Going the distance: Mapping mobility in the Kalahari Desert during the Middle Stone Age through multi-site geochemical provenancing of silcrete artefacts.

This study utilises geochemical provenancing of silcrete raw materials, in combination with chaîne opératoire 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 ≠Gi 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 ≠Gi, 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 distance-decay 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.

Provenancing of silcrete raw materials indicates long-distance transport to Tsodilo Hills, Botswana, during the Middle Stone Age.

Lithic artifacts from the African Middle Stone Age (MSA) offer an avenue to explore a range of human behaviors, including mobility, raw material acquisition, trade and exchange. However, to date, in southern Africa it has not been possible to provenance the locations from which commonly used stone materials were acquired prior to transport to archaeological sites. Here we present results of the first investigation to geochemically fingerprint silcrete, a material widely used for tool manufacture across the subcontinent. The study focuses on the provenancing of silcrete artifacts from the MSA of White Paintings Shelter (WPS), Tsodilo Hills, in the Kalahari Desert of northwest Botswana. Our results suggest that: (i) despite having access to local quartz and quartzite at Tsodilo Hills, MSA peoples chose to transport silcrete over 220 km to WPS from sites south of the Okavango Delta; (ii) these sites were preferred to silcrete sources much closer to Tsodilo Hills; (iii) the same source areas were repeatedly used for silcrete supply throughout the 3 m MSA sequence; (iv) during periods of colder, wetter climate, silcrete may have been sourced from unknown, more distant, sites. Our results offer a new provenancing approach for exploring prehistoric behavior at other sites where silcrete is present in the archaeological record.