One of the theories about why humans are such good runners is that they are built to run run long distance so that they can run down game. Other animals can go much faster in short bursts, but inevitably their muscles will overheat and fatigue, while human muscle sheds heat well and can keep going for miles. Early hominids, the theory goes, would simply have to keep chasing the gazelle and eventually they would catch it.
I have to admit I doubted this could be really true. But Outside magazine did an actual test with marathon runners chasing an antelope in the desert. Even the runners were surprised that after 20 miles they actually were able to get close enough to catch the antelope (although they didn’t).
I still think that one of the prime ways that running helped early hominids is in running to scavenge kills that other animals had made. They needed to be safely inside their Acacia fenced Kraals at night, so the growth of the tribe was limited by how far they could go in one day. I imagine that if they saw buzzards circling in the distance and could run there to chase away other animals before these other scavengers consumed the carcass, they could bring back a fair amount of food.