“This first 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 lack of which would have
  meant swift and terrible death.” (Wang, 2011: 24)
It was the harsh and hazardous environment in the distant primitive north that witnessed the continuing improvement in the ability of self-reliance of Buck and the great changes in Buck, and trained Buck, with the heredity in his blood, to step forward towards the wild world.

3.2.2 The Fierce Competition from Counterparts
In the rule environment, every minute was filled harshness and shock. Here was neither peace, nor rest, nor a moment’s safety. All this made the dogs here be constantly alert and know no law but the law of club and fang. Buck had never seen so fierce fight among these wolfish creatures before. Curly was the victim of that bloody fight by the huskies, lying there limp and lifeless in the bloody, trampled snow, almost torn to pieces. From this fighting, Buck learned that there was no fair game. Once down, it was your end (London, 2011:17).

Among the dog group, there was a strong fellow called Spitz, the leader of the group, who always bullied the poor like Billee, but gave up the effort to provoke the one holding not to have any compromise like Joe and the thin husky with scars on face. As for counterpart like Spitz, Buck learned that he had to behave serious, be strong enough, never compromise and promote himself, or he would wait to be bullied or humiliated. As the primordial beast was stronger and stronger in Buck, he began to provoke Spitz and had an open fighting with him.

Another several fighting stimulated the potential of Buck, that is the mad chasing of Dolly; the fierce tearing with other dog races stirred up the primitive wilderness and ferocity; the chasing game brought a sense of satisfaction and pleasure and delight as well as the desire for blood and stimulus:
  “The blood lust, the joy to kill—all this was Buck’s, only it was infinitely more intimate. He was
  Ranging at the head of the pack, running the wild thing down, the living meat, to kill with his
  own teeth and wash his muzzle to the eyes in warm blood.” (Wang, 2011: 35)
The long competition with dogs and the nature left scars on the face and body of Buck, but he was still swift and merciless, because he was aware of the lesson in the wild that there exist no yield or mercies in any ruthless competition, or you would be vanish from it, and any mercy was witnessed as fear and coward. Slay or be slayed, eat or be eaten. That is a rule unchanged.   

3.2.3 The Mercilessness of Ever-changing masters
When the dog Buck was sold by the traitor gardener to the rule stranger, his comfort experience in the garden of Judge Miller’s was over and his fate had been totally changed in the following control of his new masters in the freezing Klondike and other icy places in the north. Since then, Buck begun learned a lot of lessons in the merciless treat and training of his masters or drivers until he encountered Thornton, his last dear master.

At first, Buck was controlled by a rope wrapped around his neck, but he was tamed to be obedient to that by his usual trust in human beings in the sun-kissed south. He did not realize the huge change in his position at the present, but to his surprise, the rope tightened intensely to shutting off his breath. In quick rage, he sprang to the man, but only found to be twisted and threw onto the cold ground. Then the rope tightened mercilessly, while Buck struggled in a fury with eyes glazed, tongue lolling out of his mouth, but nothing changed. When he was put on a dirty and noisy train, he was in raged in the small cabin, and then was mocked by the dealers. For two days and nights, he neither ate nor drank during the long torment, but was mad to bark furiously with mountains of flames of fury. When he was free from the cabin by a stout man in red sweater, with a hatchet and a club in hand, Buck, a red-eyed devil, swoop straightly on the man with the pent passion and fury accumulated, but what he received was not the revenge he wanted but a shock on his head to bring him severe pain with screech. The more he revolt, the more serious shock he received, and finally he was trained to curl up without conscious. This was the first lesson he learned with sweat and blood that whoever is strong enough is the king, the controller. The ferocious and gloomy side of life was unveiled, and Buck had to face and handle all of those with all of his intelligence and trick buried in his heredity. 自然主义在《野性的呼唤》中的体现(6):http://www.751com.cn/yingyu/lunwen_132.html