The researchers put the increase in violence in the 5th and 4th millennia BCE down to the agglomeration of humans in the first, still poorly organized, cities. The rate of violence only reduced significantly once legal systems, a centrally controlled army, and religious institutions (for example, religious festivals) developed.
this seems to be the origins of the Tower of Babel story to me.. in the Late Bronze Age people still told stories about a time long before (3000 years prior), when people had tried to settle down in those poorly organized, agglomeration cities mentioned in the article.. they still told stories about the chaos of cities without laws/religion and no common language..