Introduction Summary Conclusion Abstracts of key studies Resources FAQ

The Eurasian Heartland: A continental perspective on Y-chromosome diversity, PNAS | August 28, 2001 | vol. 98 | no. 18 | 10244-10249, http://www.pnas.org/cgi/content/full/98/18/10244  abstract

Independent Origins of Indian Caste and Tribal Paternal Lineages, Current Biology, Vol. 14, 231–235, February 3, 2004 abstract

Am. J. Hum. Genet., 68:537-542, 2001 
0002-9297/2001/6802-0028$02.00 
© 2001 by The American Society of Human Genetics. All rights reserved.

Y-Chromosome Lineages Trace Diffusion of People and Languages in Southwestern Asia

Lluís Quintana-Murci,¹ Csilla Krausz,¹ Tatiana Zerjal,² S. Hamid Sayar,³ Michael F. Hammer,⁴ S. Qasim Mehdi,⁵ Qasim Ayub,⁵ Raheel Qamar,⁵ Aisha Mohyuddin,⁵ Uppala Radhakrishna,⁶ Mark A. Jobling,⁷ Chris Tyler-Smith,² and Ken McElreavey^{1  
 
1}Unité d'Immunogénétique Humaine, INSERM E0021, Institut Pasteur, Paris; ²Department of Biochemistry, University of Oxford, United Kingdom; ³Medical Genetics Centre, Iranian Blood Transfusion Organisation, Tehran; ⁴Laboratory of Molecular Systematics and Evolution, University of Arizona, Tucson; ⁵Biomedical & Genetic Engineering Laboratories, Islamabad, Pakistan; ⁶Green Cross Voluntary Blood Bank and RIA Laboratory, Ahmedabad, India; and ⁷Department of Genetics, University of Leicester, Leicester, United Kingdom

Received October 27, 2000; accepted for publication December 4, 2000; electronically published December 27, 2000.

ABSTRACT

The origins and dispersal of farming and pastoral nomadism in southwestern Asia are complex, and there is controversy about whether they were associated with cultural transmission or demic diffusion. In addition, the spread of these technological innovations has been associated with the dispersal of Dravidian and Indo-Iranian languages in southwestern Asia. Here we present genetic evidence for the occurrence of two major population movements, supporting a model of demic diffusion of early farmers from southwestern Iranand of pastoral nomads from western and central Asiainto India, associated with Dravidian and Indo-Europeanlanguage dispersals, respectively 
 
 

Vol. 11, Issue 6, 994-1004, June 2001

Genetic Evidence on the Origins of Indian Caste Populations

http://www.genome.org/cgi/content/full/11/6/994 

Michael Bamshad,^1,10,12 Toomas Kivisild,² W. Scott Watkins,³ Mary E. Dixon,³ Chris E. Ricker,³ Baskara B. Rao,⁴ J. Mastan Naidu,⁴ B.V. Ravi Prasad,^4,5 P. Govinda Reddy,⁶ Arani Rasanayagam,⁷ Surinder S. Papiha,⁸ Richard Villems,² Alan J. Redd,⁷ Michael F. Hammer,⁷ Son V. Nguyen,⁹ Marion L. Carroll,⁹ Mark A. Batzer,^9,11 and Lynn B. Jorde³

¹ Department of Pediatrics, University of Utah, Salt Lake City, Utah 84112, USA; ² Institute of Molecular and Cell Biology, Tartu University and Estonian Biocentre, Tartu 51010, Estonia; ³ Department of Human Genetics, University of Utah, Salt Lake City, Utah 84112, USA; ⁴ Department of Anthropology, Andhra University, Visakhapatnam, Andhra Pradesh, India; ⁵ Anthropological Survey of India, Calcutta, India; ⁶ Department of Anthropology, University of Madras, Madras, Tamil Nadu, India; ⁷ Laboratory of Molecular Systematics and Evolution, University of Arizona, Tucson, Arizona 85721, USA; ⁸ Department of Human Genetics, University of Newcastle-upon-Tyne, UK; ⁹ Department of Pathology, Biometry and Genetics, Biochemistry and Molecular Biology, Stanley S. Scott Cancer Center, Louisiana State University Health Science Center, New Orleans, Louisiana 70112, USA

