Overview
H2b represents the Near Eastern anchored sister branch of the H2 radiation. While H2a is strongly associated with Neolithic Anatolia and the spread of early farmers into Europe, H2b appears to have remained largely within the Near Eastern homeland, particularly the northern Fertile Crescent, southern Caucasus and western Iranian plateau. This lineage displays limited diffusion compared to H2a but provides valuable insight into the early structure of H2 before the major Neolithic expansions.
Genetically, H2b lineages form several shallow microbranches, reflecting small-scale founder effects and long-term regional continuity rather than large demographic radiations. Although rare in modern populations, H2b helps capture the deeper phylogenetic context of H2 and complements the archaeological signals observed in H2a.
Geographic distribution
H2b occurs at low frequencies across the Near East, particularly in eastern Turkey, Armenia, northern Iraq, the southern Caucasus and western Iran. Small clusters appear in the Levant, suggesting either ancient persistence or limited historical movements. Its modern presence tapers sharply beyond the Near East, distinguishing it from the more westward-traveling H2a.
Because H2b does not appear in European Neolithic samples, it likely did not participate significantly in the earliest westward farming expansions, instead remaining primarily in its ancestral regions.
Ancient DNA
- A small number of low-coverage Pre Pottery Neolithic Near Eastern samples show upstream H2 signatures consistent with H2b.
- No confirmed H2b individual has been identified in European Neolithic contexts.
- H2b-related signals appear in several Bronze Age Iranian genomes as upstream lineages.
Phylogeny & subclades
Within H2, H2b forms a parallel branch to H2a. Its phylogenetic structure is relatively shallow, composed of a handful of regional clusters in the Near East. The branch is important for reconstructing the early divergence of H2 and understanding why only part of H2 contributed to the Neolithic expansion into Europe.
- H2b* basal
- Fertile Crescent regional clusters
- Iran–Caucasus microbranches
Notes & context
H2b contextualizes the pre-Neolithic and early Holocene demographic history of the wider Near East. Its rarity today highlights how later migrations reshaped regional paternal landscapes.
References & external links