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

Variation in plantar pressure distribution in habitually unshod humans


1Department of Biology, James Madison University, 2Center for the Advanced Study of Hominid Paleobiology, Department of Anthropology, The George Washington University, 3Hominid Paleobiology Doctoral Program, The George Washington University, 4Human Origins Program, Natural Museum of Natural History, Smithsonian Institution

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Fossil footprints provide a unique record of locomotor behavior in extinct species, yet the interpretation of fossil footprints requires a clear understanding of foot biomechanics in modern analogs. The recent discovery of 1.5 million-year-old hominin footprints near Ileret, Kenya has highlighted the importance and the paucity of quantitative pedal biomechanics data on humans whose feet have not been influenced by modern footwear. Human foot shape differs across ethnic groups, yet only one study has quantified plantar pressure distribution in habitually unshod humans (D’Août 2009, Footwear Science, on unshod Indians). We examined plantar pressure distribution in two African populations, both unshod-minimally shod, in order to assess natural variation in human foot function and to develop a more inclusive model of human foot function that can be used to interpret fossil footprints and skeletal material.

Fifty adults from Ileret, Kenya and from Mahajoarivo, Madagascar walked barefoot across a plantar pressure mat at a self-selected pace. Video was collected for kinematic analysis, and steps were compared within a restricted speed range. Peak pressures follow general trends observed in other unshod samples such as lower overall peak values, however some differences (e.g. lack of reduced heel pressures) were observed. Both groups exhibited similarly low medial and central metatarsal head and toe peak pressures compared to shod humans. Lateral forefoot peak pressures were higher in the Kenyan group. Understanding the nature and variation of foot function among unshod populations is necessary to make reliable inferences about locomotor function in hominin fossils and footprints.

This study was funded by NSF grants BCS-0924476 and DGE-0801634. This research was approved by the GW and JMU Institutional Review Boards.

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