Submitted by Pendekar & Waspie: The ancestors of humans began walking upright while they were still living in trees - not out on open land, according to a new theory. The traditional view is of bipedalism evolving gradually from the four-legged "knuckle-walking" displayed by chimpanzees and gorillas today. Now, a study published in the journal Science disputes this idea. The British authors of the study say that upright walking was always a feature of great ape behaviour. Humans inherited it without ever passing through a knuckle-walking phase. They believe that knuckle-walking evolved only recently as a way of getting around the forest floor. Susannah Thorpe, Robin Crompton and Roger Holder came to their conclusions after analysing the movement of wild orangutans, which spend most of their lives in trees. They found that orangutans used upright locomotion to fetch food from the small branches of trees and to cross directly from one tree to another.

"Both access to fruits and crossing gaps in the trees would require an ability to navigate very thin, terminal tree branches which are liable to bend under body mass," said Professor Robin Crompton, from the University of Liverpool. "The logical conclusion from the environmental, fossil, and experimental evidence is that upright, straight-legged walking originally evolved as an adaptation to tree-dwelling."

View: Full Article | Source: BBC News