Genetic diversity of Indian population studied

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  1. RPK

    RPK Indyakudimahan Senior Member

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    The Hindu : Sci Tech : Genetic diversity of Indian population studied

    A paper published online today (September 24) in the journal Nature, shows that all diverse groups seen spread out in India today come from two major ancient populations that are genetically divergent.

    The two ancient populations are the Ancestral North Indians (ANI) and the Ancestral South Indians (ASI). The study was based on genetic analysis.

    While the Ancestral North Indians (ANI) group is genetically close to Middle Easterners, Central Asians, and Europeans, the Ancestral South Indians (ASI) are not related to any group outside India, notes the paper.

    The study was undertaken by the Hyderabad-based Centre for Cellular and Molecular Biology (CCMB) and three other institutions in the U.S.

    Samples from 132 people representing 25 groups from 15 States and speaking six language families (including two language families from the Andaman Islands) were studied.

    The study also looked for genetic variations based on caste — upper and lower caste — from two the States of Uttar Pradesh and Andhra Pradesh.

    The study found the groups (seen today) that emerged from the two ancient populations have distinct genetic affinity. “The populations (groups) that emerged from ANI show 40-80 per cent genetic affinity to European population.

    “But the populations that emerged from ASI don’t show any affinity to any population outside India,” said Dr. Kumarasamy Thangaraj, Senior Scientist at CCMB, and one of the authors of the paper. “The Hyshi and Ao Nage population from north-east India show genetic affinity to the Chinese.”

    The indigenous population seen in the Andamans have more affinity to the ASI. “Otherwise, they have no relationship with any other population anywhere in the world,” said Dr. Thangaraj.

    Unlike the European and Chinese population, the Indian population are more scattered in a genetic sense.

    Medical implications


    While consanguinity is often implicated for many recessive gene disorders in a population, this study found that the “shared descent from a common ancestral population plays a bigger role. This is called as the ‘founder effect.’

    Founder effect is nothing but the fact that many groups seen today have descended from a small group of founding individuals, and these founding individuals in turn have been isolated from other groups, genetically speaking.

    It is based on this fact that the authors state that the founder effect plays a bigger role. “We propose that the founder effect is responsible for an even higher burden of recessive diseases in India than consanguinity,” the paper states.

    Dr. Thangaraj explained the significance of this. A disease can occur due to the presence of a recessive gene due to mutation. In a small population with high endogamy [where people marry within the population], the mutation persists and spreads to more number of people.

    After a point of time, a large number of people have the recessive gene and this increases the chance of a child receiving a recessive gene from both the parents and thus becoming diseased.

    Existence of caste

    Contrary to popular perception by historians that the caste system seen today is an invention of colonialism, the study found scientific evidence to show that “many current distinctions among groups are ancient.”

    “The caste system is not recent,” said Dr. Thangaraj. “The social stratification existed right from early human divergence, some 50,000-60,000 years ago when initial settlement happened in India.”

    The paper adds a word of caution: “Models in population genetics should be treated with caution. Although they provide an important framework for testing historical hypotheses, they are oversimplifications.”
     
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  3. RPK

    RPK Indyakudimahan Senior Member

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    All Indians have some north, south in them - Home - livemint.com

    [​IMG]

    Bangalore: In one of the boldest attempts to reconstruct the population history of the country, which has so far held that north Indians descended from the Aryans and south Indians from Dravidian speakers, researchers now say nearly all Indians are a mixture of two ancestral groups which predate the arrival of Indo-European and Dravidian speakers in the country.



    Map: Sandeep Bhatnagar / Mint

    In Thursday’s issue of Nature, scientists from the Centre for Cellular and Molecular Biology (CCMB) in Hyderabad, Harvard Medical School and Broad Institute at Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts, report that different Indian groups have inherited 40-80% of their ancestry from a population which they call Ancestral North Indians (ANI) and the rest from a population called Ancestral South Indians (ASI).

