1. Palaeogenetics Group, Institute of Anthropology, Johannes Gutenberg University, 55099 Mainz, Germany.
2. Department of Anthropology, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada.
3. Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany.
4. Department of Archaeology, University of Durham, Durham, DH1 3LE, UK.
5. Institute of Prehistoric Archaeology, Free University of Berlin, 14195 Berlin, Germany.
6. Research Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK.