Paleolakes and socioecological implications of last-glacial "greening" of the South African interior

Determining the timing and drivers of Pleistocene hydrological change in the interior of South Africa is critical for testing hypotheses regarding the presence, dynamics and resilience of human populations. Combining geological data and physically-based distributed hydrological modelling, we demonstrate the presence of large paleolakes in South Africa’s central interior during the last glacial period, and infer a regional-scale invigoration of hydrological networks, particularly during marine isotope stages (MIS) 3 and 2, most notably 55-39 ka and 34-31 ka. The resulting hydrological reconstructions further permit investigation of regional floral and fauna responses using a modern analogue approach. These suggest that the climate change required to sustain these water bodies would have replaced xeric shrubland with more productive, eutrophic grassland or higher grass-cover vegetation, capable of supporting a substantial increase in ungulate diversity and biomass. The existence of such resource-rich landscapes for protracted phases within the last glacial period likely exerted a recurrent draw on human societies, evidenced by extensive pan-side artifact assemblages. Thus, rather than representing a perennially uninhabited hinterland, the central interior’s under-representation in late Pleistocene archeological narratives likely reflects taphonomic biases stemming from a dearth of rockshelters and regional geomorphic controls. These findings suggest that South Africa’s central interior experienced greater climatic, ecological and cultural dynamism than previously appreciated, and potential to host human populations whose archaeological signatures deserve systematic investigation.