Young dogs jump up on each other or their parents in mock battles that imitate future hunts. In a controlled fashion, they snap and bite at each other just as they will at a prey animal. To preserve some sort of order in the associations, a social hierarchy is established. To prevent constant and potentially harmful battles for who gets what or who is allowed to breed, the individual dogs learn their relative position in the pack. Rather than have vicious battles on a daily basis, these positions are maintained through behavioral interactions.
Dogs soon learn what submissive and dominant actions are and how to play the game.
Specific postures and facial expressions are used as signals to maintain this order. Still, because of their instinctive will to survive and do what is best for themselves as an individual, most animals constantly try to improve their rank in the pack and this can lead to brief skirmishes. This is their way of life, the best way for their species to survive. Dogs naturally dig holes for protection. This may be to cool their bodies on hot days or make dens in which to whelp and raise their litters.