Comment by Qem

I wonder if the extinction of most megafauna happening just before the advent of agriculture and the first civilizations is not just coincidence but direct causation. We spent ~200kyr with a lot of "easy" calories roaming around. So no need for complex societies. Once we caused our first "end of the world" overhunting with stone age technology, and they were gone, the only remaining alternative for the survivors was meager small game that had to be complemented with backbreaking work in the fields trying to raise more plant food. Thus agriculture got popular. With it the need for record keeping and sedentary lifestyle. Only then civilization could be kickstarted.