The earliest long-distance obsidian transport: Evidence from the ~200 ka Middle Stone Age Sibilo School Road Site, Baringo, Kenya Nick Blegen Department of Anthropology, Harvard University, Peabody Museum of Archaeology and Ethnology,11 Divinity Avenue, Cambridge, MA 02138, USA article info Article history: Received 8 June 2016 Accepted 15 November 2016 Keywords: Geoarchaeology Obsidian sourcing Tephrostratigraphy Lithic technology Middle Pleistocene East Africa abstract This study presents the earliest evidence of long-distance obsidian transport at the ~200 ka Sibilo School Road Site (SSRS), an early Middle Stone Age site in the Kapthurin Formation, Kenya. The later Middle Pleistocene of East Africa (130e400 ka) spans significant and interrelated behavioral and biological changes in human evolution including the first appearance of Homo sapiens. Despite the importance of the later Middle Pleistocene, there are relatively few archaeological sites in well-dated contexts (n < 10) that document hominin behavior from this time period. In particular, geochemically informed evidence of long-distance obsidian transport, important for investigating expansion of intergroup interactions in hominin evolution, is rare from the Middle Pleistocene record of Africa. The SSRS offers a unique contribution to this small but growing dataset. Tephrostratigraphic analysis of tuffs encasing the SSRS provides a minimum age of ~200 ka for the site. Levallois points and methods of core preparation demonstrate characteristic Middle Stone Age lithic technologies present at the SSRS. A significant portion (43%) of the lithic assemblage is obsidian. The SSRS obsidian comes from three different sources located at distances of 25 km, 140 km and 166 km from the site. The majority of obsidian derives from the farthest source, 166 km to the south of the site. The SSRS thus provides important new evidence that long-distance raw material transport, and the expansion of hominin intergroup interactions that this entails, was a significant feature of hominin behavior ~200 ka, the time of the first appearance of H. sapiens, and ~150,000 years before similar behaviors were previously documented in the region. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction The later Middle Pleistocene of East Africa is an important time period for understanding the evolution of our species. The earliest fossil Homo sapiens specimens date to 195 ka in the Kibish For- mation of the Omo-Turkana Basin and between 154 and 160 ka in the upper Herto Member of the Bouri Formation in central Ethiopia (Clark et al., 2003; White et al., 2003; McDougall et al., 2005). Also during this period, the large hand-held stone tools of the Acheu- lean, such as handaxes and cleavers, were replaced by more diverse and smaller stone tools of the Middle Stone Age (MSA) character- ized by diverse disc core preparation technologies, including mul- tiple Levallois techniques, smaller cores and flakes, pointed pieces and hafted tools (Clark, 1988; Tryon et al., 2005). Understanding human evolution in this period thus requires understanding of the timing and pattern in which behavioral changes, including new technologies, mobility patterns, subsistence strategies and ecological adaptations, were acquired in relation to biological changes and environmental circumstances (McBrearty and Brooks, 2000). In the Late Pleistocene, particularly of southern Africa, the chronology and pattern of technological and other behavioral in- novations in the MSA is relatively well understood due to a robust and important body of work in this region (Deacon, 1979; Singer and Wymer, 1982; Wadley and Jacobs, 2006). A comparable chro- nology and pattern of behavioral and technological change is also being established for the Late Pleistocene in eastern Africa (Tryon and Faith, 2013). However, a similarly complete archaeological re- cord is lacking for the earliest MSA of the later Middle Pleistocene. This relative lack of Middle Pleistocene archaeology in Africa limits our understanding of this time period, leading to the perception that hominin behavior surrounding the appearance of H. sapiens was relatively homogenous and static (Klein, 2000; McBrearty and Tryon, 2006; Tryon and Faith, 2013). To address these issues, in- vestigations on a limited but steadily increasing number of later Middle Pleistocene MSA archaeological sites in both southern Af- rica (Marean, 2010; Wilkins et al., 2012) and eastern Africa (Tryon E-mail addresses: nick_blegen@fas.harvard.edu, nick.blegen@gmail.com. Contents lists available at ScienceDirect Journal of Human Evolution journal homepage: www.elsevier.com/locate/jhevol http://dx.doi.org/10.1016/j.jhevol.2016.11.002 0047-2484/© 2016 Elsevier Ltd. All rights reserved. Journal of Human Evolution 103 (2017) 1e19