Most of our dog breeds have some form of
aggression in them, since they needed different forms of
aggression to do their work: terriers are often aggressive
towards other dogs and
animals — they were and are fighters, the man working dogs imprint humans as being of their same species so they
show the same kind of
aggression that they
show towards other dogs, the sight hounds were bred to be killers of game and sometimes
other canines, the mastiffs were bred to take down large game and guard property, the flock guards were bred to be aggressive
towards canines, the hounds were bred to be aggressive
towards furred
animals, some of the pointers were bred to be able to guard the hunter's game, etc., etc..