Science Daily: Ancient Footprints Show Human-Like Walking Began Nearly 4 Million Years Ago.
ScienceDaily (July 19, 2011) — Scientists at the University of Liverpool have found that ancient footprints in Laetoli, Tanzania, show that human-like features of the feet and gait existed almost two million years earlier than previously thought.
Many earlier studies have suggested that the characteristics of the human foot, such as the ability to push off the ground with the big toe, and a fully upright bipedal gait, emerged in early Homo, approximately 1.9 million years-ago.
Liverpool researchers, however, in collaboration with scientists at the University of Manchester and Bournemouth University, have now shown that footprints of a human ancestor dating back 3.7 million years ago, show features of the foot with more similarities to the gait of modern humans than with the type of bipedal walking used by chimpanzees, orangutans and gorillas.
The footprint site of Laetoli contains the earliest known trail made by human ancestors and includes 11 individual prints in good condition. Previous studies have been primarily based on single prints and have therefore been liable to misinterpreting artificial features, such as erosion and other environmental factors, as reflecting genuine features of the footprint. This has resulted in many years of debate over the exact characteristics of gait in early human ancestors.