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Y-DNA Haplogroup Atlas

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Haplogroup I2a2d

I2-CTS616

Macro-haplogroup
I
Parent clade
I2a2
Formed (estimate)
c. 8,500–10,000 years before present
TMRCA (estimate)
c. 4,500–5,500 years ago

Overview

I2a2d (CTS616) is an early Neolithic branch of haplogroup I2-M223 associated with farming communities of the upper Danube, Alps and central European Neolithic cultures. This lineage appears to have played a role in the early stages of farmer–forager interaction in central Europe, maintaining local paternal continuity while integrating into agricultural societies.

Geographic distribution

Modern carriers are most frequent in Austria, southern Germany, Switzerland and eastern France. Lower frequencies occur in the Czech Republic, Slovakia and northern Italy.

Ancient DNA

  • LBK (Linearbandkeramik) associated individuals show I2-M223 substrata ancestral to CTS616.
  • Bavarian Early Bronze Age genomes include clades close to I2a2d.
  • Neolithic Alpine samples reveal persistence of non-expanding I2 lines consistent with this branch.

Phylogeny & subclades

I2a2d sits parallel to I2a2a, I2a2b and I2a2c within the M223 complex. CTS616 and L801 anchor the clade, which displays moderate but regionally specific downstream branching patterns.

  • I2-L801
  • I2-Y17013
  • Basal CTS616*

Notes & context

I2a2d helps reconstruct the paternal demographic impact of early farmers in central Europe, as well as the persistence of indigenous hunter-gatherer ancestry during the Neolithic transition.