    Genetically, ANIs are closest to present-day Europeans, and ASIs to the disappearing Andamanese tribe of Onge, which CCMB scientists, in another study, have shown to be similar to the first humans that migrated out of Africa some 65,000 years ago.

    The present research’s claim is indeed grandiose, but the scientific evidence is compelling and it’s a “bold idea”, says Aravinda Chakravarti, a professor at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine in Baltimore. “At least other samples will allow acceptance or rejection of this hypothesis.”

    Calling the Indian set of ancestries akin to the “many hands that can be dealt from a deck of cards”, Chakravarti says the diversity in Indian population is due to the varying proportions of ancestry and specific genomic content that is inherited.

    Also Read Genetic mutation behind heart failure risk of 45 mn Indians

    Indian gene map links ethnic groups, diseases

    The “gradient” in genetic diversity that these researchers have captured, showing the decrease in Central Asian ancestry as one goes from the north to south, corroborates what historians have proposed earlier, but that doesn’t necessarily mean that there’s an ASI population, says Analabha Basu, a scientist at the National Institute of Biomedical Genomics at Kalyani in West Bengal.

    “This study is too neat to be true; I’d need more evidence to believe the findings.”

    Researchers studied the genomes of 132 Indians from 25 population groups that represented all six language families across 15 states and included traditionally “upper” and “lower” castes and tribal groups.

    Analysis of 500,000 genetic markers—random mutations that serve as milestones—using extensive statistical tools, shows that diversity within India is three-four times higher than that seen within Europe.

    Based on this, they suggest that many groups in modern India descend from a small number of founding individuals and have been genetically isolated from other groups.

    In science, it is called a “founder event”; in plainspeak, this means certain types of genetic diseases, particularly single gene disorders, will be more common, just as breast cancer is more common in the Parsi community due to inbreeding.

    In another instance, the Vaishya community in Andhra Pradesh lacks an enzyme that metabolizes anaesthesia and hence people end up with complications, says Kumarasamy Thangaraj, a co-author from CCMB. In Europe, Finns and Ashkenazi Jews have experienced founder events, and have a high rate of single-gene (or recessive) diseases as a result.

    The surprise in India is that such a large proportion of the population is expected to have a similar effect, says David Reich, a co-author from the department of genetics at Harvard Medical School. “As far as I know, this is not generally appreciated by geneticists as a major cause of recessive diseases in India, but our findings suggest that it will be a much more important cause of recessive diseases than consanguinity (marriages between close relatives), which is the focus of many Indian genetic studies at present.”

    The widespread history of founder events, says co-author Lalji Singh from CCMB, helps explain why the incidence of genetic diseases among Indians is different from the rest. “This also indicates that many drugs tested on the Western population will not be as effective on the Indian population,” says Singh.

    For the first time, dealing with prehistoric India through genetic tools, researchers also show that the ANI and ASI theory applies to traditional tribes as well as castes; one cannot be distinguished from the other.

    “The genetics proves that they are not systematically different and supports the view that castes grew directly out of tribal-like organizations during the formation of Indian society,” says Thangaraj.

    India did not participate in any global human genome diversity project, including the HapMap. If it had, say experts, some of these findings would have come sooner.

    “African, East Asian, European, and American populations have participated in these international genetic projects, and as a result are further ahead in terms of medical genetic technology than India,” says Reich.

    India occupies centre stage in human evolution, says Basu, and this study will put many things in perspective.

    For the researchers though, the next stage will involve going back in history to see when this admixture of ANI and ASI took place.

    Reich says in principle the genetic data contains this information, but they haven’t succeeded in cracking it. “One complication is that the ANI-ASI mixture may have occurred at different times in different places in India, and possibly reflects multiple historical mixture events in the history of each group.”
     
  4. RPK

    RPK Indyakudimahan Senior Member

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    The Telegraph - Calcutta (Kolkata) | Nation | Two roots for Indians

    New Delhi, Sept. 23: A new genetic study has provided glimpses of India’s population patterns from deeper in the past than before, revealing the existence of two distinct, ancestral populations in the country about 45,000 years ago.

