Going the distance: Mapping mobility in the Kalahari Desert during the Middle Stone Age through multi-site geochemical provenancing of silcrete artefacts David J. Nash a, b, * , Sheila Coulson c , Sigrid Staurset c , J. Stewart Ullyott a , Mosarwa Babutsi d , Martin P. Smith a a School of Environment and Technology, University of Brighton, Lewes Road, Brighton BN2 4GJ, United Kingdom b School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa c Institute of Archaeology, Conservation and History, University of Oslo, Blindernveien 11, 0315 Oslo, Norway d Department of National Museum and Monuments, 331 Independence Avenue, Gaborone, Botswana article info Article history: Received 16 January 2015 Accepted 4 May 2016 Keywords: Raw material procurement Silcrete provenancing Middle Stone Age Human mobility Lithic technology Chaîne op eratoire abstract This study utilises geochemical provenancing of silcrete raw materials, in combination with chaîne op eratoire analyses, to explore lithic procurement and behavioural patterns in the northern Kalahari Desert during the Middle Stone Age (MSA). New data from the sites of Rhino Cave, Corner Cave, and sGi in northwest Botswana, combined with earlier results from White Paintings Shelter, reveal that the long distance transport of silcrete for stone tool manufacture was a repeated and extensively used behaviour in this region. Silcrete was imported over distances of up to 295 km to all four sites, from locations along the Boteti River and around Lake Ngami. Significantly, closer known sources of silcrete of equivalent quality were largely bypassed. Silcrete artefacts were transported at various stages of production (as partially and fully prepared cores, blanks, and finished tools) and, with the exception of sGi, in large volumes. The import occurred despite the abundance of locally available raw materials, which were also used to manufacture the same tool types. On the basis of regional palaeoenvironmental data, the timing of the majority of silcrete import from the Boteti River and Lake Ngami is constrained to regionally drier periods of the MSA. The results of our investigation challenge key assumptions underlying predictive models of human mobility that use distanceedecay curves and drop-off rates. Middle Stone Age peoples in the Kalahari appear to have been more mobile than anticipated, and repeatedly made costly choices with regard to both raw material selection and items to be transported. We conclude that (i) base transport cost has been overemphasised as a restrictive factor in predictive models, and (ii) factors such as source availability and preference, raw material quality, and potential sociocultural influences significantly shaped prehistoric landscape use choices. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Studies of the distance over which lithic raw materials were transported from source to site form the foundation of our under- standing of patterns of early human mobility through prehistoric landscapes. Mobility is influenced by a wide range of physical, so- cioeconomic, and sociocultural factors (see Table 1 and references therein). The ability to identify specific sources of raw material can yield data on both how far and where our ancestors travelled to obtain raw materials. When such information is combined with lithic analyses, it then becomes possible to gain insights into time- specific resource procurement and transport strategies. The most accurate means of determining source locations is through geochemical provenancing of lithic raw materials. A range of stone types have been used successfully in provenancing studies, including obsidian (e.g., Shackley, 1995; Roth, 2000; Negash and Shackley, 2006; Vogel et al., 2006; Eerkens et al., 2007; Negash et al., 2007; Morgan et al., 2009; Phillips and Speakman, 2009; Smith, 2010; Smith and Kielhofer, 2011; Ambrose, 2012; Freund, 2013), chert (e.g., Thacker and Ellwood, 2002; Evans et al., 2007; Milne et al., 2009; Parish, 2011; Gauthieret al., 2012; Speer, 2014; * Corresponding author. E-mail address: d.j.nash@brighton.ac.uk (D.J. Nash). Contents lists available at ScienceDirect Journal of Human Evolution journal homepage: www.elsevier.com/locate/jhevol http://dx.doi.org/10.1016/j.jhevol.2016.05.004 0047-2484/© 2016 Elsevier Ltd. All rights reserved. Journal of Human Evolution 96 (2016) 113e133