The role of raw material differences in stone tool shape variation: an experimental assessment Metin I. Eren a, b, * , Christopher I. Roos c , Brett A. Story d , Noreen von Cramon-Taubadel e , Stephen J. Lycett e a Department of Anthropology, University of Missouri, Columbia, MO, 65211, USA b Department of Archaeology, Cleveland Museum of Natural History, Cleveland, OH 44106-1767, USA c Department of Anthropology, Southern Methodist University, Dallas, TX 75275, USA d Department of Civil and Environmental Engineering, Southern Methodist University, Dallas, TX 75275, USA e Department of Anthropology, University at Buffalo SUNY, 380 MFAC-Ellicott Complex, Buffalo, NY 14261-0005, USA article info Article history: Received 27 March 2014 Received in revised form 29 May 2014 Accepted 30 May 2014 Available online 12 June 2014 Keywords: Raw material Handaxes Experimental archaeology Acheulean Experiment abstract Lithic raw material differences are widely assumed to be a major determining factor of differences in stone tool morphology seen across archaeological sites, but the security of this assumption remains largely untested. Two different sets of raw material properties are thought to influence artifact form. The first set is internal, and related to mechanical flaking properties. The second set is external, namely the form (size, shape, presence of cortex) of the initial nodule or blank from which flakes are struck. We conducted a replication experiment designed to determine whether handaxe morphology was influ- enced by raw materials of demonstrably different internal and external properties: flint, basalt, and obsidian. The knapper was instructed to copy a “target” model handaxe, produced by a different knapper, 35 times in each toolstone type (n ¼ 105 handaxes). On each experimental handaxe, 29 size-adjusted (scale-free) morphometric variables were recorded to capture the overall shape of each handaxe in or- der to compare them statistically to the model. Both Principal Components Analysis (PCA) and a Multivariate Analysis of Variance (MANOVA) were used to determine if raw material properties were a primary determinate of patterns of overall shape differences across the toolstone groups. The PCA results demonstrated that variation in all three toolstones was distributed evenly around the model target form. The MANOVA of all 29 size-adjusted variables, using two different tests, showed no statistically signif- icant differences in overall shape patterns between the three groups of raw material. In sum, our results show that assuming the primacy of raw material differences as the predominant explanatory factor in stone tool morphology, or variation between assemblages, is unwarranted. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Understanding the role that stone raw materials played in lithic artifact form and assemblage variability is an issue fundamental to archaeological research in all times and places in which flaked stone technology was utilized. Indeed, raw material “quality” has long been cited as a potentially important factor influencing lithic artifact morphology (Abbott, 1911; Goodman, 1944). Despite the fact that “quality” is often a subjective, poorly defined characteristic of knappable stone, for which there is no consensus (Brantingham et al., 2000; Braun et al., 2009; Browne and Wilson, 2011), several lithic analysts have emphasized the role that stone raw material “quality” plays in artifact form. For instance, Andrefsky (1994:23) suggested that the “quality” of lithic raw materials is one of the two most important factors in the organization of stone technology (the other being lithic “abundance”), and that “the quality … of lithic raw materials played a direct role in prehistoric tool makers de- cisions to produce various types of stone tools.” Twenty years on, Manninen and Knutsson (2014:95) underscore this notion, stating that “when lithic technological organization is viewed as an inter- section of many varying dimensions, the properties and availability of raw materials can be considered the most important de- terminants in how these dimensions intersect within any organi- zational context.” The motivation for these inferences perhaps stems from the inevitable co-variation between particular stone raw materials and * Corresponding author. Department of Anthropology, University of Missouri, Columbia, MO 65211, USA. E-mail address: metin.i.eren@gmail.com (M.I. Eren). 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.2014.05.034 0305-4403/© 2014 Elsevier Ltd. All rights reserved. Journal of Archaeological Science 49 (2014) 472e487