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Natural Science Forum / Biology / Paleontology / October 2005Paper: Stride lengths, speed and energy costs in walking of Australopithecus afarensis - using evolutionary robotics to predict locomotion of early human ancestors
Journal of The Royal Society Interface ISSN: 1742-5689 (Paper) 1742-5662 (Online) Issue: Volume 2, Number 5 / December 22, 2005 Pages: 431 - 441 DOI: 10.1098/rsif.2005.0060 URL: Linking Options Stride lengths, speed and energy costs in walking of Australopithecus afarensis: using evolutionary robotics to predict locomotion of early human ancestors William I. Sellers A1, Gemma M. Cain A1, Weijie Wang A2, Robin H. Crompton A3 A1 Loughborough University Department of Human Sciences Loughborough LE11 3TU, UK A2 University of Dundee Section of Oncology and Surgery, Ninewells Medical School, Institute of Motion Analysis and Research Dundee DD1 9SY, UK A3 University of Liverpool School of Biomedical Sciences, Sherrington Buildings Liverpool L69 3GE, UK Abstract: This paper uses techniques from evolutionary robotics to predict the most energy-efficient upright walking gait for the early human relative Australopithecus afarensis, based on the proportions of the 3.2 million year old AL 288-1 'Lucy' skeleton, and matches predictions against the nearly contemporaneous (3.5-3.6 million year old) Laetoli fossil footprint trails. The technique creates gaits de novo and uses genetic algorithm optimization to search for the most efficient patterns of simulated muscular contraction at a variety of speeds. The model was first verified by predicting gaits for living human subjects, and comparing costs, stride lengths and speeds to experimentally determined values for the same subjects. Subsequent simulations for A. afarensis yield estimates of the range of walking speeds from 0.6 to 1.3ms?1 at a cost of 7.0Jkg?1m?1 for the lowest speeds, falling to 5.8Jkg?1m?1 at 1.0ms?1, and rising to 6.2Jkg?1m?1 at the maximum speed achieved. Speeds previously estimated for the makers of the Laetoli footprint trails (0.56 or 0.64ms?1 for Trail 1, 0.72 or 0.75ms?1 for Trail 2/3) may have been underestimated, substantially so for Trail 2/3, with true values in excess of 0.7 and 1.0ms?1, respectively. The predictions conflict with suggestions that A. afarensis used a 'shuffling' gait, indicating rather that the species was a fully competent biped. Abstract and full text links at The Royal Society http://tinyurl.com/avswp  SignaturePosted by Robert Karl Stonjek Thank you! I'm glad you still remember to send SAP "good stuff". Jois Journal of The Royal Society Interface ISSN: 1742-5689 (Paper) 1742-5662 (Online) Issue: Volume 2, Number 5 / December 22, 2005 Pages: 431 - 441 DOI: 10.1098/rsif.2005.0060 URL: Linking Options Stride lengths, speed and energy costs in walking of Australopithecus afarensis: using evolutionary robotics to predict locomotion of early human ancestors William I. Sellers A1, Gemma M. Cain A1, Weijie Wang A2, Robin H. Crompton A3 A1 Loughborough University Department of Human Sciences Loughborough LE11 3TU, UK A2 University of Dundee Section of Oncology and Surgery, Ninewells Medical School, Institute of Motion Analysis and Research Dundee DD1 9SY, UK A3 University of Liverpool School of Biomedical Sciences, Sherrington Buildings Liverpool L69 3GE, UK Abstract: This paper uses techniques from evolutionary robotics to predict the most energy-efficient upright walking gait for the early human relative Australopithecus afarensis, based on the proportions of the 3.2 million year old AL 288-1 'Lucy' skeleton, and matches predictions against the nearly contemporaneous (3.5-3.6 million year old) Laetoli fossil footprint trails. The technique creates gaits de novo and uses genetic algorithm optimization to search for the most efficient patterns of simulated muscular contraction at a variety of speeds. The model was first verified by predicting gaits for living human subjects, and comparing costs, stride lengths and speeds to experimentally determined values for the same subjects. Subsequent simulations for A. afarensis yield estimates of the range of walking speeds from 0.6 to 1.3ms?1 at a cost of 7.0Jkg?1m?1 for the lowest speeds, falling to 5.8Jkg?1m?1 at 1.0ms?1, and rising to 6.2Jkg?1m?1 at the maximum speed achieved. Speeds previously estimated for the makers of the Laetoli footprint trails (0.56 or 0.64ms?1 for Trail 1, 0.72 or 0.75ms?1 for Trail 2/3) may have been underestimated, substantially so for Trail 2/3, with true values in excess of 0.7 and 1.0ms?1, respectively. The predictions conflict with suggestions that A. afarensis used a 'shuffling' gait, indicating rather that the species was a fully competent biped. Abstract and full text links at The Royal Society http://tinyurl.com/avswp -- Posted by Robert Karl Stonjek |
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