Speed/traction have little to do with energy efficiency. The cooling adaptions we have allows to outperform most animals in long distance _running_ which is how

Speed/traction have little to do with energy efficiency. The cooling adaptions we have allows to outperform most animals in long distance _running_ which is how the whole concept of 'persistence hunting' is based on. What I was pointing to is energy-efficiency in _walking_ long distances (we migrated long distances by walking not running). The bi-pedal flat foot heel-strike and roll gait that we have is the most energy efficient gait, the dogs in your example can keep up with us but still spend more energy per mile per kilo walking on four legs. The downside is that it is actually pretty hard to keep your center of mass on top of such a small Base of Support between your feet.