Edge damage distribution at the assemblage level on Middle Stone Age lithics: an image-based GIS approach Catherine Bird a , Tom Minichillo b, * , Curtis W. Marean c a School of Human Evolution and Social Change, PO Box 872402, Arizona State University, Tempe, AZ 85287-2402, USA b Department of Anthropology, University of Washington, Seattle, USA c Institute of Human Origins, School of Human Evolution and Social Change, PO Box 872402, Arizona State University, Tempe, AZ 85287-2402, USA Received 3 April 2006; received in revised form 17 August 2006; accepted 22 August 2006 Abstract Lithic artifacts represent the most abundant cultural remains from Middle Stone Age sites in southern Africa. Of these, pointed forms (under a variety of names), blades, and flakes have long been recognized as the three most abundant general types, and retouch on all three is rare relative to similar forms of equivalent age elsewhere. Here we offer a new technique for documenting concentrations of edge damage on an assemblage level to infer taphonomic processes and to record usewear and retouch. This approach is specifically aimed at patterning on the assemblage scale, rather than on individual artifacts. We use points from a Middle Stone Age assemblage from Pinnacle Point Cave 13B, near Mossel Bay, South Africa, to illustrate the technique. Combining GIS, rose diagrams, and polar statistics, we were able to visually and statistically summarize lithic artifacts for patterns of edge damage. For the points made on quartzite in this assemblage, edge damage was found to be significantly patterned and taphonomic causes of the damage were rejected. The technique also opens avenues for many other quantitative analyses that are either impossible or difficult with current non-visual systems of recording, such as measurements of distance, angle, and area of edge damage. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Middle Stone Age; Lithics; Edge damage; GIS; Image Analysis; Taphonomy 1. Introduction The Middle Stone Age (MSA) is a broad technologically and temporally defined period of African archaeology, beginning at least 300,000 years ago (Tryon and McBrearty, 2006) and per- sisting in some parts of Africa as late as 25,000 years ago (Villa et al., 2005; Wadley and Vogel, 1991). It is marked by increas- ing technological and symbolic sophistication (Henshilwood et al., 2001, 2002, 2004; Yellen, 1996) and the first appearance of Homo sapiens (McDougall et al., 2005; White et al., 2003). The MSA is currently a topic of discussion that is mostly focused its importance in understanding the origin of our spe- cies (Henshilwood and Marean, 2003; Klein, 1992; McBrearty and Brooks, 2000). This paper does not address that topic and instead utilizes the data from an MSA assemblage to illustrate a methodological approach. Overviews and current discussions of the MSA are available elsewhere (Barham, 2000; Deacon and Deacon, 1999; Henshilwood and Marean, 2003; Klein, 1999; McBrearty and Brooks, 2000; Mitchell, 2002; Wurz, 2002; Wurz et al., 2003, 2005). MSA people in southern Africa produced toolkits containing points, bifacial points, unifacial points, scrapers, blades, bladelets, flakes, and backed blades (Shea, 2006; Singer and Wymer, 1982; Thackeray, 1992; Wurz, 2002). MSA toolkits are dominated by unretouched pieces, with retouch often restricted in distribution and intensity (Volman, 1981). This is in contrast to many Eurasian Middle Paleolithic sites of similar age, where retouched pieces are * Corresponding author. 2323 NE 86th Street, Seattle, WA 98115, USA. Tel./ fax: þ1 206 525 7404. E-mail addresses: kiwiyama@aol.com (C. Bird), tom.minichillo@hotmail. com (T. Minichillo), curtis.marean@asu.edu (C.W. Marean). 0305-4403/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jas.2006.08.005 Journal of Archaeological Science 34 (2007) 771e780 http://www.elsevier.com/locate/jas