Buried by lake sediments, revealed by deflation: the MSA of Makgadikgadi, central southern Africa

<p>Central southern Africa is often viewed as an archaeological void, especially when compared to the continent&#8217;s heavily researched coastal regions. This is in part due to its geomorphological context: the Kalahari basin is a flat depositional void with few archaeological sites due to limited traditionally-favoured preservation contexts. Yet recently, the Kalahari&#8217;s Makgadikgadi mega-palaeolake basin has been controversially proposed, through DNA research, as the &#8216;ancestral homeland&#8217; of modern humans, prior to MSA dispersal c130k yr ago, with only small residual populations remaining thereafter (Chan et al., 2019), despite the absence of supporting archaeological data.</p><p>Rather than being archaeologically-sterile, we provide new data from four field seasons that demonstrate the richness (hundreds) of MSA sites in the Makgadikgadi basin, their unique context on the palaeolake floor, and the significance of geomorphological processes in explaining their location, high preservation quality, and modern exposure at the surface. Six sites have been excavated, including extensive undisturbed silcrete MSA lithic spreads. One can be dated to within 81-68 ka, another occurred after 57ka, both resting on, and then buried by, OSL-dated palaeolake sediments derived from high lake stands. Human use of the basin floor occurring during low, or seasonally dry, phase of the basin&#8217;s complex hydrological history. Sites are being exposed at the surface of today&#8217;s dry basin through processes of aeolian deflation, removing ancient lake sediments from one of Africa&#8217;s major atmospheric dust sources.</p><p>Our work shows that without a clear understanding of Makgadikgadi&#8217;s geomorphological history, and of the processes operating in the system, it is difficult to appropriately explain the preservation and quality of the MSA sites in the basin. Our work shows a more complex environmental dynamic, and likely a more complex early human history, that previous research has suggested.</p><p>Reference: Chan EKF et al 2019 &#8216;Human origins in a southern African palaeo-wetland and first migrations&#8217;. <em>Nature 575, 185-189</em></p>