    Indian and US scientists have used human genes to explore a largely uncharted domain of prehistoric populations and shown that nearly all Indians are descendants in varying genetic proportions of these two distinct populations.

    The researchers also found that after the ancient admixture, endogamy has shaped marriage patterns in India for thousands of years, predating the caste system.

    They analysed more than 560,000 genetic markers from the genomes of 132 Indians representing 25 population groups, six language families and several castes and tribes. The findings will appear in the journal Nature on Thursday.

    The study has suggested two ancient populations — ancestral North Indians and ancestral South Indians — that had diverged from older population groups, derived from the earliest modern humans who trudged out of Africa some 70,000 years ago.

    “They appear to be progenitor populations — nearly all the groups we studied have descended from mixtures of the two,” said Kumarasamy Thangaraj, a co-author and senior scientist at the Centre for Cellular and Molecular Biology (CCMB), Hyderabad.

    Thangaraj and Lalji Singh from the CCMB collaborated with scientists at the Broad Institute of Harvard and the Massachusetts Institute of Technology to study variations of a large number of genetic markers in individuals from different population groups. The patterns of variation can provide information about genetic distances between the groups and their history.

    The genetic patterns suggest that most present-day Indian population groups have inherited 39 per cent to 71 per cent of their ancestry from the ancestral North Indians who are genetically close to central Asians or Eurasians.

    The balance comes from ancestral South Indians who do not appear to share genetic proximity with any group outside India. “The ancestral South Indians may have diverged from the earliest of modern humans to arrive in India,” Thangaraj said.

    The new study was not designed to explore how far back in time the distinct populations arrived, or when they began to mix. But the new data combined with earlier research would put the ancestral South Indians in India about 65,000 years ago and the ancestral North Indians about 20,000 years later.

    Although there is abundant archaeological evidence — rock shelters, stone tools and wooden spears — for prehistoric human settlements in India, population patterns and movements of the earliest modern humans in India remain unclear.

    “It seems to me that attempts to postulate a population pattern so far back in history, going back to before 10,000 BC, would have many uncertainties,” said Romila Thapar, emeritus professor of ancient Indian history at Jawaharlal Nehru University, Delhi. “Our data on population groups for such early periods is limited,” Thapar told The Telegraph.

    Genetic studies by other research teams have indicated that modern humans began walking out of Africa into West Asia, central Asia and South Asia, about 70,000 years ago. The new study has also confirmed earlier findings from the CCMB that the Onges in the Andamans are the descendants of the first modern humans who moved out of Africa, but have remained isolated on the islands.

    The Onges appear exclusively related to the ancestral South Indians.

    “Understanding the origins of the Andamanese (tribes) could provide a window into the history of ancestral South Indians,” Nick Patterson, a mathematician and a team member from the Broad Institute, said in a statement.

    The CCMB-Broad Institute study has shown that genetic contribution of ancestral North Indians is high in upper caste and Indo-European language speakers on the subcontinent — such as the Pathans from Pakistan or the Kashmiri Pandits, Vaish, Srivastava groups from India.

    But some tribal and lower caste groups appear closer to the ancestral South Indians.

    The study also indicated that four groups — the Onges from Andamans, the Siddhis from Karnataka, and the Nyshi and Ao Naga from the Northeast — have genetic proximity to populations outside India and do not have detectable contributions from either the ancestral North Indians or ancestral South Indians.
     
  5. Sridhar

    Sridhar House keeper Moderator

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    Genetically, as good as chalk and cheese

    Kalyan Ray, New Delhi, Sep 24, DH News Service:
    That all life is related by common ancestry, and that populations change form over time, constitute the bases of human evolution. And yet recent research now reveals that the great North-South divide existed even in pre-historic India, at least genetically.

    So far, sociologists and historians have made much of the differences between inhabitants of northern and southern India. Now, after analysing thousands of tiny genes, scientists have identified two distinct genetic traits separating north and south
    Indians almost 45,000 years ago, predating history.

