Early Hominin Locomotion

One of the earliest, defining features of our own lineage is that we walk upright on our hind legs. Chimpanzees and other apes can do this (you can see plenty of examples in our video archive) but they keep their knees and hips bent - so called “Bent Hip Bent Knee” or “Groucho” walking. One of the challenges has been to work out when in the fossil record this occurred. One important piece of evidence is the 3.5 million year old footprint trails found at Laetoli in Africa. This contains several footprints that were clearly made by a bipedal animal - probably Australopithecus afarensis, a species that may well have been an early human ancestor. By producing computer simulations of this animal we have shown that it is very unsuitable for Groucho walking and that the Laetoli footprints were almost certainly made by a fully upright walking animal.

Final Footprint Composite 660 wide

Simulation of the famous “Lucy” skeleton performing both upright and Groucho walking and showing the foot-pressure distributions. The foot pressure distributions can be used to predict the depths of the footprints which match the upright condition where the heel print is deeper than the toe print.