Overview
I3d (Y18615) is a deeply divergent Upper Paleolithic branch of haplogroup I3, preserved primarily among populations inhabiting the rugged highland corridors of eastern Anatolia and the northern Zagros. The clade likely emerged during the harsh climatic oscillations preceding the Last Glacial Maximum, surviving in ecological refugia along the Armenian Highland and Lake Van region. Its persistence suggests long-term genetic continuity in one of West Eurasia’s key Paleolithic refugial zones.
Geographic distribution
Modern carriers occur at low but stable frequencies in eastern Turkey (Van–Muş–Erzurum region), northern Iraq, western Iran, Armenia and parts of the South Caucasus. Occasional finds in Levantine and Anatolian populations likely represent ancient diffusion rather than recent migration.
Ancient DNA
- Upper Paleolithic genomic clusters around the Caucasus and eastern Anatolia show signals aligned with basal I3 lineages, including ancestry compatible with I3d.
- Pre-Pottery Neolithic individuals from the northern Fertile Crescent contain components consistent with deep West Eurasian paternal lineages related to I3 substructure.
- Chalcolithic and early Bronze Age samples from the Armenian Highlands exhibit upstream haplotypes connecting to the I3 radiation.
Phylogeny & subclades
I3d diverges alongside I3a, I3b and I3c as one of four primary branches within the I3 lineage. Y18615, together with markers such as Y18617 and FGC5621, defines a stable and slow-diversifying lineage with limited downstream branching. This contrasts with I1 and I2 radiations but matches expectations for isolated Upper Paleolithic populations.
- I3-Y18617
- I3-FGC5621
- Basal I3d* lineages
Notes & context
I3d is critical for reconstructing the genetic landscape of highland West Eurasia during the Upper Paleolithic. Its presence underscores the importance of the Anatolia–Zagros corridor as a long-term refugium for ancient paternal diversity.
References & external links