Like many of his works, The Call of the Wild is a prime example of Jack London's descriptive writing style. Many scenes are described simply and objectively, with no preconceived bias. Most critics agree that Call is a major work in the Naturalist style.
Naturalism focuses on science and reality, eschewing the depressive views of Realism in favor of examining the social and biological causes of behavior. In Call, London presents the Yukon during the Gold Rush and the life of Buck, a mixed-breed dog who is sold into service as a sled and work dog. Much of the book is presented from Buck's point of view:
He could not understand what it all meant. What did they want with him, these strange men? Why were they keeping him pent up in this narrow crate?
Although the reader, in seeing events through Buck's perception, is able to hear and understand the larger schemes, Buck is not able to understand; he is, after all, a dog. London does not present Buck as a super-intelligent creature able to comprehend the universe around him, because that would be unrealistic. The Naturalist view shows Buck as a domesticated creature, willing to be led by a master:
...the lesson was driven home to Buck: a man with a club was a lawgiver, a master to be obeyed, though not necessarily conciliated. Of this last Buck was never guilty....
Even in this perception, Buck understands only that the club is a tool of violence, not that he is meant to be "broken" for tamed use. London's refusal to humanize Buck gives his sections a unique flavor, because he cannot understand the Men's motives:
...at such times that money passed between them the strangers took one or more of the dogs away with them. Buck wondered where they went, for they never came back, but the fear of the future was strong upon him....
(All Quotes: London, The Call of the Wild, Google Books)
Events are straightforward, with a minimum of flowery or purpose prose, and even less metaphor; everything that happens on the pages happens in the story. London's style is in the Naturalist vein, with strong Realist tendencies.