Genetic structure of ancient Europe. Caucasus hunter-gatherers are represented by the Satsurbila and Kotias specimens.
Genetic affinity of modern populations to the ancient Kotias specimen.
Admixture graph of deep Eurasian lineages (Allentoft et al. 2024)
Formation and development
The CHG lineage is suggested to have diverged from the ancestor of
Western Hunter-Gatherers (WHGs) probably during the
Last Glacial Maximum (sometimes between 45,000 to 26,000 years ago).[6] They further separated from the "
Anatolian hunter-gatherer (AHG) lineage later, suggested to around 25,000 years ago during the late LGM period.[3][7] The Caucasus hunter-gatherers managed to survive in isolation since the late LGM period as a distinct population, and display high genetic affinities to Mesolithic and Neolithic populations on the Iranian plateau, such as Neolithic specimens found in
Ganj Dareh. The CHG display higher genetic affinities to European and Anatolian groups than Iranian hunter-gatherers do, suggesting a possible cline and geneflow into the CHG and less into Mesolithic and Neolithic Iranian groups.[2][8]
The Mesolithic/Neolithic Iranian lineage basal to the Caucasus hunter-gatherers are inferred to derive significant amounts of their ancestry from
Basal Eurasian (
c. 38–48%), with the remainder ancestry being closer to
Ancient North Eurasians or
Eastern European Hunter-Gatherer (ANE/EHG;
c. 52–62%). The CHG displayed an additional ANE-like component (
c. 10%) than the Neolithic Iranians do, suggesting they may have stood in continuous contact with
Eastern Hunter-Gatherers to their North. The CHG also carry around 20% additional Paleolithic Caucasus/Anatolian ancestry.[2][9][10] An alternative model without the need of significant amounts of ANE ancestry has been presented by Vallini et al. 2024, suggesting that the initial Iranian hunter-gatherer-like population which is basal to the CHG formed primarily from a deep Ancient West Eurasian lineage ('WEC2',
c. 72%), and from varying degrees of
Ancient East Eurasian (
c. 10%) and
Basal Eurasian (
c. 18%) components. The Ancient West Eurasian component associated with Iranian hunter-gatherers (WEC2) is inferred to have diverged from the West Eurasian Core lineage (represented by
Kostenki-14; WEC), with the WEC2 component staying in the region of the
Iranian Plateau, while the proper WEC component expanded into Europe.[11]
At the beginning of the
Neolithic, at
c. 8000 BC, they were probably distributed across western Iran and the Caucasus,[12] and people similar to northern Caucasus and Iranian plateau hunter-gatherers arrived before 6000 BC in Pakistan and north-west India.[13] A roughly equal merger between the CHG and
Eastern Hunter-Gatherers in the
Pontic–Caspian steppe resulted in the formation of the
Western Steppe Herders (WSHs). The WSHs formed the
Yamnaya culture and subsequently expanded massively throughout Europe during the
Late Neolithic and
Early Bronze Age
c. 3000—2000 BC.[14]
Caucasus hunter gatherer/Iranian-like ancestry, was first reported as maximized in hunter-gatherers from the
South Caucasus and early herders/farmers in
northwestern Iran, particularly the
Zagros, hence the label “CHG/Iranian”.[15]
Jones et al. (2015) analyzed genomes from males from western Georgia, in the Caucasus, from the Late Upper Palaeolithic (13,300 years old) and the Mesolithic (9,700 years old). These two males carried
Y-DNAhaplogroup:
J* and
J2a, later refined to J1-FT34521, and J2-Y12379*, and mitochondrial haplogroups of K3 and H13c, respectively.[16] Their genomes showed that a continued mixture of the Caucasians with
Middle Eastern populations took place up to 25,000 years ago, when the coldest period in the last Ice Age started.[4]
Margaryan et al. (2017) analysing South Caucasian ancient mitochondrial DNA found a rapid increase of the population at the end of the Last Glacial Maximum, about 18,000 years ago. The same study also found continuity in descent in the maternal line for 8,000 years.[17]
