The Call of the Wild is, first and foremost, the story of Buck’s gradual transformation from a tame beast into a wild animal. But even as the novel celebrates the life of a wild creature, it presents us with the character of John Thornton, whose connection to Buck suggests that there may be something good and natural in the human-dog relationship, despite its flaws. Thornton, a seasoned gold prospector, saves Buck from being beaten to death by the odious Hal and then becomes Buck’s master. From then on, a deep and abiding love blossoms between man and dog. Their relationship is a reciprocal one—Thornton saves Buck, and Buck later saves Thornton from drowning in a river. It is clear that Buck is more of a partner than a servant to the prospector. This mutual respect, we are assured, is characteristic of all Thornton’s relationships to dogs—every one of his animals bears an abiding love for him, which is returned in kind. Even as Buck is increasingly drawn to a life away from humanity, a life in the wild, his affection for Thornton keeps him from making the final break. Indeed, so strong is their bond that it is broken only when Thornton dies, and even then Buck makes an annual pilgrimage to his last master’s final resting place.
Buck is prone to visions of more primitive worlds, and sometimes he sees the humans around him as ancient men, wearing animal skins and living in caves or trees. In some of these visions, he is running alongside these men, protecting them from the terrors of the night. His relationship to Thornton, the novel implies, is like these ancient man-dog connections; it is primitive rather than civilized, and so it remains strong even as Buck leaves the civilized world behind.