This is a good point, and recent history counts for social trends a lot more than ancient history does, but way, way too many people seem to believe that cave people lived like the Flintstones - with modern social configurations and just a few less technological advances. This is not remotely true, and it's good for us to have a reality check around that because I encounter this belief All.Of.The.Time - primarily from men who want to someone justify dominance hierarchy dynamics as inevitable because they are timeless (which they aren't).

And that being said, I'm reading a book on social dominance theory which is quite academic but also fascinating. The general consensus is, that whenever there is economic surplus, there is some sort of hierarchy. It's a lot more nuanced than that, but that is the base supposition. It does appear to be human nature on some level whenever there is economic surplus - in other words, not hunter/gatherers. More on that later as I get far enough along to write something about it.