Unravelling the distinct strains of Tharu ancestry

Health status of tribes of Uttar Pradesh with special reference to health-seeking behaviour of uncharted Tharu tribe: A mapping review

Background & objectives

The tribal population in India is considered as one of the vulnerable groups with respect to their achievements in health and other developmental issues. In this context, this mapping review attempted to understand the health profile of the Tharu tribal community residing in the northern State of Uttar Pradesh, India through literature mining. Tharu tribe is one of the indigenous groups living in the Terai plain on the Indo-Nepal border. In 1967, this tribe was documented as a Scheduled Tribe by the Government of India. The present review aimed to map the health-seeking behaviour of the Tharu population and review other factors pertaining to their health such as socioeconomic, developmental, employment, education, etc.

Methods

Online data search was carried out on PubMed and Google Scholar using search terms 'Tharu' AND 'India'. In addition, official reports avaibale in public domain and grey literature was also searched.

Results

Twenty seven studies including reviews, articles, books/book chapters were evaluated along with 13 reports (including reports from government organizations and grey literature) were retrieved and analyzed. Of the 27 published reports, 16 were found relevant to Tharu tribe in India. A total of 29 (16 articles + 13 reports ) were included in this review.

Interpretation & Conclusions

This mapping review highights the health seeking behaviour of the Tharu tribe in India that can help inform future interventions to improve the health status of the Tharu tribe as well as other aspects of their development.

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.

G6PD deficiency in malaria endemic areas of Nepal

Background

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is currently a threat to malaria elimination due to risk of primaquine-induced haemolysis in G6PD deficient individuals. The World Health Organization (WHO) recommends G6PD screening before providing primaquine as a radical treatment against vivax malaria. However, evidence regarding the prevalence and causing mutations of G6PD deficiency in Nepal is scarce.

Methods

A cross-sectional, population-based, prevalence study was carried out from May to October 2016 in 12 malaria-endemic districts of Nepal. The screening survey included 4067 participants whose G6PD status was determined by G6PD Care Start™ rapid diagnostic test and genotyping.

Results

The prevalence of G6PD deficiency at the national level was 3.5% (4.1% among males and 2.1% among females). When analysed according to ethnic groups, G6PD deficiency was highest among the Janajati (6.2% overall, 17.6% in Mahatto, 7.7% in Chaudhary and 7.5% in Tharu) and low among Brahman and Chhetri (1.3%). District-wise, prevalence was highest in Banke (7.6%) and Chitwan (6.6%). Coimbra mutation (592 C>T) was found among 75.5% of the G6PD-deficient samples analysed and Mahidol (487 G>A) and Mediterranean (563 C>T) mutations were found in equal proportions in the remaining 24.5%. There was no specific geographic or ethnic distribution for the three mutations.

Conclusions

This study has identified populations with moderate to high prevalence of G6PD deficiency which provides strong evidence supporting the WHO recommendations to screen G6PD deficiency at health facility level before the use of primaquine-based radical curative regimen for Plasmodium vivax.

Ethnogenetic analysis reveals that Kohistanis of Pakistan were genetically linked to west Eurasians by a probable ancestral genepool from Eurasian steppe in the bronze age

Despite the unique geographic, ethnic, social and cultural features of Kohistan in Pakistan, the origin and descent of Kohistanis remain still obscure. In an effort to address questions concerning the genetic structure, origin and genetic affinities of Kohistanis, we herein applied an ethnogenetic approach consisting on mitochondrial DNA (mtDNA) analysis and dental morphology analysis. We sequenced HVS1 of mtDNA, observed 14 haplotypes and assigned a total of 9 haplogroups belonging to macrolineages M (17%) and N (83%). Genetic diversity estimates in Kohistanis (Hd = 0.910 ± 0.014; Pi = 0.019 ± 0.001; θw = 0.019 ± 0.006) were similar to that of previous studies in other Pakistani populations. Overall, the analyses of dental morphology and mtDNA profile of Kohistanis resulted in similar findings. All the analyses indicate that Kohistanis share affinities to populations from Europe, Near East, Central Asia and South Asia. The Kohistani HVS1 haplotype 2 shares 100% identity to HVS1 haplotypes across the Europe. These results in light of recent insights into ancient genomics lead us to conclude that ancestry from Eurasian Steppe genetically linked Kohistanis to all these populations in the Bronze Age. This is consistent with linguistic evidence and also with the Indo-Aryan migration model for the peopling of South Asia.

Gut microbiome transition across a lifestyle gradient in Himalaya

The composition of the gut microbiome in industrialized populations differs from those living traditional lifestyles. However, it has been difficult to separate the contributions of human genetic and geographic factors from lifestyle. Whether shifts away from the foraging lifestyle that characterize much of humanity's past influence the gut microbiome, and to what degree, remains unclear. Here, we characterize the stool bacterial composition of four Himalayan populations to investigate how the gut community changes in response to shifts in traditional human lifestyles. These groups led seminomadic hunting-gathering lifestyles until transitioning to varying levels of agricultural dependence upon farming. The Tharu began farming 250-300 years ago, the Raute and Raji transitioned 30-40 years ago, and the Chepang retain many aspects of a foraging lifestyle. We assess the contributions of dietary and environmental factors on their gut-associated microbes and find that differences in the lifestyles of Himalayan foragers and farmers are strongly correlated with microbial community variation. Furthermore, the gut microbiomes of all four traditional Himalayan populations are distinct from that of the Americans, indicating that industrialization may further exacerbate differences in the gut community. The Chepang foragers harbor an elevated abundance of taxa associated with foragers around the world. Conversely, the gut microbiomes of the populations that have transitioned to farming are more similar to those of Americans, with agricultural dependence and several associated lifestyle and environmental factors correlating with the extent of microbiome divergence from the foraging population. The gut microbiomes of Raute and Raji reveal an intermediate state between the Chepang and Tharu, indicating that divergence from a stereotypical foraging microbiome can occur within a single generation. Our results also show that environmental factors such as drinking water source and solid cooking fuel are significantly associated with the gut microbiome. Despite the pronounced differences in gut bacterial composition across populations, we found little differences in alpha diversity across lifestyles. These findings in genetically similar populations living in the same geographical region establish the key role of lifestyle in determining human gut microbiome composition and point to the next challenging steps of determining how large-scale gut microbiome reconfiguration impacts human biology.

