What message does The Call of The Wild reveal about the past?

The Call of the Wild is a story of transformation in which the old Buck has to adjust to harsher realities of life where survival is only imperative.

Explanation:

So all and all he has to get better with his surroundings and make the transformation with his survival skills in order to survive.

Side bar: The moral of it is to follow your instincts. And although Buck is loyal to his owner he follows his gut instead.

evertheless he ought to be slow to believe and to act, nor should he himself show fear, but proceed in a temperate manner with prudence and humanity, so that too much confidence may not make him incautious and too much distrust render him intolerable.

explanation:

it can make them lose love for themselves