A sero-biochemical genetic study of Jalari and Brahmin caste populations of Andhra Pradesh, India

Blood specimens from Jalari and Brahmin caste populations of Andhra Pradesh, India, were examined for blood groups, red cell enzymes, and serum proteins. Of 33 genetic loci studied, 16 were observed to be invariant among both the castes, while common polymorphism or rare variants were observed in one or both populations for the other loci. Three rare heterozygotes at the phosphoglucoisomerase locus, two different peptidase A variants occurring once each and single cases of rare 6-phosphogluconate dehydrogenase and transferrin variants were recorded. Also a few cases of hemoglobin AS and anhaptoglobinemia were observed. The difference in rare variants between the two castes is conspicuous but large differences in their gene frequencies at the polymorphic loci were not observed. It is pointed out that the frequency of rare variants in the tribal and caste populations of Southern India appears to be higher than observed in temperate-dwelling civilized populations.     

Independent origins of Indian caste and tribal paternal lineages

The origins of the nearly one billion people inhabiting the Indian subcontinent and following the customs of the Hindu caste system 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, whereas recent genetic data seem to favor the former hypothesis. 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 approximately 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, which may reflect the sociocultural characteristics of the Indian caste society.     

Anthropological studies in Assam, India

Four Assamese caste groups--Jogis, Hiras, Kumars and Kaibartas--have been analysed for the distribution of anthropometric and dermatoglyphic traits as well as for the distribution of ABO blood groups and PTC taste sensitivity. The differences among these four caste groups are statistically mostly significant, which can be connected with the history of these groups and their genetic isolation from each other.     

Genetic distance and gene diversity among ten endogamous groups in Chhattisgarh,Central India

A genetic survey has been conducted among the Rawats and Telis, two endogamous caste populations of Chhattisgarh, Central India. Using the gene frequency data for three genetic loci, genetic distance among ten population groups have been calculated. The gene differentiation among these population groups is only about 2 per cent.     

Gene differentiation among ten endogamous groups of West Bengal, India

Ten endogamous populations of West Bengal, India have been surveyed for genetic variation in 12 systems. These populations encompass all social ranks in the caste hierarchy and cover almost the entire geographic area of the state. Gene diversity analysis suggests that these groups exhibit significant allele frequency variation at all but three loci. The overall genetic difference is not, however, in accord with the classification based on caste. Two low-ranking scheduled caste groups are, in fact, in close proximity with the high-caste ones, suggesting evidence of past generations of gene flow among them. Three different clusters of groups emerge from the present data, providing support for the anthropologic assertion that in Bengal Proto-Australoid, Caucasoid, and Mongoloid racial elements generally coexist. However, these three components are not uniformly present in all groups. Geographic separation of the groups is a strong determinant of the gene differentiation that exists among these populations.     

Integrating Linguistics,Social Structure,and Geography to Model Genetic Diversity within India

India represents an intricate tapestry of population substructure shaped by geography, language, culture, and social stratification. Although geography closely correlates with genetic structure in other parts of the world, the strict endogamy imposed by the Indian caste system and the large number of spoken languages add further levels of complexity to understand Indian population structure. To date, no study has attempted to model and evaluate how these factors have interacted to shape the patterns of genetic diversity within India. We merged all publicly available data from the Indian subcontinent into a data set of 891 individuals from 90 well-defined groups. Bringing together geography, genetics, and demographic factors, we developed Correlation Optimization of Genetics and Geodemographics to build a model that explains the observed population genetic substructure. We show that shared language along with social structure have been the most powerful forces in creating paths of gene flow in the subcontinent. Furthermore, we discover the ethnic groups that best capture the diverse genetic substructure using a ridge leverage score statistic. Integrating data from India with a data set of additional 1,323 individuals from 50 Eurasian populations, we find that Indo-European and Dravidian speakers of India show shared genetic drift with Europeans, whereas the Tibeto-Burman speaking tribal groups have maximum shared genetic drift with East Asians.     

Gene differentiation among the Dhangar caste-cluster of Maharashtra, India

Genetic differentiation among the 22 Dhangar castes of Maharashtra, India, is studied using data on several polymorphic serological and biochemical loci employing Nei's distance measures. The intercaste genetic distances and the coefficient of gene diversity among these caste groups are found to be rather small. The relationship between gene identity and geographic distance is also studied empirically from the gene frequency data. All these analyses indicate that genetic differentiation among the Dhangar castes is at its very early stage only. It is also suggested that these caste groups probably originated from a common stock and are in the process of differentiation by fission with very little intercaste migration in the recent past.     

