I am particularly intrigued by the bonobo society. Although they appear matriarchial, I do not see any strong evidence of hierarhial structure. There is some evidence of a lead female, but I am not so sure this is as much a leadership structure as a preference organization based on respect.
The bonobo organization seems to be driven primarily by sex, with the males and females primarily favoring female contact. I see the net result of this organization is to center the females within the group and place the males on the outside. This makes sense if the bonobos are at high risk from predators, although I am not sure this is the case. I may not have considered other possible advantages to female centering. From an investment point of view in regards to population growth rate, females are definitely the most valuable.
