what is the tone of the first chapter in the call of the wild?

The first chapter of The Call of the Wild, "Into the Primitive," sets the tone for the rest of the book. The central tension London explores is that between the supposedly primitive and civilized worlds. As the story opens, Buck lives a happy life in a nice, civilized part of the United States. Life on a Californian ranch is quite agreeable for a dog like Buck. He is thoroughly domesticated and good with the kids; he really could not be further removed from his wolf ancestors.
Then it all goes terribly wrong. Poor Buck gets kidnapped by a devious Spanish gardener and ends up being loaded onto a ship headed north. Buck has been roped in (quite literally) to drag greedy prospectors across the snow-covered wastes of the Klondike in search of gold.
The first chapter sees the stirrings of a wolf-consciousness in Buck. Up until now, he has gotten along just fine with humans. They have fed him, played with him, given him a nice warm place to sleep, and given him the run of the ranch and its extensive grounds. But for the first time he is now starting to see the ugly side of man, the cruel, vicious, exploitative side that always seems to come to the fore when there is a stench of filthy lucre in the air. Maybe civilization is not all it is cracked up to be. Maybe the so-called primitive world is more conducive to leading a dog's life in a good way.