Haplogroup K2

{{Short description|Human Y chromosome DNA grouping indicating common ancestry}}

{{about|the Y-chromosome haplogroup K2|mitochondrial DNA haplogroup K2|Haplogroup K (mtDNA)|the Y-DNA haplogroup known until 2008 as K2|Haplogroup T (Y-DNA)|the haplogroup sometimes known as "K-P256"|Haplogroup M-P256}}

{{Use dmy dates|date=January 2025}}

{{Infobox haplogroup

| name = K2

| map = Haplogroup K of Ydna haplotree.png

| origin-date = 47,000-50,000 years BP{{cite journal |last1=Fu |first1=Qiaomei |last2=Li |first2=Heng |last3=Moorjani |first3=Priya |last4=Jay |first4=Flora |last5=Slepchenko |first5=Sergey M. |last6=Bondarev |first6=Aleksei A. |last7=Johnson |first7=Philip L. F. |last8=Aximu-Petri |first8=Ayinuer |last9=Prüfer |first9=Kay |last10=de Filippo |first10=Cesare |last11=Meyer |first11=Matthias |last12=Zwyns |first12=Nicolas |last13=Salazar-García |first13=Domingo C. |last14=Kuzmin |first14=Yaroslav V. |last15=Keates |first15=Susan G. |last16=Kosintsev |first16=Pavel A. |last17=Razhev |first17=Dmitry I. |last18=Richards |first18=Michael P. |last19=Peristov |first19=Nikolai V. |last20=Lachmann |first20=Michael |last21=Douka |first21=Katerina |last22=Higham |first22=Thomas F. G. |last23=Slatkin |first23=Montgomery |last24=Hublin |first24=Jean-Jacques |last25=Reich |first25=David |last26=Kelso |first26=Janet |last27=Viola |first27=T. Bence |last28=Pääbo |first28=Svante |title=Genome sequence of a 45,000-year-old modern human from western Siberia |journal=Nature |date=October 2014 |volume=514 |issue=7523 |pages=445–449 |doi=10.1038/nature13810 |pmid=25341783 |pmc=4753769 |bibcode=2014Natur.514..445F }}

| origin-place = Possibly Middle East, Central Asia or Southeast Asia{{Cite journal|doi=10.1007/s00439-020-02204-9|title=A Southeast Asian origin for present-day non-African human y chromosomes|year=2021|last1=Hallast|first1=Pille|last2=Agdzhoyan|first2=Anastasia|last3=Balanovsky|first3=Oleg|last4=Xue|first4=Yali|last5=Tyler-Smith|first5=Chris|journal=Human Genetics|volume=140|issue=2|pages=299–307|pmid=32666166|pmc=7864842}}

| ancestor = K

| descendants = K2a (M2308); K2b (MPS); K2c; K2d; K2e.

| mutations = rs2033003 (M526)

| Highest frequencies =

}}

Haplogroup K2, also known as K-M526 and formerly known as MNOPS,{{cite journal | last1 = Chiaroni | first1 = Jacques | last2 = Underhill | first2 = Peter A. | last3 = Cavalli-Sforza | first3 = Luca L. | year = 2009 | title = Y chromosome diversity, human expansion, drift, and cultural evolution | journal = PNAS | volume = 106| issue = 48| pages = 20174–9| doi = 10.1073/pnas.0910803106 | pmid = 19920170 | pmc=2787129| bibcode = 2009PNAS..10620174C | doi-access = free }} is a human Y-DNA haplogroup.

Relative to its age, the internal structure of K2 is extremely complex, and subclades of it are carried by males native to regions including Australasia, Oceania, Southeast Asia, South Asia, East Asia, Central Asia, the Americas, Europe, and the Horn of Africa. Many of its branches are very common, the most numerically important being R in Europe and South Asia and O in East and Southeast Asia (as well as recent immigrants to other continents). Haplogroups N and Q, while they are less common overall, are also very widespread, in northern Eurasia and the Americas respectively. M and S are almost entirely restricted to Oceania and eastern Indonesia, where they occur at high frequency.

Rare subclades outside of these major lineages are known mainly from Island Southeast Asia (including the Andaman Islands and the Philippines).

