Whether pre-agricultural societies were generally peaceful is a matter of some debate. If they were, it is probably because disease, accident and predators kept

Whether pre-agricultural societies were generally peaceful is a matter of some debate. If they were, it is probably because disease, accident and predators kept the population in balance with resources. See, for example, "Resource scarcity drives lethal aggression among prehistoric hunter-gatherers in central California" at https://www.pnas.org/content/113/43/12120 https://www.pnas.org/content/113/43/12120 >Results reveal that sharp force trauma, the most common form of violence in the record, is better predicted by resource scarcity than relative sociopolitical complexity. Blunt force cranial trauma shows no correlation with mean net primary productivity or political complexity and may reflect a different form of close contact violence. This study provides no support for the position that violence originated with the development of more complex hunter-gatherer adaptations in the fairly recent past. Instead, findings show that individuals are prone to violence in times and places of resource scarcity.