Human-like features of the feet and gait existed almost two million years earlier than previously thought of, according to a new study. 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.

3.7 million years ago

University of Liverpool researchers, however, in collaboration with scientists at the University of Manchester and Bournemouth University, studying ancient footprints in Laetoli, Tanzania 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.

The team used a new statistical technique, based on methods employed in functional brain imaging, to obtain a three-dimensional average of the 11 intact prints in the Laetoli trail, according to a University of Liverpool press release. This was then compared to data from studies of footprint formation and under-foot pressures generated from walking in modern humans and other living great apes. Computer simulation was used to predict the footprints that would have been formed by different types of gaits in the likely printmaker, a species called Australopithecus afarensis.

Professor Robin Crompton, from the University of Liverpool's Institute of Ageing and Chronic Disease, said: “It was previously thought that Australopithecus afarensis walked in a crouched posture, and on the side of the foot, pushing off the ground with the middle part of the foot, as today's great apes do.

We found, however, that the Laetoli prints represented a type of bipedal walking that was fully upright and driven by the front of the foot, particularly the big toe, much like humans today, and quite different to bipedal walking of chimpanzees and other apes.”

More In: Sci-Tech