    Because of their distinctive signatures, ancient north and south Indians are genetically as different as chalk and cheese. Today, nearly all Indians carry genomic contributions from these two distinct ancestral populations.

    Ancient south Indians evolved almost 65,000 years ago when one of the direct descendent of the first human being on the planet – Onges of Andaman – settled on the islands. South Indians – much ancient compared to the north Indians – are genetically similar to the Onge tribal who retain some of the pristine genes from the first ever human being on the planet.

    The ancient north Indians branched out from modern European population almost 45,000 years ago. They are genetically similar to West Asians, Central Asians and Europeans, a group of researchers have claimed in a scholarly paper published in the peer reviewed journal Nature that will appear on Thursday. “Their genes are 40 to 80 per cent similar to that of Europeans,” K Thangaraj, one of the team members at the Centre for Cellular and Molecular Biology (CCMB), Hyderabad told Deccan Herald.

    The finding suggests that much before the Indus Valley civilisation and the so-called Aryan invasion, north Indians had ancestors who were genetically close to modern-day Europeans. Indian history has recorded detailed information about the Harappans and provided sketchy ideas on the Stone and Bronze ages.

    But history is mostly blank beyond 8,000 years. Comparing 10 lakh pieces of Indian genes with European and Chinese genes, scientists from India and the USA inferred that two genetically distinct population branches existed 45,000 years ago.

    Thangaraj said the findings do not support the “Aryans-bringing-foreign-genes-to-India” theory since thousands of years before the Aryans there were people in India with distinctive traits.

    “This is a significant revelation which shows the variation of Indian genome, “ Council for Scientific and Industrial Research Director General Samir K Brahmachari said.

    The researchers from CCMB, Harvard Medical School and Harvard School of Public Health analysed genes taken from the whole genome of 132 individuals from 25 diverse groups, representing 13 states, six language families, traditionally “upper” and “lower” castes, and tribal groups.

    The finding that nearly all Indian groups descend from mixtures of two ancestral populations applies to traditional “tribes” as well as “castes”. The findings suggest castes are inseparable from tribes. Genetics proves that they are not systematically different. Castes grew directly out of tribal-like organisations during the formation of Indian society.

    Social practices like marriage within the same caste helped preserve unique genetic signatures that aided the researchers in understanding India’s population history.
    However, everybody is not convinced with the north-south divide theory. “It’s not that simplistic. There may be many more such settlements,” RM Pitchappan, an independent geneticist from Madurai Kamraj University said. “I will take the conclusions with a pinch of salt,” Pitchappan said.

    [​IMG]Distinctive features

    * Scientists identify two distinct genetic traits separating north and south Indians
    * South Indians are much ancient compared to the north Indians
    * North Indian genes are 40 to 80 per cent similar to that of Europeans
    * Before Aryans, there were people in India with distinctive traits


    Genetically, as good as chalk and cheese
     
  6. Sridhar

    Sridhar House keeper Moderator

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    DNA trawl shows long history of India's castes

