The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Locomotor kinematics of two semi-wild macaque species (Macaca assamensis and M. arctoides) in Thailand: a preliminary report


1Primate Research Institute, Kyoto University, 2Primate Research Center of Thailand, Chulalongkorn University

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The global goal of this project is to noninvasively study primate locomotor kinematics in the wild environment using advanced apparatus and techniques. In this preliminary study, we tried to develop the methods for such measurements in a semi-wild environment. The Assamese macaques (Macaca assamensis) at Wat Tham Pla, and the stump-tailed macaques (Macaca arctoides) at the Khao-Krapook-Khao-Taomor non-hunting area, both in Thailand, were chosen as the subjects because although they are originally wild, they are now living around the temple, being partly provisioned by humans. We recorded their positional behavior by using two video cameras, and estimated kinematic parameters during terrestrial quadrupedal locomotion. Limited data analyzed so far revealed that both species walked with greatly protracted forelimb and retracted hind limb postures, as compared with Japanese macaques. The stump-tailed macaque did so to increase stride length, and the shoulder girdle largely contributed to that. Their digitigrade gait and extended elbow joint suggest that this species is well-adapted to terrestrial locomotion, in which longer stride is one of the important factors. The gait of the Assamese macaques, on the other hand, did not seem to be optimized to terrestrial locomotion; their hands were often used in palmigrade postures, and were more abducted than those of the other two species. We postulate that protracted forelimbs and retracted hind limbs may be related to their cliff-climbing, in which it is important to keep the center of body mass close to the cliff.

Supported by JSPS20255006

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