Running performance in Australopithecus afarensis

Current Biology, vol. 35, pp. 224–230.e4

Abstract

The evolution of bipedal gait is a key adaptive feature in hominids, 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 but the running abilities of early hominins have not been extensively studied. 2 Here, we present physics simulations of Australopithecus afarensis that demonstrate this genus was mechanically capable of bipedal running but with absolute and relative (size-normalized) maximum speeds considerably inferior to modern humans. Simulations predicted running energetics for Australopithecus that are generally consistent with values for mammals and birds of similar body size, therefore suggesting relatively low cost of transport across a limited speed range. Through model parameterization, we demonstrate the key role of ankle extensor muscle architecture (e.g., the Achilles tendon) in the evolution of hominin running energetics and indeed in an increase in speed range, which may have been intrinsically coupled with enhanced endurance running capacity. We show that skeletal strength was unlikely to have been a limiting factor in the evolution of enhanced running ability, which instead resulted from changes to muscle anatomy and particularly overall body proportions. These findings support the hypothesis that key features in the human body plan evolved specifically for improved running performance 2 , 3 and not merely as a byproduct of selection for enhanced walking capabilities.

Authors 8

1. Karl T. Bates corresponding

   University of Liverpool

   Affiliation as printed

   Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical Sciences, University of Liverpool, The William Henry Duncan Building, 6 West Derby Street, Liverpool L7 8TX, UK. Electronic address: k.t.bates@liverpool.ac.uk

2. Evie Donald

   University of Sunderland

   Affiliation as printed

   School of Medicine, Faculty of Health Sciences and Wellbeing, University of Sunderland, Murray Health, Chester Road, Sunderland SR1 3SD, UK

3. Samuel J. Coatham

   University of Manchester

   Affiliation as printed

   School of Natural Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK

4. Charlotte Brassey

   Manchester Metropolitan University

   Affiliation as printed

   Department of Natural Sciences, Manchester Metropolitan University, Manchester M1 5GD, UK

5. James P. Charles

   University of Liverpool

   Affiliation as printed

   Department of Musculoskeletal & Ageing Science, Institute of Life Course & Medical Sciences, University of Liverpool, The William Henry Duncan Building, 6 West Derby Street, Liverpool L7 8TX, UK

6. Thomas O'mahoney

   Anglia Ruskin University

   Affiliation as printed

   School of Life Sciences, Faculty of Science and Engineering, Anglia Ruskin University, Cambridge CB1 1PT, UK

7. Pasha A. van Bijlert Aachen

   Naturalis Biodiversity Center · Utrecht University

   Affiliation as printed

   Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Vening Meinesz Building A, Princetonlaan 8a, 3584 CB Utrecht, the Netherlands; Naturalis Biodiversity Center, Darwinweg 2, 2333 CR Leiden, the Netherlands

8. William I. Sellers

   University of Manchester

   Affiliation as printed

   School of Natural Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK