Overview
I2b represents a set of western and central European associated branches within the wider I2 radiation. Historically, nomenclature for this clade has varied between classification schemes, but in an atlas context I2b is used to group those I2 lineages that trace their deepest roots to western and central Europe, rather than to the Balkan and Carpathian core of I2a. These lineages were part of the Mesolithic paternal landscape of western Europe and also appear in early Neolithic and Chalcolithic contexts.
Ancient DNA from regions such as France, Germany, the Low Countries and the British Isles reveals the presence of I2 lineages that are phylogenetically distinct from the main Balkan and Danubian I2a clusters. These are captured under I2b in this atlas, emphasizing that western Europe had its own I2 refugial and postglacial histories, even if later demographic events reduced the visibility of some branches in modern populations.
Geographic distribution
Today, I2b is found at relatively low frequencies compared to I2a, but it remains detectable across western, central and northwestern Europe. It appears in Germany, the Low Countries, France, England, Wales and Ireland, as well as in parts of Scandinavia and Poland. Typically, it is overshadowed by I1, R1b and other lineages in these regions, but careful phylogenetic analysis reveals persistent I2b subclusters.
In the Balkans and Carpathians, I2b is less frequent than I2a but can be present due to historical movements and secondary expansions. Outside Europe, I2b occurs mainly in populations with European ancestry.
Ancient DNA
- Mesolithic hunter gatherers from western Europe, including sites in Iberia and France, sometimes carry I2 lineages that fall outside typical I2a Balkan clades and may belong to I2b like structures.
- Early Neolithic individuals from central Europe and the Rhine region show I2 lineages that appear to descend from local western hunter gatherers, consistent with an I2b component.
- Later Neolithic and Chalcolithic contexts in western and central Europe occasionally contain I2b males alongside R1b and G2a, forming mixed paternal profiles.
Phylogeny & subclades
In a simplified atlas representation, I2b groups the western and central European oriented branches of I2 that are not part of the main I2a Balkan Carpathian Sardinian complex. Some of these lineages correspond in technical trees to clades under labels such as I2c or specific L596 derived branches. The overall structure is less densely populated than I2a, but it plays an important role in documenting the parallel histories of I2 in western Europe.
Downstream of I2b, several microclades can be recognized that correspond to regional founder events in the British Isles, the North Sea region and central Europe. These will be treated in separate nodes where they add clear geographic or historical resolution.
- I2b* basal western and central European lineages
- I2b1 – North Sea and British Isles clusters
- I2b2 – central European microbranches
- I2b3 – western European residual Mesolithic derived clades
Notes & context
Including I2b as a distinct trunk in the atlas ensures that western and central European I2 diversity is not collapsed into a single Balkan centered framework. It allows the user to see how I2 radiations in different parts of Europe followed partially independent trajectories during the Mesolithic and Neolithic.
References & external links