Wolf packs are loosely hierarchical. A large, well-established pack may consist of a small "upper class" that includes only a single breeding pair (the so called alpha male and female), a "middle class" of nonbreeding adults, perhaps an "underclass" of outcasts, and an up and coming group of pups and immature animals who are less than two years of age. The leaders of the pack, usually the parents of the younger animals, wear their status with confidence. In social encounters, they stand tall, hold their ears and tails erect, and look other animals directly in the eyes. Simply by doing this, they are declaring and reinforcing their superior rank. A subordinate animal, on the other hand, slips towards the leader on bent legs, tail low and ears slicked back. Like a pup begging for food, it bunts its nose against the superior's face in greeting, as if to say, "I'm little and you're big; I like you. so please be nice to me." This gesture had been dubbed "active submission." If the subordinate animal feels a to make its point more emphatically--"I accept that you are the leader and that I am a social underling; I'm no threat to you"--it may sprawl on its back with its feet in the air, exactly like a dog that wants its belly scratched. This behaviour, known as "passive submission," may also carry a reference to infancy, because it is very like the position of a tiny pup that is being massaged by an adult to make its bowels work. You can look for these dominance/submission routines in the wolf cage at the zoo, or see how the wolves react if you use your hands to mimic ears up and ears back postures. (Ironically, most of our intimate knowledge of these spirits of the wilderness has been gained by observing animals in captivity.)
With a bit of luck, you may also have a chance to watch a wolf greeting ceremony, one of those noisy, wagful, face-licking get-togethers in which the animals rediscover one another after waking from a snooze or reunite after a brief separation. In the wild, these celebrations of family solidarity also often occur when the animals first scent prey before a hunt or after a kill. Frequently, the focus of the festivities is the alpha male-often the most popular animal in the pack-who suddenly finds himself closely surrounded by half a dozen eager, howling relatives, all doing their best to plaster up deside him and stick their muzzles in his face. Through this affectionate ritual, the animals define their group ("this is us; all other wolves are outsiders") and reaffirm their attachment to their father and to one another.
As a rule, a dominant male wolf is not particularly aggressive, at least towards other members of his group. In fact, the opposite is likely to be true: most top-ranking male wolves are exceptionally tolerant. Wolves in a pack are constantly checking one another, with a sniff to the coat here, a lick on the cheek there; and no animal is more active in receiving this kind of rountine social contact than the dominant male. He provides an emotional centre for the community and a focus for friendly feeling in the pack. One of the family. If he loses his position to a younger male in a coup (as happens from time to time), he will probably also lose his ability to serve the pack in this way.