Haplogroup R2 (Y-DNA)

From Wikipedia, the free encyclopedia

Haplogroup R2 (M124) is a Y-chromosome haplogroup. Unlike the other subgroups of haplogroup R, it is confined to South Asia and nearby regions.

1 Origins
2 Locale
3 R2 and World Populations
4 R2 in South Asia
5 Phylogeography of R2 in South Asia
6 Relationship to other haplogroups
7 Prediction with Haplotypes
8 See also
9 References

[edit] Origins

Haplogroup R2 is a subgroup of haplogroup R. According to The Genographic Project [1] an individual in the R* paragroup carried the new M207 mutation on his Y-chromosome. His descendants ultimately split into two distinct groups, with one (R1, defined by M173 marker) continuing onto the European subcontinent, making this man the ancestor of most European men alive today (R1a: East Europe, R1b: West Europe). The second group, R2, defined by the M124 marker, is made up of the descendants of a man who lived somewhere in South Central Asia about 25,000 years before present. This second group did not head west into Europe, but rather likely turned south, ultimately ending their journey in the Indian subcontinent and giving rise to many men whose lineages survive there today. This distribution adds weight to linguistic and archaeological evidence suggesting that a large migration from the Asian steppes into India occurred within the last 10,000 years. However, the distribution of genetic lineages that the second group ultimately gave rise to, still remains largely a mystery. This is because there is precious little data with which to uncover the history of this haplogroup.

Sanghamitra Sengupta [2]however, has an Indo-centric viewpoint about R2 origins and he believes that the haplogroup coalesced somewhere in Northern India with a subsequent pan-Indian spread.

The presence of R2 in Central Asia and the Caucasus (with traces in Eastern Europe) tends to reinforce the The Genographic Project's conjecture about Central Asia's centrality as regards R2 origins and subsequent distribution.

[edit] Locale

The highest frequency is found in South Asia. It is also reported in lower frequencies in Caucasian and Central Asian populations.

[edit] R2 and World 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.

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.

Haplogroup R2 is also observed at a frequency of 16% among Chechens.

One of the Kurdish tribes in Georgia, ie Kurmanji, is found to have this haplogroup at a frequency of 12%.

In Caucasus, around 3% of Azerbaijanis, 2% of Armenians and 1% of Georgians belong to the R2 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.

[edit] R2 in South Asia

Highlights of a study by Sanghamitra Sengupta et al, 2006 are as follows:

• Haplogroup R2 is present both in Dravidian and Indo-European populations, meaning that R2 has a pan-Indian presence, and is not restricted to any linguistic group.

• 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).

• Contrary to Spencer Well's findings, 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.

• 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.