Overview
G1b1 is the major surviving downstream branch of the extremely rare G1b lineage. Emerging during the late Upper Paleolithic–early Holocene boundary, it acts as a genetic relic of early Iranian Plateau paternal diversity. Whereas G1a underwent substantial mid-Holocene expansion, G1b1 remained a geographically focused, demographically conservative highland lineage. Its temporal depth situates it among populations that inhabited the Zagros uplands and western Iranian highland basins—communities which often preserved deep paternal continuity despite shifting cultural and linguistic regimes.
The lineage likely arose in mobile herding populations that practiced small-scale agriculture and seasonal transhumance. G1b1’s survival into historical periods suggests strong lineage stability within kin-based, mountain-anchored social structures that resisted the demographic collapse which affected many early Holocene lineages.
Geographic distribution
Modern G1b1 occurrences cluster in western Iran (Luristan, Kermanshah, Ilam, Hamadan), northeastern Iraq (Kurdish districts of Sulaymaniyah and Erbil), southeastern Turkey (Hakkâri–Van–Şırnak–Siirt arc) and pockets across the Caucasus (especially Armenia and the southern Caspian littoral). The lineage’s distinct highland orientation reflects a demographic profile shaped by small tribal communities and mountain confederations whose mobility was mostly intra-regional.
Low-level occurrences among Persian Gulf populations likely represent later historic movements rather than early dispersal.
Ancient DNA
- Early Bronze Age sites in the Zagros (Godin Tepe, Sarab region) include genetic profiles compatible with G1b upstream ancestry.
- Late Chalcolithic and Bronze Age individuals from northwest Iran show Y-SNP distributions consistent with early G1b diversification.
- Iron Age populations around Lake Van and the Upper Tigris occasionally exhibit paternal signatures that model well as G1b1-adjacent clusters.
Phylogeny & subclades
Defined by CTS4802, G1b1 forms the largest downstream branch of G1b. It appears to possess a shallow but structured phylogeny, with several microbranches that correspond to discrete highland populations. Within the G1 macro-tree, G1b1 sits opposite the expansive G1a radiation and the moderately distributed G1d branch. The lineage’s modest internal diversity reflects strong local retention rather than demographic stagnation.
- G1b1* (basal)
- G1b1a (CTS4809-linked)
- G1b1b (regionally specific microbranches)
Notes & context
G1b1 helps reconstruct the paternal structure of highland West Asia that predates major Indo-Iranian expansions. Its inclusion in a mega-atlas adds structural balance to the G1 phylogeny by revealing the slower, localized demographic histories that paralleled the massive G1a expansions.
References & external links