Overview
J2a-Y18340 is a downstream upland lineage within the J2a-M67 radiation and is closely associated with the demographic history of eastern Anatolia, the Armenian highlands and the northern Zagros foothills. Its early formation period coincides with the consolidation of highland farming systems in the early Holocene, when villages in mountain basins and valley floors developed mixed cereal cultivation, orchard agriculture and seasonal herding. Archaeological parallels include early terrace agriculture, obsidian circulation networks and the emergence of fortified hilltop sites in the Upper Tigris and Lake Van regions. During the Bronze Age, Y18340-bearing populations appear to have been embedded in highland cultural formations that mediated the flow of people and resources between Mesopotamia, the Caucasus and the Iranian plateau. The downstream structure of the clade indicates repeated microregional founder effects in enclosed valleys and plateau edge microregions rather than wide lowland dispersal. Iron Age and classical populations in the Armenian plateau, northern Mesopotamia and adjacent uplands preserve patterns compatible with the continued presence of Y18340-derived branches, pointing to strong long term highland continuity.