The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)


Chimpanzee bipedalism: integrating experiments and musculoskeletal modeling

MATTHEW C. O'NEILL1, BRIGITTE DEMES1, NATHAN E. THOMPSON1, SUSAN G. LARSON1, JACK T. STERN, JR.1, LENG-FENG LEE2 and BRIAN R. UMBERGER2.

1Department of Anatomical Sciences, Stony Brook University SOM, 2Department of Kinesiology, University of Massachusetts Amherst

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Chimpanzee bipedalism has long provided important context for understanding the evolution of human walking. However, previous studies of chimpanzee gait have been limited to two-dimensional measurements. Yet, it is well known that chimpanzee bipedalism involves exaggerated mediolateral movement as compared to humans, requiring substantial hip joint rotation and ab/adduction. In this study, we integrate experimental data with a musculoskeletal model of the pelvis and hind limb to generate the first 3D kinematic analysis of the chimpanzee bipedal gait cycle.

Data were collected from three chimpanzees (Pan troglodytes) walking on two legs along an ~11 m runway. A four-camera motion capture system recorded the movements of joint and segment markers over a full stride (stance + swing). Marker data were integrated with scaled, subject-specific musculoskeletal models of the chimpanzee pelvis and hind limb, and used to solve for joint and segment angles via inverse kinematics in OpenSim®.

These data represent the first 3D kinematics for bipedal walking in chimpanzees, and provide functional estimates of muscle moment arms over the gait cycle. A model-based, inverse kinematics approach to determining joint motion may be less sensitive to skin marker errors than traditional approaches, as movements must conform to the underlying skeletal geometry. Further, this approach allows for tighter integration between inverse and forward dynamics analyses of locomotion.

Supported by NSF BCS-0935321 and NSF BCS-0935327

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