Genetic relationships of the populations in eastern India

An initial investigation of dental morphology variation among three southern Naga ethnic groups of Northeast India

OBJECTIVES

This study examines dental morphology trait prevalence among three southern Naga groups and compares them to 10 ethnic groups from other regions of South Asia to accomplish two objectives: assess the biological relationship of these Tibeto-Burman-speakers to speakers of non-Tibeto-Burman languages in other South Asian regions, and determine which traits distinguish northeast Indians from other South Asians.

METHODS

Dental morphology traits were scored with the Arizona State University Dental Anthropology System. Tooth-trait combinations were evaluated for significant inter-trait correlation and intra-trait correspondence within dental fields. Comparisons were based on simple trait prevalence and with Smith's MMD. Affinities based on the former were accomplished with correspondence analysis and principal components analysis. Affinities based on the latter were undertaken with neighbor-joining cluster analysis and multidimensional scaling.

RESULTS

After elimination due to inter-trait correlations and uniform prevalence, biodistances based on the remaining 17 tooth-trait combinations identify significant differences between northeast Indians and other South Asian ethnic groups due to high frequencies of shoveling on the maxillary incisors and Cusp 6 on the mandibular molars coupled with low frequencies of Carabelli's trait and Cusp 5 on UM1 and UM2, respectively.

CONCLUSIONS

Patterns of biodistances obtained from dental morphology are consilient with those obtained from DNA indicating statistically significant differences between northeast Indians from members of ethnic groups of other regions of South Asia. Researchers should explore the sex-specific patterns. Biodistances should not be limited to "key" teeth within dental fields, for in almost every case traits present on mesial and distal teeth yield non-redundant information.

Inter-regional differences in body proportions in Indian children and adolescents-a cross-sectional multicentric study

Background: Sitting height (SH) and leg length (LL) help in assessing disproportionate growth. Anthropometric dissimilarity has been observed in different ethnicities.Aim: To (1) study sitting height and body proportions in children from different regions of India; and (2) compare sitting height and body proportions with data from other countries.Subjects and methods: This was a cross-sectional multicentric observational study, where 7961 (4328 boys) 3-18 year old children from five regions (north, south, east, west and central) were measured (height, weight and SH).Results: Boys from north India and girls from central India were taller and heavier (mean height 153.2 ± 18, 146.4 ± 11), while western boys and girls were the shortest (131.1 ± 20.7, 129.8 ± 19.5) (p < 0.05 for all). The highest SH was observed in the north (79.2 ± 8.5) and the lowest in the west (68.8 ± 9.1). Mean SH:LL ratio was highest in children from the northeast (1.13) followed by those from western, northern and central India (1.12, 1.10 and 1.07, respectively) and the ratio was the least in children from south India (1.05) (p < 0.0.5 for all except northeast and west). Children from the north and west were similar to the Dutch, children from the south were similar to South (black) Africans and the north-eastern children were similar to Chinese children.Conclusion: There were inter-regional differences in body proportions; similarities in body proportions with children from other ethnicities may throw light on the migration history of Indian people.

Hemoglobin E in Northeast India: A review on its origin, distribution, migration and health implication

A systematic review of the studies on hemoglobin E in Northeast India has been carried out to understand the magnitude of research undertaken on this aspect during the last seven decades. Owing to the high prevalence of hemoglobin E in this part of India different authors have studied this hemoglobin from different perspectives and found conflicting results. However a systematic review of such studies is lacking from a holistic point of view. Most of the epidemiological, in vitro as well as in vivo studies show signatures of selection with this hemoglobin locus. However, how this polymorphism is maintained at different rates at different geographical region is still a matter of contention. This review will fill the gap from all perspectives starting from the frequency distribution of hemoglobin E and its spread in different parts of Northeast India, its relationship with malaria hypothesis, the population migration, population affinity and most importantly the health implication arising out of it. A probable origin of hemoglobin E among an Austroasiatic population of Northeast India has been postulated with the help of advance molecular anthropological knowledge like the deep rooted markers of mt DNA and Y-chromosome haplotypes.

