Caucasus hunter-gatherer (CHG), also called Satsurblia cluster, is an

anatomically modern human Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science ...

genetic lineage, first identified in a 2015 study, based on the

population genetics Population genetics is a subfield of genetics that deals with genetic differences within and among populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as Adaptation (biology), adaptation, s ...

of several modern Western Eurasian (

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

an, Caucasian and

Near Eastern The Near East () is a transcontinental region around the Eastern Mediterranean encompassing the historical Fertile Crescent, the Levant, Anatolia, Egypt, Mesopotamia, and coastal areas of the Arabian Peninsula. The term was invented in the 20th ...

) populations. It represents an ancestry maximised in some

Upper Paleolithic The Upper Paleolithic (or Upper Palaeolithic) is the third and last subdivision of the Paleolithic or Old Stone Age. Very broadly, it dates to between 50,000 and 12,000 years ago (the beginning of the Holocene), according to some theories ...

and

Mesolithic The Mesolithic (Ancient Greek language, Greek: μέσος, ''mesos'' 'middle' + λίθος, ''lithos'' 'stone') or Middle Stone Age is the Old World archaeological period between the Upper Paleolithic and the Neolithic. The term Epipaleolithic i ...

hunter-gatherer groups in the

Caucasus The Caucasus () or Caucasia (), is a region spanning Eastern Europe and Western Asia. It is situated between the Black Sea and the Caspian Sea, comprising parts of Southern Russia, Georgia, Armenia, and Azerbaijan. The Caucasus Mountains, i ...

. These groups are also very closely related to Mesolithic hunter-gatherers and

Neolithic The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...

farmers and

pastoralists Pastoralism is a form of animal husbandry where domesticated animals (known as "livestock") are released onto large vegetated outdoor lands (pastures) for grazing, historically by nomadic people who moved around with their herds. The anima ...

in the Iranian Plateau ( Iranian hunter-gatherer cluster), who are sometimes included within the CHG group. Ancestry that is closely related to CHG-Iranian hunter gatherers and farmers is also known from further east, including from the Bactria–Margiana Archaeological Complex and the Harappan/Indus Valley Civilisation. Caucasus hunter-gatherers and Eastern hunter-gatherers are ancestral in roughly equal proportions to the Western Steppe Herders (WSH), who were widely spread across Europe and Asia beginning during the

Chalcolithic The Chalcolithic ( ) (also called the Copper Age and Eneolithic) was an archaeological period characterized by the increasing use of smelted copper. It followed the Neolithic and preceded the Bronze Age. It occurred at different periods in di ...

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 The Last Glacial Maximum (LGM), also referred to as the Last Glacial Coldest Period, was the most recent time during the Last Glacial Period where ice sheets were at their greatest extent between 26,000 and 20,000 years ago. Ice sheets covered m ...

(sometime between 45,000 and 26,000 years ago). They further separated from the Anatolian hunter-gatherer (AHG) lineage later, suggested to around 25,000 years ago during the late LGM period. 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. According to one model, the Mesolithic/Neolithic Iranian lineage basal to the Caucasus hunter-gatherers are inferred to derive significant amounts of their ancestry from Basal Eurasian (), with the remainder ancestry being closer to

Ancient North Eurasian In archaeogenetics, the term Ancient North Eurasian (ANE) refers to an ancestral component that represents the lineage of the people of the Mal'ta–Buret' culture () and populations closely related to them, such as the Upper Paleolithic individ ...

s or Eastern European Hunter-Gatherer (ANE/EHG; ). The CHG displayed an additional ANE-like component () 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. Lazaridis et al. (2016) models the CHG as a mixture of Neolithic Iranians, Western Hunter-Gatherers and Eastern Hunter-Gatherers. In addition, CHG cluster with early Iranian farmers, who significantly do not share alleles with early Levantine farmers. 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', ), and from varying degrees of Ancient East Eurasian () and Basal Eurasian () 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 The Iranian plateau or Persian plateau is a geological feature spanning parts of the Caucasus, Central Asia, South Asia, and West Asia. It makes up part of the Eurasian plate, and is wedged between the Arabian plate and the Indian plate. ...

