Ice-Age Euro-trips

Recent works that attempt to get at human migrations inside Europe paint a complex portrait of migratory events, admixture with archaic hominids, and adaptive evolution to new geographies, and a changing global climate. Analyzing whole genomes of 51 ancient humans (from 45,000-7,000 ybp) across Europe, Fu et al. (2016) sought to address these complexities with quite possibly the largest ancient genome study till date.

Location and age of the 51 ancient modern humans, Image courtesy: Q Fu et al. Nature 1–16 (2016) doi:10.1038/nature17993

Location and age of the 51 ancient modern humans, Image courtesy: Q Fu et al. Nature 1–16 (2016) doi:10.1038/nature17993

Analyzing percentages of Neanderthal ancestry across these individuals, Fu et al. (2016) report conformity with expected declines (3.2-4.2% to 1.8-2.3%), with a stronger signal around genic regions than in others due to selection against Neanderthal DNA. Analyses of shared Y chromosome haplogroup variation among samples revealed the presence of the R1b (prominent in Western Europe) in the ~14,000 year old Villabruna sample in Italy pointing to a much ancient wave of migrants from East into West (than the Bronze Age migrations that are largely accepted). This observation was also supported by presence of the eye color variant allele (HERC2), and other haplogroups in more ancient Western European individuals.

Fu et al. (2016) also study clustering of individuals (based on shared drift), describing the 51 individuals into five clusters (Vestonice, Mal’ta, El Miron, Villabruna, and Satsurblia, after the oldest individual in each cluster), based largely on their age, while few individuals were admixed among clusters. Reconstructing their history by building an admixture graph, the authors report a complex sequence of historical events that point to (1) refuting previous evidence of three major lineages in modern European genomes, (2) modern Europeans share ancestry with at least ancient Europeans dating to 37,000 ybp, and (3) possible long distance migrations between Europe and the Near East around 14,000 ybp.

An important direction for future work will be to generate similar ancient DNA data from southeastern Europe and the Near East to arrive at a more complete picture of the Upper Paleolithic population history of western Eurasia.

Reference:

Fu, Q., Posth, C., Hajdinjak, M., Petr, M., Mallick, S., Fernandes, D., Furtwängler, A., Haak, W., Meyer, M., Mittnik, A. and Nickel, B., 2016. The genetic history of Ice Age Europe. Nature. DOI: 10.1038/nature17993

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About Arun Sethuraman

I am a computational biologist, and I build statistical models and tools for population genetics. I am particularly interested in studying the dynamics of structured populations, genetic admixture, and ancestral demography.
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