I dont think that the validity of such a graph is very far at all from how people were back then based on the evidence Ive seen during my own reaserch.

The theory is looking at human group behavioral trends in general over a long period of time, as opposed to giving focus on individual actions.

In other words the focus is on the entire forrest, not a few tress here and there.

Taking things out of that context to focus on specific areas becuase one loves the new age ideal of peacful primitive societiy being preferable to modern scoiety as somthing to be sought after (which history shows us to be way off the mark) will of course make one think that the pattern isnt there, even if its a spurious coorelation.

Its like the difference between making an argument based on looking at the behavior of an individual cell in the body thats been attacked by a virus instead of looking at the overall responce of the entire immune system over the life span of an organism's homeostatic proccess.