, while the proper WEC component expanded into Europe. Irving-Pease et al. (2024) models CHG as being derived from an Out of Africa population that split into basal Northern Europeans and West Asians. The latter was where CHG originated from. At the beginning of the

, at , they were probably distributed across western Iran and the Caucasus, and people similar to northern Caucasus and Iranian plateau hunter-gatherers arrived before 6000 BC in Pakistan and north-west India. A roughly equal merger between the CHG and Eastern Hunter-Gatherers in the

Pontic–Caspian steppe The Pontic–Caspian Steppe is a steppe extending across Eastern Europe to Central Asia, formed by the Caspian and Pontic steppes. It stretches from the northern shores of the Black Sea (the ''Pontus Euxinus'' of antiquity) to the northern a ...

resulted in the formation of the Western Steppe Herders (WSHs). The WSHs formed the

Yamnaya culture The Yamnaya ( ) or Yamna culture ( ), also known as the Pit Grave culture or Ochre Grave culture, is a late Copper Age to early Bronze Age archaeological culture of the region between the Southern Bug, Dniester, and Ural rivers (the Pontic–C ...

and subsequently expanded massively throughout Europe during the

Late Neolithic In the Near Eastern archaeology, archaeology of Southwest Asia, the Late Neolithic, also known as the Ceramic Neolithic or Pottery Neolithic, is the final part of the Neolithic period, following on from the Pre-Pottery Neolithic and preceding th ...

and

Early Bronze Age The Bronze Age () was a historical period characterised principally by the use of bronze tools and the development of complex urban societies, as well as the adoption of writing in some areas. The Bronze Age is the middle principal period of ...

. Caucasus hunter gatherer/Iranian-like ancestry, was first reported as maximized in hunter-gatherers from the

South Caucasus The South Caucasus, also known as Transcaucasia or the Transcaucasus, is a geographical region on the border of Eastern Europe and West Asia, straddling the southern Caucasus Mountains. The South Caucasus roughly corresponds to modern Armenia, ...

and early herders/farmers in northwestern Iran, particularly the

Zagros The Zagros Mountains are a mountain range in Iran, northern Iraq, and southeastern Turkey. The mountain range has a total length of . The Zagros range begins in northwestern Iran and roughly follows Iran's western border while covering much of s ...

, hence the label "CHG/Iranian".

Further research

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-DNA The Y chromosome is one of two sex chromosomes in therian mammals and other organisms. Along with the X chromosome, it is part of the XY sex-determination system, in which the Y is the sex-determining chromosome because the presence of the Y ...

haplogroup A haplotype is a group of alleles in an organism that are inherited together from a single parent, and a haplogroup (haploid from the , ''haploûs'', "onefold, simple" and ) is a group of similar haplotypes that share a common ancestor with a sing ...

: J* and J2a, later refined to J1-FT34521, and J2-Y12379*, and mitochondrial haplogroups of K3 and H13c, respectively. Their genomes showed that a continued mixture of the Caucasians with

Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...

ern populations took place up to 25,000 years ago, when the coldest period in the last Ice Age started. CHG ancestry was also found in an

Upper Palaeolithic The Upper Paleolithic (or Upper Palaeolithic) is the third and last subdivision of the Paleolithic or Old Stone Age. Very broadly, it dates to between 50,000 and 12,000 years ago (the beginning of the Holocene), according to some theories ...

specimen from Satsurblia cave (dated ), and in a

one from Kotias Klde cave, in western Georgia (dated ). The Satsurblia individual is closest to modern populations from the

. 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. 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 lsocharacteristic of northern Caucasus and Iranian plateau hunter-gatherers." According to Ghalichi et al. (2024), find that the Anatolia Neolithic to CHG-Iran_N cline formed around 6300–6000 BC, consistent with previous estimates, and the EHG–CHG cline formed around 5800–5300 BC. Interaction between Anatolia and the Caucasus increased during the Chalcolithic and the Bronze Ages, leading to the spread of CHG ancestry. It also diffused into the Mediterranean, an early indication of which is found in Anatolian farmer groups from Tepecik-Çiftlik.

Proto-Indo Europeans

During the

and early

Eneolithic The asterisk ( ), from Late Latin , from Ancient Greek , , "little star", is a typographical symbol. It is so called because it resembles a conventional image of a heraldic star. Computer scientists and mathematicians often vocalize it as st ...

