What evidence showed that Jack London wanted his readers to admire Buck despite his savage life?

Buck becomes a super dog of the wild. Despite being loyal to Thornton, Buck feels the "call of the wild". He befriends a wild wolf, kills a bear and kicks butt out of a whole tribe of angry natives who are beating up on his master. Still, we can see Buck distancing himself from man to become Alpha-Dog of the forest! That’s pretty cool!