Click on image to view larger version.

Fig. 3. Illustration of the walking postures (at heel-strike, midstance and
toe-off) and vertical ground reaction forces (expressed as % body weight) in a
human (A) and a chimpanzee (B). The chimpanzee uses a more flexed hip and knee
posture throughout stance phase, has lower oscillations of the center of mass,
and generates a flatter, lower vertical peak force curve. Human and chimpanzee
redrawn from Elftman (1944);
force traces re-drawn from Kimura et al.
(1979).