I would disagree. The overwhelming majority of the average human's life is spent peacefully. It is actually fairly remarkable how rarely we have significant conflict, especially considering the relatively overcrowded places that humans live. Not to mention that it is only a small proportion of the human population that engages other humans destructively (not by proxy).
The overwhelming majority of the average human's life is also spent in conditions where they are on relatively even grounds with everyone else. But once you start looking at what happens when people end up in situations where they are clearly more powerful than others? And can treat those others the way they like and without fear of retribution? Ugly.
I declare this Open Thread open for discussion of Less Wrong topics that have not appeared in recent posts.