The CHG lineage is suggested to have diverged from the ancestor of
Western Hunter-Gatherers (WHGs) probably during the
Last Glacial Maximum (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 Eurasians 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, 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
Neolithic, 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.
Further research in Georgia. 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 haplogroup:
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 Eastern 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 specimen from
Satsurblia cave (dated ), and in a
Mesolithic one from Kotias Klde cave, in
western Georgia (dated ). The Satsurblia individual is closest to modern populations from the
South Caucasus. 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 [also] characteristic of northern Caucasus and Iranian plateau hunter-gatherers." 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. Among modern populations, CHG ancestry peaks in indigenous Caucasian populations, as well as in populations that live in the east of the Caucasus, Iran and South Asia. However, high affinities between CHG and South Asians probably reflect affinities to both CHG and Iranian Neolithic individuals. ==Proto-Indo Europeans==