Haplogroup K2a is a human Y-chromosome DNA haplogroup. K2a is a primary subclade of haplogroup K2, which in turn is a primary descendant of haplogroup K. Its sole primary descendant is haplogroup K-M2313. As of 2020, K-M2313 is known to have two primary subclades: Haplogroup NO, which has numerous members and the extremely rare K-Y28299. Basal, undivergent K2a* has been found only in the remains of two Upper Paleolithic individuals, known as "Ust'-Ishim man and "Oase-1", who lived in Siberia and the Banat region of south-central Europe, respectively, about 37–45 ky BP. No examples of K-M2313* or NO* have been identified in living males or remains. However, subclades of NO-M214 include a majority of living males in East Asia, Northern Eurasia and South East Asia. K-Y28299 has been found in three living individuals from India. Another two other living males, who have been documented as belonging to K-M2313, have not been tested for Y28299. These K-M2313 individuals have ethnic ties to South Asia and South East Asia respectively: a Telugu from India and an ethnic Malay from Singapore.
Discoveries since 2016
Before 2016, many authorities considered that the SNP M2308 was always found in conjunction with SNPs such as M2313 and M214. However, researchers such as G. David Poznik discovered examples of Y-DNA that had some, but not all, of the SNPs peculiar to NO, but also lacked SNPs identifying other primary subclades of K2. Poznik et al. 2016 therefore identified K2a, K-M2313 and NO as "parent", "child" and "grandchild" clades respectively. Poznik et al. also found that K-Y28301 – which has living members in India – is descended from K-M2313. The above findings by Poznik et al. were reiterated by the work of Moreno-Mayar et al. in 2018. As of 2018, authorities like the International Society of Genetic Genealogy and YFull have not integrated the discoveries of Poznik et al., and differ from each other in nomenclature.
ISOGG has continued to use the names "K2a" and "NO" in reference to an undifferentiated clade combining K2a and K-M2313, while referring to NO-M214 as "NO1".
YFull does not distinguish between K-M2308 and K-M2313, referring to both as "K-M2335".
There is evidence of at least two additional primary branches within K-M2308 and/or K-M2313.
YFull alone lists a clade, known only as K-Y28299, branching from an undifferentiated K-M2308/K-M2313. In addition, a newer, more divergent subclade named K-Y28301 is a primary branch of K-Y28299, according to YFull. Furthermore, according to both Poznik and Moreno-Mayar, K-Y28301 is also descended from K-M2313, suggesting the following lineage: K-M2313 > K-Y28299 > K-Y28301. Three living individuals in India have been found to carry K-Y28299* or K-Y28301.
ISOGG alone lists a haplogroup known only as "NO1~" identified by the SNP CTS707/M2306, as a sibling of NO-M214. NO1~ is likely a primary branch of either K-M2313 or NO-M214, because, as of 2018, YFull regards CTS707/M2306 as synonymous with M214/PAGE39/PAGES00039, and yet NO1~ is also not ancestral to either Haplogroup N or Haplogroup O .
K2a* has been found only in the paleolithic remains mentioned above:
"Ust'-Ishim man" – the name given to 45,000 year old remains of one of the early modern humans to inhabit western Siberia. The fossil was named after the Ust'-Ishim District of Siberia where it had been discovered. Until 2016, Ust'-Ishim man was classified as belonging to Haplogroup K2*.
"Oase-1", the remains of an individual who lived approximately 37,800 years ago, in Eastern Europe.
K-M2313
As of 2016, two living males had been found to carry K-M2313 – a British Asian who identifies as Telugu and an ethnic Malay sampled in Singapore. Note that they were NOT tested for Y28299.
NO (M214)
Basal examples of haplogroup NO* have not been identified. Subclades of haplogroup NO include a majority of living males in East Asia, South East Asia and northern Eurasia.
K-Y28299*
K-Y28299 has been found in a living male from India. K-Y28301, a subclade of K-Y28299, has been found in living individuals with their origins in Andhra Pradesh and Arunachal Pradesh India.