    Wed Sep 23, 2009 10:57pm IST

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    By Maggie Fox, Health and Science Editor
    WASHINGTON (Reuters) - A genetic search of India's diverse populations shows most people have mixtures of European and ancient south Indian genes, and helps illustrate the deep roots of the country's caste system, researchers reported on Wednesday.
    It also shows that Indians, much like the Finns and European-origin Jews, may be susceptible to recessive genetic diseases, they report in the journal Nature.
    Dr. David Reich of Harvard Medical School in Boston and colleagues found "strong evidence for two ancient populations, genetically divergent, that are ancestral to most Indians today".
    "One, the 'Ancestral North Indians', is genetically close to Middle Easterners, Central Asians, and Europeans, whereas the other, the 'Ancestral South Indians', is as distinct from ancestral north Indians and East Asians as they are from each other," they wrote.
    "Nobody's even close to having all of one or the other," Reich said in a telephone interview. "People in India are almost all a mixture of these two ancestral populations."
    And virtually all also carry a risk of genetic mutations that can confer disease, Reich said.
    He said his group and others should look in to that, to see if Indians have higher rates of recessive diseases, which can include deadly and incurable cystic fibrosis, sickle cell disease, and Tay-Sachs disease.
    Reich's team, including a group at the Broad Institute at Harvard and the Massachusetts Institute of Technology, looked at genetic mutations in people from 25 different Indian groups -- a small sampling of the 6,000 or so estimated groups that restrict intermarriage.
    FOUNDER EFFECT
    What they found, time and again, was the so-called founder effect -- large numbers of people descended from what was originally a small group of ancestors. People in Finland and Ashkenazi Jews are other groups marked by the founder effect.
    The limits on marrying outside the group can create the risk of recessive diseases -- conditions that only occur if people have two mutated genes. Marriage within groups raises this risk.
    "Many Indian groups have a pattern of having been founded by a small number of individuals. They have been isolated from other groups since that time by restricted marriage across groups," Reich said.
    Some people get tested for recessive genes before having children, and some people also use assisted fertility techniques to test embryos for recessive diseases.
    Reich said no one had documented a higher number of recessive diseases among Indians, but it also was not something anyone had looked for. "It probably affects hundreds of millions of people in India today," he said.
    While the genes clearly show that the caste system has existed for hundreds of generations, the genes do not line up by caste.
    "It is impossible to distinguish castes from tribes using the data," Kumarasamy Thangaraj of the Center for Cellular and Molecular Biology in Hyderabad, India, who worked on the study, said in a statement.
    "This supports the view that castes grew directly out of tribal-like organizations during the formation of Indian society."
    (Editing by Julie Steenhuysen and David Storey)


    DNA trawl shows long history of India's castes | Lifestyle | Reuters
     
  7. Sridhar

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    Gene sweep shows Indians descended from two groups[​IMG] AFP/Paris


    Nearly all Indians can claim descent from two ancestral groups, a study released yesterday said, adding that millennia of inter-marriage may have left the country’s population more at risk to some inherited diseases.
    US and Indian scientists took blood samples from 132 individuals from 25 diverse groups in India, representing 13 states, all six language families as well as tribal groups and “upper” and “lower” castes. They then unravelled the volunteers’ genetic code, sifting through key areas of DNA for similarities and differences.
    Two ancestral populations emerge, and their genes dominate the Indian genome today, the researchers said.
    “Different Indian groups have inherited 40% to 80% of their ancestry from a population that we call the Ancestral North Indians, who are related to western Eurasians, and the rest from the Ancestral South Indians, who are not related to any group outside India,” said Harvard Medical School geneticist David Reich.
    The north-and-south findings chime with a scenario whereby a small number of venturers, the so-called Austro-Asiatic people, first moved into the sub-continent about 60,000 years ago.
    Around 5,000 years ago, the arrival of a Dravidian-speaking tribe caused the community to disperse. Its members went on to form enclaves of small, tightly-knit groups. The Dravidians themselves were then driven to the south when Indo-European tribes arrived around 500 years later.
    These early events helped form a patchwork of groups that is visible today, according to this theory.
    Adding DNA spice have been India’s successive waves of conquerors, from the Persians, the Macedonians, the Portuguese, the Mughals and the British.
    Trade and regional contacts have added to the mix.
    The Siddi people in southwestern India have a signature of African genes, consistent with their origin, which involved the Arab slave trade. The Nyshi and Ao Naga groups in the far northeast, cluster with Chinese genotypes, which correlates with their use of Tibeto-Burman languages.
    The investigators, whose work is published by the British journal Nature, point to a range of intriguing discoveries.
    One is the strong genetic similarities within groups that can be traced to a “founder event” - the establishment of a community by a tiny number of people who migrated after the ancestral population was dispersed.
    Six Indo-European- and Dravidian-speaking groups have evidence of “founder events” that happened 30 generations ago, while the Vysya group had a “founder event” that occurred at least 100 generations in the past.
    “Founder events” mean a community starts with a relatively small gene pool whose confines may then be maintained or reinforced by geographical isolation or by endogamy, the term for marriage within a tribe or caste.
    The paper says endogamy’s role in shaping India’s DNA has deeper roots than many might think.
    “Some historians have argued that ‘caste’ in modern India is an ‘invention’ of colonialism in the sense that it became more rigid under colonial rule,” it says.
    “However, our results indicate that many current distinctions among groups are ancient, and that strong endogamy must have shaped marriage patterns in India for thousands of years.”
    The downside of “founder events” and enduring endogamy is that genetic flaws which boost the chance of inherited disease get transmitted through the generations, rather than get erased by mixing genes with other communities.
    Screening and mapping India’s diversity could have benefits in health, enabling doctors to help people at risk from their genetic inheritance, says the study.
    It gives the example of a tiny deletion on a gene called MYBPC3, which increases the risk of heart failure by about sevenfold. Around four% of the Indian population have this genetic variant, yet it is nearly absent elsewhere.
    Little is known about the genomics of India. The country has the world’s second-largest population but has been under-represented in surveys of the human genome.


