In chapter 7 of the novel The Call of The Wild, we are introduced to a ''hairy man'' whom Buck sees crouching next to a fire.

''When he watched the hairy man sleeping by the fire, head between his knees and hands clasped above, Buck saw that he slept restlessly, with many starts and awakenings at which times he would peer fearfully into the darkness and fling more wood upon the fire. Did they walk by the beach of a sea, where the hairy man gathered shellfish and ate them as he gathered, it was with eyes that roved everywhere for hidden danger and with legs prepared to run like the wind at its first appearance'' (Stasz).

The man is actually merely a vision Buck is having.  To Buck, the man symbolizes one who is more primitive in nature, and symbolizes how he must exist in his new world if he is to thrive.  He sees the man gather his own food in order to stay nourished, sees him use fire to stay warm, and sees him constantly on guard for any danger, ready to take action to survive.  Throughout the novel, as Buck slowly adjusts to life in the wild, he, like the man he is visualizing, becomes more primal, as he must now survive in adverse conditions.  He gradually becomes more in tune with nature, and more aware of how he must live, and how he must react to his surroundings in order to stay alive.

According to enotes.com, ''Under the harsh conditions of trail life, he [Buck] develops certain primal traits: he becomes more cunning, deliberate, and calculating. He learns how to kill mercilessly and to show no sign of weakness.''  The man Buck sees by the campfire is nothing more than a figment of his imagination, a vision of the primitive being he must become in order to be successful in his wild new world.