I read in one of B1's science magazines about running, how humans appear to be evolutionarily-disposed to run (including the presence of the Achilles' Tendon, which is integral to the process), and glutes -- having buns helps one run! Something about how it counterbalances the forward momentum of the chest when propelling oneself forward -- that if we didn't have buns, we'd lose that vital ability to propel ourselves while remaining upright. There's a clear biomechanical edge glutes provide with running, and it's not simply about energy storage.
What I found most interesting was discussion about sweating and the nature of human running, which favored distance-running, and how it appears to have been used by early humans to run down prey animals. Herd animals like antelopes and what-not rely on sprinting to escape danger, and are capable of great bursts of speed, but, like most (all?) animals, they rely on their mouths to cool off, basically panting themselves cool. So, what that means is that, in the (literal) short run, they can escape people, but what people (particularly early human hunters) could do is simply jog after the animals, maintaining enough of a distance from the animals to force them to sprint/rest, sprint/rest, sprint/rest until they ran themselves out. All animals, no matter how fast, simply overheat after having run (or being made to run) a certain distance, and they will just collapse, exhausted. Something like when their body temperature reaches 105 degrees F.
So, early humans would basically jog animals to death, and, surprisingly, it didn't take that great a distance -- usually around six (6) miles of running would do it, if you were able to keep after the animals. That's apparently how early humans would do it, and why we evolved the muscle/tendon and pulmonary combination we have that lets us run distances. If you were able to run, you could (eventually) eat. Six miles isn't even that much running, in the larger scheme of things. Of course, early humans had to be even more hardcore, when you figure they were running barefoot across the African plains for prey! Ouch!
