https://www.bmj.com/content/bmj/1/6059/515.3.full.pdf

Handbook of Enzyme Electrophoresis in Human Genetics

We examine the distribution and structure of human genetic diversity for 710 individuals representing 31 populations from Africa, East Asia, Europe, and India using 100 Alu insertion polymorphisms from all 22 autosomes. Alu diversity is highest in Africans (0.349) and lowest in Europeans (0.297). Alu insertion frequency is lowest in Africans (0.463) and higher in Indians (0.544), E. Asians (0.557), and Europeans (0.559). Large genetic distances are observed among African populations and between African and non-African populations. The root of a neighbor-joining network is located closest to the African populations. These findings are consistent with an African origin of modern humans and with a bottleneck effect in the human populations that left Africa to colonize the rest of the world. Genetic distances among all pairs of populations show a significant product-moment correlation with geographic distances (r = 0.69, P < 0.00001). F(ST), the proportion of genetic diversity attributable to population subdivision is 0.141 for Africans/E. Asians/Europeans, 0.047 for E. Asians/Indians/Europeans, and 0.090 for all 31 populations. Resampling analyses show that approximately 50 Alu polymorphisms are sufficient to obtain accurate and reliable genetic distance estimates. These analyses also demonstrate that markers with higher F(ST) values have greater resolving power and produce more consistent genetic distance estimates.

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Genetic Variation Among World Populations: Inferences From 100 Alu Insertion Polymorphisms

The Indian subcontinent comprises a vast collection of peoples with different morphological, genetic, cultural, and linguistic characteristics. While much of this variability is indigenous, a considerable fraction of it has been introduced through large-scale immigrations into India in historical times. From an evolutionary standpoint, it is of immense interest to quantify biological diversity in contemporary human populations, to study biological affinities and to relate observed patterns of affinities with cultural, linguistic and demographic histories of populations. Such efforts are intended to shed light on the peopling of India. The purpose of this paper is to present a broad overview of the physical (anthropometric) and genetic diversities and affinities of the peoples of India. I shall also attempt to examine how well biological, particularly genetic, diversities and affinities correlate with geographical, socio-cultural, and linguistic diversities and affinities. © 1998 Wiley-Liss, Inc.

People of India: Biological diversity and affinities

Knowledge of high resolution Y-chromosome haplogroup diversification within Iran provides important geographic context regarding the spread and compartmentalization of male lineages in the Middle East and southwestern Asia. At present, the Iranian population is characterized by an extraordinary mix of different ethnic groups speaking a variety of Indo-Iranian, Semitic and Turkic languages. Despite these features, only few studies have investigated the multiethnic components of the Iranian gene pool. In this survey 938 Iranian male DNAs belonging to 15 ethnic groups from 14 Iranian provinces were analyzed for 84 Y-chromosome biallelic markers and 10 STRs. The results show an autochthonous but non-homogeneous ancient background mainly composed by J2a sub-clades with different external contributions. The phylogeography of the main haplogroups allowed identifying post-glacial and Neolithic expansions toward western Eurasia but also recent movements towards the Iranian region from western Eurasia (R1b-L23), Central Asia (Q-M25), Asia Minor (J2a-M92) and southern Mesopotamia (J1-Page08). In spite of the presence of important geographic barriers (Zagros and Alborz mountain ranges, and the Dasht-e Kavir and Dash-e Lut deserts) which may have limited gene flow, AMOVA analysis revealed that language, in addition to geography, has played an important role in shaping the nowadays Iranian gene pool. Overall, this study provides a portrait of the Y-chromosomal variation in Iran, useful for depicting a more comprehensive history of the peoples of this area as well as for reconstructing ancient migration routes. In addition, our results evidence the important role of the Iranian plateau as source and recipient of gene flow between culturally and genetically distinct populations.

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Ancient Migratory Events in the Middle East: New Clues from the Y-Chromosome Variation of Modern Iranians

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.

Genetic variation in India.

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.

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

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 heterogeneity and population structure in north-west India.

Regional variation in the genetic constitution and genetic structure of the populations of the Kinnaur district Himachal Pradesh India was examined from the data of 9 blood group 11 red cell enzyme and 4 serum protein loci. Not only the two main ethnic groups - Kanet and Koli - showed genetic differences but also the Kanet population itself was found to be genetically heterogeneous. The Kanet from the Puh region appears to be distinct. There was sufficient gene differentiation among the regional subpopulations to allow an overall excess of homozygosity. The mean F(IS) value for each locus was found consistently higehr than F(ST) suggesting that the infrastructure of the populations of Kinnaur is highly influenced by inbreeding. Various measures of genetic distance show consistent results with each other. There is no evidence that selection has any appreciable effect on the local differentiation but the analysis suggests that the differences are more likely to be due to inbreeding admixture and ethnic affiliation. (authors)

Genetic differentiation and population structure in Kinnaur District, Himachal Pradesh, India.

From some 500 members of Christian communities in Iran (Armenians and Assyrians from six localities), blood specimens were obtained and examined for a number of blood group, red cell enzyme, and serum protein systems. The results indicate the relatively closed nature of the Christian community as a whole but that moderate differentiation has already occurred among the local groups. One factor in this diversification process that can be distinguished is the effect of urbanization in Tehran, but otherwise it seems to be largely random.

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S. S. Papiha

Papers

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

Genetic heterogeneity and population structure in north-west India.

Genetic differentiation and population structure in Kinnaur District, Himachal Pradesh, India.

Genetic differentiation among Iranian Christian communities.

Population genetics of the Persians and other peoples in Iran.