An experimental assessment of the influences on edge damage to lithic artifacts: a consideration of edge angle, substrate grain size, raw material properties, and exposed face Shannon P. McPherron a, * , David R. Braun b , Tamara Dogand  zi  c a , Will Archer a , Dawit Desta a , Sam C. Lin c a Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, Leipzig, Germany b Department of Anthropology, George Washington University, Washington, D.C., USA c Department of Anthropology, University of Pennsylvania, Philadelphia, USA article info Article history: Received 4 November 2013 Received in revised form 2 April 2014 Accepted 4 April 2014 Available online xxx Keywords: Trampling Experiment Edge damage Edge angles Usewear Lithics Taphonomy abstract Functional analyses of stone tool assemblages face a number of methodological challenges. Aside from determining specific uses, it can be difficult to know which artifacts in an assemblage were used at all. Typically retouch is taken as a proxy for indicating past use, but ignoring unretouched flakes means excluding the overwhelming majority of most assemblages. Assessing whether an unretouched flake has been used is complicated. Edge damage on flakes can be caused by use or by taphonomic processes. One of the more important of these processes is trampling. Experiments have shown that trampling can create damage mimicking retouch, and unlike some other taphonomic processes trampling is otherwise difficult to detect. One possible solution is to look for patterning in the placement (left vs. right, ventral vs. dorsal, proximal vs. distal) of edge damage, and recent studies using GIS based approaches have shown the utility of this method at an assemblage level. Here we trampled a set of experimental flakes made from two raw materials on two substrate types and analyzed the edge damage patterns using a newly developed image analysis program that is similar to previous GIS based approaches. We found that a previously unquantified variable, edge angle, is strongly correlated with the likelihood of damage. Thus in circumstances where edge angles are non-randomly distributed across flake types, trampling damage will be patterned. These results have implications for previously published edge damage studies, and further indicate that basic flake mechanics need to be considered in studies where function is inferred from edge damage patterns. Approaches to the archaeological record that employs assemblage level assessments of edge damage, must consider a range of factors when inferring behaviors from these patterns. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction The vast majority of lithic assemblages consist of unretouched flakes. While these flakes do typically factor into technological analyses of assemblages, they are more difficult to analyze from a functional perspective (Shott and Sillitoe, 2004, 2005). The diffi- culty with assessing function in these tools lies in knowing which flakes, of potentially thousands in an assemblage, were actually used and which simply represent unused debris. Microscopic usewear or residue analysis can potentially shed some insights; however, these techniques can be difficult to apply to entire as- semblages. These techniques are applied typically only to unre- touched flakes which are suspected of being so-called desired end- products, normally based on analyses of the flake scar patterns on cores, e.g. bladelets, Kombewa flakes, and small Levallois flakes (Tixier and Turq, 1999; Dibble and McPherron, 2006; Eren and Lycett, 2012). Additionally, both usewear and residue analysis have been the subject of considerable methodological debate that has left their accuracy unclear (Shea, 1992; Odell, 2001; Bamforth et al., 1990; Young and Bamforth, 1990). Recently, Bird et al. (2007) and then Schoville (2010; see also Brown et al., 2012; Wilkins et al., 2012) have presented a promising * Corresponding author. Tel.: þ49 341 3550 363; fax: þ49 341 3550 399. E-mail address: mcpherro@eva.mpg.de (S.P. McPherron). Contents lists available at ScienceDirect Journal of Archaeological Science journal homepage: http://www.elsevier.com/locate/jas http://dx.doi.org/10.1016/j.jas.2014.04.003 0305-4403/Ó 2014 Elsevier Ltd. All rights reserved. Journal of Archaeological Science 49 (2014) 70e82