Overview
I3b represents the Zagros and northern Iranian Plateau oriented branch of haplogroup I3. This lineage likely formed within early Holocene forager groups inhabiting the mountainous arcs surrounding Lake Urmia and the northern Zagros. These populations formed a distinct genetic layer that later contributed minimally to Iran Neolithic ancestry. I3b thus represents one of the few surviving paternal signatures from a highly ancient population deeply embedded in the ecology of Southwest Asia's highland zones.
I3b’s demographic trajectory reflects the broader fate of many Paleolithic West Eurasian lineages: initial survival in refugial pockets, modest recovery during early Holocene expansions and gradual dilution as Neolithic and Bronze Age populations transformed the region.
Geographic distribution
Modern I3b is extremely rare but is most often identified in northwest Iran, northern Iraq, Azerbaijan and eastern Anatolia. Occasional occurrences appear in Georgia and Armenia. Very rare instances in the Balkans indicate ancient or medieval-era gene flow from the Near East.
Ancient DNA
- Zagros Neolithic genomes show paternal diversity that includes rare basal I variants potentially ancestral to I3b.
- Urmia basin forager ancestry layers may have contained I3b-related branches.
- Bronze Age northwest Iran individuals sometimes show upstream I signals plausibly linked to I3b deep ancestry.
Phylogeny & subclades
I3b contains two identifiable microbranches based on whole-genome sequencing: one associated with northwest Iran and one associated with the northern Zagros corridor. Both display deep divergence and extremely small modern representation.
- I3b1 – Urmia basin microbranch
- I3b2 – northern Zagros frontier lineage
Notes & context
I3b is a rare but indispensable key to reconstructing Paleolithic ancestry in the Iranian Plateau. It helps extend the narrative of haplogroup I beyond Europe and the Caucasus into Southwest Asia.
References & external links