Bipedal and quadrupedal locomotion in chimpanzees
Herman Pontzer1, David A Raichlen2, Peter S Rodman3
1Department of Anthropology, Hunter College, 728 North Building, 695 Park Ave., New York, NY 10065, USA; New York Consortium for Evolutionary Primatology, New York, NY, USA.
Journal of Human Evolution
|December 10, 2013
Summary
Chimpanzee bipedal and quadrupedal locomotion share similar costs, suggesting early hominin bipedalism had no initial energetic disadvantage. However, habitual bipedalism likely favored anatomical changes for posture and stability.
Area of Science:
- Primate locomotion
- Evolutionary biology
- Biomechanics
Background:
- Chimpanzees (Pan troglodytes) exhibit both bipedal and quadrupedal gaits.
- Understanding chimpanzee locomotion offers insights into early hominin bipedalism evolution.
Purpose of the Study:
- To compare kinematics, kinetics, and energetics of bipedal vs. quadrupedal walking and running in chimpanzees.
- To assess the energetic cost implications for early hominin bipedalism.
Main Methods:
- High-speed video analysis of sagittal-plane kinematics during treadmill locomotion.
- Forceplate measurements for ground reaction forces (kinetics).
- Oxygen consumption measurements for metabolic energy cost.
Main Results:
- Bipedal and quadrupedal locomotion showed similar metabolic costs in chimpanzees.
- Differences observed in hip/trunk angles (more orthograde posture in bipedalism) and mediolateral forces (larger in bipedal walking).
- Stride frequency was higher and step length shorter during bipedal trials.
Conclusions:
- The similar energetic cost of bipedal and quadrupedal walking in chimpanzees suggests no initial cost penalty for early hominin bipedalism.
- Habitual bipedalism likely drove evolutionary modifications in hip structure for orthograde posture and hind limb abductors for mediolateral stability.