According to Narasimhan et al. (2019) Iranian farmer related people arrived before 6000 BCE in Pakistan and north-west India, before the advent of farming in northern India. They suggest the possibility that this "Iranian farmer–related ancestry [...] was [also] characteristic of northern Caucasus and Iranian plateau hunter-gatherers."[13]
The question of where the Yamnaya come from has been something of a mystery up to now […] we can now answer that, as we've found that their genetic make-up is a mix of Eastern European hunter-gatherers and a population from this pocket of Caucasus hunter-gatherers who weathered much of the last Ice Age in apparent isolation.[4]
While some scholars argue that the archaic PIE ('
Indo-Anatolian') language may have originated among a CHG-rich population in
Western Asia, based on the lack of EHG ancestry in the probable speakers of
Anatolian languages.[23] Others, such as Anthony, suggest that the PIE were spoken by EHGs living in
Eastern Europe.[24]
According to Jones et al. (2015), Caucasus hunter-gatherers (CHG) "genomes significantly contributed to the Yamnaya steppe herders who migrated into Europe ~3,000 BCE, supporting a formative Caucasus influence on this important Early
Bronze Age culture. CHG left their imprint on modern populations from the
Caucasus and also
Central and
South Asia possibly correlating with the arrival of
Indo-Aryan languages."[25] Wang et al. (2018) analysed genetic data of the North Caucasus of fossils dated between the 4th and 1st millennia BC and found correlation with modern groups of the South Caucasus, concluding that "unlike today – the Caucasus acted as a bridge rather than an insurmountable barrier to human movement".[26]
Ancient Greece and Aegean
Beyond contributing to the population of mainland Europe through Bronze Age pastoralists of the Yamnaya, CHG also appears to have arrived on its own in the Aegean without Eastern European hunter–gatherer (EHG) ancestry and provided approximately 9–32% of ancestry to the
Minoans. The origin of this CHG component might have been Central Anatolia.[27]
^"'Fourth strand' of European ancestry originated with hunter-gatherers isolated by Ice Age". University of Cambridge. 16 November 2015. By reading the DNA, the researchers were able to show that the lineage of this fourth Caucasus hunter-gatherer strand diverged from the western hunter-gatherers just after the expansion of anatomically modern humans into Europe from Africa.
^Jones et al. 2015: "Caucasus hunter-gatherers (CHG) belong to a distinct ancient clade that split from western hunter-gatherers ~45 kya, shortly after the expansion of anatomically modern humans into Europe and from the ancestors of Neolithic farmers ~25 kya, around the Last Glacial Maximum."
^Lazaridis, Iosif; Mittnik, Alissa; Patterson, Nick; Mallick, Swapan; Rohland, Nadin; Pfrengle, Saskia; Furtwängler, Anja; Peltzer, Alexander; Posth, Cosimo; Vasilakis, Andonis; McGeorge, P. J. P.; Konsolaki-Yannopoulou, Eleni; Korres, George; Martlew, Holley; Michalodimitrakis, Manolis; Özsait, Mehmet; Özsait, Nesrin; Papathanasiou, Anastasia; Richards, Michael; Roodenberg, Songül Alpaslan; Tzedakis, Yannis; Arnott, Robert; Fernandes, Daniel M.; Hughey, Jeffery R.; Lotakis, Dimitra M.; Navas, Patrick A.; Maniatis, Yannis; Stamatoyannopoulos, John A.; Stewardson, Kristin; Stockhammer, Philipp; Pinhasi, Ron; Reich, David; Krause, Johannes; Stamatoyannopoulos, George (2017).
"Genetic origins of the Minoans and Mycenaeans". Nature. 548 (7666): 214–218.
Bibcode:
2017Natur.548..214L.
doi:
10.1038/nature23310.
PMC5565772.
PMID28783727.
Sources
Anthony, David (2009b), "Ancient DNA, Mating Networks, and the Anatolian Split", in Serangeli, Matilde; Olander, Thomas (eds.), Dispersals and Diversification: Linguistic and Archaeological Perspectives on the Early Stages of Indo-European, BRILL