Kinematic analysis of bipedal locomotion of a Japanese macaque that lost its forearms due to congenital malformation

Naomichi Ogihara, Hiraku Usui, Eishi Hirasaki, Yuzuru Hamada, Masato Nakatsukasa

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Spontaneously acquired bipedal locomotion of an untrained Japanese monkey (Macaca fuscata) is measured and compared with the elaborated bipedal locomotion of highly trained monkeys to assess the natural ability of a quadrupedal primate to walk bipedally. The subject acquired bipedalism by himself because of the loss of his forearms and hands due to congenital malformation. Two other subjects are performing monkeys that have been extensively trained for bipedal posture and locomotion. We videotaped their bipedal locomotion with two cameras in a lateral view and calculated joint angles (hip, knee, and ankle) and inertial angle of the trunk from the digitized joint positions. The results show that all joints are relatively more flexed in the untrained monkey. Moreover, it is noted that the ankle is less plantar flexed and the knee is more flexed in mid-to-late stance phase in the untrained monkey, suggesting that the trunk is not lifted up to store potential energy. In the trained monkeys, the joints are extended to bring the trunk as high as possible in the stance phase, and then stored potential energy is exchanged for kinetic energy to move forward. The efficient inverted pendulum mechanism seems to be absent in the untrained monkey's locomotion, implying that acquisition of such efficient bipedal locomotion is not a spontaneous ability for a Japanese monkey. Rather, it is probably a special skill that can only be acquired through artificial training for an inherently quadrupedal primate.

Original languageEnglish
Pages (from-to)11-19
Number of pages9
Issue number1
Publication statusPublished - 2005 Jan
Externally publishedYes


  • Bipedal locomotion
  • Joint angles
  • Macaca fuscata
  • Monkey performance
  • Training

ASJC Scopus subject areas

  • Animal Science and Zoology


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