# Iranian hunter-gatherers

The term Iranian hunter-gatherers or Neolithic Iranians, sometimes also "East Meta", is used to refer to a population genomics lineage representing the Mesolithic to early Neolithic population of the Iranian plateau, South-Central Asia and the Caucasus.
The Iranian hunter-gatherer lineage is represented by Mesolithic hunter-gatherers and Neolithic herders and early farmers in present-day Iran, such as remains excavated from the Hotu and Kamarband Caves and Ganj Dareh, as well as Wezmeh. A deeply diverged sister branch (> 12kya) best represented by remains from Shahr-i-Sokhta, formed the dominant ancestry component of the Indus Valley Civilisation in Northwestern India, next to a local East Eurasian component termed Ancient Ancestral South Indian (AASI). The Iranian hunter-gatherers also represent an important source for the formation of the Central Asian gene pool, primarily via the Bactria–Margiana Archaeological Complex. They further displayed close genetic affinities to the Caucasus hunter-gatherers, who descend primarily from a similar source population as Iranian hunter-gatherers, but were distinct from preceding Paleolithic Caucasus populations, which were closer related to Anatolian hunter-gatherers, Western hunter-gatherers and Levantine groups.

## Origins

While the exact origin of the Mesolithic and Neolithic Iranian hunter-gatherers and later farmers remains unclear, there have been different proposals to explain their formation.
A commonly cited model argues that Neolithic Iranians emerged as admixture between a Basal Eurasian lineage and a lineage closer to Ancient North Eurasians (ANE) or Eastern European Hunter-Gatherers (EHG). According to this model the Mesolithic/Neolithic Iranian lineage derives significant amounts of their ancestry from a Basal Eurasian-like source (ranging from 35 to 62%), with the remainder ancestry being closer to Ancient North Eurasians (38–65%). Genetic data however suggest a more complex formation process, including at least four different sources.
Vallini et al. (2024) presented a revised model on the formation of Mesolithic/Neolithic Iranians. They argue that the peopling of Eurasia can best be explained by successive expansions from a population hub on the Persian plateau. After the divergence and expansion of Ancient East Eurasians during the Initial Upper Paleolithic period (c. 48kya), 'ancestral West Eurasians' stayed a prolonged time in the Hub together, and started to expand at roughly 40kya, with one branch (WEC) giving rise to contemporary West Eurasian lineages (such as the ancestral lineage to Kostenki-14), while a remnant group (WEC2) stayed in the Persian plateau. After contact events with other lineages, including populations harboring elevated "Basal" and East Eurasian ancestry, this lineage resurfaced in the palaeogenetic record as the Iranian Neolithic, the Iranian Hunter Gatherer’ or the "East Meta". According to a qpAdm model by Vallini et al. 2024, including the simulated proxies for the WEC/WEC2 and BEA componets, the genetic makeup of Neolithic Iranians (Ganj_Dareh_N) consists of c. 76.5% West Eurasian (WEC/WEC2), c. 16.3% broadly East Eurasian (EEC), and c. 7.2% "Basal-like" (BEA) ancestries.
While Iranian hunter-gatherers and Neolithic Iranian groups fall into the wider 'West Eurasian' cluster within a Eurasian-wide Principal component analysis (PCA), they are only distantly related to the geographical close Anatolian or Levantine lineages, taking up an "extreme position" compared against other ancient and modern West Eurasian populations. In contrast, Mesolithic and Neolithic Iranians are closely related to Mesolithic Caucasus hunter-gatherers, while both are largely distinct from the earlier Upper Paleolithic Caucasus population.
While initially absent from Anatolia, Mesopotamia and the Caucasus, as well as India, it reached these regions via the expansion of Mesolithic and Neolithic groups, resulting in a cline between Iran Neolithic-like and local sources.

### Uniparental haplogroups

The main human Y-chromosome DNA haplogroups found among Mesolithic and Neolithic Iranian-affiliated specimens include subclades of G-M201, J, L, and R2. Others included subclades of T-M184, while subclades of H are observed among 'IVC periphery' like remains. The oldest sample of haplogroup R2a to date has been found in one of the remains from Ganj Dareh in western Iran. Common Human mitochondrial DNA haplogroups found among Mesolithic and Neolithic Iranian specimens include subclades of haplogroup U, HV, X, R, H, W, T, and M.

## Contributions to other populations
### Caucasus

An Iranian hunter-gatherer related source contributed around 72% ancestry to the Caucasus hunter-gatherers, with the remainder beind made up by c. 18% UP Caucasus (Dzudzuana) ancestry and c. 10% Eastern hunter-gatherer ancestry.

### West Asia

The later Chalcolithic Iranians are modeled to have formed from a merger of local Neolithic Iranians and a Neolithic Anatolian-like source population, as well as additional Caucasus hunter-gatherer-like geneflow. During the Late Neolithic/Early Chalcolithic period they formed a cline stretching from Western Anatolia along the lowlands of the Southern Caucasus to the Zagros mountains, reaching as far as to Southern Central Asia, as well as southwards to the Southern Levant. This cline was primarily characterized by expansive Anatolian-like ancestry and secondarily by the spread of Neolithic Iranian and Levantine-like ancestries.
A Neolithic Iranian-like contribution is needed in models for modern Middle Eastern and certain Eastern African populations. This geneflow may have happened primarily via an admixed population from the Mesopotamia.

### South Asia

In 2019, the genome sequence of a skeleton remain from a cemetery near Rakhigarhi dating to around 2,800-2,300 BCE suggested that the majority of the genome was related to Iranian hunter-gatherers. The divergent (>12kya) sister lineage, sharing a recent common ancestor with Neolithic Iranians, but having diverged from them prior to the development of agriculture, forms the main ancestry component of the Indus Valley Civilisation, in tandem with variable amounts of a local East Eurasian ancestry termed Ancient Ancestral South Indian (AASI). The spread of Ancient Iranian-like ancestry, and or IVC-like ancestry, may be related to the dispersal of early Dravidian languages, although this remains uncertain, with opposing views having been presented as well.

### Central Asia

Neolithic Iranians, in tandem with Anatolian Farmers, also contributed to the formation of the Bactria–Margiana Archaeological Complex, which subsequently contributed to other Central Asian populations, and possibly later Tarim mummies from Alwighul (700–1 BCE) and Krorän (200 CE).

### Europe

Neolithic Iranians, in contrast to the related Caucasus hunter-gatherers, only made minor contributions to the European gene pool. Neolithic Iranians instead represent a better source of geneflow among most West Asian populations when compared against Caucasus hunter-gatherers, while the contrary is true for European populations.