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Haplogroup I2a2a1a1

I2-M284 Insular British

Macro-haplogroup

Parent clade

I2a2a1

Formed (estimate)

c. 4,500–6,000 years before present

TMRCA (estimate)

c. 2,800–3,500 years ago

PF3865
A12035
Y57839

Overview

I2a2a1a1 represents the deeper insular British branch of the I2-M284 lineage, one of the most distinctive paternal lineages associated with prehistoric Britain. Unlike continental I2a2 subclades, M284 and its downstream branches appear almost entirely confined to the British Isles, reflecting an ancient local founder event predating the Bronze Age.

Geographic distribution

Nearly exclusive to Britain, especially England and Wales. Small frequencies appear in Ireland and Scotland. Diaspora presence in North America and Australia corresponds to modern British migration.

Ancient DNA

Neolithic and Bronze Age British remains include I2 lineages close to the root of the M284 expansion.
Iron Age and Romano-British individuals show continuity with insular I2-M284 derivatives.
No strong continental parallels exist, supporting long-term insular isolation.

Phylogeny & subclades

Defined by PF3865, A12035 and Y57839. A downstream branch of I2a2a1 (M284) representing insular diversification. Internal branching is limited but highly geographically specific.

I2-PF3865
I2-A12035
I2-Y57839
Basal I2a2a1a1*

Notes & context