Nurture affects gender differences in spatial abilities

Women remain significantly underrepresented in the science, engineering, and technology workforce. Some have argued that spatial ability differences, which represent the most persistent gender differences in the cognitive literature, are partly responsible for this gap(.) The underlying forces at work shaping the observed spatial ability differences revolve naturally around the relative roles of nature and nurture. Although these forces remain among the most hotly debated in all of the sciences, the evidence for nurture is tenuous, because it is difficult to compare gender differences among biologically similar groups with distinct nurture. In this study, we use a large-scale incentivized experiment with nearly 1,300 participants to show that the gender gap in spatial abilities, measured by time to solve a puzzle, disappears when we move from a patrilineal society to an adjoining matrilineal society. We also show that about one-third of the effect can be explained by differences in education. Given that none of our participants have experience with puzzle solving and that villagers from both societies have the same means of subsistence and shared genetic background, we argue that these results show the role of nurture in the gender gap in cognitive abilities.

A comparison of palmar dermatoglyphics in two ethnic Indian populations of north Bengal, India

Dermatoglyphic print comparisons can be utilized to establish personal identification in forensic cases. The northern part of the state of West Bengal, India, is the home to many ethnic populations. Two such populations are the Rajbanshi and the Mech. Palm prints were collected from 192 adult Rajbanshi (105 men and 87 women) and 100 adult Mech (50 men and 50 women) individuals for print comparison using the standard ink and roll print method. The dermatoglyphic variables studied were mainline formulae, termination of mainline, positional variation of axial triradii, and true pattern of hypothenar and thenar configuration area. There were differences between the Rajbanshi and Mech individuals with respect to these dermatoglyphic variables. The uses of these variables appear to be limited only to ethnic identification, not personal identification. The present investigation further highlights the racial affinity, sex, and bilateral differences among Rajbanshi individuals using dermatoglyphic palmar variables.

Antiquity, geographic contiguity and genetic affinity among Tibeto-Burman populations of India: A microsatellite study

BACKGROUND

The Tibeto-Burman (TB) populations are one of the four major linguistic population groups of India. They are considered belonging to different stocks and show wide variation in culture and language; however, their genetic relationship, antiquity and migration history among the regional populations has been little investigated. Molecular genetic studies are expected to clearly show the antiquity and genetic diversity of these populations.

AIM

This paper seeks to understand the extent and magnitude of genetic affinities and diversities among 14 TB populations (12 Indian and two global groups), investigate the findings based on classical genetic markers and verify the historical accounts of their migration and genetic history based on 12 microsatellite markers.

SUBJECTS AND METHODS

The allele frequency data for 12 STR loci of 13 Asian (Tibeto-Burman) populations were obtained from the literature and the Adi Pasi data was obtained by microsatellite typing of their blood samples. The 12 loci studied are D5S818, FGA, D8S1179, D21S11, D7S820, CSF1PO, D3S1358, THO1, D13S317, vWa, TPOX, D18S51. Three different distance measures, two phylogenetic trees and PCA plot have been employed to understand the genetic relationship of the studied populations.

RESULTS

Average heterozygosity values range from 68 to 79% and the average G(ST) value is 4.7%. The dendrogram, based on the D(A) distance, shows the clustering of populations based on their diversities and geographical contiguity; the Mizoram and Arunachal Pradesh populations especially cluster together, populations from Sikkim form a separate subcluster and Manipur populations along with the Garo of West Bengal separate out from the other clusters. The Harpending and Ward regression model shows isolated populations positioned below the regression line and others, who experience external gene flow, placed above the line. The results support folklore migration accounts of their possible antiquity with the Tibetan and southern Chinese populations.

CONCLUSIONS

Overall, geographic contiguity, punctuated by isolating barriers, is a major influencing factor of genetic affinity among the TB population; contiguous populations within a region show greater genetic relationship than with distant TB populations over a wide geographical area. The results of the microsatellite study also support the history of diverse routes of migration of these populations.

