Overview
R1b-L23 is the key backbone branch of R1b-M269 that connects the early expansions of steppe populations with the later diversification of western Eurasian R1b lineages. It likely formed in or near the Pontic Caspian steppe region during the late Neolithic or early Chalcolithic period. The rise of L23 coincides with the emergence of mobile pastoralist groups who combined animal husbandry, wheeled transport and early metal working traditions.
Ancient DNA shows that L23 and its immediate derivatives are heavily represented among populations associated with the Yamnaya horizon and related steppe cultures. These groups expanded westward toward the Balkans and central Europe and southward into the Caucasus and Anatolia. As a result, L23 stands at the root of both the Balkan Anatolian lineage R1b Z2103 and the western European lineage R1b L51. The phylogenetic position of L23 therefore links the demographic history of southeastern Europe and western Asia with the massive R1b dominated expansions that reshaped the genetic landscape of much of Europe in the Bronze Age.
R1b-L23 is not usually observed in a basal state in modern populations because most carriers belong to its downstream branches, but its presence can be inferred from the shared ancestry of Z2103 and L51. It represents the node at which steppe related R1b-M269 began to split into distinct regional trajectories.
Geographic distribution
Modern distributions of clearly basal L23 are sparse, but its descendant branches are common across southeastern Europe, the Caucasus, Anatolia and much of western and central Europe. Z2103, one of its main subclades, is most frequent in the Balkans, the Caucasus and parts of Anatolia and the Near East, while L51 and its descendants dominate in western and central Europe. Taken together, the L23 complex is widely represented from the steppe and Black Sea regions to Iberia and the British Isles.
Ancient DNA
- Early Bronze Age Yamnaya individuals across the Pontic Caspian steppe frequently carry L23 derived lineages.
- Steppe influenced individuals from the Balkans and Carpathian Basin show R1b-L23 and its subclades, reflecting early movements of Yamnaya related groups into southeastern Europe.
- Bronze Age populations of the Caucasus and Anatolia include R1b-L23 derived haplogroups that point to southward expansions from the steppe.
- Ancient individuals in the Bell Beaker and related cultures in central and western Europe often carry L23 through its L51 branch.
- Later Bronze and Iron Age groups in southeastern Europe and western Asia retain significant frequencies of L23 derived lineages, demonstrating long term continuity.
Phylogeny & subclades
R1b-L23 splits into two very important macro branches. One is R1b-Z2103, which is especially common in the Balkans, Caucasus and Anatolia. The other is R1b-L51, which became the primary ancestor of the U106 and P312 branches that dominate western and central Europe. L23 thus forms a pivotal fork in the R1b-M269 tree, separating southeastern European and western Asiatic trajectories from western and northwestern European ones.
Notes & context
L23 is a central node for understanding how steppe derived R1b-M269 lineages spread into both southeastern Europe and broader western Eurasia. It is a bridge between Yamnaya associated expansions and the later regionalization of R1b across Europe and western Asia.
References & external links