Two million years ago, our human ancestors were small-brained apemen and in the past many scientists have assumed the meat they ate had been gathered from animals that had died from natural causes or had been left behind by lions, leopards and other carnivores.
But I think that our ape-men ancestors, although primitive and fairly puny, were capable of ambushing herds of large animals after carefully selecting individuals for slaughter. The appearance of this skill so early in our evolutionary past has key implications for the development of human intellect.