http://www.owlapps.net/owlapps_apps/articles?id=4148423&lang=en
H2
The earliest sample of H2 is found in the Pre-Pottery Neolithic B culture of the Levant 10,000 years ago. From ancient samples, it is clear that H2 also has a strong association with the spread of agriculture from Anatolia into Europe, and is commonly found with haplogroup G2a. H2 was found in Neolithic Anatolia, as well as in multiple later Neolithic cultures of Europe, such as the Vinča culture in Serbia, and the Megalith culture of Western Europe.

The 2021 study "Using Y-chromosome capture enrichment to resolve haplogroup H2 shows new evidence for a two-path Neolithic expansion to Western Europe" found that while H2 is less than 0.2% in modern-day western European populations it was more common during the Neolithic, between 1.5 and 9%. They identified two major clades H2m and H2d. With respect to the current ISOGG nomenclature, H2m appears to be defined by a mix of H2, H2a, H2a1 and H2c1a SNPs while H2d appears to be defined by two H2b1 SNPs, and four additional SNPs which were previously undetected. They estimated TMRCA for H2d and H2m was  ~15.4 kya with H2m and H2d estimated TMRCAs of  ~11.8 and  ~11.9 kya respectively. H2 diversity probably existed in Near-Eastern hunter-gatherers and early farmers, and subsequently spread via the Neolithic expansion into Central and Western Europe. H2d was found along the inland/Danubian route into central Europe, but most H2m individuals are found along the Mediterranean route into Western Europe, the Iberian Peninsula and ultimately, Ireland.

There were also two occurrences of H2a found in the Neolithic Linkardstown burials in the southeast Ireland. More Neolithic H2 samples have been found in Germany and France.