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Development of quadrupedal locomotion on level surfaces in Japanese macaques
1Division of Anthropology, Graduate School of Science, University of Tokyo, Japan. kimura@biol.s.u-tokyo.ac.jp
Insights
Infant Japanese macaques show varied locomotion patterns, with distinct forelimb and hindlimb force differences emerging early. This early differentiation in quadrupedal locomotion resembles adult patterns, offering insights into primate development.
Area of Science:
- Primate locomotion
- Developmental biology
- Biomechanics
Background:
- Understanding the developmental trajectory of quadrupedal locomotion is crucial for primate research.
- Early motor skills in infant primates provide insights into evolutionary adaptations.
Purpose of the Study:
- To longitudinally analyze high-speed quadrupedal locomotion in infant Japanese macaques.
- To compare infant and adult locomotion patterns, focusing on limb force dynamics.
Main Methods:
- Longitudinal observation of 4 infant Japanese macaques (Macaca fuscata) during locomotion.
- Analysis of foot force components (braking, accelerating, vertical) in forelimbs and hindlimbs.
Main Results:
- Infant locomotion exhibited significant variability in step patterns compared to adults.
- Forelimb braking forces were larger than hindlimb braking forces in infants.
- Hindlimb accelerating forces were larger than forelimb accelerating forces.
- Vertical forces showed less differentiation between forelimbs and hindlimbs in very young infants (1-2 months).
Conclusions:
- Despite variations, infant Japanese macaques display early fore- and hindlimb differentiation in locomotion.
- These developmental patterns in limb mechanics resemble those observed in adult macaques.
Abstract:
Longitudinal comparisons of high-speed quadrupedal locomotion on level surfaces were made on 4 infant Japanese macaques (Macaca fuscata) with normal mother-infant relationships. Compared to adults, infants exhibited considerable variation in each step of locomotion. Braking components of foot force tended to be larger in the forelimb than in the hindlimb during the infant stage of development. Conversely, accelerating components were larger in the hindlimb than in the forelimb. In 1- and 2-month-old infants, vertical components in the hindlimb were not significantly larger than those of the forelimb. Fore- and hindlimb differentiation in infant Japanese macaques resembles that of adult macaques even at this early stage of development.