, likely during the

4th millennium BC File:4th millennium BC montage.jpg, 400x400px, From top left clockwise: The Temple of Ġgantija, one of the oldest freestanding structures in the world; Warka Vase; Bronocice pot with one of the earliest known depictions of a wheeled vehicle; Kish ...

, Caucasus hunter-gatherers (CHGs) mixed with Eastern Hunter-gatherers (EHGs) on the

, with the resulting population, almost half-EHG and half-CHG, forming the genetic cluster known as Western Steppe Herder (WSH). To David W. Anthony, Caucasus hunter-gatherer ancestry of

Yamnaya The Yamnaya ( ) or Yamna culture ( ), also known as the Pit Grave culture or Ochre Grave culture, is a late Copper Age to early Bronze Age archaeological culture of the region between the Southern Bug, Dniester, and Ural rivers (the Pontic–C ...

is often with higher than 50%. As well as an overwhelming WSH ancestry, Yamnaya also have additional admixture from Anatolian and Levantine farmers, and the Western Hunter-gatherers (WHGs). According to co-author Andrea Manica of the

University of Cambridge The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...

: Some scholars argue that the archaic PIE (' Indo-Anatolian') language may have originated among a CHG-rich population in

Western Asia West Asia (also called Western Asia or Southwest Asia) is the westernmost region of Asia. As defined by most academics, UN bodies and other institutions, the subregion consists of Anatolia, the Arabian Peninsula, Iran, Mesopotamia, the Armenian ...

, based on the lack of EHG ancestry in the probable speakers of

Anatolian languages The Anatolian languages are an extinct branch of Indo-European languages that were spoken in Anatolia. The best known Anatolian language is Hittite, which is considered the earliest-attested Indo-European language. Undiscovered until the late ...

. Others, such as Anthony, suggest that PIE was spoken by EHGs living in

Eastern Europe Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural and socio-economic connotations. Its eastern boundary is marked by the Ural Mountain ...

. According to Jones ''et al''. (2015), Caucasus hunter-gatherer (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 The Bronze Age () was a historical period characterised principally by the use of bronze tools and the development of complex urban societies, as well as the adoption of writing in some areas. The Bronze Age is the middle principal period of ...

culture. CHG left their imprint on modern populations from the

and also Central and

South Asia South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...

possibly correlating with the arrival of

Indo-Aryan language The Indo-Aryan languages, or sometimes Indic languages, are a branch of the Indo-Iranian languages in the Indo-European language family. As of 2024, there are more than 1.5 billion speakers, primarily concentrated east of the Indus river in Ba ...

s." For example, about 50–70% of

Armenian Armenian may refer to: * Something of, from, or related to Armenia, a country in the South Caucasus region of Eurasia * Armenians, the national people of Armenia, or people of Armenian descent ** Armenian diaspora, Armenian communities around the ...

ancestry is derived from CHG, persisting from Neolithic times to the present. 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". According to Allentoft ''et al.'' (2024), The arrival and admixture of CHG with Caspian steppe cultures is dated to about 7,300-years-old, which is seen in two ancient samples from Golubaya Krinitsa with 18–24% admixture. suggestive of CHG-related ancestry extending past the middle Don to the Azov Sea coast and the Dnipro Valley during the second half of the 6th millennium BCE. A 7000-year-old genome from the Caucasus (Nalchik) links the Volga's first herders to farmers of W. Asia and it seems that in the first half of the 5th millennium BCE cultural and mating networks helped agriculture and pastoralism spread from West Asia across the Caucasian, into the steppes between the Don and the Volga in Eastern Europe.

