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Wednesday, November 26, 2008

Elamo-Harappan origins for Haplogroup J2 in India?

The presence of Haplogroup J2 in India, including the subclades M410 and M241 has been an often overlooked clue to the origins of M172. Sengupta et al, in 2005 worked to explain the presence of M172 in India. Their paper provides an immediate acknowledgement of the proposed spread of proto-Elamo-Dravidian speaking peoples into India originating from the Indus Valley and southwest Persia. The idea that M172 may have been carried into India with proto-Elamo-Dravidian groups is supported by the frequencies of Haplogroup J in one of the only remaining Dravidian Speaking ethnic groups in the Iranian Plateau, the Brahui. 28% of the Brahui, an ethnic Dravidian speaking group from Western Pakistan were found to carry the mutation defining Haplogroup J. Overall Haplogroup J2 in India represented 9.1% of this very populous nation. In Pakistan, M172 accounted for 11.9% of the Y-Chromosomes typed. Sengupta's paper broke down the frequencies of Haplogroup J2 into various caste and language groups. J2 was found to be significantly higher among Dravidian castes at 19% than among Indo-European castes at 11%. J2a-M410 in particular may be a strong candidate for a proposed migration of proto-Dravidian peoples from the Iranian Plateau or the Indus Valley since J2a M410 is a very high component of the haplogroup J2 chromosomes found in Pakistan. Over 71% of the M172 found in Pakistan was M410+.

Another interesting characteristic in the distribution of M172 and more specifically, M410, in India was its higher frequencies in Upper Caste Dravidians. M410+ chromosomes were found in 13% of Upper Caste Dravidians. Sengupta goes on to suggest an Indian origin of Dravidian speakers but from a Y chromosome perspective, the paper seems to acknowledge M172 arriving in India from Middle Eastern and Indus Valley Civilizations.

Despite an apparent exogenous frequency spread pattern of J2a toward North and Central India from the west, it is premature to attribute the spread to a simplistic demic expansion of early agriculturists from the Middle may also reflect subsequent Bronze Age Harappans of uncertain provenance.

Subclades of M172 such as M67 and M92 were not found in either Indian or Pakistani samples which also might hint at a partial common origin. And while there may be multiple events and origins for M172 lineages in India, it does seem likely that the Indus Valley and Elamo-Dravidian speaking groups may be the origin of some of the M172 found in India today.

Friday, November 14, 2008

Y chromosomes of Sicily

In May of 2008, Cornelia Di Gaetano et al submitted an article to the European Journal of Human Genetics studying the Y chromosome makeup of the island of Sicily. Sicily has one of the highest frequencies of Haplogroup J2 (M172) in the mediterranean. J2-M172 made up 33% of the Y chromosome signatures on the island and was non-randomly distributed occurring at higher frequencies in the eastern areas of the island. This distinction was evident in the subclades, M67 and M92, which have previously been linked to Greek and proto-greek colonization. Both M67 and M92 were twice as frequent on the eastern portion of Sicily which displays more archaelogical traces from the Greek classic era. Even the paragroup of undistinguished J2 haplotypes (M172) was more than twice as frequent in Eastern Sicily. One of the more interesting subclades, referred to as J2a1k (DYS445=6) showed an interesting non-random distribution in Sicily. This subclade is also commonly referred to as J2a1h (ISOGG) or J2a-Lambda (J2 DNA Project). Most striking was differences in frequencies between Mazara Del Vallo and Sciacca. Mazara Del Vallo is a port city established by the Phoenicians in the 9th century B.C. while Sciacca, known as Thermae in Greek times, was founded in the 5th century B. C. by the Greeks. These 2 cities, founded by different groups are only 57 KM apart. Yet 11.11% of the Y chromosomes in Mazara del Vallo were J2 M172 with DYS 445=6 while this subclade was absent from the sample data from Sciacca. Trapani, another port city in Western Sicily also exhibited high levels of J2-M172 with DYS 445=6 at 9.09%. This subclade was absent from the inland cities of Santa Ninfa and Piazza Armerina and the northern Sicily town of Caccamo. The data seems to suggest that J2a1h (J2a1k)'s distribution is stronger in coastal regions of Western Sicily and more rare in inland and Eastern parts of the island. The sole exception to this trend was the data from Troina which did report 10% J2 M172 with DYS 445=6. Overall the non-random and high levels of J2 on the island of Sicily seem to reflect the complex history of the island and might represent multiple migrations by multiple groups over various periods of the islands history.

The general heterogeneous composition of Hgs seen in our Sicilian data is consistent with similar patterns observed in other major islands of the Mediterranean, like Sardinia and Crete, possibly reflecting the complex histories of settlements in these islands during the Holocene.