The main problem with applying the concepts of Naturalism to the reading of London's short story "The Law of Life" is that the mere player in the world controlled by natural forces is a man who, to some extent, is able to exert his own will against his inexorable fate.
While there is certainly the Naturalistic superiority of nature over the individual in London's narrative, there is also throughout this narrative the emphasis upon the memory of old Koskoosh. And, it is his recurring memory of the old moose that serves as a reminder of the cognitive superiority of man, and his ability to act outside the realm of instinct. In recalling the attack of the wolves upon the moose, Koskoosh goes over in his mind what will happen to him when the fire is gone and it no longer prevents the wolves from closing in on him. The old chief, whose "glimmering intelligence which yet abode behind the withered forehead" also can decide what he will do when the wolves finally come for him.
After his son departs and Koskoosh abandons his hope that his son will return, he hears a howl break "the void" and he realizes that the wolves are near. He envisions the old bull moose and the actions of death:
He saw the flashing form of gray, the gleaming eyes, the lolling tongues, the slavered fangs. And he saw the inexorable circle close in till it became of dark point....
Unlike the moose whose instinct makes it fight when such effort is futile, Koskoosh comprehends the futility of resisting "the law of life." Thus, he exerts his human free will and chooses not to resist once the wolves close in. "Why should he cling to life?" Because he knows the effort is futile, he exerts his ability to decide at what point he will die. Therefore, the conclusion must be made that although he is a subject of the naturalistic world, man is the sole creature who is able to exert some will against the inexorable forces of an indifferent universe and make choices, albeit limited. Certainly, he is the only creature who is cognizant of his fate even if he is helpless against it and London draws the reader's awareness to this paradoxical condition in "the law of life" in his short story.