tested bone fragments of a grave found near Pokrovsk, a locale the Russian federal republic of Sakha (Yakutia
The Pokrovsk grave is located at the top of a glacial terrace near the Lena-Pokrovsk river junction. Radiocarbon datin
 |
| Allelic Frequencies |
auDNA Analysis
Nine auDNA STR’s were retrieved from the Pokrovsk Man's remains. Unfortunately, the utilisation of STR's is questionable given they have a large margin of error and lack of population specificity due to the presence of multiple alleles within a single population, as well as heavy inter-population overlapping. This investigative tool has largely been made redundant by SNP testing, which employ thousands of markers rather than a few. Nonetheless, processing of these results will still be attempted.
The allelic frequencies per worldwide regional groups for the retrieved STR’s are shown opposite. All markers from the Profiler+ Multiplex were utilised in the subsequent popSTR search. The sample populations are largely derived from the HGDP-CEPH Human Genome Diversity Cell Line Panel. [4]
African frequencies of the Pokrovsk alleles are generally lower relative to Eurasian, Oceanian and American regional groups. This warrants the exclusion of such values from the analysis hereon due to their uninformative nature, apart from confirming the Pokrovsk Man had no recent African ancestry, which is in accordance with anthropological, historical and linguistic data from Siberia. Allele frequencies of remaining regions are shown in the
Data Sink.
To elucidate the regional affinities of the Pokrovsk Man, averages for the alleles across the given regions were taken and ranked in order of descending magnitude (found again in the
Data Sink).
The results indicate his affinity was greatest to the Americas, followed by East Asia and Europe (discussed later) in joint position, ending with the Middle-East and South-Central Asia. The discrepancy between the American and East Asian scores are explained by the East Asia regional group being constituted largely of ethnic groups from East Asia proper and Southeast Asia, such as the She, Naxi and Japanese. The Yakuts, who are the only sample population located in Siberia, are a part of this group, reducing the specificity further. However, the greater score to native American and East Asian populations than others is still consistent with both geographic position and the known demic expansions into of both regions.
The decreased allelic frequency average of South-Central Asians and Middle-Easterners with the Pokrovsk Man supports the above further. However, the Middle-Eastern group did not include populations from West Asia or the Caucasus, such as Anatolian Turks, Iranians or Georgians. Additionally, the lack of North-Central Asian ethnic groups such as the Kazakh, Tatars or Altaians may affect the results further.
It would have been preferable if auDNA SNP’s were obtained instead and compared with specific sample populations - Better yet if IBD segment analysis was also undertaken. SNP analysis could have been possible in 2006, given the HGDP-CEPH samples were made available at least four years prior, [4] which would have opened the door to analysis far deeper than the extent undertaken by Amory
et al. or even this investigation.
The authors greatly limited the extent of their own investigation, noting the Pokrovsk Man showed identical matches with Buryats, West Siberians, Altaian Mansis, ancient and modern Yakuts, one Evenk and an Egyin Gol necropolis female [5] in their private haplotype database.
mtDNA Analysis
Of the ten loci tested, only three yielded consistent nucleotide variations (16223T-16362C-16368C). The mitosearch 1-step matches with a known maternal ancestor location were considered only (
Data Sink). These results not only confirm Amory
et al.'s conclusion the Pokrovsk Man belonged to mtDNA Haplogroup D, but the bulk of the distribution within Asia is expected based on modern samples. [6]
Unfortunately, once more, the scope of the initial investigation has hindered any further analysis, as the lack of testing regions beyond HVS1 cannot elucidate the extent of mitochondrial sharing outside of the data showcased here.
Y-DNA Analysis
None of the eleven Y-DNA STR's provided a successful return. The only SNP tested for was TAT, where a T→C mutation is considered equivalent to the M46 marker, which is defined as Haplogroup N1c under the current
International Society of Genetic Genealogy (ISOGG) nomenclature. [7]
As the Pokrovsk Man yielded a T allele at this locus, his Y-DNA Haplogroup could not have been N1c-M46. However, this does not rule out him belonging to a lineage upstream of N1c-M46.
European Affinities & Conclusion
Despite the great limitations, several invaluable inferences can be made from the data presented in the furthering of Amory
et al.'s
Early influence of the steppe tribes in the peopling of Siberia which cannot be reasonably excluded as anomalous without also discarding conclusions made from other sources.
The auDNA results, though derived from STR data, fully agree with the SNP-based analysis of the
Eurogenes Project by David W. in a previous run (
described in an earlier Vaêdhya entry), as modern Siberian populations show trace values of various European or Caucasian ADMIXTURE components at the least with an absence of Southwest or South Asian specific components, whilst being predominantly Siberian and East Asian.
The European affinity in this investigation coming third may form a convenient explanation for why the Pokrovsk Man's features were less Mongoloid anthropometrically than Middle-Age Yakuts. It may suggest a West Eurasian physical element existed prior to the tribal and political upheavals that resulted in the Yakut settlement deeper into this portion of Siberia. Although the origins of this element were not elaborated upon, there may also be a connection with the postulated "migration corridor"
covered previously and described in Malyarchuk
et al.'s On the Origin of Mongoloid Component in the Mitochondrial Gene Pool of Slavs. [10]
This result supplements the picture of a West Eurasian genetic component of ambiguous origins being brought towards Siberia, challenging one interpretation of West Eurasian physical influence in the region stopping abruptly at Lake Baikal. [9] Instead, the totality of the evidence presented raises the possibility of this influence extending itself beyond the lake and manifesting itself simply as a "reduction" of Mongoloid cranial characteristics, which the Pokrovsk Man demonstrated, whose anthropometric configuration may well have been an artefact of this.
Unfortunately, the mtDNA and Y-DNA results were far too non-specific to merit further analyses. Their generality, however, do pose several questions; what subtype of mtDNA Haplogroup D did the Pokrovsk Man belong to? If he was not Y-DNA Haplogroup N1c-M46, what was he?
The material goods found in the Pokrovsk Man's gravesite may point us in the direction of the orientation his apparent European affinities came from. As South Siberia was the source of his iron and horse-derived goods, could he also have inherited West Eurasian genes from there? Were the benefactors ancient, or prehistoric?
Acknowledgements
Pokrovsk map from
WolframAlpha.
References
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8. Amigo J, Phillips C, Salas T, Fernández Formoso L, Carracedo A. pop.STR - An online population frequency browser for established and new forensic STRs. Forensic Sci. Int. Gene. Suppl. 2009.
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