Haplogroup K2b (Y-DNA)

Haplogroup K2b is a primary subclade of haplogroup K2. Due to its unusually wide and rapid geographical dispersal, with at least five primary subclades (including K2b) and its basal form (K2*),^[6] haplogroup K2 probably emerged in close proximity to K* and K2b. According to the population geneticist Tatiana Karafet et al. (2014), the estimated dates for the branching of K, K2, K2b and P point to a "rapid diversification" within K2 "that likely occurred in Southeast Asia," with subsequent "westward expansions" of P1, Q and R.^[2]

Haplogroup K2b is a secondary subclade of haplogroup K-M9. Geneticist Spencer Wells had argued that because haplogroup K-M9 has a geographically wide distribution, the lineage may have originated near the central part of this range in the Middle East or Central Asia, perhaps in Iran or Pakistan.^[7]

Basal paragroup K2b* has not been identified among living males, but was detected in the Tianyuan man found in China, an individual dated to the Upper Paleolithic (about 40,000 years BP).^[8]

K2b1 (P397/P399), known previously as haplogroup MS, and haplogroup P (P-P295), also known as K2b2, are the only primary subclades of K2b. Karafet and other researchers (2014) point out that K2b1, its subclades and P* are virtually restricted geographically to South East Asia and Oceania.^[2] Whereas, in a striking contrast, subclades of P1, namely Q and R, now make up "the most frequent haplogroup in Europe, the Americas, and Central Asia and South Asia".

• K2b (P331), also known as MPS.
  • K2b1 (P397, P399), similar to the previous haplogroup MS.
    • K2b1a (P405)
      • K2b1a1 (P60)
      • K2b1a2 (P79)
      • K2b1a3 (P315)
      • Haplogroup S (B254), previously known as K2b1a.
    • Haplogroup M (P256), also known as K2b1b.
  • Haplogroup P (P-F5850)
    • P1 (P295/PF5866/S8, 92R7_1, 92R7_2, F91/PF5862/V231)
      • P1a (B253/Z33760/Z33761/Z33762/Z33763), formerly P2.
      • P1b (FT292000)
      • P1c (M45/PF5962), descendant subclades include the major haplogroups Q and R.

There is a distinct contrast between the distribution of two, de facto geographical groups comprising, respectively:

• K2*, K2b1 (all subclades), P* (also known as K2b2*; P-P295*) and P2 (also known as K2b2b; P-B253), and;
• P1 (also known as K2b2a) and its descendants, including Q and R.

To the extent that both groups overlap, it is in populations native to the southwest Pacific region, where some Negrito populations carry very high levels of K2b at the subclade level. It is carried, for instance, by more than 83% of males among the Aeta (or Agta) people of the Philippines, in the form of subclades of K2b1 (haplogroups M and S, at levels of more than 60%), as well as P*, P1*, and P2*.

Modern populations with living members of K2*, K2b1 (haplogroups M and S), P* (P-P295*) and P2 (also known as K2b2b) are the predominant haplogroups in New Guinea, some subgroups of indigenous Australians, as well as males native to other parts of Oceania and parts of Island South East Asia.

P1 (also known as K2b2a), including primary subclades such as P1c (P-M45*; previously P1), in modern times, is distributed among populations native to a wide area that includes Europe, Central Asia, South East Asia, and Native Americans.

• Ancient population haplogroups are assumed from small ancient sample sizes.
• † Stands for assumed extinction (no living sample of the same haplogroup).
• ^[2] Entire phylogeny except for haplogroup X, K2b1 clades, K2* clades, and K2c, K2d, as well as P(xM45).
• ^{[12][13][14][15]} Ancient DNA samples.
• ^{[16][17][18][19][20][21][22][23][24][25][26][27]} Modern populations and ancient Basques.
• ^[5][28] Y-chromosome DNA haplogroup X.

Assuming 70,000 years BP for the TMRCA of M168 chromosomes, we estimate the interval of time between the diversification of K-M9 and that of K-P331 to be less than 3,000 years. This rapid diversification has also been assessed using whole Y-chromosome sequence data. In addition, we estimate the total time between the common ancestor of K-M9 and that of P-P295 to be less than 5,000 years, and the time between the common ancestor P-P295 and that of P-P27 to be around 12,300 years.^[2]