the fittest,” is a popular Darwinian concept that appears in many of London’s stories, applying to humans as well as to animals. In contrast to Francois and Perrault, who know how to survive in the harsh arctic environment, the incompetent miners Charles, Hal, and Mercedes are unable to adapt to their surroundings. The trio lacks discipline, skill, imagination, and self-control. They attempt to use fourteen dogs instead of nine, not considering that their sled cannot carry food for so many dogs. They also insist upon unnecessary luxuries, which only serve to burden them further and lead to their inevitable doom.
When John Thornton befriends Buck and saves his life, London introduces another theme that is popular in animal stories-the love and loyalty between human and beast. In The Call of the Wild, the bond between Buck and John Thornton is especially important, because their mutual survival depends upon it. When Thornton is murdered by the Yeehats, a group of Native Americans, Buck avenges the death by killing Thornton’s murderers. In doing so, he discovers just how vulnerable humans are.
Buck’s retrogression, which culminates in his transformation into the leader of a wolf-pack, is probably the most provocative theme of the book. It reflects London’s belief that environment determines character. Away from the ease of civilized life, Buck must rely increasingly upon his survival instincts. Under the harsh conditions of trail life, he develops certain primal traits: he becomes more cunning, deliberate, and calculating. He learns how to kill mercilessly and to show no sign of weakness.
As Buck adapts to life in the wild, he begins to experience primordial visions, to imagine life in some earlier, more primitive age. He dreams of savage beasts and a hairy man crouching beside a fire. He hears the howl of the wolves and instinctively responds; he becomes increasingly restless and begins to wander into the forest. After the death of John Thornton, Buck answers the call of the wild and takes up the life of his ancestors.