Genetic studies on Bulgarians
Whilst haploid markers such as mtDNA and Y-DNA can provide clues about past population history, they only represent a single genetic locus, compared to hundreds of thousands present in nuclear, autosomes.
Analyses of autosomal DNA markers gives the best approximation of overall 'relatedness' between populations, presenting a less skewed genetic picture compared to Y-DNA haplogroups.
[60] The Balto-Slavic study itself calculated genetic distance by SNP data of the multiple autosomes and ranked most proximal to Bulgarians the Serbs, followed by Macedonians, Montenegrins, Romanians, Gagauzes, Macedonian Greeks apart from Thessaloniki, the rest of the South Slavs, Hungarians, Slovaks, Czechs, and then by Greeks from Thessaloniki, Central Greece and Peloponnese.
[8] Bulgarians are also only modestly close to their eastern neighbours – the Anatolian Turks, suggesting the presence of certain geographic and cultural barriers between them.
[8] The South Slavic group, despite sharing a common language, is separated and has a largely different genetic past from their northern linguistic relatives.
[5][8][9] Therefore, for the Bulgarians and most other South Slavs the most plausible explanation would be that their most sizable genetic components were inherited from indigenous Balkan pre-Slavic and pre-Bulgar population.
[8] Southeastern Europeans share large numbers of common ancestors that date roughly to the times of the Slavic expansion around 1,500 years ago.
The eastern European populations with high rates of (IBD) are highly coincident with the modern distribution of Slavic languages including Hungary, Romania, Greece and Albania, so it is speculated for Slavic expansion, anyway it was concluded that additional work and methods would be needed to verify this hypothesis.
This study detects a considerable connection between Bulgarians and North Slavs that is the result of migrations no earlier than 1500 years ago.
A signal at a low frequency among Balkan Slavs was detected that may have been inherited from the medieval Slavic settlers, but it was confirmed that this issue requires further investigation.
This might suggest Slavic gene flow across the wide area and physical boundaries such as the Carpathian Mountains, including Hungarians, Romanians and Gagauz.
The highest percentage of the total number of shared pairwise IBD segments is detected between the group of East-West Slavs and South Slavs (41% from the total number of IBD segments detected); Baltic speakers, Estonians (40%) and "inter-Slavic" Hungarians, Romanians and Gagauz (37%).
East-West Slavs share these segments with Western Europeans (32%), Volga region populations (30) and North Caucasus (21%).
The Slavic frequency of the Bulgarians is determined lower than that of Poles and Hungarians, higher than that of Greeks and roughly the same as Romanians.
[7] In the publication by Hellenthal et al., based on a database of 94 modern populations, the authors inferred over 40% of the total autosomal make-up of the Bulgarians to a legacy of the "Slavic (500-900CE)" expansion.
[76] Recent studies of ancient DNA have revealed that European populations are largely descending from three ancestral groups.
According to this, Bulgarians are predominantly (52%) descending from early Neolithic farmers spreading the agriculture from Anatolia, and from West Asian Bronze Age invaders and cluster together with other Southern Europeans.
[78] The Bacho Kiro Cave has yielded the oldest human remains ever to be found in Bulgaria which are unrelated to the modern-day Europeans.
At one of the earliest known Aurignacian burials (layer 11), two pierced animal teeth were found and ordered into the distinct Bachokiran artifact assemblage.
[86][87] In 2022, a study determined that the IUP-affiliated Bacho Kiro remains were part of an Initial Upper Paleolithic wave (>45kya) "ascribed to a population movement with uniform genetic features and material culture" (Ancient East Eurasians), and sharing deep ancestry with other ancient specimens such as the Ust'-Ishim man and the Tianyuan man, as well as ancestors of modern day Papuans (Australasians).
The Bacho Kiro population associated with the IUP material culture in Europe went extinct and replaced by the later Upper Paleolithic migration associated with West Eurasians (represented by the Kostenki-14 remains).
