R-DF21 is a major British Isles lineage that was born in the British Isles 1900 BC. It is one of 22 established child lineages of parent R-DF13 who was also likely born and spent his entire life in the British Isles.
It had 125 samples on YFull as of Dec 29, 2019 that have been geolocated to the Old World.
While R-DF21 has only one ancient sample on the YFull tree from Iceland, Rathlin1 has been classified as R-DF21 as well. This attests to an Early Bronze Age presence (2026-1885 BC) in the British Isles and the association of this lineage with a new wave of migrants that greatly replaced existing male lineages throughout the British Isles (link to paper).
The new migrants are linked to the spread of the Bell Beaker culture, specifically from a subpopulation that had been living in the lower Rhein.
I'm hoping experts in this haplogroup will collaborate with me to improve the accuracy of the subclade analysis of these ancient samples on PhyloGeographer, as I myself am not an expert in any lineage of haplogroup R.
At the time of this article, eight lineages of R-DF21 had been discovered.
- R-S3058 (research article written 1/12/2020)
So far, all R-DF21 on YFull are positive for one of these eight lineages (except perhaps Rathlin1, please contact me if it ends up sharing a SNP with an established child lineage of DF21).
I want to note that the accuracy of the computed child lineages is somewhat problematic due to a large number of geographically non-specific samples.
It's also important to note that the computed location of the origin of R-DF21 as approximately around the Island of Man is based on an algorithm that to some extent will favor a central location for subclades relatively evenly distributed away from the center. Only one sample is actually from the Isle of Man, in BY13823.
Of the 125 samples which have been geolocated to the Old World, many are designated to non-specific regional levels of "Scotland", "England", "Wales", "Ireland", even a "Great Britain". Please reach out to these individuals in your haplogroup research projects and urge them to update their samples with a more specific regional code for the birthplace of their most distant known male line ancestor.