Natural Science Forum / Biology / Paleontology / December 2004

Study: Learning to run no small step in human evolution
By Travis Reed, Associated Press Writer  |  November 17, 2004

SALT LAKE CITY --No one has ever doubted that, in the beginning,
primitive man learned to walk before he could run.

But how about it taking three million years for that second part --
after the whole walking thing was already down? Or, when it finally
happened, the idea that simply being able to run radically propelled
our evolution as a species?

That's the conclusion from new research authored by University of Utah
biology professor Dennis Bramble and Harvard anthropologist Daniel
Lieberman and published in Thursday's edition of the journal Nature.

Their work suggests that primitive man's evolution from walking to
running was an instrumental step in human evolution -- forsaking the
capacity to live in trees, but vastly improving the species' ability
to find food. They also hypothesize that running preceded brain
enlargement -- and may have precipitated brain development by allowing
primitive man to locate and consume more protein.

"The structure of specializations required for hunting are sort of
counter to those that are useful for climbing," Bramble said. "We sort
of favor the notion that humans may have evolved running initially to
increase their intake. But not through hunting -- probably through
scavenging."

Several anatomical changes enabled early man to run, according to the
study, including a narrowed waist, shorter forearms, larger buttocks
and skull modifications allowing the body to cool itself.

Previously, researchers hadn't much focused on running, instead
considering it simply a byproduct of walking. But Bramble points to
specific adaptations not used in walking -- like the Achilles
tendon -- as evidence that man wasn't capable of running until
evolution accommodated it.

"It turns out that that's a terrific spring, and it makes a huge
difference in the economy of running, but it makes no difference in
walking," he said of the Achilles.

Bramble said scientists might have overlooked the importance of
running because humans aren't considered particularly fast --
especially in comparison with four-legged animals.

However, Bramble says endurance, more than speed, was the key for
early man -- enabled by adaptations allowing the body to cool itself
and function over long distances.

Furthermore, Bramble suggests that early runners could even have been
faster than our contemporaries, perhaps in part because projectile
hunting weapons made running less necessary as humans evolved.

"Some of our ancestors very likely could have been better runners than
some of the best runners today," he said.

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