Genotyping of 390,000 SNPs in more than forty 3,000-9,000 year old humans from the ancient Russian steppe

David Reich 1 ,2, Nadin Rohland1 ,2, Swapan Mallick1 ,2, Iosif Lazaridis1, Eadaoin Harney1, Susanne Nordenfelt1, Qiaomei Fu3, Matthias Meyer3, Dorcas Brown4, David Anthony4, Nick Patterson2
1Harvard Medical School, Boston, MA, USA, 2Broad Institute of Harvard and MIT, Cambridge, MA, USA, 3Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany, 4Hartwick College, Oneonta, NY, USA

 A central challenge in ancient DNA research is that for many bones that contain genuine DNA, the great majority of molecules in sequencing libraries are microbial. Thus, it has been impractical to carry out whole genome analyses of substantial numbers of ancient individuals.  We report a strategy for in-solution capture of ancient DNA from approximately 390,000 single nucleotide polymorphism (SNP) targets, adapting a method of Fu et al. PNAS 2013 who enriched a 40,000 year old DNA sample for the entire chromosome 21. Of the SNPs targets, the vast majority overlap the Affymetrix Human Origins array, allowing us to compare the ancient samples to a database of more than 2,700 present-day humans from 250 groups.

We applied the SNP capture as well as mitochondrial genome enrichment to a series of 65 bones dating to between 3,000-9,000 years ago from the Samara district of Russia in the far east of Europe, a region that has been suggested to be part of the Proto-Indo-European homeland. We successfully extracted nuclear data from 10-90% of targeted SNPs for more than 40 of the samples, and for all of these samples also obtained complete mitochondrial genomes. We report three key findings:

We report modeling analyses showing how the steppe samples may relate to ancient and present-day DNA samples from the rest of Europe, the Caucasus, and South Asia, thereby clarifying the relationship of steppe groups to the genetic, archaeological and linguistic transformations of the late Neolithic and Bronze ages.