Jack London’s adventure stories made him one of the most popular writers of his day. In works such as The Call of the Wild, White Fang (1906), and Jerry of the Islands (1917) London makes animals into compelling leading characters, as engaging and sympathetic as any human protagonists. London’s animal stories do not anthropomorphize animals simply to play on the heartstrings of his audience. Some of his contemporaries criticized him for writing maudlin beast fables suitable only for children, but these critics misrepresented London’s books and misunderstood his literary aims. London resisted the sentimental beast fables of his day, which personified animals to manipulate the reader’s emotions. London’s stories, instead, reflect more substantial scientific and philosophical issues. His goal is not to make animals appear human, but to emphasize the hereditary connection that humans have with animals.

London was heavily influenced by the works of Charles Darwin (On the Origin of Species by Means of Natural Selection, 1859, and The Descent of Man and Selection in Relation to Sex, 1871). In The Call of the Wild, Buck’s experience follows Darwinian principles. He is molded by the changes in his environment, thriving because he possesses the necessary genetic gifts of strength and intelligence to adapt to his mutable circumstances. He is an example of a popular understanding of Darwin’s theories: survival of the fittest. Although raised in the domestic ease of Judge Miller’s estate, Buck learns quickly what it takes to endure the brutal world of dog-sledding—the “law of club and fang.” When Buck first learns to steal food from one of his French Canadian masters, readers are told that this “theft marked Buck as fit to survive in the hostile Northland environment. It marked his adaptability, his capacity to adjust himself to changing conditions.” The Call of the Wild also reflects London’s admiration for the works of nineteenth century German philosopher Friedrich Nietzsche. In the North, might makes right, and Buck proves to be the animal equivalent of Nietzsche’s superman, possessing physical and mental abilities superior to those of the other dogs.

Buck, however, does not experience only raw nature. With John Thornton he returns to a more civilized existence. London’s dog stories shuttle between the poles of the domesticated and the wild, of the civilized and the natural. The Call of the Wild begins in a domesticated environment and ends in the wild. (Conversely, White Fang begins in nature and ends in civilization.) Thornton’s compassionate influence helps temper the savage ferocity Buck develops to survive in a crueler world. The wild instinct still remains. Buck’s love for Thornton compels Buck to be obedient, loyal, and altruistic, but his wild half keeps calling to him. Buck’s romp in the woods with the wolf that seems like a brother to him anticipates his complete surrender to nature when Thornton dies. In the end, Buck obeys the call of the wild.

The Call of the Wild suggests that the reader draw a corollary between the divided nature of Buck and that of every human being. Inspired by Darwin, London believed in the evolutionary continuity between animals and human beings. If human beings evolved from animals, then what exists on a lower level in animals must hold true on a higher level for human beings. London does not give Buck human qualities but suggests that animals and humans share common traits and experiences because of their evolutionary connection. Buck’s vision of the short-legged, hairy man sleeping restlessly near the fire symbolizes the primitive beast lurking within all civilized beings. Being an animal, Buck can completely surrender to his primitive half. London seems to celebrate the primordial throughout the book, lauding the “surge of life” Buck experiences when he hunts down prey, the “ecstasy” of tasting living meat and warm blood. For human beings the rift between nature and civilization is much more complicated. People cannot and should not revert completely to their animalistic ancestry. In White Fang, for example, human beings dominated by their primitive halves are degenerates and criminals. London deals more directly with this human struggle in The Sea-Wolf (1904), suggesting that for humans a balance between the brutish and the civilized is best.

Readers can also see how The Call of the Wild reflects London’s socialism. No single philosophical system satisfied London, so he accepted bits and pieces of many different, even contradictory ideas. When the ideas of Darwin or Nietzsche fell short in his estimation, those of Karl Marx seemed attractive. From a Marxist perspective, Buck can be interpreted as a representative of the oppressed, subject to the whims of cruel masters and their corrupt use of power. Under these brutal conditions Buck must do what he has to do to survive. He becomes a brute and a thief himself, struggling individually to fend for himself. Thornton’s benevolent, more equitable treatment encourages socialistic values in Buck. He cooperates with the other dogs, becoming productive and working for the good of the group. Without Thornton’s guidance Buck once again is left with his instinct for survival. Under corrupt power the Darwinian and Nietzschean principles of “survival of the fittest” and “might makes right” apply. Under such conditions, the primitive brute, the evolutionary residue of millions of generations, takes control out of necessity. With a less oppressive system, cooperation can flourish; the civilized half is nurtured and is able to contain the brute. Whether read as a demonstration of Darwinian ideas, an homage to Marxist socialism, or an engaging adventure, The Call of the Wild is considered by many critics to be the best of London’s dog tales. The story of Buck is the most popular of London’s many books.