Ancient Greece, Aegean and Italy

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. Genetic analysis shows that Iranian-related ancestry, which was widespread in the Aegean by the Middle Bronze Age in association with the Minoan and Mycenaean cultures, had also spread as far west as Sicily in substantial proportion at least by the time of the Mycenaeans. One possibility is this ancestry spread west along with the Mycenaean cultural expansion. An arrival of the CHG-related component in Southern Italy from the Southern part of the Balkan Peninsula, including the Peloponnese, is compatible with the identification of genetic corridors linking the two regions and the presence of Southern European ancient signatures in Italy. Collected data from Iron Age individuals dating from 900 to 200 BCE (including the Republican period) group shows a clear ancestry shift from the Copper Age, interpreted by ADMIXTURE as the addition of a Steppe-related ancestry component, and an increase in the Neolithic-Iranian component. Iran/Caucasus-related genetic influx was inferred in published individuals from the later Neolithic phases on the mainland (Peloponnese, around the fifth millenium BC) —but not earlier— as well as most of the EBA individuals from Euboea, Aegina and Koufonisia. comparison between ancient and modern samples, showing an overall similarity between Southern Italian and Iron Age Individuals, may suggest that the CHG/Iran_Neolithic signature reached the East side of the Adriatic Sea multiple times, or possibly as a continuous gene flow. In prehistoric Sardinia, the component associated with Iranian farmers, or Caucasus-related ancestry, present in Mainland Italy since the Neolithic (together with the EEF and WHG components), gradually increases from 0% in the Early Chalcolithic to about 5.8% in the Bronze Age. In Novilara, Iron age, PN43 is slightly shifted towards Near Eastern populations in the PCA and shows a high proportion of the CHG/Iran Neolithic component in Admixture analysis. they confirmed these results also with Admixture analysis, where a great genetic influence from the CHG/Iran Neolithic component is observed in all Late Antiquity Pesaro individuals. Although largely absent in the preceding Iron Age, Iran N-like admixture entered Balkan populations in a multiphased manner, with some Roman-era-Early Medieval populations being modelled as deriving 0-15% of their ancestry from this source (Croatia Roman Beli Manastir and Šćitarjevo, Montenegro Doclea Roman), which in adjacent regions can be as high as 20-30% (Croatia Novo Selo Bunje, Zadar, and Trogir Dragulin).

Central Asia and South Asia

CHG/Iranian Plateau Neolithic-like ancestry is prominent in pre-steppe admixture

and

(4500–2000 BCE) populations in Central Asia, like the Bactria–Margiana Archaeological Complex (which also had Anatolian Neolithic Farmer-related ancestry) as well as in the northwestern Indian subcontinent such as in sites in or adjacent to the

Indus Valley Civilisation The Indus Valley Civilisation (IVC), also known as the Indus Civilisation, was a Bronze Age civilisation in the Northwestern South Asia, northwestern regions of South Asia, lasting from 3300 Common Era, BCE to 1300 BCE, and in i ...

(who have mixed CHG-related and Ancient Ancestral South Indian ancestry). It is unclear as to whether the dispersal of CHG/Iranian Plateau-related ancestry eastwards to the Indian subcontinent was the result of the migration of farmers or an earlier dispersal of hunter-gatherers who later adopted farming, but this dispersal likely occurred sometime before 6000 BCE due to the lack of Anatolian Farmer-related ancestry in ancient South Asians, but which is present in the Iranian Plateau after this time. This pre-steppe CHG-related ancestry makes up a significant proportion of the ancestry of modern South Asians. WSHs, who were of significant CHG ancestry, also later migrated into Central Asia and South Asia. Maier et al. (2023), show four graphs with four admixture events that model the Indus Periphery group as a mixture of three or four sources, with a significant fraction of its ancestry derived from the Hajji Firuz Neolithic or Tepe Hissar Chalcolithic lineages including both Iranian and Anatolian ancestries. According to Kerdoncuff et al. (2024), obtain good fits for all 22 ASI individuals when the Iranian-related ancestry derives from early Neolithic and Copper Age individuals from Central Asian cultures of either Sarazm_EN or Namazga_CA or a group containing Sarazm_EN and Parkhai_Anau_EN that was previously suggested as the source for Indus Periphery Cline. The latter two models also provide good fits for Indus Periphery West, though using Sarazm_EN alone as the source does not yield a good fit. they're data are consistent with a common source for the ancient Iranian-related ancestry in ANI, ASI, Austroasiatics-related and East Asian-related individuals in India, suggesting that the Iranian-related gene flow occurred well before the arrival of Steppe pastoralist-related ancestry in Bronze Age (~1900–1500 BCE).

References

Sources

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External links

Caucasus Hunter-Gatherer ancestry and Indo-Hittite
{{Human genetics Peopling of Europe Last Glacial Maximum Mesolithic Europe Mesolithic Asia Upper Paleolithic Europe Upper Paleolithic Asia Prehistoric Caucasus CHG Hunter-gatherers of Asia Hunter-gatherers of Europe