| Quote #10
There were fierce fighters among them, but three battles with the fiercest brought Buck to mastery, so that when he bristled and showed his teeth they got out of his way. (4.22)
Once Buck has established his dominance, he never reverts to his former state.
| Quote #11
Charles and Hal wrangled whenever Mercedes gave them a chance. It was the cherished belief of each that he did more than his share of the work, and neither forbore to speak this belief at every opportunity. (5.43)
As a contrast to the competition among the dogs, the human’s compete in petty and frivolous ways.
| Quote #12
His face and body were scored by the teeth of many dogs, and he fought as fiercely as ever and more shrewdly. Skeet and Nig were too good-natured for quarrelling--besides, they belonged to John Thornton; but the strange dog, no matter what the breed or valor, swiftly acknowledged Buck's supremacy or found himself struggling for life with a terrible antagonist. And Buck was merciless. He had learned well the law of club and fang, and he never forewent an advantage or drew back from a foe he had started on the way to Death. He had lessoned from Spitz, and from the chief fighting dogs of the police and mail, and knew there was no middle course. He must master or be mastered; while to show mercy was a weakness. Mercy did not exist in the primordial life. It was misunderstood for fear, and such misunderstandings made for death. Kill or be killed, eat or be eaten, was the law; and this mandate, down out of the depths of Time, he obeyed. (6.9)
Buck applies the extremes of the wilderness to his own state of leadership and dominance.