Overview
G2a5 (CTS946) is a rare upstream branch of G2a that developed during the early Holocene in the West Asian highlands. It is a sister lineage to G2a3 and G2a4, all of which represent the ‘silent’ Near Eastern radiations that predate the massive G2a2 Neolithic expansions into Europe. G2a5 likely belonged to pre-agricultural or proto-agricultural communities inhabiting the foothills and upland zones stretching from northern Mesopotamia to the South Caucasus.
While G2a5 never achieved the demographic success of G2a2, its structure provides valuable insight into the earliest ancestral diversification processes of G2a before the advent of large-scale Neolithic migrations.
Geographic distribution
G2a5 is today found at extremely low frequencies in Armenia, eastern Turkey, northern Iraq and western Iran. Its distribution correlates strongly with early Holocene refugia and upland settlement systems rather than later widespread farmer movements.
It is virtually absent from Europe, consistent with its lack of participation in Neolithic expansions.
Ancient DNA
- A few Pre-Pottery Neolithic northern Mesopotamian individuals show upstream variants consistent with proto-G2a5 ancestry.
- Possible G2a5-adjacent signals occur in early highland Armenian prehistoric samples.
- No evidence links G2a5 to European Neolithic contexts.
Phylogeny & subclades
G2a5 has a shallow but distinct WGS-resolved topology, forming a small series of microclades. These branches reveal minor founder events in the Armenian Highlands and northern Mesopotamia.
Its position between basal G2a lineages and the major G2a2 radiation makes it important for reconstructing the early internal stratification of G2a.
- G2a5* basal
- Armenian–Anatolian microbranches
- Northern Mesopotamian clades
Notes & context
G2a5 underscores how only a subset of G2a lineages participated in the Neolithic expansion. Its restricted West Asian continuity represents an alternative demographic trajectory within the broader G2a phylogeny.
References & external links