Running Key to Shapely Human :: Astrobiology Magazine :: Search for Life in the Universe

Running Key to Shapely Human :: Astrobiology Magazine :: Search for Life in the Universe:

"Another of humankind's most distinctive features, the gluteus maximus muscle that comprises the buttocks, also helps establish humans as far more skilled runners than their ancestors: A quick look at fossil australopithecines reveals that their pelvises, like those of chimps, support only a modest gluteus maximus.

'Your gluteus maximus stabilizes your trunk as you lean forward in a run,' Lieberman says. 'A run is like a controlled fall, and the buttocks help to control it.'

Runners also get a lot of help from their Achilles tendons, tough bands of tissue that anchor the calf muscles to the heel bone, and related tendons along the back of the leg and foot. This extensive system of springs in the leg and foot effectively store and release significant elastic energy during running, but they're not needed for walking.

'There were 2.5 million to 3 million years of bipedal walking [by australopithecines] without ever looking like a human, so is walking going to be what suddenly transforms the hominid body?' Bramble asks. 'We're saying, no, walking won't do that, but running will.'"