Which instinct does Buck notably embrace as the story progresses?

As the story progresses, Buck notably embraces the instinct for hunting and survival. This transformation is central to his character development as he adapts to the harsh realities of life in the wilderness. Initially a domesticated dog, Buck is thrust into an environment where he must rely on his primal instincts to endure the challenges posed by nature and other animals. Embracing his hunting instincts allows him to become a fierce competitor and a formidable presence in the wild, which is highlighted by his growing ability to track and hunt for food, as well as defend himself and assert dominance within a pack.

The other instincts, such as gathering resources, building shelter, and socializing with humans, do exist in the story, but they are not as prominently featured in Buck's journey. His ability to hunt and embrace survival instincts is what ultimately leads him to reconnect with his ancestral legacy and thrive in his new surroundings, illustrating a powerful theme of adaptation and the return to a more primal state of existence. This focus on survival showcases the stark contrast between his former life and his new reality, emphasizing the raw and often brutal nature of the environment he inhabits.