ABSTRACT 

The origins and affinities of the ~1 billion people living on the subcontinent of India have long been contested. This is owing, in part, to the many different waves of immigrants that have influenced the genetic structure of India. In the most recent of these waves, Indo-European-speaking people from West Eurasia entered India from the Northwest and diffused throughout the subcontinent. They purportedly admixed with or displaced indigenous Dravidic-speaking populations. Subsequently they may have established the Hindu caste system and placed themselves primarily in castes of higher rank. To explore the impact of West Eurasians on contemporary Indian caste populations, we compared mtDNA (400 bp of hypervariable region 1 and 14 restriction site polymorphisms) and Y-chromosome (20 biallelic polymorphisms and 5 short tandem repeats) variation in ~265 males from eight castes of different rank to ~750 Africans, Asians, Europeans, and other Indians. For maternally inherited mtDNA, each caste is most similar to Asians. However, 20%-30% of Indian mtDNA haplotypes belong to West Eurasian haplogroups, and the frequency of these haplotypes is proportional to caste rank, the highest frequency of West Eurasian haplotypes being found in the upper castes. In contrast, for paternally inherited Y-chromosome variation each caste is more similar to Europeans than to Asians. Moreover, the affinity to Europeans is proportionate to caste rank, the upper castes being most similar to Europeans, particularly East Europeans. These findings are consistent with greater West Eurasian male admixture with castes of higher rank. Nevertheless, the mitochondrial genome and the Y chromosome each represents only a single haploid locus and is more susceptible to large stochastic variation, bottlenecks, and selective sweeps. Thus, to increase the power of our analysis, we assayed 40 independent, biparentally inherited autosomal loci (1 LINE-1 and 39 Alu elements) in all of the caste and continental populations (~600 individuals). Analysis of these data demonstrated that the upper castes have a higher affinity to Europeans than to Asians, and the upper castes are significantly more similar to Europeans than are the lower castes. Collectively, all five datasets show a trend toward upper castes being more similar to Europeans, whereas lower castes are more similar to Asians. We conclude that Indian castes are most likely to be of proto-Asian origin with West Eurasian admixture resulting in rank-related and sex-specific differences in the genetic affinities of castes to Asians and Europeans. 
 
 

Vol. 11, Issue 6, 931-932, June 2001

Indian Caste Origins: Genomic Insights and Future Outlook

Partha P. Majumder  

Anthropology and Human Genetics Unit, Indian Statistical Institute, Calcutta 700035, India

The main feature of Indian society, seen at its strongest in the rural areas, is caste. A caste is a collection of people who share similar cultural and religious values and practices. Members within a caste generally marry among themselves; intercaste marriages are a cultural taboo. These social regulations governing the institution of marriage have resulted in a substructuring of the Indian gene pool. There are also elaborate social regulations of avoidance of marriages within castes, and thus there is genomic substructuring even within a caste.

The origins of the castes in India remain an enigma. Many castes are known to have tribal origins, as evidenced from various totemic features that manifest themselves in these caste groups (Kosambi 1964). The caste system in northern India may have developed as a class structure from within tribes: As agriculture spread from the Indus River valley to the Gangetic basin, knowledge and ownership of the means of food production may have created hierarchical divisions within tribal societies (Kosambi 1964). Karve (1961) has also argued that "something very like castes were in India" even before Aryan speakers entered India.

The Aryan world comprised three classes (varnas): priests, nobles, and commoners. Aryans as the conquering people possibly placed their three classes on the indigenous Indian society. The varna organization is hierarchical. Initially, the system had names for two ranks, Brahma (Brahmin) and Kshatra (Kshatriya), Brahmin being of a socially higher rank than Kshatriya. The third rank was made up of Vis, that is, all the subjects. To this society, a fourth rank was added: Shudra, who had no rights to Aryan ritual. In southern India, the menial workers, the so-called "untouchables", were placed in a new varna, Panchama (meaning fifth). It is conceivable that the Aryan speakers had greater contact, including genetic admixture, with the Brahmins, who were professionally the torchbearers and promoters of Aryan rituals. The Aryan contact should have been progressively less as one descended the varna ladder. The genetic expectation, therefore, is that the proportions of those genes (or genomic features, such as haplotypes or haplogroups) that "characterized" the Aryan speakers should progressively decline from the highest varna to the lowest and a reverse trend should be observed with respect to those genes that "characterized" the indigenous Indians.

Although some previous studies have sought to test this expectation, the observed trends were equivocal. The primary reason was the lack of data on a large uniform set of markers from populations of India and central/west Asia (the region from which the Aryans speakers who entered India originated). The study by Bamshad et al. (2001), who have also sought to test the above expectation, is clearly a landmark. Using a very large battery of genomic markers and DNA sequences, spanning autosomal, mitochondrial, and Y-chromosomal genomic regions, they have shown that the observed trend of genetic admixture estimated from castes belonging to different varnas is congruent with expectations. This trend was observed in each of the three data subsets. The only exception was in respect of mtDNA restriction site haplotypes, which was also noted in a recent study conducted by us (Roychoudhury et al. 2000). However, after combining these haplotype data with DNA sequence data, Bamshad and colleagues were able to capture the expected trend. Thus, this study not only provides a wonderful genomic view of the castes and of their origins, but also underscores the need for careful statistical analysis of genomic data for drawing appropriate inferences.

