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Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins.

Publication ,  Journal Article
Kozma, EE; Webb, NM; Harcourt-Smith, WEH; Raichlen, DA; D'Août, K; Brown, MH; Finestone, EM; Ross, SR; Aerts, P; Pontzer, H
Published in: Proceedings of the National Academy of Sciences of the United States of America
April 2018

The evolutionary emergence of humans' remarkably economical walking gait remains a focus of research and debate, but experimentally validated approaches linking locomotor capability to postcranial anatomy are limited. In this study, we integrated 3D morphometrics of hominoid pelvic shape with experimental measurements of hip kinematics and kinetics during walking and climbing, hamstring activity, and passive range of hip extension in humans, apes, and other primates to assess arboreal-terrestrial trade-offs in ischium morphology among living taxa. We show that hamstring-powered hip extension during habitual walking and climbing in living apes and humans is strongly predicted, and likely constrained, by the relative length and orientation of the ischium. Ape pelves permit greater extensor moments at the hip, enhancing climbing capability, but limit their range of hip extension, resulting in a crouched gait. Human pelves reduce hip extensor moments but permit a greater degree of hip extension, which greatly improves walking economy (i.e., distance traveled/energy consumed). Applying these results to fossil pelves suggests that early hominins differed from both humans and extant apes in having an economical walking gait without sacrificing climbing capability. Ardipithecus was capable of nearly human-like hip extension during bipedal walking, but retained the capacity for powerful, ape-like hip extension during vertical climbing. Hip extension capability was essentially human-like in Australopithecus afarensis and Australopithecus africanus, suggesting an economical walking gait but reduced mechanical advantage for powered hip extension during climbing.

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Published In

Proceedings of the National Academy of Sciences of the United States of America

DOI

EISSN

1091-6490

ISSN

0027-8424

Publication Date

April 2018

Volume

115

Issue

16

Start / End Page

4134 / 4139

Related Subject Headings

  • Walking
  • Range of Motion, Articular
  • Posture
  • Pelvis
  • Male
  • Hylobatidae
  • Humans
  • Hominidae
  • Hip
  • Hamstring Muscles
 

Citation

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Kozma, E. E., Webb, N. M., Harcourt-Smith, W. E. H., Raichlen, D. A., D’Août, K., Brown, M. H., … Pontzer, H. (2018). Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins. Proceedings of the National Academy of Sciences of the United States of America, 115(16), 4134–4139. https://doi.org/10.1073/pnas.1715120115
Kozma, Elaine E., Nicole M. Webb, William E. H. Harcourt-Smith, David A. Raichlen, Kristiaan D’Août, Mary H. Brown, Emma M. Finestone, Stephen R. Ross, Peter Aerts, and Herman Pontzer. “Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins.Proceedings of the National Academy of Sciences of the United States of America 115, no. 16 (April 2018): 4134–39. https://doi.org/10.1073/pnas.1715120115.
Kozma EE, Webb NM, Harcourt-Smith WEH, Raichlen DA, D’Août K, Brown MH, et al. Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins. Proceedings of the National Academy of Sciences of the United States of America. 2018 Apr;115(16):4134–9.
Kozma, Elaine E., et al. “Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins.Proceedings of the National Academy of Sciences of the United States of America, vol. 115, no. 16, Apr. 2018, pp. 4134–39. Epmc, doi:10.1073/pnas.1715120115.
Kozma EE, Webb NM, Harcourt-Smith WEH, Raichlen DA, D’Août K, Brown MH, Finestone EM, Ross SR, Aerts P, Pontzer H. Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins. Proceedings of the National Academy of Sciences of the United States of America. 2018 Apr;115(16):4134–4139.
Journal cover image

Published In

Proceedings of the National Academy of Sciences of the United States of America

DOI

EISSN

1091-6490

ISSN

0027-8424

Publication Date

April 2018

Volume

115

Issue

16

Start / End Page

4134 / 4139

Related Subject Headings

  • Walking
  • Range of Motion, Articular
  • Posture
  • Pelvis
  • Male
  • Hylobatidae
  • Humans
  • Hominidae
  • Hip
  • Hamstring Muscles