My FB is showing all sorts of interesting articles today. This one is too long to cut and paste: Why Won't Dominance Die? | Association of Pet Behaviour Counsellors
Most of you will already know most of what is said, but there are some interesting points in there. Like the mention of the original domesticated dog being a scavenger of human waste and that that only changed when humans started breeding them for specific purposes, which resulted in behaviours which might make them more difficult to train as companion animals.