That is the conclusion of a study published in the Nov. 18 issue of the journal Nature by University of Utah biologist Dennis Bramble and Harvard University anthropologist Daniel Lieberman. The study is featured on Nature's cover.

Bramble and Lieberman argue that our genus, Homo, evolved from more ape-like human ancestors, Australopithecus, 2 million or more years ago because natural selection favored the survival of australopithecines that could run and, over time, favored the perpetuation of human anatomical features that made long-distance running possible.

"We are very confident that strong selection for running which came at the expense of the historical ability to live in trees was instrumental in the origin of the modern human body form," says Bramble, a professor of biology. "Running has substantially shaped human evolution. Running made us human at least in an anatomical sense. We think running is one of the most transforming events in human history. We are arguing the emergence of humans is tied to the evolution of running."

That conclusion is contrary to the conventional theory that running simply was a byproduct of the human ability to walk. Bipedalism the ability to walk upright on two legs evolved in the ape-like Australopithecus at least 4.5 million years ago while they also retained the ability to travel through the trees. Yet Homo with its "radically transformed body" did not evolve for another 3 million or more years Homo habilis, Homo erectus and, finally, our species, Homo sapiens so the ability to walk cannot explain anatomy of the modern human body, Bramble says.

"There were 2.5 million to 3 million years of bipedal walking [by australopithecines] without eve
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17-Nov-2004