The White Fang by Jack London

This is a thematic question. One of the major themes is survival of the fittest. Jack London write many books with Darwin's popular ideas in mind, particularly White Fang and The Call of the Wild. The process of "natural selection" means that only the strongest, brightest, and most adaptable elements of a species will survive. This idea is embodied by the character, White Fang. From the onset, he is the strongest wolf-cub, the only one of the litter to survive the famine. His strength and intelligence make him the most feared dog in the Indian camp. While defending Judge Scott, White Fang takes three bullets but is miraculously able to survive.