Perspectives on Pliocene and Pleistocene Pedal Patterns and Protection: Implications for Footprints

As a framework for interpreting Pliocene and Pleistocene hominin footprints, the functional implications of australopith and Homo pedal remains are reviewed. Despite minor variations in pedal proportions and articular morphology, all of these remains exhibit tarsometatarsal skeletons fully commensurate with an efficient (human) striding bipedal gait. The Middle and Late Pleistocene Homo pedal phalanges exhibit robust and distally flattened metatarsal 1 heads, hallux valgus, relatively short lateral digits with largely straight proximal phalanges with dorsally oriented metatarsal facets, all similar to those of recent humans. The Pliocene and Early Pleistocene halluces lack hallux valgus and have bulbous metatarsal 1 heads. The australopith pedal remains have lateral proximal phalanges that are relatively long and dorsally curved and have more proximally oriented metatarsal facets. In addition, pre-Upper Paleolithic Homo lateral phalanges have robust diaphysis implying the habitual absence of protective footwear, whereas the Upper Paleolithic ones are variably gracile, especially at higher latitudes, indicating more consistent use of footwear. These paleontological considerations provide a framework for interpreting the distal portions of earlier hominin footprints (especially with respect to hallucal orientation and digital length) and suggest that many of the Late Pleistocene footprints may be unrecognized given the use of footwear.