A microsatellite guided insight into the genetic status of adi, an isolated hunting-gathering tribe of northeast India

Tibeto-Burman populations of India provide an insight into the peopling of India and aid in understanding their genetic relationship with populations of East, South and Southeast Asia. The study investigates the genetic status of one such Tibeto-Burman group, Adi of Arunachal Pradesh based on 15 autosomal microsatellite markers. Further the study examines, based on 9 common microsatellite loci, the genetic relationship of Adi with 16 other Tibeto-Burman speakers of India and 28 neighboring populations of East and Southeast Asia. Overall, the results support the recent formation of the Adi sub-tribes from a putative ancestral group and reveal that geographic contiguity is a major influencing factor of the genetic affinity among the Tibeto-Burman populations of India.

Genetic structure of four socio-culturally diversified caste populations of southwest India and their affinity with related Indian and global groups

Background

A large number of microsatellites have been extensively used to comprehend the genetic diversity of different global groups. This paper entails polymorphism at 15 STR in four predominant and endogamous populations representing Karnataka, located on the southwest coast of India. The populations residing in this region are believed to have received gene flow from south Indian populations and world migrants, hence, we carried out a detailed study on populations inhabiting this region to understand their genetic structure, diversity related to geography and linguistic affiliation and relatedness to other Indian and global migrant populations.

Results

Various statistical analyses were performed on the microsatellite data to accomplish the objectives of the paper. The heretozygosity was moderately high and similar across the loci, with low average G_ST value. Iyengar and Lyngayat were placed above the regression line in the R-matrix analysis as opposed to the Gowda and Muslim. AMOVA indicated that majority of variation was confined to individuals within a population, with geographic grouping demonstrating lesser genetic differentiation as compared to linguistic clustering. D_A distances show the genetic affinity among the southern populations, with Iyengar, Lyngayat and Vanniyar displaying some affinity with northern Brahmins and global migrant groups from East Asia and Europe.

Conclusion

The microsatellite study divulges a common ancestry for the four diverse populations of Karnataka, with the overall genetic differentiation among them being largely confined to intra-population variation. The practice of consanguineous marriages might have attributed to the relatively lower gene flow displayed by Gowda and Muslim as compared to Iyengar and Lyngayat. The various statistical analyses strongly suggest that the studied populations could not be differentiated on the basis of caste or spatial location, although, linguistic affinity was reflected among the southern populations, distinguishing them from the northern groups. Our study also indicates a heterogeneous origin for Lyngayat and Iyengar owing to their genetic proximity with southern populations and northern Brahmins. The high-ranking communities, in particular, Iyengar, Lyngayat, Vanniyar and northern Brahmins might have experienced genetic admixture from East Asian and European ethnic groups.

Genetic heterogeneity in northeastern India: reflection of Tribe-Caste continuum in the genetic structure

We critically examined the gene frequency data for 11 genetic markers commonly available in the literature for 22 populations of northeastern India in the light of their geographic, linguistic, and ethnic affiliations. The markers investigated were three blood groups (A1A2BO, MNS, and Rh), four serum proteins (KM, Gc, Hp, and Tf), and four enzyme systems (AP, AK, EsD, and Hb). The neighbor-joining tree and multidimensional scaling of the distance matrix suggest relatively high genetic differentiation among the Mongoloid groups, with probably diverse origins when compared to the Caucasoid Indo-European populations, which had probably come from relatively more homogeneous backgrounds. Broadly speaking, the pattern of population affinities conforms to the ethno-historic, linguistic, and geographic backgrounds. An interesting and important feature that emerges from this analysis is the reflection of the effect of the sociological process of a Tribe-Caste continuum on genetic structure. While on one end we have the cluster of Caucasoid caste populations, the other end consists of Mongoloid tribal groups. In between are the populations which were originally tribes but now have become semi-Hinduized caste groups, viz., Rajbanshi, Chutiya, and Ahom. These groups have currently assumed caste status and speak Indo-European languages. Therefore, one may infer that what appears to be a purely sociological phenomenon of a Tribe-Caste continuum may well reflect in their genetic structure.

