1 Bioinformatics and Integrative Biology, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA; Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA.
2 The Palaeogenomics and Bio-Archaeology Research Network, Research Laboratory for Archaeology and History of Art, University of Oxford,1 South Parks Road, Oxford OX1 3TG, UK.
3 Bioinformatics and Integrative Biology, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA; Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA; Program in Molecular Medicine, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605, USA. Electronic address: elinor@broadinstitute.org.