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Y-DNA Haplogroup Atlas

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Haplogroup I1-Z138

I1-Z138 Western and North Sea branch

Macro-haplogroup
I
Parent clade
I1
Formed (estimate)
c. 4,000-4,500 years before present (estimate)
TMRCA (estimate)
c. 3,600-4,000 years ago (estimate)

Overview

Haplogroup I1-Z138 is one of the principal branches of the I1-Z58 complex and is strongly associated with western and northern European populations. It likely emerged during the Late Bronze Age in northern Europe, in communities situated between the North Sea coastal plain, Jutland and southern Scandinavia. This clade shows a demographic profile consistent with the early development of Germanic-speaking populations, and it later provided important paternal lineages to both continental and maritime Germanic expansions.

Geographic distribution

Modern distributions of I1-Z138 peak in Britain, the Low Countries, northern Germany, Denmark and southern Sweden, with significant frequencies also in Norway. Elevated levels in eastern England, the Scottish Lowlands and parts of Ireland reflect historical Anglo-Saxon and later Scandinavian input. Lower but detectable frequencies occur across France, Iberia and central Europe, largely due to medieval and early modern migrations.

Ancient DNA

  • Early Iron Age genomes from northern Germany and Denmark show I1-Z58 lineages that cluster in the phylogenetic neighborhood of Z138, suggesting that the clade formed within this macro-region.
  • Anglo-Saxon cemetery burials in eastern England include I1 haplotypes that can be phylogenetically assigned to the Z138 complex, matching the historical link to continental Germanic settlers.
  • Viking Age individuals from Britain and Scandinavia often belong to subbranches of the Z138 radiation, underlining the importance of this clade in the maritime Germanic sphere.

Phylogeny & subclades

I1-Z138 is a major downstream node of I1-DF29 and I1-Z58. It is defined by SNPs Z138, Z139, S296 and S338, which collectively separate it from neighboring branches such as I1-Z131, I1-Z63 and I1-Z59. Within Z138, several large sub-branches have been described, including S2293 and Z2541, which further structure the clade into continental and maritime oriented lineages.

  • I1-S2293
  • I1-Z2541
  • Additional regional microclades within the Z138 complex

Notes & context

Because I1-Z138 is widely tested and forms a large subtree of I1, it is a common label in genetic genealogy and is frequently used in surname and regional projects focused on British, North Sea and western Scandinavian ancestry. Its broad but structured distribution makes it a key marker for the study of Germanic population history.