The use of "upper", "middle", and "lower" to designate caste hierarchy is much more recent than the use of varna. Whereas varnas are traditionally defined, different anthropologists have used different definitions of upper, middle, and lower castes, in terms of the castes that they included in each of these clusters. Sometimes these differences in definitions have stemmed from socio-cultural similarities or differences as noted or perceived by different anthropologists, and sometimes ranked caste-cluster compositions were altered for convenience, such as pooling to adjust for small sample sizes. As noted earlier, in studies such as Bamshad et al.'s, the most appropriate classification is by varna. As the reader will note, the authors have analyzed their data using different compositions of hierarchical caste-clusters and have obtained homologous results. However, it needs to be emphasized that traditional varna system is the only unequivocally accepted hierarchical system. In studies pertaining to the origins of castes, one is liable to draw incorrect inferences by including castes belonging to different varnas in the same ranked cluster.

Bamshad et al. have chosen to study caste populations drawn from a restricted geographical region of India. They have rightly emphasized the need to replicate their findings. This is absolutely essential because, as Karve (1961) has noted, "it is not generally realized that the caste society in a sense was a very elastic society." Indeed, a caste bearing the same name may have very different origins in different geographical regions. There are examples in which a tribe dispersed over a large geographical region, took up different occupations in different sub-regions, and "fitted" itself into the caste hierarchy on different rungs. Karve's work has also indicated that each of the different Brahmin castes (Chitpavan, Sarasvat, etc.) in Maharashtra probably has a different origin. Thus, the origin of caste populations may not be uniform over the entire India geographical space, and it is crucial to undertake studies to replicate Bamshad et al.'s findings. Finally, I would also like to suggest that in future studies bearing on the origins of the Indian castes, it would be a good idea to include tribal populations inhabiting the same region along with the caste populations.  
 
 

PNAS | August 28, 2001 | vol. 98 | no. 18 | 10244-10249

The Eurasian Heartland: A continental perspective on Y-chromosome diversity

http://www.pnas.org/cgi/content/full/98/18/10244 

R. Spencer Wells^a,b, Nadira Yuldasheva^a,c, Ruslan Ruzibakiev^c, Peter A. Underhill^d, Irina Evseeva^e, Jason Blue-Smith^d, Li Jin^f, Bing Su^f, Ramasamy Pitchappan^g, Sadagopal Shanmugalakshmi^g, Karuppiah Balakrishnan^g, Mark Read^h, Nathaniel M. Pearsonⁱ, Tatiana Zerjal^j, Matthew T. Webster^k, Irakli Zholoshvili^l, Elena Jamarjashvili^l, Spartak Gambarov^m, Behrouz Nikbinⁿ, Ashur Dostiev^o, Ogonazar Aknazarov^p, Pierre Zalloua^q, Igor Tsoy^r, Mikhail Kitaev^s, Mirsaid Mirrakhimov^s, Ashir Chariev^t, and Walter F. Bodmer^a,u

^a Imperial Cancer Research Fund Cancer and Immunogenetics Laboratory and Wellcome Trust Centre for Human Genetics, University of Oxford, Headington OX3 9DS, United Kingdom; ^c Institute of Immunology, Academy of Sciences, Tashkent, Uzbekistan; ^d Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305; ^e Department of Medical Genetics, Archangelsk State Medical Academy, Archangelsk, Russia; ^f Department of Human Genetics, School of Public Health, University of Texas, Houston, TX 77030; ^g Centre for Advanced Studies in Functional Genomics, School of Biological Sciences, Madurai Kamaraj University, Madurai, India; ^h Mark Read Photography, 2 Beatty Road, London N16 8EB, United Kingdom; ⁱ Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637; ^j Department of Biochemistry, University of Oxford, Oxford OX3 1QU, United Kingdom; ^k Institute of Molecular Medicine, University of Oxford, Headington OX3 9DS, United Kingdom; ^l Department of Pediatrics, State Medical Institute, Tbilisi, Georgia; ^m Immunology Laboratory, Mikaelin Surgical Institute, Yerevan, Armenia; ⁿ Department of Immunology, University of Medical Sciences, Tehran 14496, Iran; ^o Tajik State Medical Institute, Dushanbe, Tajikistan; ^p Pamir Biological Laboratory, Khorog, Tajikistan; ^q Genetics Research Laboratory, Chronic Care Center, Hazmieh, Lebanon; ^r Institute of Nutrition, Almaty, Kazakstan; ^s Institute of Cardiology, Bishkek, Kyrgyzstan; and ^t State Medical Institute, Ashgabad, Turkmenistan

Contributed by Walter F. Bodmer, June 15, 2001

ABSTRACT 

The non-recombining portion of the human Y chromosome has proven to be a valuable tool for the study of population history. The maintenance of extended haplotypes characteristic of particular geographic regions, despite extensive admixture, allows complex demographic events to be deconstructed. In this study we report the frequencies of 23 Y-chromosome biallelic polymorphism haplotypes in 1,935 men from 49 Eurasian populations, with a particular focus on Central Asia. These haplotypes reveal traces of historical migrations, and provide an insight into the earliest patterns of settlement of anatomically modern humans on the Eurasian continent. Central Asia is revealed to be an important reservoir of genetic diversity, and the source of at least three major waves of migration leading into Europe, the Americas, and India. The genetic results are interpreted in the context of Eurasian linguistic patterns.  

