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Saturday, February 16, 2013

Post-Mesolithic population replacements/extinctions in Northeastern Europe


The main theme of this paper by Der Sarkissian et al. is the changing character of the Northeastern European gene pool from the Mesolithic to the present. According to the authors, the genetic history of Northeastern Europe probably goes something like this...

- Northwestern Eurasia, all the way from Iberia to Central Siberia, was home to a relatively homogenous gene pool during the Mesolithic, with high frequencies of mtDNA haplogroups U4, U5 and U2e.

- Populations carrying high levels of East Eurasian mtDNA haplogroups (C, Z and D) migrated to Northeastern Europe during the early metal ages.

- Waves of migrants from Western and Central Europe caused large-scale population replacement/extinctions in Northeastern Europe possibly from the Neolithic onwards.

The paper is obviously open access, just like all PLoS articles, but below are some quotes and figures that caught my eye:

On the basis of modern genetic data, hg U was proposed to have originated in the Near East and spread throughout Eurasia during the initial peopling by anatomically modern humans in the early Upper Palaeolithic (around 45,000 yBP, [5]). It is then plausible that hg U constituted the major part of the Palaeolithic/Mesolithic mtDNA substratum from Southern, Central and North East Europe to Central Siberia. It can also be suggested that the Palaeolithic/Mesolithic mtDNA substratum has been preserved longer in NEE (Northeastern Europe) than in Central and southern parts of Europe, where new lineages arrived with incoming farmers during the Neolithisation from the Near East [16]. This is supported by ancient genomic data obtained from hunter-gatherers of Scandinavia [58] and Spain [57], that shows a genetic affinity between Mesolithic individuals and present-day northern Europeans and supports genetic discontinuity between Mesolithic and Neolithic populations of Europe.

The detection of haplogroup H in the Mesolithic site of aUz (one haplotype) is noteworthy. To date, haplogroup H has either been rare or absent in groups of hunter-gatherers previously described. It has not been found in hunter-gatherer mtDNA datasets of eastern Europe [12] and Scandinavia [13], but has been found in two hunter-gatherers of the Upper Palaeolithic sites of La Pasiega and La Chora in northern Spain [20]. The closest match to the ancient H haplotype in aUzPo belongs to subhaplogroup H2a2 [59], which is more common in eastern Europe [60] with highest frequencies in the Caucasus.

...

Interestingly, samples from aBOO, which are 4,000 years younger and located further North-West than aUzPo, were characterized by a large proportion and elevated diversity of mtDNA lineages showing a clear ‘Central/East Siberian’ origin (hgs C, D, and Z). Haplogroups C and D are the most common hgs in northern, central and eastern Asia. They are thought to have originated in eastern Asia and expanded through multiple migrations after the Late Glacial Maximum (,20,000 yBP [63]). Notably, haplotypic matches were observed between aBOO and modern-day central Siberian Buryats of the peri-Baikal region, which was proposed to be the origin of ancient migrations that disseminated hgs C and D [63]. Today, the sharp western boundary for the distribution of hgs C, D and Z lies in the VUB (Volga-Ural Basin), where they display intermediate frequencies: C (0.3–11.8%), Z (0.2–0.9%), and D (0.6–12%) [64].

...

The present-day Saami populations display clear haplotypic differences from all the ancient populations sampled for DNA so far (prehistoric hunter-gatherer populations of North/South/Central/East Europe, aUzPo and aBOO) where none of the hg V and U5b1b1a lineages distinctive of the Saami could be detected. We show here that the mitochondrial ancestors of the Saami could not be identified in the ancient NEE populations of aUzPo or aBOO, despite the latter site being within the area occupied by Saami today. The widespread modern-day distribution of U5b1 and V lineages makes it difficult to identify the origins of the Saami [32].

...

Saami mtDNA diversity has been influenced by a combination of founder event(s), (multiple) bottlenecks, and reproductive isolation, which are likely due to the challenging conditions of life in the subarctic taiga/tundra [32]. The complex demographic history of Saami renders their population history difficult to reconstruct on the basis of modern genetic data alone. Further temporal population samples will be required, especially along the proposed alternative western migration route into sub-arctic Europe.

...

The results of our coalescent simulation analyses show that the models that take account of genetic input(s) from CE (Central Europe) are better supported and could explain the genetic discontinuity observed between either aUzPo or aBOO and the modern population of NEE (Figure 5). The mtDNA lineages with a clear Central/Western European signature and currently prevalent in NEE might have reached the western Baltic and southern Scandinavia during the continuing influx of farming populations from Central or lastly southeastern Europe [13], [58], as from 6,000 yBP onwards [71–74]. However, intruding Neolithic farmers never reached Karelia and Fennoscandia [75], so the change in population would have to be a post-Neolithic process or to be due to migrations from other sources.





Der Sarkissian C, Balanovsky O, Brandt G, Khartanovich V, Buzhilova A, et al. (2013) Ancient DNA Reveals Prehistoric Gene-Flow from Siberia in the Complex Human Population History of North East Europe. PLoS Genet 9(2): e1003296. doi:10.1371/journal.pgen.1003296

See also...

New subclade of mtDNA haplogroup C1 from Mesolithic Northeastern Europe


2 comments:

Dan Kalina said...

i would die to have ancient y-dna from this region of the world that was pre-neolithic.

andrew said...

The story of the Saami is told partially by mtDNA V which is found in the NW African Berbers, in Iberia including ancient DNA, and then in many Atlantic coastal areas of Continental Europe. I suspect that this is an expansion in both directions by maritime foragers from the Franco-Cantabrium refugium in the Mesolithic. The U5b1 also fits this hypothesis.