"There is an interesting phenomenon that occurs when two vertebrae class animals meet in the wild - a pecking order is immediately established.
Abraham H. Maslow, who is responsible for the now famous hierarchy of human needs, did extensive research into this phenomenon in the animal kingdom because he knew that observations of animal behavior are usually directly applicable to human behavior as well.
He conducted many very interesting studies. Most pertinent to our discussion, he found that when a pair of monkeys are introduced to each other for the first time they will, WITHOUT EXCEPTION, form a dominance-subordination hierarchy. One will assume the lesser, submissive role while the other will assume the superior status of the dominate overlord."
a sample from "MONKEYS, DOMINATION, MASLOW, AND ATTRACTION", and article by David Kwan - March 21, 2003 - http://www.DatingClass.com