Haplogroup O-M122 (Y-DNA)

Haplogroup O-M122
Isofrequency map portraying spatial distribution of Haplogroup O-M122 in Asia and Oceania as per (Kumar 2007). The dots indicate the populations and the regions from where it was sampled.
Possible time of origin	About 30,000 years ago (Shi 2009) 35,000 (with slower average mutation rate) or 30,000 (with faster average mutation rate) years ago 31,200 [95% CI 29,400 <-> 33,100] years before present
Possible place of origin	China (GenographicProject 2005) or Southeast Asia (Shi 2009)
Coalescence age	28,400 [95% CI 26,000 <-> 30,900] years before present
Ancestor	O-M175
Defining mutations	M122 (Krahn and FTDNA 2013)

In human population genetics, haplogroups define the major lineages of direct paternal (male) lines back to a shared common ancestor in Africa. Haplogroup O-M122 （also known as Haplogroup O2 (formerly Haplogroup O3)）is an Eastern Eurasian Y-chromosome haplogroup. The lineage ranges across Southeast Asia and East Asia, where it dominates the paternal lineages with extremely high frequencies.

This lineage is a descendant haplogroup of haplogroup O-M175.

Researchers believe that O-M122 first appeared in Southeast Asia approximately 25,000-30,000 years ago (Shi 2009). In a systematic sampling and genetic screening of an East Asian–specific Y-chromosome haplogroup (O-M122) in 2,332 individuals from diverse East Asian populations, results indicate that the O-M122 lineage is dominant in East Asian populations, with an average frequency of 44.3%. Microsatellite data show that the O-M122 haplotypes are more diverse in Southeast Asia than those in northern East Asia (Shi 2009). This suggests a southern origin of the O-M122 mutation to be likely.

It was also part of the settlement of East Asia. However, the prehistoric peopling of East Asia by modern humans remains controversial with respect to early population migrations and the place of the O-M122 lineage in these migrations is ambivalent.

Although Haplogroup O-M122 appears to be primarily associated with Chinese people, it also forms a significant component of the Y-chromosome diversity of most modern populations of the East Asian region.

Haplogroup O-M122's brother clade, Haplogroup O-MSY2.2, displays a similar geographical distribution, being found among nearly all the populations of East and Southeast Asia, but generally at a frequency much lower than that of Haplogroup O-M122. Another brother clade, Haplogroup O-P31, has an impressive extent of dispersal, as it is found among the males of populations as widely separated as the Kolarians of India and the Japanese of Japan; however, Haplogroup O-P31's distribution is much more patchy, and the Haplogroup O-P31 Y-chromosomes found among the Mundas and the Japanese belong to distinct subclades.