October 2003

Ethnic India: A Genomic View, With Special Reference to Peopling and Structure

Analabha Basu^1,4, Namita Mukherjee^1,4, Sangita Roy^2,4, Sanghamitra Sengupta^1,4, Sanat Banerjee¹, Madan Chakraborty¹, Badal Dey¹, Monami Roy¹, Bidyut Roy¹, Nitai P. Bhattacharyya³, Susanta Roychoudhury² and Partha P. Majumder^1,5

¹ Anthropology & Human Genetics Unit, Indian Statistical Institute, Calcutta 700 108, India ; ² Human Genetics & Genomics Department, Indian Institute of Chemical Biology, Calcutta, India; ³ Crystallography & Molecular Biology Division, Saha Institute of Nuclear Physics, Calcutta, India

ABSTRACT

We report a comprehensive statistical analysis of data on 58 DNA markers (mitochondrial [mt], Y-chromosomal, and autosomal) and sequence data of the mtHVS1 from a large number of ethnically diverse populations of India. Our results provide genomic evidence that (1) there is an underlying unity of female lineages in India, indicating that the initial number of female settlers may have been small; (2) the tribal and the caste populations are highly differentiated; (3) the Austro-Asiatic tribals are the earliest settlers in India, providing support to one anthropological hypothesis while refuting some others; (4) a major wave of humans entered India through the northeast; (5) the Tibeto-Burman tribals share considerable genetic commonalities with the Austro-Asiatic tribals, supporting the hypothesis that they may have shared a common habitat in southern China, but the two groups of tribals can be differentiated on the basis of Y-chromosomal haplotypes; (6) the Dravidian tribals were possibly widespread throughout India before the arrival of the Indo-European-speaking nomads, but retreated to southern India to avoid dominance; (7) formation of populations by fission that resulted in founder and drift effects have left their imprints on the genetic structures of contemporary populations; (8) the upper castes show closer genetic affinities with Central Asian populations, although those of southern India are more distant than those of northern India; (9) historical gene flow into India has contributed to a considerable obliteration of genetic histories of contemporary populations so that there is at present no clear congruence of genetic and geographical or sociocultural affinities.  

Current Biology, Vol. 14, 231–235, February 3, 2004, ©2004 Elsevier Science Ltd. All rights reserved. DOI 10.1016/j.cub.2004.01.024 

Independent Origins of Indian Caste and Tribal Paternal Lineages 

http://www.eva.mpg.de/genetics/pdf/CordauxCurBiol2004.pdf  

Richard Cordaux,^1,5,* Robert Aunger,² Gillian Bentley,³ Ivane Nasidze,¹
S.M. Sirajuddin,⁴ and Mark Stoneking¹ 

¹Max Planck Institute for Evolutionary Anthropology, D-04103 Leipzig, Germany 
²Environmental Health Group, London School of Hygiene and Tropical Medicine, London WC1E 7HT, England
³Department of Anthropology, University College London, London WC1E 6BT, England 
⁴Anthropological Survey of India, Mysore 570002, Karnataka State, India 

Summary 

The origins of the nearly one billion people inhabiting the Indian subcontinent and following the customs of Hindu caste system [1, 2] are controversial: are they largely derived from Indian local populations (i.e. tribal groups) or from recent immigrants to India? Archaeological and linguistic evidence support the latter hypothesis [2–4], whereas recent genetic data seem to favor the former hypothesis [5]. Here, we analyze the most extensive dataset of Indian caste and tribal Y chromosomes to date. We find that caste and tribal groups differ significantly in their haplogroup frequency distributions; caste groups are homogeneous for Y chromosome variation and more closely related to each other and to central Asian groups than to Indian tribal or any other Eurasian groups. We conclude that paternal lineages of Indian caste groups are primarily descended from Indo-European speakers who migrated from central Asia 3,500 years ago. 

Conversely, paternal lineages of tribal groups are predominantly derived from the original Indian gene pool. We also provide evidence for bidirectional male gene flow between caste and tribal groups. In comparison, caste and tribal groups are homogeneous with respect to mitochondrial DNA variation [5, 6], which may reflect the sociocultural characteristics of the Indian caste society.

Introduction Summary Conclusion Abstracts of key studies