Genetic Affinity of the Bhil,Kol and Gond Mentioned in Epic Ramayana

Kol, Bhil and Gond are some of the ancient tribal populations known from the Ramayana, one of the Great epics of India. Though there have been studies about their affinity based on classical and haploid genetic markers, the molecular insights of their relationship with other tribal and caste populations of extant India is expected to give more clarity about the the question of continuity vs. discontinuity. In this study, we scanned >97,000 of single nucleotide polymorphisms among three major ancient tribes mentioned in Ramayana, namely Bhil, Kol and Gond. The results obtained were then compared at inter and intra population levels with neighboring and other world populations. Using various statistical methods, our analysis suggested that the genetic architecture of these tribes (Kol and Gond) was largely similar to their surrounding tribal and caste populations, while Bhil showed closer affinity with Dravidian and Austroasiatic (Munda) speaking tribes. The haplotype based analysis revealed a massive amount of genome sharing among Bhil, Kol, Gond and with other ethnic groups of South Asian descent. On the basis of genetic component sharing among different populations, we anticipate their primary founding over the indigenous Ancestral South Indian (ASI) component has prevailed in the genepool over the last several thousand years.     

Phylogeography of mitochondrial DNA and Y-chromosome haplogroups reveal asymmetric gene flow in populations of Eastern India

Polymorphisms in mitochondrial (mt) DNA and Y-chromosomes of seven socially and linguistically diverse castes and tribes of Eastern India were examined to determine their genetic relationships, their origin, and the influence of demographic factors on population structure. Samples from the Orissa Brahmin, Karan, Khandayat, Gope, Juang, Saora, and Paroja were analyzed for mtDNA hypervariable sequence (HVS) I and II, eight Y-chromosome short tandem repeats (Y-STRs), and lineage-defining mutations diagnostic for Indian- and Eurasian-specific haplogroups. Our results reveal that haplotype diversity and mean pairwise differences (MPD) was higher in caste groups of the region (>0.998, for both systems) compared to tribes (0.917-0.996 for Y-STRs, and 0.958-0.988 for mtDNA haplotypes). The majority of paternal lineages belong to the R1a1, O2a, and H haplogroups (62.7%), while 73.2% of maternal lineages comprise the Indian-specific M*, M5, M30, and R* mtDNA haplogroups, with a sporadic occurrence of West Eurasian lineages. Our study reveals that Orissa Brahmins (a higher caste population) have a genetic affinity with Indo-European speakers of Eastern Europe, although the Y-chromosome data show that the genetic distances of populations are not correlated to their position in the caste hierarchy. The high frequency of the O2a haplogroup and absence of East Asian-specific mtDNA lineages in the Juang and Saora suggest that a migration of Austro-Asiatic tribes to mainland India was exclusively male-mediated which occurred during the demographic expansion of Neolithic farmers in southern China. The phylogeographic analysis of mtDNA and Y-chromosomes revealed varied ancestral sources for the diverse genetic components of the populations of Eastern India.     

Serogenetic variation in four caste populations of Haryana, India

The phenotypes and gene frequencies of 3 blood groups, 7 red-cell enzymes and a serum protein were studied in 4 caste population groups of Haryana, North India. The results indicate that the distribution of these blood markers is rather homogeneous in the 4 groups and generally resembles that observed in various populations from neighbouring North Indian states.     

Genetic studies on Gadaba: a tribal population of Andhra Pradesh, India.

Blood samples were collected from Gadaba, a tribal population of Andhra Pradesh, South India, in order to examine the distribution of blood groups, red cell enzymes and the gammaglobulin polymorphism. Out of 20 genetic markers studied seven protein loci exhibited monomorphism. Surprisingly a case of a rare homozygous variant and twenty-one heterozygous variants at the phosphogluconate dehydrogenase locus (6-PGD), six variants at the phosphohexose isomerase locus (PHI) and a single case of phosphoglucomutase locus 1 (PGM 1) variant were observed. Further, the tribal populations of South India reveal higher frequencies of rare variants than the caste populations. However, the presence of rare variants that are phenotypically neutral may be plausibly due to their high selective value.     

Y-chromosomal insights into the genetic impact of the caste system in India

The caste system has persisted in Indian Hindu society for around 3,500 years. Like the Y chromosome, caste is defined at birth, and males cannot change their caste. In order to investigate the genetic consequences of this system, we have analysed male-lineage variation in a sample of 227 Indian men of known caste, 141 from the Jaunpur district of Uttar Pradesh and 86 from the rest of India. We typed 131 Y-chromosomal binary markers and 16 microsatellites. We find striking evidence for male substructure: in particular, Brahmins and Kshatriyas (but not other castes) from Jaunpur each show low diversity and the predominance of a single distinct cluster of haplotypes. These findings confirm the genetic isolation and drift within the Jaunpur upper castes, which are likely to result from founder effects and social factors. In the other castes, there may be either larger effective population sizes, or less strict isolation, or both. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. Tatiana Zerjal and Arpita Pandya contributed equally to this work.     

