The article Expectations, Legitimation, and Dominance Behavior in Task Groups, Cecilia Ridgeway and Joseph Berger discuss how a group structure forms from expectation, is solidified through legitimation and is practiced with dominance behavior.
Expectations are what the group thinks will happen with the group structure based on the characteristics of the group and of the individuals. For example, individuals that are more highly skilled will be expected to outperform those that are less skilled at the task. Senior members of a group will be expected to do better as well. As these expectations are formed the a power and prestige bases is built around those who most meet or exceed expectations.
Legitimation is the process by which these power and prestige orders gain differences in status value. This becomes part of the group when individuals who have gained power and prestige begin to believe that what they do is of greater importance to the group and believe that they have group backing.
After a power structure is legitimated, those who are at the top will being to show dominating behavior. This includes commands, staring others down, and shouting. The opposite of this occurs at the bottom of the ranks and is referred to as propitiating behavior. This involves hand wringing, slumped posture and downcast eyes.