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

Understanding footprints: intra-trail variability and its causes


1Musculoskeletal Biology II - Institute of Ageing and Chronic Disease, University of Liverpool, 2School of Applied Sciences, Bournemouth University

Friday 9:00-9:15, Grand Ballroom II Add to calendar

Here we examine the influence of substrate on footprint formation, and explore the role of substrate as a cause of intra-trail variability with new software developed for the analysis of plantar pressure data (pSPM). Using a Holocene footprint site from Namibia, this new approach to human ichnology attempts to move the discipline away from subjective interpretations of single prints to objective interpretations based on mean and median prints from complete trails. This allows the intra-trail variability to be documented quantitatively, and linked to changes in substrate. We suggest that doing so will allow more sophisticated interpretations of biomechanical inference than hitherto possible, and we argue for consideration of the importance of factors that lead to variability in footprint morphology within and between trails, especially when interpreting sites of significance to paleoanthropology such as those at Laetoli (~3.6Ma) or Ileret (~1.5Ma). Laetoli was formed via ashfall in open terrain while Ileret was associated with fluvial overbank deposits close to standing water. Comparing these two sites is critical to understanding the transition in foot anatomy and gait across the transition from Australopithecus spp. to Homo spp.. Data presented here provides a model case to help us identify the likely role of substrate at these two ancient sites, and the factors which need to be considered in making quantitative comparisons. A series of preliminary comparisons of the Ileret and Laetoli footprint sites are presented using pSPM with the benefit of knowledge of intra-trail variability obtained from the Holocene footprint site in Namibia.

This research is funded by a grant from the Natural Environment Research Council.

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