Early Hominid Simulation

One of the best uses of simulation is to reconstruct the movements of fossil animals. A natural extension from our work on human gaits was to look at the gaits of our ancestors. This requires us to match the physical paramaters of the model as closely as possible to the fossil record and then to generate plasuible gaits. By plausible we mean stable and efficient. After all a gait is no use if you fall over, and theories of early human evolution suggest than the efficiency of bipedal locomotion was a key selective advantage. A model was constructed based on the famous 'Lucy' fossil AL-288-1 since this is the only reasonably complete skeleton that we have of an australopithecine. An area of dispute is whether this animal used a fully upright gait like modern humans or the more crouched gait used by chimpanzees when they walk bipedally (so called 'Groucho Walking' or 'Bent-Hip, Bent-Knee Walking'). For this reason we modelled both sorts of gait and compared their performance in terms of speed and economy. We concluded (unsuprisingly) that fully upright walking was much more efficient. The full results were published in the Journal of Anatomy (Sellers et al 2004) and you can see the sample movies here.

References

• Wang W, Crompton RH, Carey TS, Günther MM, Yu L, Savage R, Sellers WI. Comparison of inverse-dynamics musculo-skeletal models of AL 288-1 Australopithecus afarensis and KNM-WT 15000 Homo ergaster to modern humans, with implications for the evolution of bipedalism. Journal of Human Evolution. 2004 47:453-478.
• Sellers WI, Dennis LA, Wang W, Crompton RH. Evaluating alternative gait strategies using evolutionary robotics. Journal of Anatomy. 2004 204: 343-351.