    http://www.gulf-times.com/site/topics/article.asp?cu_no=2&item_no=316273&version=1&template_id=40&parent_id=22
     
  8. Sridhar

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    DNA points to India's two-pronged ancestry
    Diverse groups in the South Asian nation may derive from a pair of ancient populations
    By Bruce Bower
    Web edition : Wednesday, September 23rd, 2009
    [​IMG] [​IMG] Text Size

    [​IMG]Enlarge[​IMG]
    Genetic SpreadView Larger Version | Despite India’s genetic diversity (seen on a map showing the states inhabited by each of 25 groups), a new DNA study traces today’s lineages back to just two ancestral groups. Colors denote the language families of tongues spoken by each group (see legend at right).K. Thangaraj/Nature

    India’s 1.2 billion people belong to more than 4,600 ethnic and religious groups separated by caste, customs and language. But a shared genetic heritage runs deep in this teeming nation, a new DNA analysis suggests.
    Indians today possess varying proportions of ancestry from two genetically distinct populations, concludes a team led by David Reich, a geneticist at Harvard Medical School in Boston. Members of one ancient population share DNA patterns with modern Middle Easterners, central Asians and Europeans, the researchers report in the Sept. 24 Nature. The other population shows no strong connection to any modern mainland group. The first group is dubbed “Ancestral North Indians” and the second “Ancestral South Indians.” Both of the groups existed before the founding populations that contributed to today’s genetic diversity moved to South Asia.
    Members of each modern Indian group have inherited between 40 and 80 percent of their DNA from Ancestral North Indians and the rest from Ancestral South Indians, Reich and his colleagues say. This pattern applied to all castes within India and to traditional tribes as well. Each of these groups was derived from separate founding populations, according to the analysis. These founding populations arrived in South Asia between about 200 and 2,500 years ago, well before the colonial era, suggesting that current caste and ethnic divisions predate that time.
    “This supports the view that castes grew directly out of tribal-like organizations during the formation of Indian society,” says molecular biologist and study coauthor Kumarasamy Thangaraj of the Center for Cellular and Molecular Biology in Hyderabad, India.
    Members of upper castes and speakers of Indo-European languages, including Hindi, possessed the most genetic traits attributed to Ancestral North Indians.
    A shared genetic ancestry from two ancient populations “may be the strong, invisible thread that binds all Indians” despite barriers of caste and custom, writes geneticist Aravinda Chakravarti of Johns Hopkins School of Medicine in Baltimore in a comment appearing in the same issue of Nature.
    Reich’s team examined alterations of more than 560,000 nucleotides—the basic constituents of DNA—across the genome. DNA samples came from 132 individuals who belong to 25 groups representative of India’s ethnic and linguistic diversity. The researchers plugged this information into a new statistical model that they developed to reconstruct India’s genetic roots.
    Many groups in India share an unusually large number of DNA alterations at precise spots. These findings fit a scenario in which many Indian populations were founded by small numbers of people that married and reproduced within their own groups, Reich’s team proposes. Marriage with outsiders would have diluted the number of shared DNA variations.
    Other populations that have grown in relative isolation, such as Finns and Ashkenazi Jews, display many recessive genetic diseases. Further studies in India may identify genes involved in such diseases, the investigators say.
    In one exception to the pattern of genetic mixture in Indian groups, Onge hunter-gatherers living on the Andaman Islands in the Indian Ocean display purely Ancestral South Indian ancestry, Reich and his colleagues say. Andaman Islanders possess direct genetic links to modern humans that left Africa around 70,000 years ago and eventually colonized what is now India, they suggest.
    According to earlier research, India’s initial settlers arrived around 60,000 years ago. Speakers of Dravidian languages arrived roughly 5,000 years ago, followed by Indo-European speakers approximately 3,500 years ago. If the new analysis holds up, these early populations wouldn’t have contributed to modern mainland India’s genetic makeup. And founding populations of today’s Indian groups wouldn’t have reached South Asia until well after Indo-European speakers.
    The team’s model can’t yet determine the original genetic makeup of India’s two ancestral populations or estimate when the two ancestral populations originated and first mixed. But the new analysis better dissects genetic relationships among groups in India than a 2008 study that analyzed variation at 405 nucleotides in 55 groups, Thangaraj says.


