Extended Data Fig. 3: RAVs and morphologies of human and chimpanzee tracks.

(a) As an example we focus on one Laetoli track, one Walvis Bay track and one experimental chimpanzee track, with similar RAV and relative depth measurements (red circle). (b) The morphologies of the two hominin tracks and their respective arch models are similar to each other and readily distinguished from those of the bipedal chimpanzee (all models from right feet). The arch volume of hominin tracks is concentrated beneath the medial midfoot, while that of the bipedal chimpanzee track is concentrated distally, in between the first and second rays. Thus, the hominin tracks are arched longitudinally, while the bipedal chimpanzee track is not. Two different colour scales are applied to map relative heights, one for tracks and one for arch models, to optimize visualization of each set. Scale bar at right is 10 cm.