Diverse genetic origins of medieval steppe nomad conquerors

Abstract

Over millennia, steppe nomadic tribes raided and sometimes overran settled Eurasian civilizations. Most polities formed by steppe nomads were ephemeral, making it difficult to ascertain their genetic roots or what present-day populations, if any, have descended from them. Exceptionally, the Khazar Khaganate controlled the trade artery between the Black and Caspian Seas in VIII-IX centuries, acting as one of the major conduits between East and West. However, the genetic identity of the ruling elite within the polyglot and polyethnic Khaganate has been a much-debated mystery; a controversial hypothesis posits that post-conversion to Judaism the Khazars gave rise to modern Ashkenazim. We analyzed whole-genome sequences of eight men and one woman buried within the distinctive kurgans of the Khazar upper (warrior) class. After comparing them with reference panels of present-day Eurasian and Iron Age populations, we found that the Khazar political organization relied on a polyethnic elite. It was predominantly descended from Central Asian tribes but incorporated genetic admixture from populations conquered by Khazars. Thus, the Khazar ruling class was likely relatively small and able to maintain a genetic identity distinct from their subjugated populations over the course of centuries. Yet, men of mixed ancestry could also rise into the warrior class, possibly providing troop numbers necessary to maintain control of their large territory. However, when the Khaganate collapsed it left few persistent genetic traces in Europe. Our data confirm the Turkic roots of the Khazars, but also highlight their ethnic diversity and some integration of conquered populations.

Diverse genetic origins of medieval steppe nomad conquerors – a response to Mikheyev et al. (2019)

“…Following Klyosov and Faleeva (2017) who sequenced the first Y chromosomes of the Khazar, Mikheyev et al (2019) have pioneered the first ancient genome study of nine Khazar samples deemed to belong to upper (warrior) class. We have shown that consistently throughout their study Mikheyev et al (2019) carried out experiments and analyses that are inconsistent with the standards in Paleogenomics and population genetics. We questioned the authors' choice of analyses, populations, and markers and demonstrated that the authors' analyses are biased and lead to erroneous conclusions.…”

“…A further curiosity concerns the author's emphasis on demonstrating the correlation between genetics and geography in their samples and their results for Ashkenazic Jews. Their analyses (Mikheyev et al (2019) Figure 1A) shows that Ashkenazic Jews cluster with North Ossetia and Caucasus populations, rather than their neighboring communities. It is difficult to reconcile this finding with the authors' beliefs that the high genetic-geographic correlation makes their populations "strongly informative about the geographic origins of the Khazars" and their criticism towards past studies that showed a Caucasus origin for Ashkenazic Jews (Das et al 2016;Das et al 2017).…”

“…Analyzing 367 Ashkenazic Jews, Das et al (2016) Several points are noteworthy from this analysis: first, that similarity in haplogroups cannot support or disprove the relationships between Ashkenazic Jews and the Khazars, provided the great heterogeneity of the two groups. The apparent heterogeneity of the "Khazars" apparent in all the analyses casts doubts on the ability to consider them a single group; second that Das et al's (2016) study is sufficient to refute the authors' allegation of the "genetic homogeneity of the worldwide Jewish population," employed to excuse their small sample sizes; and third that the authors hypothesis that Ashkenazic Jews have descended from a minority group of Khazar royalty is a novel absurdity conjectured by Mikheyev et al (2019). Even assuming that the Ashkenazic Jews who descended directly from the Khazar royalty survived to modern time, a comprehensive analysis of various Ashkenazic Jews would have still yielded "no significant trace of Ashkenazi genetic composition in either nuclear, mitochondrial or Y-chromosome data.…”

“…Working in a "clean room," while satisfying the basic criteria of any lab work, is insufficient to prevent contamination and cannot guarantee reproducible and authentic results. To the best of our knowledge, the study design of Mikheyev et al (2019) has failed to adhere to these standard requirements.…”

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Recently, Mikheyev et al (2019) have produced a preprint study describing the genomes of nine Khazars archeologically dated from the 7 th to the 9 th centuries found in the Rostov county in modern-day Russia. Skull morphology indicated a mix of "Caucasoid" and "Mongoloid" shapes.

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