This tangential reference to Thomas Hobbes' Leviathan or The Matter, Forme and Power of a Commonwealth Ecclesiasticall and Civil is quite delicious here.

While this is one of the most oft-quoted portions of Hobbes's Leviathan (1651), compare the idea to the decrease of violence in human history theorized by Steven Pinker in The Better Angels of Our Nature: Why Violence Has Declined.

Was there always excessive violence that has been increasing? What happened for that first 150,000 years of human evolution before the modern era (or since the introduction of agriculture)? Was there an uptick in violence due to larger populations impinging on each other at this point and it's been decreasing since?