Late Pleistocene Human Dispersals Across Eurasia

The dispersal of anatomically modern humans (AMH) out of Africa during the Late Pleistocene (c. 120 - 10 kya) is an important stage of the human past. Suggested timings and routes of dispersals have been significantly revised over recent decades due to technological advances and new finds of hominin fossils, particularly with regards to spatial and chronological overlap between AMH and other hominin populations (Sankararaman et al. 2012; Prufer et al. 2014; Bae et al. 2017). While general consensus supports an African origin for Homo sapiens, chronologies of their 'arrival and survival' in regions outside Africa remain debated (Bae et al. 2017: 1). The expansion of AMH out of Africa occurred during the archaeological period known as the Upper Palaeolithic (UP). The UP is defined by key changes in material culture that broadly demonstrate an increase in cultural complexity and symbolism alongside more frequent technological innovation and variation (Hoffecker 2011). UP technology is often associated with AMH, thus its earliest occurrence at archaeological sites across Eurasia has been inferred as the 'arrival' of AMH. Middle Palaeolithic (MP) industries that predate the UP in Eurasia are, by extension and contrast, typically associated with other hominin populations in Eurasia such as Neanderthals and Denisovans. However, clear-cut distinctions between MP and UP industries and populations are problematised at Initial Upper Palaeolithic (IUP) sites. The IUP is a collective term for a material culture used across Eurasia between 50 and 35 calibrated years before present (cal. BP), defined by a style of blade production resembling the Levallois industry that incorporates both MP and UP tool types (Kuhn 2019). While at some sites in the Levant UP material such as beads and bone tools are found in association with the IUP (Kuhn et al. 2009), the IUP's chronostratigraphic position consistently falls between MP and UP layers. Currently, the makers of the IUP - whether AMH, Neanderthals, Denisovans, or another hominin species - cannot be inferred with any certainty, given the lack of hominin remains found in any IUP layer. Improving understanding of the process of AMH dispersal requires confidently associating the IUP with its maker(s). Long-term environmental change across Eurasia is also likely to have had effects on hominin population dynamics and distribution (Muller et al. 2011). Whilst oxygen isotope records from Greenland ice cores imply largescale temperature change through the Late Pleistocene, at regional and local scales these changes are likely to have been more nuanced (Timmerman and Freidrich 2016; Carto et al. 2011). Environmental change may have constrained or enabled period(s) of interaction between hominin species indicated by genetic evidence (Sankararaman et al. 2012; Prufer et al. 2014; Fu et al. 2015), and restricted populations toward refugia during glacial periods (Stewart and Stringer 2012). Continental-scale reconstructions of Late Pleistocene environmental change in Eurasia will therefore contextualise AMH dispersal processes, while also contributing to discussions on the extinction of non-human hominin species. This project will attempt to answer three questions:
i) Who were the makers of the IUP? Can the IUP be considered a material proxy for the arrival of AMH in Eurasia?
ii) Can Late Pleistocene environmental change in Eurasia be reconstructed by integrating proxy evidence and palaeoclimate models?
iii) How did environmental changes affect hominin distributions and AMH dispersal?
To answer question i), sediments at IUP sites will be analysed for hominin DNA, while ii) and iii) involve broader incorporation of interdisciplinary palaeoenvironmental evidence, into which sediment DNA results will be incorporated.