What I mean by the former is that the status hierarchy for females is more diffuse and has fewer strata; there are coalitions of females, and typically eldest females occupy a de facto "alpha" position.

As to paternity certainty -- yeah, bonobos don't form any sort of exclusive or permanent sexual connection. Male/male, male/female, female/female and group sex are all standard behaviors (they're also the only nonhuman primate species seen engaged in mouth/tongue kissing and oral sex). Instead of "securing access" to desirable mates, you pretty much don't know who's going to be the parent of your future children, and it doesn't matter; both males and females will socialize, care for and protect children.