Genomic view on the peopling of India

Abstract

India is known for its vast human diversity, consisting of more than four and a half thousand anthropologically well-defined populations. Each population differs in terms of language, culture, physical features and, most importantly, genetic architecture. The size of populations varies from a few hundred to millions. Based on the social structure, Indians are classified into various caste, tribe and religious groups. These social classifications are very rigid and have remained undisturbed by emerging urbanisation and cultural changes. The variable social customs, strict endogamy marriage practices, long-term isolation and evolutionary forces have added immensely to the diversification of the Indian populations. These factors have also led to these populations acquiring a set of Indian-specific genetic variations responsible for various diseases in India. Interestingly, most of these variations are absent outside the Indian subcontinent. Thus, this review is focused on the peopling of India, the caste system, marriage practice and the resulting health and forensic implications.

Unity in diversity: an overview of the genomic anthropology of India

“…It seems likely that a major demographic expansion of modern humans took place within India, and although the period of this expansion remains uncertain, it appears to have taken place 60,000-85,000 years before present (ybp) (Kivisild et al 1999;. The traces of socio-cultural, linguistic physiographical boundaries and evolutionary forces leading to diversity are well documented in the recent studies (Kivisild et al 1999;Metspalu et al 2004;Reich et al 2009;Tamang and Thangaraj 2012;Moorjani et al 2013). It has been shown that, with the exception of Africa, India harbours more genetic diversity than other comparable global regions (Papiha 1996).…”

“…The early history of its populations is like a jigsaw puzzle with many missing pieces. However there is enough anthropological and archaeological evidence to show that from time immemorial peoples of many different ethnic stocks, cultures and languages have entered India and contributed to the present day gene pool of the subcontinent (Bhasin et al 1994;Papiha, 1996;Kivisild et al 1999;Bhasin and Walter 2001;Kashyap et al 2004;Metspalu et al 2004;Reich et al 2009;Tamang and Thangaraj 2012;Moorjani et al 2013). There are traces of human activity in India around 200,000 B.C.…”

“…The unique mtDNA haplogroups in Indian populations include: U2a,b,c, R5-8, R30, R31, N1d and N5 in haplogroup N and M2-6, M30-47 in macrohaplogroup M. (Kivisild et al 1999(Kivisild et al , 2003Corduex et al 2003;Thangaraj et al 2006a, b;Chaubey et al 2011). More than 60% of Indians find their maternal roots in Indian-specific branches of macrohaplogroup M (Kivisild et al 1999(Kivisild et al , 2003Tamang and Thangaraj 2012) . Because of its deep time depth and virtual absence in West Eurasians it has been suggested that haplogroup M was brought to Asia from East Africa along the southern route by the earliest migration wave of anatomically modern humans approximately 60 thousand years ago (Kivisild et al 1999, Kivisild et al 2003, Basu et al 2003.…”

“…The completion of the Human Genome Project and its descendant, the HapMap project, has provided researchers with enormous opportunities and genetic markers for disease, population, forensic and evolutionary studies. In the late-1990s, a number of molecular genetic studies on Indian populations tried to untangle or reconstruct the complex relationship of Indian population groups (Bhasin et al 1994;Papiha, 1996;Kivisild et al 1999;Bhasin and Walter 2001;Kashyap et al 2004;Metspalu et al 2004;Reich et al 2009;Tamang and Thangaraj 2012;Moorjani et al 2013). Some of the early studies dealt with populations which were neither anthropologically well-defined nor were really representative Indian populations.…”

Association of ACE <i>DD</i> Genotype with Hypertension among the Tribal Populations of South India

“…Dating back to time immemorial, this system is characterized by its well stratified, endogamous and close-cultural values, which could strongly prohibit any exchange from outside. Genetically, this restriction significantly control the gene flow between the population subgroups, which creates specific genetic patterns, that could make the groups either susceptible or resistant to various diseases [2][3].…”