Genetic structure and affinity among eight ethnic populations of Eastern India: based on 22 polymorphic DNA loci

The nature and extent of genetic variation at 22 polymorphic DNA loci, belonging to three distinct classes, especially, 12 STR loci (D3S1358, vWA, FGA, D5S818, D13S317, D7S820, D8S1179, D21S11, D18S51, HPRTB, F13B, LPL), four VNTR loci (D1S7, D4S139, D5S110, D17S79), and six coding loci (HLDQA1, LDLR, GYPA, HBGG, D7S8, GC) were investigated among eight population groups of West Bengal and Manipur regions of India. Of these, two groups from West Bengal belong to Caucasoid and six (one in WB and five in Manipur) belong to Mongoloid stock. Both STR and the expressed loci show wide diversity among the eight populations. For example, Manipur Muslims show differences in allele frequency when compared to four other regional populations. Similarly, Garo, one of the Mongoloid populations of West Bengal, differ in allele frequency from their counterparts in the Manipur region. Departure from Hardy-Weinberg expectations was observed at certain loci in a few populations (e.g., D21S1137 in Kayastha and Brahmin, HUM F13B in Meitei). Heterozygosity values were higher for Caucasoid than Mongoloid groups. The overall gene differentiation (GST) for STR loci is higher (5.3%) than for those at the expressed region (4.6%). The clustering pattern of the eight populations differs with respect to different classes of genetic markers used. The dendrograms based on six coding loci (HLDQA1, LDLR, GYPA, HBGG, D7S8, GC) differs from those based on STR and VNTR markers. Caucasoid and Mongoloid groups form different clusters and Manipur Muslims are distinct from others. The clustering pattern corresponded with the spatial and ethnic affiliations of the populations. Using different classes of DNA loci at the coding and noncoding region will help to better understand the influence of population structure variables on the genetic structure of populations.

Deciphering diversity in populations of various linguistic and ethnic affiliations of different geographical regions of India: Analysis based on 15 microsatellite markers

The extent of genetic polymorphism at fifteen autosomal microsatellite markers in 54 ethnically, linguistically and geographically diverse human populations of India was studied to decipher intrapopulation diversity. The parameters used to quantify intrapopulation diversity were average allele diversity, average heterozygosity, allele range (base pairs), and number of alleles. Multilocus genotype frequencies calculated for selected populations were utilized for testing conformity with the assumption of Hardy-Weinberg equilibrium. The exact test values, after Bonferroni correction, showed significant deviation amongst Gowda (vWA, Penta E); Dhangar, Satnami and Gounder (D8S1179); Hmar (FGA); Kuki and Balti (vWA) groups. Relatively low number of alleles and allelic diversity (base-pairs size) had been observed in populations of central India as compared with southern and northern regions of the country. The communities of Indo-Caucasoid ethnic origin and Indo-European linguistic family (Kshatriya of Uttar Pradesh) showed highest allelic diversity, as well as rare alleles, not reported in any other Indian populations. Analysis based on average heterozygosity was also found to be lowest among the populations of central India (0.729) and highest among the populations from north (0.777) and west (0.784) regions of the country, having Indo-Caucasoid ethnic origin and Austro-Asiatic linguistic affiliation. The maximum power of discrimination (85%-89%) had been observed at loci FGA, Penta E, D18S51 and D21S11, suggested high intrapopulation diversity in India. Genetic diversity revealed by STR markers was consistent with the known demographic histories of populations. Thus, the present study clearly demonstrated that the intrapopulation diversity is not only present at the national level, but also within smaller geographical regions of the country. This is the first attempt to understand the extent of diversity within populations of India at such a large scale at genomic level.

Genetic profile based upon 15 microsatellites of four caste groups of the eastern Indian state, Bihar

BACKGROUND

The formation of caste groups among the Hindu community and the practice of endogamy exert a great impact on the genetic structure and diversity of the Indian population. Allele frequency data of 15 microsatellite loci clearly portray the genetic diversity and relatedness among four socio-culturally advanced caste groups: Brahmin, Bhumihar, Rajput and Kayasth of Caucasoid ethnicity of Bihar.

