What does the phrase “The dominant primordial beast was strong in Buck” mean?

Question

Buck was eager to fight his rival.
Buck followed his deepest instincts.
Buck gained physical strength.

Answer 1

The phrase "The dominant primordial beast was strong in Buck" means that Buck's natural, animalistic instincts and characteristics were prevailing and powerful. This implies that Buck's primal nature and survival instincts were significant influences on his behavior and actions.