An estimate of the admixture time for Finns

Using a similar procedure as in my recent post on the Baltic (Update II), I used 15 FIN individuals from the 1000 Genomes together with 12 Nganasans from Rasmussen et al. (2010) as reference populations, and 15 other FIN individuals to estimate admixture LD in a rolloff analysis. Three outlier Nganasan individuals (GSM558800, GSM558802, GSM558807) were removed.

The estimated time of admixture is 86.095 +/- 10.187 generations, or 2500 +/- 300 years. It corresponds rather well to the beginning of the Iron Age in northern Europe.

As I mention in my previous post, there is evidence for intrusive cultures (Battle Axe and Seima Turbino) converging on the area from different directions during the preceding Bronze Age. If the above date is accurate, it will suggest a rather late admixture event between the Europeoid and Siberian elements of Finns. The former may have included both the descendants of Mesolithic European hunter-gatherers and intruders from Central Europe (Corded Ware/Battle Axe); the latter may have included both Comb Ceramic and the descendants of the Seima Turbino metallurgists.

Medieval West Siberian mtDNA

J Hum Genet. 2011 Jul 14. doi: 10.1038/jhg.2011.68. [Epub ahead of print]

Genetic features of ancient West Siberian people of the Middle Ages, revealed by mitochondrial DNA haplogroup analysis.

Sato T, Razhev D, Amano T, Masuda R.

In order to investigate the genetic features of ancient West Siberian people of the Middle Ages, we studied ancient DNA from bone remains excavated from two archeological sites in West Siberia: Saigatinsky 6 (eighth to eleventh centuries) and Zeleny Yar (thirteenth century). Polymerase chain reaction amplification and nucleotide sequencing of mitochondrial DNA (mtDNA) succeeded for 9 of 67 specimens examined, and the sequences were assigned to mtDNA haplogroups B4, C4, G2, H and U. This distribution pattern of mtDNA haplogroups in medieval West Siberian people was similar to those previously reported in modern populations living in West Siberia, such as the Mansi, Ket and Nganasan. Exact tests of population differentiation showed no significant differences between the medieval people and modern populations in West Siberia. The findings suggest that some medieval West Siberian people analyzed in the present study are included in direct ancestral lineages of modern populations native to West Siberia.

Link

Multidimensional scaling and ADMIXTURE across Northern Eurasia corresponds to geography and language

Here is a multi-dimensional scaling plot of a number of North Eurasian populations. In comparison to my previous post, I have excluded Americans and Greenlanders, and added several other populations from Central Asia and West Eurasia.

Population labels have been printed in the co-ordinates of the population averages; these largely correspond with identifiable blobs of colored points, but note that some populations have several outliers, so labels appear in white space. Most notable in that respect are the Koryak, Chukchi, and the Nganasan, all of whom have some apparently European-admixed individuals.

"Mongol" corresponds to Rasmussen et al. (2010) Mongol sample, while "Mongola" to the HGDP-CEPH one. The population codes on the left may not be clearly visible as they overlap with each other and are CEU, LT, HU (relatively unadmixed Caucasoids), FI/RU (Uralian-admixed northern Caucasoids), IR/TR (Altaic-admixed southern Caucasoids). The West Eurasian part of the plot can be seen blown up on the right.

The correspondence with geography and language is striking. Siberian isolates from the extreme north and east, Koryak and Chuckhi are on top; HapMap Chinese at the bottom. Between them are Uralians (Selkup, Yukagir, Nganassan) and Altaics (Mongol-Tungus-Turkic people).

Below is ADMIXTURE analysis for the same set of populations, for K=7:

Finns and Russians seem to have an excess of the "Nganasan" component over the Altaic, while Turks have the opposite. Below is a table of Fst distances between components:

The close relationship between the two Caucasoid components is apparent (Fst=0.033), but note fairly large Fst divergences between the morphologically Mongoloid groups. I attribute this mostly to the very low population sizes of these groups, which have probably affected them by drift. For the less demographically constrained Altaic and East Asian components, Fst=0.044.

If you are not familiar with these ethnic groups, the Red Book of the Peoples of the Russian Empire and the Ethnologue indexes on Altaic and Uralic are invaluable, as are the portraits of ethnic groups of China. On the right a picture of a Nganasan.

UPDATE: Also, a past post from the blog, collating Y-haplogroup N frequencies with anthropological descriptions. Nganasans apparently belong to haplogroup N at a frequency of 92.1%!