AIM

The study seeks to understand the impact of the man-made caste system on the genetic profile of the four major caste groups of Bihar.

METHODS AND PROCEDURE

Computation of average heterozygosity, most frequent allele, allele diversity and coefficient of gene differentiation (Gst), along with genetic distance (DA)and principal coordinate analysis were performed to assess intra-population and inter-population diversity.

MAIN OUTCOMES AND RESULTS

The average Gst value for all the loci was 0.012 +/- 0.0033, and the level of average heterozygosity was approximately 75.5%, indicating genetic similarity and intra-population diversity. Genetic distance (DA) values and the phylogenetic tree along with other higher caste groups of India indicate the relative distance between them.

CONCLUSION

The present study clearly depicts the genetic profile of these caste groups, their inherent closeness in the past, and the impact of the imposed caste system that later restricted the gene flow. The study highlights the status of Bhumihar and Kayasth in the Hindu caste system. The former was found clustering with the Brahmin group (as expected, since Bhumihar is known to be a subclass of Brahmin), whereas the distance between the Brahmin and Kayasth caste groups was found to be large. North-eastern Indian Mongoloids form a separate cluster.

Genetic variation at minisatellite loci D1S7, D4S139, D5S110 and D17S79 among three population groups of eastern India

Genetic variation at four minisatellite loci D1S7, D4S139, D5S110 and D17S79 in three predominant population groups of eastern India, namely Brahmin, Kayastha and Garo, are reported in this study. The Brahmin and Kayastha are of Indo-Caucasoid origin while the Garo community represents the Indo-Mongoloid ethnic group. The methodology employed comprised generation of HaeIII-restricted fragments of isolated DNA, Southern blotting, and hybridization using chemiluminescent probes MS1, pH30, LH1 and V1 for the four loci. All four loci were highly polymorphic in the population groups. Heterozygosity values for the four loci ranged between 0.68 and 0.95. Neither departure from Hardy Weinberg expectations nor evidence of any association across alleles among the selected loci was observed. The gene differentiation value among the loci is moderate (GST = 0.027). A neighbour-joining tree constructed on the basis of the generated data shows very low genetic distance between the Brahmin and Kayastha communities in relation to the Garo. Our results based on genetic distance analysis are consistent with results of earlier studies based on serological markers and linguistic as well as morphological affiliations of these populations and their Indo-Caucasoid and Indo-Mongoloid origin. The minisatellite loci studied here were found to be not only useful in showing significant genetic variation between the populations but also to be suitable for human identity testing among eastern Indian populations.

Genetic variation observed at three tetrameric short tandem repeat loci HumTHO1, TPOX, and CSF1PO--in five ethnic population groups of northeastern India

This paper portrays the genetic variation observed at three tetrameric short tandem repeat (STR) loci HumTHO1, TPOX, and CSF1PO in five ethnic population groups from northeastern India. The study also specifies the suitability of use of these markers for forensic testing. The populations studied included three tribal groups (Kuki, Naga and Hmar), one Mongoloid caste group (Meitei), and a religious caste group (Manipuri Muslims). The loci were highly polymorphic in the populations, and all loci met Hardy-Weinberg expectations. No evidence for association of alleles among the loci was detected. The probability of match for the three loci of the most frequent genotype in the five population groups ranged between 2.6 x 10(-4) and 6.6 x 10(-5). The average heterozygosity among the population groups was approximately 70% with the overall extent of gene differentiation among the five groups being high (Gst = 0.046). Genetic affinity among the populations reveal very close association between the Kuki, Hmar, Naga, and Meitei. The Manipuri Muslims, despite being found in the same region, have had no admixture with these populations and maintain a substantial distance with the other groups. The genetic polymorphism data suggest that the studied systems can be used for human identity testing to estimate the frequency of a multiple locus STR DNA profile in population groups of northeastern India.