The genetic makings of South Asia

South Asia is home for more than a billion people culturally structured into innumerable groups practicing different levels of endogamy. Linguistically South Asia is broadly characterized by four major language families which has served as access way for disentangling the genetic makings of South Asia. In this review we shall give brief account on the recent developments in the field. Advances are made in two fronts simultaneously. Whole genome characterisation of many extant South Asians paint the picture of the genetic diversity and its implications to health-care. On the other hand ancient DNA studies, which are finally reaching South Asia, provide new incites to the demographic history of the subcontinent. Before the spread of agriculture, South Asia was likely inhabited by hunter-gatherer groups deriving much of their ancestry from a population that split from the rest of humanity soon after expanding from Africa. Early Iranian agriculturalists mixing with these local hunter-gatherers probably formed the population that flourished during the blossoming of the Indus Valley Civilisation. Further admixture with the still persisting HG groups and population(s) from the Eurasian Steppe, formed the two ancestral populations (ANI and ASI), the north-south mixing pattern of whom is known today as the 'Indian Cline'. Studies on natural selection in South Asia have so far revealed strong signals of sweeps that are shared with West Eurasians. Future studies will have to fully unlock the aDNA promise for South Asia.

Reconstructing the population history of the largest tribe of India: the Dravidian speaking Gond

The Gond comprise the largest tribal group of India with a population exceeding 12 million. Linguistically, the Gond belong to the Gondi-Manda subgroup of the South Central branch of the Dravidian language family. Ethnographers, anthropologists and linguists entertain mutually incompatible hypotheses on their origin. Genetic studies of these people have thus far suffered from the low resolution of the genetic data or the limited number of samples. Therefore, to gain a more comprehensive view on ancient ancestry and genetic affinities of the Gond with the neighbouring populations speaking Indo-European, Dravidian and Austroasiatic languages, we have studied four geographically distinct groups of Gond using high-resolution data. All the Gond groups share a common ancestry with a certain degree of isolation and differentiation. Our allele frequency and haplotype-based analyses reveal that the Gond share substantial genetic ancestry with the Indian Austroasiatic (ie, Munda) groups, rather than with the other Dravidian groups to whom they are most closely related linguistically.

The paternal ancestry of Uttarakhand does not imitate the classical caste system of India

Although, there have been rigorous research on the Indian caste system by several disciplines, it is still one of the most controversial socioscientific topic. Previous genetic studies on the subcontinent have supported a classical hierarchal sharing of genetic component by various castes of India. In the present study, we have used high-resolution mtDNA and Y chromosomal markers to characterize the genetic structuring of the Uttarakhand populations in the context of neighboring regions. Furthermore, we have tested whether the genetic structuring of caste populations at different social levels of this region, follow the classical chaturvarna system. Interestingly, we found that this region showed a high level of variation for East Eurasian ancestry in both maternal and paternal lines of descent. Moreover, the intrapopulation comparison showed a high level of heterogeneity, likely because of different caste hierarchy, interpolated on asymmetric admixture of populations inhabiting on both sides of the Himalayas.

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.

Carriers of Mitochondrial DNA Macrohaplogroup N Lineages Reached Australia around 50,000 Years Ago following a Northern Asian Route

Background

The modern human colonization of Eurasia and Australia is mostly explained by a single-out-of-Africa exit following a southern coastal route throughout Arabia and India. However, dispersal across the Levant would better explain the introgression with Neanderthals, and more than one exit would fit better with the different ancient genomic components discovered in indigenous Australians and in ancient Europeans. The existence of an additional Northern route used by modern humans to reach Australia was previously deduced from the phylogeography of mtDNA macrohaplogroup N. Here, we present new mtDNA data and new multidisciplinary information that add more support to this northern route.

Methods

MtDNA hypervariable segments and haplogroup diagnostic coding positions were analyzed in 2,278 Saudi Arabs, from which 1,725 are new samples. Besides, we used 623 published mtDNA genomes belonging to macrohaplogroup N, but not R, to build updated phylogenetic trees to calculate their coalescence ages, and more than 70,000 partial mtDNA sequences were screened to establish their respective geographic ranges.

Results

The Saudi mtDNA profile confirms the absence of autochthonous mtDNA lineages in Arabia with coalescence ages deep enough to support population continuity in the region since the out-of-Africa episode. In contrast to Australia, where N(xR) haplogroups are found in high frequency and with deep coalescence ages, there are not autochthonous N(xR) lineages in India nor N(xR) branches with coalescence ages as deep as those found in Australia. These patterns are at odds with the supposition that Australian colonizers harboring N(xR) lineages used a route involving India as a stage. The most ancient N(xR) lineages in Eurasia are found in China, and inconsistently with the coastal route, N(xR) haplogroups with the southernmost geographical range have all more recent radiations than the Australians.

Conclusions

Apart from a single migration event via a southern route, phylogeny and phylogeography of N(xR) lineages support that people carrying mtDNA N lineages could have reach Australia following a northern route through Asia. Data from other disciplines also support this scenario.