Thanks. And that's a good point, although there was likely a division of labour in the Stone Age between men and women, and the nomadic hunter-gatherers were likely egalitarian not by nature but by practical necessity, because they had to work together to survive and to take care of the helpless babies. If we were naturally cooperative, how could civilization have changed us so radically?

I suspect we have competing drives for hierarchies (our inheritance from primates) and for cooperation. Our brain is at war with itself.