    DNA Points To India's Two-pronged Ancestry / Science News
     
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    Ancestral Populations Of India And Relationships To Modern Groups Revealed

    ScienceDaily (Sep. 23, 2009) — In a study published in the September 24th issue of Nature, an international team describes how they harnessed modern genomic technology to explore the ancient history of India, the world's second most populous nation.
    See also: Health & Medicine

    Fossils & Ruins

    Reference


    The new research reveals that nearly all Indians carry genomic contributions from two distinct ancestral populations. Following this ancient mixture, many groups experienced periods of genetic isolation from each other for thousands of years. The study, which has medical implications for people of Indian descent, was led by scientists at the Centre for Cellular and Molecular Biology (CCMB) in Hyderabad, India together with US researchers at Harvard Medical School, the Harvard School of Public Health and the Broad Institute of Harvard and MIT.
    "This work is an outstanding example of the power of international collaboration," said Lalji Singh, senior author of the Nature paper, who is a Bhatnagar Fellow and the former director of CCMB. "Scientists in India and the United States have together made discoveries that would have been impossible for either group working alone."
    Although the genome sequences of any two unrelated people differ by just 0.1%, that tiny slice of genetic material is a rich source of information. It provides clues that can help reconstruct the historical origins of modern populations. It also points to genetic variations that heighten the risk of certain diseases. In recent years, maps of human genetic variation have opened a window onto the diversity of populations across the world, yet India has been largely unrepresented until now.
    To shed light on genetic variability across the Indian subcontinent, the research team analyzed more than 500,000 genetic markers across the genomes of 132 individuals from 25 diverse groups, representing 13 states, all six language families, traditionally "upper" and "lower" castes, and tribal groups.
    These genomic analyses revealed two ancestral populations. "Different Indian groups have inherited forty to eighty percent of their ancestry from a population that we call the Ancestral North Indians who are related to western Eurasians, and the rest from the Ancestral South Indians, who are not related to any group outside India," said co-author David Reich, an associate professor of genetics at Harvard Medical School and an associate member of the Broad Institute of Harvard and MIT.
    The finding that nearly all Indian groups descend from mixtures of two ancestral populations applies to traditional "tribes" as well as "castes." Kumarasamy Thangaraj, a senior research scientist at CCMB in Hyderabad and a co-author said, "It is impossible to distinguish castes from tribes using the data. The genetics proves that they are not systematically different. This supports the view that castes grew directly out of tribal-like organizations during the formation of Indian society."
    The one exception to the finding that all Indian groups are mixed is the indigenous people of the Andaman Islands, an archipelago in the Indian Ocean with a census of only a few hundred today. The Andamanese appear to be related exclusively to the Ancestral South Indian lineage and therefore lack Ancestral North Indian ancestry.
    "The Andamanese are unique," said co-author Nick Patterson, a mathematician and researcher at the Broad Institute. "Understanding their origins provides a window onto the history of the Ancestral South Indians, and the period tens of thousands of years ago when they diverged from other Eurasians." Added Singh, "Our project to sample the disappearing tribes of the Andaman Islands has been more successful than we could have hoped, as the Andamanese are the only surviving remnant of the ancient colonizers of South Asia."
    The researchers' work also has surprising and important medical implications. They discovered that many groups in modern India descend from a small number of founding individuals, and have since been genetically isolated from other groups. In scientific parlance this is called a "founder event."
    "The finding that a large proportion of modern Indians descend from founder events means that India is genetically not a single large population, but instead is best described as many smaller isolated populations," said Singh. Thangaraj continued, "The widespread history of founder events helps explain why the incidence of genetic diseases among Indians is different from the rest of the world."
    Founder events in other groups, such as Finns and Ashkenazi Jews, are well known to increase the incidence of recessive genetic diseases, and the new study predicts that the same will be true for many groups in India. "It is important to carry out a systematic survey of Indian groups to identify which ones descend from the strongest founder events," said Reich. "Further studies of these groups should lead to the rapid discovery of genes that cause devastating diseases, and will help in the clinical care of individuals and their families who are at risk."
    "Just as important as these findings are the statistical approaches that led to them," said Alkes Price, an assistant professor of epidemiology at the Harvard School of Public Health and a co-author of the Nature study. "In studying Indian genetic variation we also developed a novel toolkit for understanding the relationships among groups and the history of mixture. We believe that these tools can drive future studies not only of Indian history but of groups worldwide."


