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Centre of gravity of the body during the ontogeny of chimpanzee bipedal walking
1Department of Anthropology, Graduate School of Science, University of Tokyo, Japan.
Insights
Infant chimpanzees expend more energy walking bipedally due to underdeveloped hindlimbs. This contrasts with adult chimpanzees and highlights key differences in bipedal locomotion evolution.
Area of Science:
- Primate locomotion
- Evolutionary biology
- Biomechanics
Background:
- Bipedal walking is a hallmark of human evolution.
- Understanding the energetic costs of bipedalism in non-human primates provides insights into its evolutionary development.
- Chimpanzees exhibit varying degrees of bipedal locomotion, making them a relevant model for comparative studies.
Purpose of the Study:
- To investigate the energetic cost of bipedal walking in chimpanzees across different age groups.
- To identify developmental changes in bipedal locomotion efficiency in chimpanzees.
- To compare energy recovery mechanisms during bipedal walking between infant and juvenile chimpanzees.
Main Methods:
- Measurement of external energy generated by the movement of the center of gravity during bipedal walking.
- Analysis of hindlimb kinematics and posture during the single stance phase.
- Comparison of energy recovery between chimpanzees less than five years old and those aged five to 19 years.
Main Results:
- Infant chimpanzees (<5 years) exhibit lower external energy recovery during bipedal walking compared to juveniles (5-19 years).
- Younger chimpanzees demonstrate a higher energy output due to insufficient lifting of the body's center of gravity during the single stance phase.
- This is attributed to their shorter, flexed hindlimbs, which limit efficient energy utilization.
Conclusions:
- The development of hindlimb extension is crucial for energy economy in human bipedalism.
- Immature hindlimb mechanics in young chimpanzees lead to inefficient bipedal walking.
- The evolution of efficient, low-energy-cost bipedal mechanisms is a significant factor in human evolution.
Abstract:
Bipedal walking was studied in chimpanzees between 1 and 19 years of age by measuring the external energy generated by the movement of the centre of gravity of the body. The 'recovery' of external energy in infant chimpanzees less than five years of age is smaller than in juveniles from 5 to 19 years of age. During the single stance phase, the short, flexed hindlimb of chimpanzees younger than 5 years is not able to lift the body centre of gravity high enough, so that these infants have a considerable energy output during bipedal walking. Extension of the hindlimb is one of the bases for energy economy in human bipedalism. The development of this low-energy-cost mechanism is an important component of the evolution of human bipedalism.