R-L21 or R1b1a2a1a2c, also known as R-M529 or R-S145, is a Human Y-chromosome DNA haplogroup. It is often linked to the Insular Celts.[1] One subclade, R-DF13 comprises over 99% of bearers. It is dominant among males in Ireland, Scotland, Wales and Brittany, present in high frequencies in England and western France and present also to a lesser extent in Iberia, Scandinavia and the Low Countries.[2]
Haplogroup R-L21 | |
---|---|
Possible time of origin | 2,600 BC |
Possible place of origin | South-west Britain |
Ancestor | R1b (R-M343) * R-M269 ** R-L151 *** R-P312 **** R-Z290 |
Descendants | R-A5846 R-S552 * R-DF63 * R-DF13 |
Highest frequencies | Irish Scottish Welsh Bretons English |
This haplogroup first emerges in the Early Bronze Age in Britain and Ireland, where the earliest samples begin to appear. Its introduction was part of a large genetic transformation associated with the Bell Beaker culture, wherein steppe descended peoples largely replaced Britain's earlier Neolithic population. The lineage reached a frequency of 90% in early Bronze Age Britain (being nearly absent in contemporary samples from the continent), it gradually declined through the Middle Bronze Age to 70% by the Iron Age (due to continental migrations which also increased the levels of EEF admixture among Britons).[note 1] It later fell to its modern levels in Britain after the Anglo-Saxon invasions. However, it still remains the dominant lineage in Ireland, Scotland, Brittany and Wales. Its origin is possibly around south west Britain as Cornwall is where the highest persistence of R-DF63 descended subclades are found, the sibling of the extremely dominant R-DF13 subclade.[note 2]
Below are listed some theorized lineages of prominent families. Some of these relationships are confirmed by Y-DNA testing of verified descendants, but others are not. In particular, Fehér (2023) is poorly sourced, does not cite confirmatory testing for most identifications, and is highly suspect.