Kangaroos jump, ostriches stride, and apes support themselves on their hands. But a Homo sapien is the only mammal that can walk elegantly on two feet the whole time. This function goes hand-in-hand with the development of a larger brain.
AT THE REAR
Nothing would work were it not for our behinds. The three muscles in this group - gluteus maximus, medius and minimus - are an evolutionary stroke of genius. They stabilise the centre of the body and allow us to stand up straight - and to run and run.
ON THE INSIDE
A kilo of TNT
During a marathon, a runner produces and uses 75kg of adenosine triphosphate, a kind of internal biodiesel. The energy expended is the equivalent to that contained in a kilo of TNT.
Humans get natural benefits from running. If the body has to produce a peak performance beyond the pain barrier, it releases endogenous opioids, which are addictive.
ON THE OUTSIDE
Any number of animals would beat us in a sprint. But in terms of stamina, we’re out there on our own. We have no fur, but three million sweat glands keep us cool over long distances. And which body part has the most sweat glands? The soles of the feet.