M S Chahal

Bio: M S Chahal is an academic researcher from Newcastle University. The author has contributed to research in topics: Population & Genetic structure. The author has an hindex of 1, co-authored 1 publications receiving 41 citations.

Genetic heterogeneity and population structure in north-west India.

Abstract: Genetic markers consisting of 11 blood group and red cell enzyme systems were investigated in 14 endogamous groups of north-west India. Genetic differentiation among the samples as indicated by FST is appreciable, reflecting the ethnic diversity characteristic of this region. Local variation within each state is lower, indicating a geographical component to the total variation. This variation is refined by calculations of genetic distances, which show that the tribals and low-caste groups are closer together but well separated from high-caste Brahmins and other non-tribal middle castes. There is a slight possibility of disruptive selection, but the analyses suggest that the differences in genetic structure in north-west India are more likely to be due to their breeding structure, differential migration and ethnic affiliation.

Genetic variation in India.

Abstract: In the last 25 years a number of genetic studies on the populations of the Indian subcontinent have been conducted. Unfortunately, most of the studies covered a limited number of genetic systems, and only a few provide information on the genetic differentiation and population structure of some regional caste, tribal, religious, and urban groups. Despite a recent report suggesting that in eastern India genetic affinity does not show any large degree of congruence with sociocultural hierarchy, three distinct surveys reported here indicate that geographic proximity, ethnohistory, and biosocial and cultural affiliation are important determinants of genetic affinity. Gene differentiation studies are few, but from the information of some previous papers and results presented in this special issue of Human Biology, the pattern of differentiation is becoming clear. In general, genetic differentiation in populations of India is low (0.26-1.7%), but overall genetic differentiation in 18 mixed populations of India is higher (2.23%), similar to the largest single study on 16 tribal groups from central India (2.18%). The tribal population of South India shows the highest FST value (4.1%), and this value is similar to a study of the Dhangar caste group. The reason for this high FST value is not clear. One possibility may be (semi-) isolation associated with such factors as random inbreeding and drift, which can cause high levels of genetic differentiation among the tribal groups of India and among the castes such as Dhangar. However, further studies are needed to explore the causes of such high values of genetic differentiation, especially in these populations.

Population structure and genetic differentiation among 16 tribal populations of central India.

Abstract: Genetic polymorphisms for six blood groups, three red cell enzymes, three serum proteins, and hemoglobin were examined in sixteen central Indian tribal populations. Nine of the tribes belonged to Orissa, five to Madhya Pradesh, and two to Maharashtra. Eleven tribes spoke the Dravidian language, three Indo-Ayran, and two the language of the Austro-Asiatic families. The population structure of these tribal populations was analyzed at the inter- and intrastate and linguistic levels, using data for 13 genetic systems (38 alleles or haplotypes). Nine of the 13 loci showed significant heterogeneity in the 16 tribes, and the pattern of heterogeneity was also discernible in the different states and in the Dravidian-speaking tribes. As expected, the extent of genetic differentiation or gene diversity was the highest so far reported from central India. The mean FIS and HS for each locus in the different state, linguistic, and total tribal groups were consistently higher than the FST and GST values, respectively, showing that the genetic structure of each tribe is highly influenced by inbreeding. In a genetic affinity analysis by genetic distance the Indo-Aryan and Austro-Asiatic language groups showed little affinity with each other, although there was some tendency toward geographic affinity. The present analysis indicates that, in addition to genetic drift, gene flow, and selection, the genetic structure of the populations of central India is also highly influenced by sociocultural adaptation and inbreeding.

Genetic structure of Indian populations based on fifteen autosomal microsatellite loci

Abstract: Indian populations endowed with unparalleled genetic complexity have received a great deal of attention from scientists world over. However, the fundamental question over their ancestry, whether they are all genetically similar or do exhibit differences attributable to ethnicity, language, geography or socio-cultural affiliation is still unresolved. In order to decipher their underlying genetic structure, we undertook a study on 3522 individuals belonging to 54 endogamous Indian populations representing all major ethnic, linguistic and geographic groups and assessed the genetic variation using autosomal microsatellite markers. The distribution of the most frequent allele was uniform across populations, revealing an underlying genetic similarity. Patterns of allele distribution suggestive of ethnic or geographic propinquity were discernible only in a few of the populations and was not applicable to the entire dataset while a number of the populations exhibited distinct identities evident from the occurrence of unique alleles in them. Genetic substructuring was detected among populations originating from northeastern and southern India reflective of their migrational histories and genetic isolation respectively. Our analyses based on autosomal microsatellite markers detected no evidence of general clustering of population groups based on ethnic, linguistic, geographic or socio-cultural affiliations. The existence of substructuring in populations from northeastern and southern India has notable implications for population genetic studies and forensic databases where broad grouping of populations based on such affiliations are frequently employed.

Morphology to Molecular Anthropology: Castes and Tribes of India*

Abstract: Within the various fields of research of the present Biological Anthropology the study of human evolution as well as the study of genetic variation in modern man, hold an eminent place. An importan...

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

Abstract: 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. Am. J. Hum. Biol. 16:334–345, 2004. © 2004 Wiley-Liss, Inc.