Subarctic climate for the earliest Homo sapiens in Europe.

Acknowledgments The re-excavation of Bacho Kiro Cave was jointly conducted by the National Institute of Archaeology with Museum, Bulgarian Academy of Sciences, Sofia and the Department of Human Evolution at the MPI-EVA. We would like to thank the National Museum of Natural History (Sofia), the Archaeology Department at the New Bulgarian University (Sofia), the Regional Museum of History in Gabrovo, and the History Museum in Dryanovo for assistance on this project and the opportunity to study the Bacho Kiro Cave faunal material. We would like to thank M. Trost, S. Hesse, M. Kaniecki, and P. Dittmann (MPI-EVA) for technical assistance during stable isotope sample preparation. S. Steinbrenner is thanked for technical assistance with TC/EA-IRMS maintenance. Thanks are also due to H. Temming and U. Schwarz (MPI-EVA) for the production of microCT scans and replicas of the sample materials. We would also like to acknowledge the assistance of to D. Veres with taking OSL samples. Last but not least we would like to thank the handling editor, S. Ortman, as well as three anonymous reviewers for their thoughtful comments that greatly improved this manuscript. Funding: The field work was financed by the Max Planck Society. The stable isotope work was funded by the Max Planck Society as part of S.P.’s doctoral project. S.P. was supported by the Max Planck Society and the University of Aberdeen. K.B. was supported by a Philip Leverhulme Prize from The Leverhulme Trust (PLP-2019-284). N.B.’s work was supported as part of a grant by the German Research Foundation (“PALAODIET” Project 378496604). V.A. was supported by a grant from the Foundation for Science and Technology, Portugal (IF/01157/2015/CP1308/CT0002). Author contributions: The study was devised by S.P., K.B., S.P.M., J.-J.H., and T.T. Archaeological excavation was undertaken by N.S. and T.T. in collaboration with Z.R. and S.P.M. who all contributed contextual information. V.A. collected sedimentological data at the site and untertook micromorphological investigations that provided information on site formation for this study. Zooarchaeological and paleontological analyses were performed by G.M.S. and R.S. OSL dating was carried out by T.L. Radiocarbon dating and recalibration of radiocarbon dates were conducted by H.F. MC-ICPMS analysis was conducted by N.B. and S.P. Sampling, sample processing for oxygen and strontium stable isotope analysis, and TC/EA-IRMS analysis were carried out by S.P. Code and data analyses were written and conducted by S.P. N.-H.T. consulted on statistical analysis and coding. S.P. wrote the paper with input from all authors. Competing interests: The authors declare that they have no competing interests. Data and materials availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. This paper and the Supplementary Materials were generated completely using R and Rmarkdown, making all analyses and figures reproducible via the RMarkdown documents. These documents containing all analysis code, as well as all underlying data files, can be found in an OSF repository at https://osf.io/tk9dc/. All stable isotope data generated here are additionally available in tables S2 and S3 of this article. The faunal remains that were sampled for stable isotope analysis have been returned to the History Museum in Dryanovo and are available to any researcher to be studied.