What does "the survival of the fittest" mean in the context of the story?

In the context of "The Call of the Wild," "the survival of the fittest" refers to the concept that in the harsh and unforgiving wilderness, only the strongest and most adaptable individuals can endure and thrive. The story illustrates this theme through the character of Buck, who transforms from a domesticated pet into a strong creature capable of surviving in a brutal environment. As Buck encounters challenges, he learns to harness his instincts and physical abilities to secure his place within the pack and the wilderness.

This idea emphasizes that strength, resilience, and adaptability are critical for survival. Throughout the narrative, Buck faces competition from other dogs and the relentless demands of nature, highlighting that only those who can assert themselves and meet these challenges head-on will prevail. As he adapts to his surroundings and asserts dominance where necessary, it becomes clear that survival is not guaranteed to everyone equally; it is determined by the ability to overcome adversity through strength and cunning.