https://www.biorxiv.org/content/10.1101/687384v3.full
"In this paper, we test the hypothesis that increased Caucasian component in contemporary SE Europeans, has been introduced on the Balkans by migrating Iron Age steppe dwellers from Pontic-Caspian steppe. We analyze available DNA datasets from both ancient and contemporary samples and identify a Caucasian signal, carried to Balkan populations by the nomadic dwellers of Early Medieval Saltovo-Mayaki Culture, located on the northern slope of Caucasus Mountains and adjacent steppe regions. We also identify two additional sources of Caucasian admixture in SEE populations, which are not specific to Bulgarian population only. Based on the results from our population genetic analysis we suggest that contemporary Bulgarians are an admixture of ancestral Slavonic groups, rich on locally absorbed EEF DNA and Proto Bulgarians, rich on Caucasian DNA and genetically related to the bearers of the Saltovo-Mayaki Culture from 8-10 century AD."
Fig. 1
Contemporary Bulgarians show an extra layer of Caucasian admixture, which is missing from the Bronze Age Balkan population (BAB). BAB are a mixture of Yamna migrants and EEF - just as rest of European populations. On the plot we can see that contemporary Bulgarians are closer to the Caucasian cluster than Bronze Age Balkan samples are. PCA after Haak W, Lazaridis I, Patterson N, et al. Massive migration from the steppe was a source for Indo-European languages in Europe. Nature. 2015;522(7555):207-11., Mathieson I, Alpaslan-Roodenberg S, Posth C, et al. The genomic history of southeastern Europe. Nature. 2018;555(7695):197-203
"On the map (Fig. 1) contemporary Bulgarians are distributed nearer to contemporary Caucasians than most European populations which suggests an extra degree of Caucasian admixture that has been absent in the rest of Europe. This implies admixture events that are specific to Bulgarian population and whose effects are limited to the area of Balkan Peninsula mostly."
"The increase in Caucasian component in contemporary Bulgarians postdates Bronze Age migrations. Historical literature suggests that the arrival of this component in Bulgarian population could be related to the migration of Protobulgarians (Bulgars) during 6-8 century AD and the foundation of First Bulgarian Kingdom (V. Zlatarski, S. Runsiman, R. Rashev). Century long archeological research has identified northern Caucasian slopes and adjacent Kuban River zone as the likely homeland of the migrating Bulgars. Archaeological research suggests intensive contacts between Bulgars and the neighboring Caucasian and Alanic tribes, including the emergency of material culture of mixed origin, suggestive of a synthesis between IA Caucasian and IA steppe traditions, emerging in the zone of Cuban river during Saltovo-Mayaki Culture (SMC, 8-10 century AD)."
"Using statistical genome-wide analysis, we detected nontrivial genetic connection between contemporary Bulgarians, inhabitants of Bronze Age Armenian plateau and Iron Age dwellers from SMC. Our analysis also suggests surprising connection between contemporary Bulgarians and Iron Age Scythians from Hungarian plain."
Fig. 2
PCA on the relationship between contemporary Bulgarians and ancient samples from BA and IA Eurasian steppe. While none of the contemporary Bulgarians yields relation to the ancient CA populations, PCA1 suggests genetic connection between contemporary Bulgarians and IA individuals AlanDA243, AlanDA164 and Alan DA146 from North Ossetia and SMC.
"The results of PCA (Fig 2) renders direct connection between contemporary Bulgarians and Inner Asian steppe nomads from migration period unlikely. None of the contemporary Bulgarians yielded any direct or mediated relation to the ancient Far Eastern and Central Asian nomadic steppe populations.
"In order to examine population transformation in what is now contemporary Bulgaria from early Bronze Age trough Iron Age till now, we also added 8 ancient samples from the late Neolithic / Early Bronze Age and early Iron Age, which we retrieved from Haak et al 2015, 207-11 and from Mathieson et al 2018, 197-203.). We present the results in Fig. 3"
Fig. 3
There is statistically significant relationship between contemporary Bulgarians and the Protobulgarians from SM. The genetic affinities detected by PAST3 suggest that SM people have contributed to contemporary Bulgarians only and their contribution to the rest of Balkan population has been transmitted from contemporary Bulgarians to their geographical neighbors.