Reproductive skew and the origin of sterile castes

Reproductive skew theory has not heretofore formally addressed one of the most important questions in evolutionary biology: How can whole-life sterile castes evolve? We construct a transactional skew model investigating under what conditions a subordinate in a multimember group is favored to develop into a morphologically specialized worker caste. Our model demonstrates that, contrary to former expectations, the ecological and genetic conditions favoring caste differentiation are far more restrictive than those favoring high skew. Caste differentiation cannot be selected in saturated, symmetrical relatedness groups unless the genetic relatedness among group members is extremely high. In contrast, it can be selected in the saturated, asymmetrical relatedness (parent-offspring) groups with complete skew. If we also consider the future reproduction of subordinates, caste differentiation is possible only after the group size reaches a certain critical point. Most importantly, caste differentiation in a parent-offspring group increases its saturated group size. The positive feedback between group size and the degree of caste differentiation can continue in principle until completely sterile worker castes emerge. Thus, at least in the case of parent-offspring groups, group size but not the degree of reproductive skew may be a better index of the level of social complexity. A scheme for the evolution of sterile worker castes that integrates the role of group size into the framework of reproductive skew theory is proposed.     

Taxonomic studies on genus Tetramorium Mayr (Hymenoptera, Formicidae) with report of two new species and three new records including a tramp species from India with a revised key

Two new species of Tetramorium Mayr, namely Tetramorium shivalikensesp. n. and Tetramorium triangulatumsp. n. are described. Tetramorium triangulatumsp. n. belongs to the inglebyi-species group and is described based on worker, queen and male caste, while Tetramorium shivalikensesp. n. belongs to the ciliatum-species group and is described based on worker caste only. Three species viz., Tetramorium caldarium (Roger), Tetramorium tonganum Mayr and Tetramorium urbanii Bolton represent first records from India. The male caste is described for the first time in the case of Tetramorium tonganum. Among these, Tetramorium caldarium is a tramp species which extends its limit to India as well. A revised key to the Indian ants of this genus is also provided herewith.     

Blood groups among brahmin and kamma caste populations of coastal Andhra Pradesh

Blood specimens from Brahmin and Kamma caste populations of Coastal Andhra Pradesh, India are examined for A₁A₂BO, MNSs, and Rhesus blood groups. Predominance of A group in Brahmins and B group in Kammas is observed. Phenotype A₂ records less than 4% in both populations. High frequencies of genes M, s, D, and e are exhibited among both populations. Statistically significant differences are found only for A₁A₂BO system between Brahmins and Kammas.     

Genetic variation in South Indian castes: evidence from Y-chromosome, mitochondrial, and autosomal polymorphisms

Background

Major population movements, social structure, and caste endogamy have influenced the genetic structure of Indian populations. An understanding of these influences is increasingly important as gene mapping and case-control studies are initiated in South Indian populations.

Results

We report new data on 155 individuals from four Tamil caste populations of South India and perform comparative analyses with caste populations from the neighboring state of Andhra Pradesh. Genetic differentiation among Tamil castes is low (R_ST = 0.96% for 45 autosomal short tandem repeat (STR) markers), reflecting a largely common origin. Nonetheless, caste- and continent-specific patterns are evident. For 32 lineage-defining Y-chromosome SNPs, Tamil castes show higher affinity to Europeans than to eastern Asians, and genetic distance estimates to the Europeans are ordered by caste rank. For 32 lineage-defining mitochondrial SNPs and hypervariable sequence (HVS) 1, Tamil castes have higher affinity to eastern Asians than to Europeans. For 45 autosomal STRs, upper and middle rank castes show higher affinity to Europeans than do lower rank castes from either Tamil Nadu or Andhra Pradesh. Local between-caste variation (Tamil Nadu R_ST = 0.96%, Andhra Pradesh R_ST = 0.77%) exceeds the estimate of variation between these geographically separated groups (R_ST = 0.12%). Low, but statistically significant, correlations between caste rank distance and genetic distance are demonstrated for Tamil castes using Y-chromosome, mtDNA, and autosomal data.

Conclusion

Genetic data from Y-chromosome, mtDNA, and autosomal STRs are in accord with historical accounts of northwest to southeast population movements in India. The influence of ancient and historical population movements and caste social structure can be detected and replicated in South Indian caste populations from two different geographic regions.     

