How do you see anarchy in the past (like, say, in ancient Rome)?

... Not to be contentious, but ancient Rome was not anarchy in any meaningful sense.

Okay, I might have worded that bad. What I meant was how do you see historical societies that were hierarchical, like ancient Rome, going anarchical instead?

IMO, we were not psychologically prepared as a species to master agriculture so quickly.

So the problem is dismatch between psychological and material development?