Honestly I think it's a mix of both. The strongest male would probably become Chief or perhaps is born into it (unless usurped). While the Chief leads the tribe in protecting, hunting & staving off bordem, the Chieftess would be left to do all the "boring" things that keep the camp functioning. The males are only leaders because as they get dumber they are more driven by their emotions/desires & wont let girls be in charge, but the females just keep things working behind the scenes. Like a faux patriarchy, which is secretly a matriarchy. How better to keep the males content then to male them beleive they are in charge?