London appears to have been heavily influenced by Darwin’s theories. For example, Buck would lie down by the fire and have dreams about an ancient “half-man." Consider this quote: “…Buck spent long hours musing by the fire. The vision of the short-legged hairy man came to him more frequently now that there was little work to be done; and often, blinking by the fire, Buck wandered with him in that other world which he remembered." (London, 1996, p. 104)
Not only does this seem strange to me, but since I do not believe the theory of evolution (for numerous reasons better discussed elsewhere), I disagree with this too. Also, Buck would “remember" things that his wild ancestors knew, and was able to adjust to his new life better because of that.
It seems unrealistic that a dog, which was domesticated for all his previous life (and so were his recent ancestors), should be able to just “know" how to survive in the wild. “It was no task for him [Buck] to learn to fight with cut and slash and the quick wolf snap. In this manner had fought forgotten ancestors. They quickened the old life within him, and the old tricks which they had stamped into the heredity of the breed were his tricks." (London, 1996, p. 38)
The author wrote a strong “survival of the fittest" theme into the book. Morals are all but forgotten, it is fine for Buck to steal, and you have to be violent to become the leader. In addition, all other characters are easily forgotten or killed. After Buck killed his rival, Spitz, he “stood and looked on, the successful champion, the dominant primordial beast who had made his kill and found it good." (London, 1996, p. 56)