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Precision dating of the Palaeolithic: chronological mapping of the Middle and Upper Palaeolithic of Eurasia

Final Report Summary - PALAEOCHRON (Precision dating of the Palaeolithic: chronological mapping of the Middle and Upper Palaeolithic of Eurasia)

This proposal explored the Middle to Upper Palaeolithic transition of Eurasia, the period between ~70-30,000 years ago which witnessed to expansion of the first modern humans out of Africa and into Eurasia. We are interested in how this occurred, what contact our ancestors had with other forms of human living outside Africa, particularly the Neanderthals (predominantly western Eurasia) and the Denisovans (the east). This is a crucially important period for understanding late human evolution. The project focused on the construction of a reliable chronology for more than 100 key sites dating to this period and spanning from western Europe to eastern Siberia. We knew prior to beginning the project that previous radiocarbon dates for the period are known to be severely problematic, principally because of difficulties in removing contaminants. Our team has been been at the forefront of developing new pretreatment chemistries that have recently transformed the situation. These include the use of ‘ultrafiltration’ to purify proteins and single amino acid dating of bones prior to radiocarbon measurement. When we apply these methods to the dating of material from European Palaeolithic sites we have observed significant differences from previous dates and this has led to a revision in the chronology of the transition. Other dating methods are also increasingly refined and applicable in the field, including optical dating of sediments, which we also applied in this project.

We have worked on the key sites in the period over the last 6 years, augmenting the chronology of these sites and this is allowing us to now build spatio-temporal models of the results to look at the pathways of modern human expansion and the decline of, particularly, Neanderthal populations as they expand. We have also worked on the Denisovans at the eponymous site in the Russian Altai. We developed the key chronology for the site, and developed a new Bayesian approach to dating the human remains within the site (this was published in Nature this January-2019).

We also applied Zooarchaeology by Mass Spectrometry (ZooMS) to identify tiny bone fragments from Palaeolithic archaeological sites to genus or species. From just a microscopic sample of bone, this analysis reveals the collagen peptide sequences in the bone that mark out one species from another. We profiled sequences from >5000 unidentified bone fragments from Denisova cave and compared the sequences obtained against a reference library of peptides from known animal species. We found the first bone fragment in 2015. It’s DNA initially suggested it was a Neanderthal, but the full nuclear genome showed that it is a genetic hybrid, with a Neanderthal mother and a Denisovan father. This was published in 2018 again in Nature. Our work here continues and thus far we have found 8 hominin bone fragments which are being genetically analysed now.

In Belgium our work has explored the latest Neanderthals living in continental Europe. As in other contexts this shows that many of the previous dates, suggesting Neanderthals may have survived after ~35,000 years ago, are not correct. Our new results refine this and suggest that instead Neanderthals disappeared from this region before ~41,000 years ago. More detailed Eurasian wide analysis of the wide suite of our results is ongoing with publication expected in the next 1-2 years.