what effect does the breaking have on Buck's latent insticts

The dog-breaking, especially by the man with the red sweater, brings out Bucks primal insincts of fear and rage. His senses are sharpened and feels as a sense of wildness.

I think what is brought out was that he was no longer in authority of Humans, like at Judge Miller's Place(Beginning of the book.) He now realizes that he is a Down under dog, where he has to follow the simple rule that Humans rule over dogs.