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Homo sapiens exhibit extreme behavioural plasticity, mediated by culture and technology, that permits us to adapt rapidly to new environments and situations. Understanding the role that past climate change played in selecting for Homo sapiens’ adaptability is a key question in human evolution research. The arid and semi-arid Kalahari Basin in southern Africa is an ideal region for addressing this question because fossil, genetic, and archaeological evidence supports an early origin for Homo sapiens in southern Africa. The growing archaeological record of the Kalahari Basin reveals that significant behavioural innovations accumulated in the region over the course of the Middle and Late Pleistocene, including ochre use, hafted hunting weapons, fishing, and figurative paintings. Here, we report the results of interdisciplinary investigations at two locales in the southern Kalahari; Ga-Mohana Hill and Witberg 1. The archaeological and palaeoenvironmental record (based on U-Th dating of tufas) at Ga-Mohana Hill reveals that site occupation correlated with a previous period of increased effective precipitation ~110-100 ka, and preliminary results suggest a more complicated relationship between occupation and precipitation after that time. At Witberg 1, Middle Stone Age archaeology is associated with the shoreline of a previously unidentified palaeolake. Current investigations are focused on dating the Witberg deposits, analysing the lithic technology, and generating palaeoenvironmental archives using phytoliths and diatoms. Collectively, this research provides a rare opportunity to evaluate Middle Stone Age occupation across a changing landscape from both stratified rockshelters and sealed open-air sites, to explore the complex interactions between past climate change and early human behaviors, and to better understand the origins of Homo sapiens extreme adaptability.

Lithic surface artefacts are anthropogenically formed stone materials (stone tools and spall generated during knapping) resting atop or being semi-embedded into the uppermost sediment layer of a stratigraphic sequence on a given landform. Such surface artefacts lack a secure stratigraphic context are encountered worldwide and often comprise a significant proportion of the archaeological record. Yet, direct absolute dating techniques for constraining the age of lithic surface scatters are currently not available. Promising recent work has shown the potential of using the optically stimulated luminescence (OSL) signal from rocks to date the emplacement of gravel pavements and blocks in both, archaeological and geological contexts (e.g. Sohbati et al., 2015; Jenkins et al., 2018). We build on this work and introduce a novel way of directly dating lithic surface artefacts using OSL-rock surface burial dating. We use this approach to date a surface lithic artefact scatter site, in southern Tibet. By calculating spatially resolved OSL burial ages for slices at 1 mm increments into each artefact’s buried surface we (i) infer the timing of artefact discard by humans at the site, (ii) demonstrate that most artefacts are not in-situ but were transported downslope and/or flipped and (iii) for some samples constrain the timing and number of cycles of artefact burial and re-exhumation. This is the first time that the OSL signal is used to date sunlight exposure of artefacts. The method is not limited to archaeological contexts but can be applied to other surface clasts that yield a reasonable OSL signal too. OSL rock surface burial dating of surface clasts and artefacts thus holds great potential to (i) constrain manufacture and artefact discard by humans and (ii) detect and reconstruct post-depositional disturbances and transport pathways. We discuss the application potential of this approach in archaeology and geomorphology. References:Jenkins, G.T.H., Duller, G.A.T., Roberts, H.M., Chiverrell, R.C., Glasser, N.F., 2018. A new approach for luminescence dating glaciofluvial deposits – High precision optical dating of cobbles. Quaternary Science Reviews 192, 263-273.Sohbati, R., Murray, A.S., Porat, N., Jain, M., Avner, U., 2015. Age of a prehistoric Rodedian cult site constrained by sediment and rock surface luminescence dating techniques. Quaternary Geochronology 30, 90–99.

In the area of the European-Asian border, in the Ural Mountains, the southern boundary of permafrost has moved in meridional direction by more than 1000 km in response to Quaternary climate variations. During cold climate states, permafrost extended as far south as the Southern Ural (53°N). We studied three independent archives in three caves in the Southern Ural (Shulgan-Tash, Victoria and Grandioznaya) in order to gain insights into the long-term dynamics of permafrost in the region.Common speleothems (e.g., stalagmites and flowstone) require liquid water to form, and are therefore restricted to permafrost-free periods. Cryogenic cave carbonates (CCC) form when the temperature in the cave is close to or slightly below 0°C (permafrost conditions). These two types of speleothems were dated using the 230Th-U method in order to determine the timing of permafrost and permafrost-free conditions. As a novel indicator of freezing conditions in caves we identified frost wedges in silty cave sediments filled by sand. These sands were dated using OSL to constrain the timing of sub-zero rock temperatures (required to form frost wedges) in caves.Stalagmites, abundant in in South Uralian caves, exhibit two prominent growth phases, associated with interglacials – MIS 5e and Holocene. In addition, mm-thin layers of flowstone formed in one chamber of Shulgan-Tash cave in association with smaller-scale warming episodes during MIS 3 (Greenland interstadials GI-9 and GI-8) and MIS 2 (GI-1; Bølling-Allerød). All CCC in Shulgan-Tash and Victora caves yielded MIS 3 ages, typically lagging cooling events (Greenland stadials) GS-16.1, GS-15.1, GS-13, GS-12, GS-10, and GS-7 by several hundred years up to one 1 ka. CCC from Grandioznaya cave formed during a single episode following GS-1 (Younger Dryas). Sand filling frost wedges in Victoria cave was washed into the cave during MIS 2, ca. 24-25 ka BP. Apparently, during this time the karst massif hosting the cave was engulfed by permafrost (to a depth of at least 90 m) and flow of water through the cave was severely restricted, which led to back-flooding of the cave passage and the accumulation of several m-thick silt deposits, interspersed with thin sand layers.