"PCA results suggest genetic connection between contemporary Bulgarians and the ancient individuals AlanDA243, AlanDA164 and Alan DA146 belonging to SM culture.
In our next PCA we added Scythian samples from Hungarian plain from 4th Century BC (classical antiquity). The plot suggests connection between Scythian samples, European Alans from the migration period and the nomads from the Saltovo-Mayaki Culture as all 3 groups showed genetic connection to contemporary Bulgarians. (fig. 4)"
Fig. 4
These results imply nomadic influence from migration period being carried over to the population genomics of contemporary Bulgarians.
"Our PCA (Fig.2) also revealed indirect connection between contemporary Bulgarians and central Asian Bronze Age nomads of East Iranic origin known as Kangju group. This relation however is dependent on the presence of sample Alan DA146 from Saltovo-Mayaki (Saltovo, SM for short) culture on the PCA Plot and disappears if we remove this sample from the plot. We suggest that this discrete connection represents earlier stages of the migration of certain proto SM groups (Sarmatians-Alans?). Yet the rest of SM samples did not yield same connection to Kangju but showed detectable connection to the samples from Bronze Age Armenian plateau (fig. 2), suggestive of multiple admixture events during different earlier stages of migrations and contacts of SM people, as one of these stages must have included Armenian plateau in Central Caucasus."
"We noted that SM (Protobulgarian-Alan) influence among contemporary Balkan nations has its strongest representation in contemporary Bulgarians (Fig 4) where it arrives directly and this Protobulgarian influence in the other Balkan nations is mediated by the contemporary Bulgarians who channel it."
Neighbor joining tree, built with PASTX software on the base of genetic relationship between the samples:
"Conclusions from the DNA data analysis
The results suggest that SMC related populations are among the precursor of contemporary Bulgarians. This makes SM culture at its precursor stage (600-700 AD) leading candidate for the source population of Asparukh Bulgarians. These results also suggest that Asparukh’s tribe(s) are indistinguishable from the Sarmato-Alanic groups from Early MA and Late antiquity and, surprisingly, do not carry Siberian and Central Asian admixture on the Balkans with them. Unlike BA Thracians and the early Slavs, SMC carry substantial Caucasus admixture, related to the tribes from Bronze Age Armenian plateau and seems to have transmitted this admixture to the contemporary Bulgarians. The relationship between Protobulgarians and Sarmato-Alanic tribes from the Late antiquity and Early medieval epoch remains to be clarified further, however genome wide-data suggest that Protobulgarians were themselves an admixture in equal proportions between two close, but distinct populations −1. Alano-Sarmatian tribe from the region north of Caucasus with some Kangju link to it and 2. Unknown tribe(s) originating from what is now Armenian Plateau. Both Scythian samples from the Hungarian steppe and the Alans from Saltovo-Mayaki culture bear strong genetic resemblance to the Bronze Age Caucasian samples, which is missing in central Asian nomads but is presented in the contemporary Bulgarians.
Our results cast a doubt on a connection between Inner Asian nomadic tribes from Antiquity and the Protobulgarians-Alans from SM culture and Northern Caucasus. The lack of Inner Asia autosomal DNA links for the Protobulgarians confirms the results from the mtDNA sampling of materials from 8th-9th c. necropolises on the Lower Danube. The main haplogroup H (H, H1, H5, and H13) prevalent in European populations has a 41.9% frequency in modern Bulgarians, and it was observed in 7 of 13 proto-Bulgarian samples. Again no evidence was found of East Asian (F, B, P, A, S, O, Y, or M derivative) haplogroups (Nesheva et al 2015, 22). An earlier major representative survey of present dale male lineages in Bulgaria (over 800 individuals) revealed that “Haplogroups C, N and Q, distinctive for Altaic and Central Asian populations, occur at the negligible frequency of only 1.5%.” (Karachanak et al 2013). Our research suggest that author’s conclusion of the survey that “…our data suggest that a common paternal ancestry between the proto-Bulgarians and the Altaic and Central Asian populations either did not exist or was negligible…”(Karachanak et al 2013, abstract) was correct."
The study from 2013 he mentioned at the end -
https://journals.plos.org/plosone/ar...l.pone.0056779
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