Final answer:
The excerpt from 'The Call of the Wild' by Jack London conveys a theme that focuses on the powerful force of innate animal nature, which can overcome societal nurturing in the face of harsh conditions, reflecting on the struggle between nature and nurture.
Step-by-step explanation:
The theme that the excerpt from The Call of the Wild by Jack London conveys is most closely aligned with the idea that innate animal nature is powerful and can prevail over societal nurturing when faced with harsh conditions. Buck, the protagonist, is a domesticated dog abruptly thrust into the brute realities of survival in the Canadian wilderness.
His transformation from a pampered pet to a feral creature illustrates a key theme that Jack London explores: the conflict between the forces of nature and nurture. This struggle echoes the philosophical influences on London's work, specifically the ideas of survival and struggle, as influenced by thinkers like Darwin, Marx, and Nietzsche.
Within this narrative, the theme of trusting one's instincts is prominent as Buck learns to revert to his primal instincts to adapt and survive in a brutal environment, this can be seen as an allegory of humanity's capacity to revert to a more animalistic state when faced with the raw forces of nature. This theme is emphasized by the contrasts between Buck and the ineptitude of some human characters when confronting the natural world.