# Haplogroup K2a (Y-DNA)

Haplogroup K2a (M2308, Z4842) is a human Y-chromosome DNA haplogroup. K2a is a primary subclade of haplogroup K2 (M526), which in turn is a primary descendant of haplogroup K (M9). Its sole primary descendant is haplogroup K-M2313 (M2313, Z4858 S11799).
As of 2020, K-M2313 is known to have two primary subclades: Haplogroup NO1 (a.k.a. NO-M214), which has numerous members and the extremely rare K-Y28299, sometimes known as NO2.
Basal, undivergent K2a* (K-M2308*) 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 NO1* (NO-M214*) have been identified in living males or remains. However, subclades of NO1 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(xM214), have not been tested for Y28299 (and therefore may belong to K-Y28299). These K-M2313(xM214) individuals have ethnic ties to South Asia and South East Asia respectively: a Telugu from India and an ethnic Malay from Singapore.

## Origin

According to geneticist Spencer Wells, haplogroup K probably originated in the Middle East or Central Asia, possibly in the vicinity of Iran or Pakistan. However, Karafet et al. (2014) proposed that "rapid diversification ... of K-M526", also known as K2, likely occurred in Southeast Asia and later expanded to mainland Asia, although they could not rule out that it might have arisen in Eurasia and later went extinct there, and that either of these scenarios are "equally parsimonius".

## 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 (M214), but also lacked SNPs identifying other primary subclades of K2 (M526). Poznik et al. 2016 therefore identified K2a (M2308), K-M2313 and NO (M214) as "parent", "child" and "grandchild" clades respectively. (While Poznik used the name "K2a1" for K-M2313, this has not been widely adopted – possibly because K2a1 has sometimes been used as an alternate name for other, less closely related haplogroups.) 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 (ISOGG) have not integrated the discoveries of Poznik et al.
* ISOGG has continued to use the names "K2a" and "NO" in reference to an undifferentiated clade combining K2a (M2308) and K-M2313 (i.e. Poznik's K2a and "K2a1"), while referring to NO-M214 as "NO1".
There is evidence of at least two additional primary branches within K-M2308 (Poznik: K2a) and/or K-M2313 (Poznik: K2a1).
* YFull alone lists a clade, known only as K-Y28299, branching from an undifferentiated K-M2308/K-M2313 (YFull name: K-M2335). 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. (As of 2018, ISOGG had not incorporated K-Y28299 or K-Y28301.)
* ISOGG alone lists a haplogroup known only as "NO1~" [sic] identified by the SNP CTS707/M2306, as a sibling of NO-M214. (Under the taxonomic conventions used by ISOGG, a tilde [~] indicates a distinct haplogroup, the position of which in the phylogeny is as yet unclear.) 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 (according to ISOGG) ancestral to either Haplogroup N (M231) or Haplogroup O (M175).

## Phylogenetic tree

K2a K-M2308 (M2308, CTS11667)
* K-M2313 (Z4952/M2339/E482, F549/M2335/S22380/V4208, Z4842/M2308/V1371, F650/M2346, Z4858/M2313/S11799/E295/E205, Z4829)
** K-Y28299 (Y28299/Y28355, Y28357, Y28412, etc.)
*** K-Y28301 (Y28301/Y28328, Y28358, Y28410)
** NO (M214/Page39, F176/M2314, CTS5858/M2325/F346, CTS11572)
*** N (M231, CTS2947/M2175, Z4891, CTS10118)
*** O (M175/P186/P191/P196, F369/M1755, F380/M1757/S27659)
? "NO1~" (CTS707/M2306)
    Notes regarding phylogenetic tree
* ↑ Some authorities, such as ISOGG and YFull, do not yet include the separation of the subclade defined by the SNP F549/M2335/S22380/V4208 from the clade defined by the SNPs M2308 and Z4842, identified by Poznik et al. (2016).
* ↑ Position of K-Y28299 and its subclade K-Y28301 based on YFull 2018. In addition, while K-Y28299 is not specifically mentioned by researchers such as Poznik et al. (2016) and Moreno-Mayar et al. (2018), these sources do state that K-Y28301 is a lineal descendant of K-M2313.
* ↑ No phylogenetic name as of 2018; according to YFull, K-Y28301 is a primary branch of K-Y28299. In addition, according to Poznik et al. 2016 and Moreno-Mayar et al. 2018, K-Y28301 is a descendant of K-M2313.
* ↑ ISOGG 2018 name NO1.
* ↑ "NO1~" is a temporary name used by ISOGG (2018). Approximate position only; YFull (2018) regards CTS707/M2306 as concurrent with M214/Page39, suggesting that NO1~ is a primary branch of K-M2313 or NO-M214.

## Distribution
### K2a* (K-M2308*)

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 (modern Romania).

### K-M2313

As of 2016, two living males had been found to carry K-M2313(xNO-M214) – 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(xY28301) 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.