I think this discussion would benefit from disentangling "hierarchy" from "power." I think it's possible to have a hierarchy without power. In fact, one sees it all the time. For example, people are very attentive to hierarchies based on skills. My daughter attends a ballet class with is based on the osmosis theory of learning. Dancers of all ages (4-60) and levels mix together in one class. They practice together and mostly learn through imitation. The teacher calls out the moves but does not appoint role models; the students choose who they want to imitate. It seems to work amazingly well and to promote a very focused but relaxed attitude in class.There also used to exist an age-based hierarchy in more traditional societies which probably did reflect the value of experience gathered by the older members.
What I'm trying to say is that man might be innately attentive to hierarchy without inferring from this that there must always be masters and slaves.
Joanna