Basal paragroup K2* has been identified among native Australians, about 27% of them carry basal K-M526∗.{{cite journal |last1=Bergström |first1=Anders |last2=Nagle |first2=Nano |last3=Chen |first3=Yuan |last4=McCarthy |first4=Shane |last5=Pollard |first5=Martin O. |last6=Ayub |first6=Qasim |last7=Wilcox |first7=Stephen |last8=Wilcox |first8=Leah |last9=van Oorschot |first9=Roland A.H. |last10=McAllister |first10=Peter |last11=Williams |first11=Lesley |last12=Xue |first12=Yali |last13=Mitchell |first13=R. John |last14=Tyler-Smith |first14=Chris |title=Deep Roots for Aboriginal Australian Y Chromosomes |journal=Current Biology |date=21 March 2016 |volume=26 |issue=6 |pages=809–813 |doi=10.1016/j.cub.2016.01.028 |pmid=26923783 |pmc=4819516 }}

K2a* has been found only in Upper Paleolithic remains from western Siberia and the Balkans, known respectively as "Ust'-Ishim man" and "Oase-1". The only primary branch of K2a, known as K-M2313*, has been documented in two living individuals, who have ethnic ties to South Asia and South East Asia respectively: a Telugu from India and an ethnic Malay from Singapore. In addition, K-Y28299, which appears to be a primary branch of K-M2313, has been found in three living individuals from India. Another subclade, NO (M214)* – which for a time was thought to be synonymous with K2a (M2308)* – has not been identified in living individuals or remains.

Basal paragroup K2b* has not been identified among living males but was found in Upper Paleolithic Tianyuan man from China.{{Cite web|url=https://reich.hms.harvard.edu/downloadable-genotypes-worlds-published-ancient-dna-data|title=Downloadable genotypes of present-day and ancient DNA data (compiled from published papers) {{!}} David Reich Lab|website=reich.hms.harvard.edu|access-date=11 September 2019|archive-date=2 November 2019|archive-url=https://web.archive.org/web/20191102180107/https://reich.hms.harvard.edu/downloadable-genotypes-worlds-published-ancient-dna-data|publisher=David Reich Lab|url-status=dead}} K2b1 (P397/P399) known previously as Haplogroup MS, and Haplogroup P (P-P295), also known as K2b2 are the only primary clades of K2b. According to geneticist Spencer Wells, haplogroup K, from which haplogroup K2 descends, originated in the Middle East or Central Asia, and it is likely that haplogroup P subsequently diverged into P1 somewhere in southern Asia; from there P1 expanded into Northern Eurasia and Siberia.{{cite book |last1=Wells |first1=Spencer |title=Deep Ancestry: The Landmark DNA Quest to Decipher Our Distant Past |date=20 November 2007 |publisher=National Geographic Books |isbn=978-1-4262-0211-7 |page=79 |url=https://books.google.com/books?id=NWgDAQAAQBAJ&pg=PT79 |language=en}} "Given the widespread distribution of K, it probably arose somewhere in the Middle East or Central Asia, perhaps in the region of Iran or Pakistan."

Population geneticist Tatiana Karafet and other researchers (2014) point out that both K2b1 and P* are virtually restricted geographically to South East Asia and Oceania. Whereas, in a striking contrast, P1 and its primary subclades Q and R now make up "the most frequent haplogroup in Europe, the Americas, and Central Asia and South Asia". According to Karafet et al., 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 P*, P1, Q and R. However, these authors also stipulated that haplogroup K might have arisen in Eurasia and later went extinct there, and that either origin hypothesis is "equally parsimonious".{{harvnb|Karafet|Mendez|Sudoyo|Lansing|2015|ps= "This pattern leads us to hypothesize a southeastern Asian origin for P-P295 and a later expansion of the ancestor of subhaplogroups R and Q into mainland Asia. An alternative explanation would involve an extinction event of ancestral P-P295* chromosomes everywhere in Asia. These scenarios are equally parsimonious. They involve either a migration event (P* chromosomes from Indonesia to mainland Asia) or an extinction event of P-P295* paragroup in Eurasia."}}