Anthropology

was (probably) the age old norm. (as evidenced by some of our closest relatives) And the 'peaceful hunter gatherer' was probably always a bit of romanticism. Wholesale extirpation (in today's terms genocide) rather than 'pressuring' a rival group to abandon or 'move along' - is probably an inflection point that signals a real shift in thinking and tactics - (and may have continued to be largely the exception rather than the norm, through most of our history). But - the violent impulse and seed was probably already there and just waiting for the right type of trigger. Social cohesion and structure brings about both positives and negatives.