Restriction isotyping of apolipoprotein E among populations of Punjab, northwestern India

The molecular polymorphism displayed by apolipoprotein E (apoE, protein; APOE, gene) has been listed as a risk factor for susceptibility to various disorders, such as those associated with lipid metabolism and arteriosclerosis. Data from many population groups are available. The present study endeavors to add to the world population database for alleles encountered at this locus. One hundred sixty-five individuals representing four castes and a mixed group from Punjab, a state in northwestern India, were analyzed for APOE isotyping. Intercaste group comparisons of allele frequencies revealed statistically insignificant differences, pointing to homogeneity at this locus among Punjabi caste groups, which can be considered as one Punjabi population. A further comparison of this Punjabi sample with other populations of the world revealed the Punjabi population to be closer to some European populations than to either African or Asian populations, a pointer to the ethnic origins of the Punjabi population.     

Population Differentiation of Southern Indian Male Lineages Correlates with Agricultural Expansions Predating the Caste System

Previous studies that pooled Indian populations from a wide variety of geographical locations, have obtained contradictory conclusions about the processes of the establishment of the Varna caste system and its genetic impact on the origins and demographic histories of Indian populations. To further investigate these questions we took advantage that both Y chromosome and caste designation are paternally inherited, and genotyped 1,680 Y chromosomes representing 12 tribal and 19 non-tribal (caste) endogamous populations from the predominantly Dravidian-speaking Tamil Nadu state in the southernmost part of India. Tribes and castes were both characterized by an overwhelming proportion of putatively Indian autochthonous Y-chromosomal haplogroups (H-M69, F-M89, R1a1-M17, L1-M27, R2-M124, and C5-M356; 81% combined) with a shared genetic heritage dating back to the late Pleistocene (10–30 Kya), suggesting that more recent Holocene migrations from western Eurasia contributed <20% of the male lineages. We found strong evidence for genetic structure, associated primarily with the current mode of subsistence. Coalescence analysis suggested that the social stratification was established 4–6 Kya and there was little admixture during the last 3 Kya, implying a minimal genetic impact of the Varna (caste) system from the historically-documented Brahmin migrations into the area. In contrast, the overall Y-chromosomal patterns, the time depth of population diversifications and the period of differentiation were best explained by the emergence of agricultural technology in South Asia. These results highlight the utility of detailed local genetic studies within India, without prior assumptions about the importance of Varna rank status for population grouping, to obtain new insights into the relative influences of past demographic events for the population structure of the whole of modern India.     

Impact of restricted marital practices on genetic variation in an endogamous Gujarati group

Recent studies have examined the influence on patterns of human genetic variation of a variety of cultural practices. In India, centuries‐old marriage customs have introduced extensive social structuring into the contemporary population, potentially with significant consequences for genetic variation. Social stratification in India is evident as social classes that are defined by endogamous groups known as castes. Within a caste, there exist endogamous groups known as gols (marriage circles), each of which comprises a small number of exogamous gotra (lineages). Thus, while consanguinity is strictly avoided and some randomness in mate selection occurs within the gol, gene flow is limited with groups outside the gol. Gujarati Patels practice this form of “exogamic endogamy.” We have analyzed genetic variation in one such group of Gujarati Patels, the Chha Gaam Patels (CGP), who comprise individuals from six villages. Population structure analysis of 1,200 autosomal loci offers support for the existence of distinctive multilocus genotypes in the CGP with respect to both non‐Gujaratis and other Gujaratis, and indicates that CGP individuals are genetically very similar. Analysis of Y‐chromosomal and mitochondrial haplotypes provides support for both patrilocal and patrilineal practices within the gol, and a low‐level of female gene flow into the gol. Our study illustrates how the practice of gol endogamy has introduced fine‐scale genetic structure into the population of India, and contributes more generally to an understanding of the way in which marriage practices affect patterns of genetic variation. Am J PhyAnthropol 2012. © Wiley Periodicals, Inc.     

Genetic studies among seven endogamous populations of the Koshi Zone, Bihar (India)

The distribution of AB0 and Rhesus blood groups, PTC taste sensitivity and colour blindness was studied among seven endogamous populations (Tharu, Mushar, Santal, Dhobi, Julaha, Kulhaiya and Karan Kayastha) in the Koshi Zone of Bihar (India). The phenotype and allele frequencies of the four gene loci (AB0, RH, PTC and colour blindness) show considerable differences between these populations. The measurement of genetic distances revealed, that the lowest genetic distance is seen between Dhobi and Julaha, the highest between Mushar and Tharu. From the genetic distance analysis there is some evidence for a close genetic relationship among the population groups belonging to the same region, irrespective of their caste, religion, linguistic or any other affinities. It may be concluded that all these populations have arisen through a common ancestor and changed gene frequencies among them is due to evolutionary forces like mutation, selection, migration, temporal variation and genetic drift. However, these populations retain their separate entities by practising endogamy. Gene diversity analysis reveals that these populations are at an early stage of genetic differentiation.