Friday, September 07, 2007

YAP insertion signature in South Asia

The YAP+ variant of the Y chromosome has been found in the Andaman and Nicobar islands off the coast of India.

YAP+ here belongs to haplogroup D as compared to haplogroup E of Africa, West Asia and Europe.

Now, haplogroup D has also been found among "tribal" peoples of Northeast India sometimes at frequencies of up to 65%.

The YAP+ insertion has been of interest in Asia because of its presence among the mysterious Ainu people of Japan.

Previously it was thought that YAP+ reached Japan from Central Asia but there was a "missing link" in the haplotype's genetic tree. That link was eventually found among Andaman and Nicobar Islanders.

Although superficially different, the Andaman Islanders and the Ainu share a similar diminutive stature on par with the Agta or "Negrito" peoples, and a type with straighter, more abundant hair in Southeast Asia; and the Khoisan, Mbuti, Twa and similar peoples of Africa.

Many earlier researchers found physical characteristics in the Ainu that pointed more toward origins in the South Seas than in Siberia, the other area theorized as the place from which the Ainu migrated to Japan. Of course, the Ainu could also carry genes from multiple migrations from different directions.


Ann Hum Biol. 2007 Sep-Oct;34(5):582-6

YAP insertion signature in South Asia.

Chandrasekar A et al.

A total of 2169 samples from 21 tribal populations from different regions of India were scanned for the Y-chromosome Alu polymorphism. This study reports, for the first time, high frequencies (8-65%) of Y Alu polymorphic (YAP) insertion in northeast Indian tribes. All seven Jarawa samples from the Andaman and Nicobar islands had the YAP insertion, in conformity with an earlier study of Andaman Islanders. One isolated case with haplotype E* was found in Dungri Bhill, a western Indian population, while YAP insertion in northeast India and Andaman tribes was found in association with haplotype D* (M168, M174). YAP insertion frequencies reported in the mainland Indian populations are negligible, according to previous studies. Genetic drift may be the causative factor for the variable frequency of the YAP insertion in the mainland populations, while the founder effect may have resulted in the highest incidence of haplotype D among the Andaman Islanders. The results of YAP insertion and the evidence of previous mtDNA studies indicate an early out of Africa migration to the Andaman and Nicobar Islands. The findings of YAP insertion in northeast Indian tribes are very significant for understanding the evolutionary history of the region.

Paul Kekai Manansala