what is the significance of the title of the chapter

Chapter 1 is titled "Into the Primitive". Although Buck lives a pampered life at the judges sprawling ranch in California, there is something missing. Buck's primal instincts lay dormant, repressed. So, when he is "dognapped" and sent North, Buck's primal adventure begins,

"Old longings nomadic leap,

Chafing at custom's chain;

Again from its brumal sleep

Wakens the ferine strain."

(Call of the Wild)