Cheddar man shares little DNA with modern English/Scots/Welsh. After him came Neolithic farmers of mediterranean appearance who wiped out the western hunter gatherers. After them came fairer, lighter skinned people from the steppes (who wiped out the earlier Neolithic farmers). Some of these later farmers had similar mtDNA to Cheddar man because they had mixed with relatives of the Western Hunter Gatherers on the Steppes
see Human Paleogenetics of Europe by Brandt G et al
and
Natural History museum 'ancient DNA shows migrants introduced farming to Britain from EU'
cheddar man would be derived for 6 out of 73 SNP's for I2a2b-L38, an extinct clade
A tale of two Y sequences:
One a very famous ancient person, and another a single Big Y, and the YFull tree:
Cheddar Man, "the first Briton" who died 9150 years ago, and the Big Y id:YF07139 from France in I-Y10705. The I-L38 YFull tree. It looked like Cheddar man was ancestral for some I-Y10705 SNPs, and therefore he was a "partial" I-Y10705, even though he is derived for some SNPs of the I-Y10705 subclade I-L38.
It turns out that this ordering of SNPs is based solely on the single Big Y, id:YF07139. With the help of Antonios Kollias, we were able to determine that in fact the Big Y of id:YF07139 had no reads for all of these supposed I-Y10705 SNPs on the YFull tree that Cheddar Man was negative for.
These 9 SNPs are not really I-Y10705 SNPs at all, they are in fact I-L38 SNPs, and so Cheddar Man is positive for at least 6 I-L38 SNPs, and also positive for all actual I-Y10705 SNPs.People on Anthrogenica and most sites got it wrong, based on an "estimation" in the YFull tree which turned out to be wrong, based on this Big Y.
Cheddar Man is a "partial" I-L38, not just I-Y10705.
I-L38 has a few hundred people in it, and is found all over Europe, but mostly in the British Isles and Northwest Europe. This is the actual Y haplogroup of the fabled "lost land" of Doggerland, not R1b-M269.
The moral of the story is, if you want a good Y sequence and an accurate YFull tree based on it, it pays to be dead for over 9000 years and get a whole genome sequence instead of getting a Big Y!
https://docs.google.com/…/1aT79s3Hax7P1EdexDL6ups_piJ…/edit…
https://yfull.com/tree/I-Y10705/