Genetic variation in India

Some recent papers from the open-access International Journal of Human Genetics.
Int J Hum Genet, 8(1-2): 21-29 (2008)

The Grandest Genetic Experiment Ever Performed on Man? A Y-Chromosomal Perspective on Genetic Variation in India (pdf )

Denise R. Carvalho-Silva and Chris Tyler-Smith

KEYWORDS Y chromosome; genetic variation; Indian caste system; endogamy; population substructure

We have analysed Y-chromosomal data from Indian caste, Indian tribal and East Asian populations in order to investigate the impact of the caste system on male genetic variation. We find that variation within populations is lower in India than in East Asia, while variation between populations is overall higher. This observation can be explained by greater subdivision within the Indian population, leading to more genetic drift. However, the effect is most marked in the tribal populations, and the level of variation between caste populations is similar to the level between Chinese populations. The caste system has therefore had a detectable impact on Y-chromosomal variation, but this has been less strong than the influence of the tribal system, perhaps because of larger population sizes in the castes, more gene flow or a shorter period of time.

Int J Hum Genet, 8(1-2): 41-50 (2008)

Language Shift by Indigenous Population: A Model Genetic Study in South Asia (pdf)

Gyaneshwer Chaubey, Mait Metspalu, Monika Karmin, Kumarasamy Thangaraj, Siiri Rootsi, Juri Parik, Anu Solnik, Deepa Selvi Rani, Vijay Kumar Singh, B. Prathap Naidu, Alla G. Reddy, Ene Metspalu1, Lalji Singh, Toomas Kivisild and Richard Villems

KEYWORDS Mushar; language shift; mtDNA; Y-chromosome

Language shift is a phenomenon where a new language is adopted by a population with virtually no influence on its genetic makeup. We report here the results of a case study, carried out on the Mushar populations, which is thought to have undergone language shift from Munda (an Austro-Asiatic language) to Hindi (an Indo- European language). We compared the mtDNA and Y-chromosomal phylogenies of this population with those of the neighbouring Indo-European and Austro-Asiatic speaking populations, standing at similar social status. The results revealed much closer genetic affinity of the Mushar people to the neighbouring Austro-Asiatic (Mundari) populations, than to the neighbouring Hindi-speaking populations. This example shows that the language shift as such is not necessarily a signal for a rapid genetic admixture, either maternally or paternally.

Int J Hum Genet, 8(1-2): 31-39 (2008)

Molecular Genetic Study on the Status of Transitional Groups of Central India: Cultural Diffusion or Demic Diffusion? (pdf)

Vikrant Kumar et al.

KEYWORDS Genetic status; Dravidians; Indo-Europeans; Austro-Asiatics; Central India

Two different models of diffusion - demic and cultural - have been proposed as an explanation for the spread of languages. Recent studies have shown that in some cases the dispersal of the language was due to the demic diffusion while for others it is purely due to the process of acculturation. There are four major linguistic families in India which have largely their own geographic domain. However, there are a few situations in which the populations affiliated to different linguistic families cohabit. For example, we find the spread of the Indo-European and Dravidian tribal populations in the core/peripheral areas of the Mundari Austro-Asiatic groups. These non-Mundari groups have been termed as transitional populations to indicate that these populations originally were probably Mundaris. However, there has been no attempt to ascertain if these populations are genetically Austro-Asiatics or do they belong to the linguistic groups that they are currently affiliated to. To examine this we have analysed Y-SNPs and STRs data of the 13 Mundari and 7 transitional groups and compared with the other populations of relevant linguistic groups. The results suggest that the Indo-European transitional groups are genetically Mundari and have acquired the present language through the process of cultural diffusion, while in the case of Dravidian transitional groups, the spread of language seems to be due to the process of both, the demic and cultural diffusion.

Int J Hum Genet, 8(1-2): 97-118 (2008)

Genetic Imprints of Pleistocene Origin of Indian Populations: A Comprehensive Phylogeographic Sketch of Indian Y-Chromosomes (pdf)

R. Trivedi et al.

KEYWORDS Population genetics, people of india, linguistic groups, migration

Paleoanthropological evidence indicates that modern humans reached South Asia in one of the first dispersals out of Africa, which were later followed by migrations from different parts of the world. The variation of 20 microsatellite and 38 binary polymorphisms on the non-recombining part of the uniparental, hapliod Y-chromosome was examined in 1434 male individual of 87 different populations of India to investigate various hypothesis of migration and peopling of South Asia Sub-continent. This study revealed a total of 24 paternal lineages, of which haplogroups H, R1a1, O2a and R2 portrayed for approximately 70% of the Indian Y-Chromosomes. The high NRY diversity value (0.893) and coalescence age of approx. 45-50 KYA for H and C haplogroups signified an early settlement of the subcontinent by modern humans. Haplogroup frequency and AMOVA results provide similar evidence in support of a common Pleistocene origin of Indian populations, with partial influence of Indo-European gene pool on the Indian society. The differential Y-chromosome and mt DNA pattern in the two Austric speakers of India signaled that an earlier male–mediated exodus from South East Asia largely involved the Austro-Asiatic tribes, while the Tibeto-Burman males migrated with females through two different routes; one from Burma most likely brought the Naga-Kuki-Chin language and O3e Y-chromosomes and the other from Himalayas, which carried the YAP lineages into northern regions of subcontinent. Based on distribution of Y-chromosome haplogroups (H, C, O2a, and R2) and deep coalescing time depths for these paternal lineages, we propose that the present day Dravidian speaking populations of South India are the descendants of earliest Pleistocene settlers while Austro-Asiatic speakers came from SE Asia in a later migration event.

Int J Hum Genet, 8(1-2): 1-20 (2008)

Trends in Molecular Anthropological Studies in India (pdf)

Vikal Tripathy et al.

KEYWORDS Population structure; molecular anthropology; mtDNA; Y-chromosome; autosomal DNA; India

Indian population is characterized by wide diversity and unique population structure shaped by different waves of migration and the practice of caste endogamy. Anthropologists have been studying the peopling of India and the relationships between different populations using traditional genetic markers. With the advent of molecular genetic techniques the focus has turned to using the DNA polymorphisms for resolving different anthropological questions and to test the different hypotheses in vogue. In this paper we make an attempt to critically review the trends in molecular anthropological studies till date and bring out salient features of the findings. An attempt has been made to evaluate the merit of the molecular studies in the perspective of unique population structure of India.

The quality of submissions published in this journals seems to be highly variable. I know I'll be waiting with bated breath for this forthcoming paper:

Origin and Spread of Dravidian Speakers
Clyde Winters
Uthman dan Fodio Institute, Chicago, Illinois 60643, USA

1 comment:

vikal said...

Are these papers the best one you have chosen from this issue.