The stratigraphy at Bacho Kiro Cave, Bulgaria, spans the Middle to Upper Palaeolithic transition, including an Initial Upper Palaeolithic (IUP) assemblage argued to represent the earliest arrival of Upper Palaeolithic Homo sapiens in Europe. We applied the latest techniques in 14C dating to an extensive dataset of newly excavated animal and human bones to produce a robust, high-precision radiocarbon chronology for the site. At the base of the stratigraphy, the Middle Palaeolithic (MP) occupation dates to >51,000 yr bp. A chronological gap of over 3,000 years separates the MP occupation from the occupation of the cave by H. sapiens, which extends to 34,000 cal bp. The extensive IUP assemblage, now associated with directly dated H. sapiens fossils at this site, securely dates to 45,820–43,650 cal bp (95.4% probability), probably beginning from 46,940 cal bp (95.4% probability). The results provide chronological context for the early occupation of Europe by Upper Palaeolithic H. sapiens.
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The re-excavation of Bacho Kiro Cave is a joint project between the National Institute of Archaeology and Museum, Bulgarian Academy of Sciences, Sofia and the Department of Human Evolution at the Max Planck Institute for Evolutionary Anthropology, Leipzig. This work was funded by the Max Planck Society. Graphitization and AMS dating in Switzerland were funded by ETH Zürich. The AixMICADAS and its operation are funded by the Collège de France and the EQUIPEX ASTER-CEREGE (Principle Investigator: E.B.). S.T. is funded by the European Research Council under the European Union’s Horizon 2020 Research and Innovation Programme (grant agreement No. 803147-951 RESOLUTION, awarded to S.T.). We acknowledge The National Museum of Natural History (Sofia), the Archaeology Department at New Bulgarian University (Sofia), the Regional Historical Museum in Gabrovo, the History Museum in Dryanovo and the guest house Platex in Dryanovo for their assistance in this project. We acknowledge the vital contribution of all the excavators who have worked at Bacho Kiro Cave since 2015.
The authors declare no competing interests.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
View of the Niche 1 (left) and Main Sector (right), looking toward the south in the cave. The concrete floor in the centre covers the 1970s excavation area.
a, Plan view of the entry hall and the excavated area, with the grid system of the recent excavations (black letters) and those of the 1971-75 excavations (grey letters). Red lines indicate the locations of the profile columns from Niche 1 (b) and Main Sector (c). b, Stratigraphic section-log in the Niche 1 in 2018. Layer attributions in the Niche 1 have an ‘N1-‘ prefix. c, Initial stratigraphic section-log in the Main Sector in 2015. Numbers in parentheses show the layer attributions from the 1970s excavations. Legend for the stratigraphic units shown on the left.
a, Main Sector and b, Niche 1, separated by layer and layer contact zones (I/J, N1-J/K, N1-I/J, N1-H/I). The dashed line shows the minimum level of collagen preservation generally considered suitable for 14C dating.
a, F6-597 comes from Layer B of the new excavations and b, BK-1653 comes from the 1970s collection (Layer 6a/7) that is stored in the National Museum of Natural History in Sofia. The purple range shows the weighted mean age and error of all the dates measured from graphite targets and directly from CO2 gas (shown in Supplementary Table 6), calculated using the R_Combine function in OxCal 4.345.
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Fewlass, H., Talamo, S., Wacker, L. et al. A 14C chronology for the Middle to Upper Palaeolithic transition at Bacho Kiro Cave, Bulgaria. Nat Ecol Evol 4, 794–801 (2020). https://doi.org/10.1038/s41559-020-1136-3
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