Haplogroup R1a1 (Y-DNA)

Archaeogenetics

See Also

• Haplogroups
• [Haplogroup R1b (Y-DNA)]?
• Haplotype?
• [Y chromosome analysis]?

Description

In human genetics, Haplogroup R1a1 (M17) is a [Y chromosome analysis? Y-chromosome haplogroup] that is spread across Eurasia.

It is common in Europe, Northern Central Asia and India. In Europe the highest frequencies are in Eastern Europe. Today it is found with its highest levels in Poland and Russia, where one out of two men has this haplogroup. Relatively high frequencies are also found in Northern Europe and is believed to have been spread across Europe by the Vikings, which accounts for the existence of it in, among other places, the British Isles. [1]

In India initial studies with limited samples and without any diversity calculation observed a correlation between the Brahmin caste and the R1a haplogroup, which is consistent with a northern migrations from Central Asia (Bamshad et al. 2001). However, another study showed this lineage forms around 35-45% among all the castes in North Indian population (Namita Mukherjee et al. 2001) thus, invalidating the association with Brahmin caste. Recent, Studies have even shown a more diverse presence in Indian tribal and lower castes (the so-called untouchables and not part of the caste system) populations, suggesting that it is not necessarily always a signature of exclusive Indo-European origin. [2]

Spread of haplogroup R1a. Image source

Origins

The first carriers of the R1a1 haplotype are believed to have been nomadic farmers in the steppes Eastern Europe about 10,000 years ago. Current theories point to them being the first speakers of the proto-Indo-European languages (the Kurgan culture) and the first ones to domesticate the horse.

Relationship to other haplogroups

R1a1 is a subgroup of [Haplogroup R (Y-DNA)? Haplogroup R] (M207).

It is related to [Haplogroup R1b (Y-DNA)? Haplogroup R1b] (M343) which is dominant in Western Europe, and more distantly related to [Haplogroup R2 (Y-DNA)? Haplogroup R2] (M124).

• [Haplogroup R (Y-DNA)? Haplogroup R] (M207)
  • Haplogroup R1 (M173)
    • Haplogroup R1a (SRY10831.2-)
      • Haplogroup R1a1 (M17)
      • Haplogroup R1a*
    • [Haplogroup R1b (Y-DNA)? Haplogroup R1b] (M343)
  • [Haplogroup R2 (Y-DNA)? Haplogroup R2] (M124)

Discussion

The current distribution of the M17 haplotype is likely to represent traces of an ancient population migration originating in southern Russia/Ukraine, where M17 is found at high frequency (>50%). It is possible that the domestication of the horse in this region around 3,000 B.C. may have driven the migration. The distribution and age of M17 in Europe and Central/Southern Asia is consistent with the inferred movements of these people, who left a clear pattern of archaeological remains known as the Kurgan culture, and are thought to have spoken an early Indo-European language.

The decrease in frequency eastward across Siberia to the Altai-Sayan mountains (represented by the Tuvinian population) and Mongolia, and southward into India, overlaps exactly with the inferred migrations of the Indo-Iranians during the period 3,000 to 1,000 B.C.. It is worth noting that the Indo-European-speaking Sourashtrans, a population from Tamil Nadu in southern India, have a much higher frequency of M17 than their Dravidian-speaking neighbors, the Yadhavas and Kallars (39% vs. 13% and 4%, respectively), adding to the evidence that M17 is a diagnostic Indo-Iranian marker. The exceptionally high frequencies of this marker in the Kyrgyz, Tajik/Khojant, and Ishkashim populations are likely to be due to drift, as these populations are less diverse, and are characterized by relatively small numbers of individuals living in isolated mountain valleys. (1)

Y chromosomal studies suggest that there is a close cladistic relationship between many europeans and north indians via the M17 haplotype

References

• Luigi Luca Cavalli-Sforza (1994), The History and Geography of Human Genes, Pub. Princeton University Press. ISBN 0691087504 (alternate, search)
• Semino et al (2000), The Genetic Legacy of Paleolithic Homo sapiens sapiens in Extant Europeans, Science, Vol 290
• Wells et al (2001), The Eurasian Heartland: A continental perspective on Y-chromosome diversity, PNAS, Vol 98
• Sanghamitra Sengupta et al. (2006), Polarity and Temporality of High-Resolution Y-Chromosome Distributions in India Identify Both Indigenous and Exogenous Expansions and Reveal Minor Genetic Influence of Central Asian Pastoralists, American Journal of Human Genetics, 78:202-221

External links

• Spread of R1a1, from the Genographic Project, National Geographic
• Y-chromosome haplotype frequencies in 49 Eurasian populations, listed according to geographic region