Haplogroup R2 (Y-DNA)

R2 is a Y-chromosome haplogroup characterized by genetic marker M124, and is rarely found outside India, Pakistan, Iran, and southern Central Asia.

Before the publication of the 2005 Y-Chromosome Phylogenetic Tree, haplogroup R2 was known as Haplogroup “P1” and formerly thought to be a sister clade of Haplogroup R rather than derived from it.

Origins
According to the Genographic Project conducted by the National Geographic Society, haplogroup R2 arose about 25,000 years ago in southern Central Asia, and its members migrated southward as part of the second major wave of human migration into India.

According to , "uncertainty neutralizes previous conclusions that the intrusion of HGs R1a1 and R2 from the northwest in Dravidian-speaking southern tribes is attributable to a single recent event. Rather, these HGs contain considerable demographic complexity, as implied by their high haplotype diversity. Specifically, they could have actually arrived in southern India from a southwestern Asian source region multiple times, with some episodes considerably earlier than others."

Distribution
At least 90% of R2 individuals are located in the Indian sub-continent. It is also reported in Caucasian and Central Asian populations. Haplogroup R2, along with haplogroups H, L, R1a1, and J2, forms the majority of the South Asian male population. The frequency is around 10-15% in India and Sri Lanka and 7-8% in Pakistan. Its spread within South Asia is very extensive, ranging from Baluchistan in the west to Bengal in the east; Hunza in the north to Sri Lanka in the south.

Within South Asia, Sinhalese have a frequency of 38% while West Bengalis have a frequency of 23%. The Parsees in Pakistan have this lineage at around 20%. Other South Asian communities that have a reasonably high frequency include Lodha, an Austro-Asiatic tribe in East India, with 35%, Pallans, a Dravidian community in South India with 14% and Konkanasth or Chitpavan Brahmins of Western India with 9%. This lineage also forms 5% of Punjabi males. The R2 haplogroup is also found in 14% of the Burusho people who speak the language isolate called Burushaski.

Some of the other studies like Bamshad et al., 2001, Kivisild et al., 2003 found Haplogroup 1(the old representation for non-R1a1 Haplogroup R subclades) at around 40% among Telugus of coastal Andhra Pradesh. The identification of this Haplogroup with R2 is confirmed from Sanghamitra Sahoo et al., 2006 study which observed R2 ranging from 35% to 55% among non-Brahmin castes of this region.

Haplogroup R2 comprises 53% of Y-chromosomes among Sinti Roma, a subgroup of the Roma living in Germany who were relocated to Central Asia. This Gypsy tribe has its ancient roots in India.

An R2 frequency of 15.8% was observed among Chechens but may not be representative because the sample size was only 19 individuals.

R2 was found at an unusually high frequency of 44% among speakers of the Kurdish dialect Kurmanji in Georgia, but at a much lower frequency of 8% among Kurmanji speakers in Turkmenistan.

In the Caucasus, around 3% of Azerbaijanis, 2% of Armenians, and 1% of Georgians belong to the R2 haplogroup. Approximately 1% of Anatolian Turks also belong to this haplogroup.

In Central Asia, Tajikistan shows Haplogroup R2 at 6%, while the other '-stan' states vary around 2%. Bartangis of Tajikistan have a high frequency of R2 at about 17%.

This haplogroup is rare among Europeans and non-existent in African, East Asian, Native American and Native Australian populations. Among Europeans there are at least two confirmed clusters of R2 individuals among Ashkenazi Jews, which may reflect either an Iranian or a Central Asian (Khazar) origin of a portion of this group.

Manoukian's (2006) summary of the Genographic Project
The following is Manoukian's (2006) summary of the findings of the Genographic Project conducted by the National Geographic Society and directed by Spencer Wells: 
 * Haplogroup R, the ancestral clade to R1 and R2, appeared on the Central Asian Steppes around 35,000 to 30,000 years ago.
 * R1, sister clade to R2, moved to the West from the Central Asian Steppes around 35,000 to 30,000 years ago. R1 pockets were established, from where R1a and R1b emerged.
 * R2 moved into the Indian sub-continent around 25,000 years ago. The routes taken are not clear, although the Indus and Ganges rivers are possible theories put forward.

Manoukian's (2006) summary of Sengupta et al. (2006)
Manoukian's (2006) summary of is as follows: 
 * Haplogroup R2 is present both in Dravidian and Indo-European populations, meaning that R2 has a pan-Indian presence, and not restricted to any linguistic group.
 * Haplogroup R2 has a more significant presence in middle and upper castes.
 * The frequencies of R2 seem to mirror the frequencies of R1a (i.e. both lineages are strong and weak in the same social and linguistic subgroups). This may indicate that both R1a and R2 moved into India at roughly the same time or co-habited, although more research is needed.
 * R1a1 and R2 haplogroups indicate demographic complexity that is inconsistent with a recent single history.
 * R2 has a particularly strong presence in the Indian states of West Bengal, Uttar Pradesh and Gujarat, and in the area of Mumbai (Bombay).
 * The paper claims that there is no evidence that Central Asia was the source of the R1a and R2 lineages in India. The theory that Central Asia could have been the recipient of the two lineages from India should not be ruled out.

Relationship to other haplogroups
R2 is a subgroup of Haplogroup R (M207).

Prediction with Haplotypes
Haplotype can be used to predict haplogroup. The chances of any person part of this haplogroup is the highest if DYS391=10, DYS392=10 and DYS426=12.