A study published in Nature (2009) reveals that India has a complex population history with two ancestral populations, Ancestral North Indians (ANI) and Ancestral South Indians (ASI), which are genetically distinct and form the basis of modern Indian populations. ANI is genetically close to Middle Easterners, Central Asians, and Europeans, while ASI is distinct from ANI and East Asians. The study used genetic data from 25 Indian groups to show that ANI ancestry ranges from 39-71% in India, with higher levels in traditionally upper caste and Indo-European speaking groups. Groups with only ASI ancestry may no longer exist in mainland India, but the Andamanese are an ASI-related group without ANI ancestry, indicating that the peopling of the islands occurred before ANI-ASI gene flow on the mainland. The study also highlights strong founder effects and endogamy in Indian populations, leading to significant allele frequency differences between groups, which may result in an excess of recessive diseases. The research also shows that Indian populations have a high level of genetic substructure, with a significant difference in allele frequency differentiation compared to Europe. The study suggests that the high level of genetic substructure in India is due to founder events and limited gene flow, which have shaped the genetic makeup of Indian populations over thousands of years. The findings have important implications for medical research, as they highlight the need for careful consideration of population stratification in genetic studies. The study also provides insights into the historical relationship between Indian and non-Indian populations, showing that Indian groups have a complex genetic history involving mixture between ANI and ASI populations. The study concludes that understanding the genetic history of Indian populations is crucial for accurate genetic mapping and disease research.A study published in Nature (2009) reveals that India has a complex population history with two ancestral populations, Ancestral North Indians (ANI) and Ancestral South Indians (ASI), which are genetically distinct and form the basis of modern Indian populations. ANI is genetically close to Middle Easterners, Central Asians, and Europeans, while ASI is distinct from ANI and East Asians. The study used genetic data from 25 Indian groups to show that ANI ancestry ranges from 39-71% in India, with higher levels in traditionally upper caste and Indo-European speaking groups. Groups with only ASI ancestry may no longer exist in mainland India, but the Andamanese are an ASI-related group without ANI ancestry, indicating that the peopling of the islands occurred before ANI-ASI gene flow on the mainland. The study also highlights strong founder effects and endogamy in Indian populations, leading to significant allele frequency differences between groups, which may result in an excess of recessive diseases. The research also shows that Indian populations have a high level of genetic substructure, with a significant difference in allele frequency differentiation compared to Europe. The study suggests that the high level of genetic substructure in India is due to founder events and limited gene flow, which have shaped the genetic makeup of Indian populations over thousands of years. The findings have important implications for medical research, as they highlight the need for careful consideration of population stratification in genetic studies. The study also provides insights into the historical relationship between Indian and non-Indian populations, showing that Indian groups have a complex genetic history involving mixture between ANI and ASI populations. The study concludes that understanding the genetic history of Indian populations is crucial for accurate genetic mapping and disease research.