Figure 1.

Examples of human, Laetoli hominin and chimpanzee footprints. These randomly selected footprints demonstrate the ‘stereotypical’ morphologies of, from left to right, human, Laetoli hominin and chimpanzee footprints. The human and chimpanzee prints were produced experimentally in this study. The Laetoli footprint shown here is G1-25. The top row includes standard photographs of these footprints while the bottom row shows depth-coloured maps of the same tracks pictured above, to emphasize their three-dimensional topographies. In the depth-coloured maps, dark blue corresponds to areas of greatest depth and depths become shallower along the gradient from blue to green to yellow to orange. In the absence of colour, areas with darker shading are deeper. Important morphological comparisons described in the main text include the similarity of proportional toe depths (toe relative to heel depths) of the Laetoli and chimpanzee footprints and their distinction from proportional toe depths of modern human footprints, and the intermediate depth of the medial midfoot region in the Laetoli tracks. Images are not set to common scale. (Online version in colour.)