Haplogroup I2a was the most frequent Y-DNA among western European mesolithic hunter gatherers (WHG) belonging to Villabruna Cluster. A 2015 study found haplogroup I2a in 13,500 year old remains from the Azilian culture (from Grotte du Bichon, modern Switzerland).[5] Subclades of I2a1 (I-P37.2), namely I-M423 and I-M26 have been found in remains of western European hunter gatherers dating from 10,000 to 8,000 years before present respectively.[6]
Haplogroup I2a1b (M423)
I2a1b (M423, L178) was known as I1b until 2007, and I2a2 from 2008 to 2010. The main subclade, representing over 90% of all M423 lineages is L621 and its subclade L147.2. The other subclades are L41.2 (very rare) and L161.1 (found mostly in Germany and the British Isles).
I2a1b (M423, L178) was known as I1b until 2007, and I2a2 from 2008 to 2010. The main subclade, representing over 90% of all M423 lineages is L621 and its subclade L147.2. The other subclades are L41.2 (very rare) and L161.1 (found mostly in Germany and the British Isles).
I2 (M438/P215/S31) is thought to have originated during the Late Paleolithic, around the time of the Last Glacial Maximum (LGM), which lasted approximately from 26,500 to 19,000 years ago. I2 probably appeared in western Europe, although its exact region of origin cannot be determined since Paleolithic Europeans were nomadic hunter-gatherers. The oldest I2 sample recovered from archeological skeletons is a 13,500 year-old man from the Grotte du Bichon in Switzerland associated with the Azilian culture (see Jones et al. (2015)). His maternal lineage was U5b1h. As of October 2016, 15 Mesolithic European Y-DNA samples have been tested. Among them one belonged to haplogroup C1a2 (in Spain), one to F (in Germany), two to I* (in France), and six to I2 (Luxembourg and Sweden), including to I2a1* (P37.2), I2a1a1a (L672), I2a1b (M423) and I2c2 (PF3827). The maternal (mtDNA) lineages that they carried were U2e, U4, U5a1, U5a2 and U5b. The four samples from Russia belonged to Y-haplogroup J*, R1a1 (2x) and R1b1a. This shows that there was already a certain amount of diversity among Mesolithic European lineages, although many of these lineages (C1a2, F, I*, J*) are now exceedingly rare. Haplogroup I2a1 seems to have come out of the Neolithic period as the big winner for reasons that are not yet clear.
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