Washington, November 24 : University of Liverpool researchers reckon that the modern human foot might have first appeared about 1.8 million years ago, but their ape-like ancestors probably took to walking several million years earlier.
Researcher Evie Vereecke believes the feet of the ancestors at the time would have been more "floppy" and ape like than humans'.
She joined forces with University of Antwerp researcher Peter Aerts to look at the flexible feet of modern gibbons to find out more about how they walk.
Since it is very difficult to work with gibbons in the lab, the researchers sought access to a troop of the semi-wild apes just down the road at Belgium's Wild Animal Park of Planckendael.
The team set up a camera outside the animals' enclosure at foot height, and sat and wait for the animals to walk past so that the camera would capture a few footfalls.
After several weeks, the researchers digitalised film footage of the animals' foot movements, and built a computer model to find out how they walked.
Vereecke revealed that the animals did not hit the ground with their hells at the start of a stride, and would move more like ballerinas, landing on their toes before the heel touched the ground.
She realised that by landing on the toes first, the gibbons were stretching the toes' tendons and storing energy in them.
According to her, it was quite different from the way that energy is stored in the human foot.
She even said that there were several differences between the gibbon and human walking patterns at the end of a stride.
Rather than picking up the foot as one long lever, the gibbon would lift its heel first, effectively bending the foot in two to form an upward-turned arch, stretching the toes' tendons even further and storing more elastic energy ready for release as the foot eventually pushed off.
Based on her analysis of the video, Vereecke came to the conclusion that gibbons were not a perfect model for the ways that early humans might have walked, for there were marked differences between modern gibbons and the fossilised remains of early humans.
However, given that modern gibbons live in trees and walk on two flexible feet, Vereecke feels that it may be possible to walk quite efficiently with a relatively bendy foot, and that our ancestors may have used energy storage mechanisms that are similar to ours, despite their dramatically different foot shapes.