Wednesday, May 24, 2023

Upper Paleolithic South African Lakes

[S]everal large bodies of water were sustained in the now arid South African interior during the last Ice Age, particularly 50,000-40,000 years ago, and again 31,000 years ago.
From Science Daily citing Andrew S. Carr, et al., "Paleolakes and socioecological implications of last glacial “greening” of the South African interior." 120(21) Proceedings of the National Academy of Sciences (May 15, 2023) DOI: 10.1073/pnas.2221082120

The paper's abstracts state:
Renowned for its rich evidence pertaining to early Homo sapiens, South Africa’s late Pleistocene archaeological record remains biased toward the continental margins. A profusion of coastal rockshelters, together with putative associations of glacial periods with intense aridity in the continental interior, has created historical impressions of an inland core hostile to human life during lengthy glacial phases. 
New geological data and large-scale hydrological modeling experiments reveal that a series of large, now-dry palaeolakes existed for protracted phases of marine isotope stages 3 and 2. Modern analog reconstructions of resulting vegetational and faunal communities suggest that glacial climates were capable of transforming South Africa’s central interior into a resource-rich landscape favorable to human populations. 
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 modeling, 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 3 and 2, most notably 55 to 39 ka and 34 to 31 ka. 
The resulting hydrological reconstructions further permit investigation of regional floral and fauna responses using a modern analog 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 underrepresentation 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.

The following illustration from the supplementary materials shows the status quo:


Guy said...

Hi Andrew, Did it show the postulated locations and sizes of the lakes?

Guy said...


Do you have a position with respect to AI X-risk?

I personally am despairing, just watching the fat lady walking up to the podium.

andrew said...

The postulated locations can actually be seen in the images in this post if blown up larger.

I am waiting to see how AI-X risk will play out. I am more optimistic than many although the risks are real.

andrew said...

I can't find the sizes of the proposed lakes easily because the article is pay per view.