1. School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
2. Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA
3. Section for Evolutionary Genomics, Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, 1307 Copenhagen K, Denmark
4. Department of Archaeology, University of York, PO Box 373, York, UK