    Ancestral Populations Of India And Relationships To Modern Groups Revealed
     
  10. RPK

    RPK Indyakudimahan Senior Member

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    India's caste system 'is thousands of years old', DNA shows - Telegraph

    India's caste system 'is thousands of years old', DNA shows
    India's caste system stretches back thousands of years and was not largely a creation of colonial rule, as some historians claim, a genetic study has shown.

    Published: 7:00AM BST 24 Sep 2009

    Researchers analysed the DNA of 132 individuals with wide-ranging backgrounds from 25 diverse groups around India.

    They found evidence of strong inbreeding leading to genetic groups that had been isolated from each other for thousands of years.


    Most people had a mixture of genes from two ancient populations representing traditionally upper-caste individuals and everyone else.

    The first was genetically close to people from the Middle East, Central Asia and Europe, while the second had an 'Ancestral South Indian' lineage confined to the subcontinent.

    The research challenges the notion that India's notorious rigid caste system, with its priestly Brahmans and low-status 'untouchables', was largely manufactured by the British.

    Some historians claim that while a caste system of sorts had existed since ancient times, in its original form it was not hereditary or inflexible and allowed people to move up and down the social ladder.

    It was the British who cemented the caste system into Indian society and culture by using it as a basis of a ''divide and rule'' policy, it is alleged. The caste system was a convenient means of keeping society under control.

    The new findings published in the journal Nature indicate that, genetically at least, Indians had been divided long before the British arrived.

    The scientists analysed more than 500,000 genetic markers from people representing 13 states, all six language families in India, traditionally ''upper'' and ''lower'' castes, and tribal groups.

    One group of Andaman islanders was, unusually, related exclusively to the Ancestral South Indian lineage.

    Co-author Dr Nick Patterson, from the Harvard University/MIT Broad Institute in Massachusetts, US, said: ''The Andamanese are unique. Understanding their origins provides a window onto the history of the Ancestral South Indians, and the period tens of thousands of years ago when they diverged from other Eurasians.''

    The research has important health implications for Indians. Other genetically isolated groups such as Ashkenazi Jews are well known to suffer from an increased incidence of genetic diseases. The same may be true for many groups in India, the scientists believe.

    "The finding that a large proportion of modern Indians descend from founder events means that India is genetically not a single large population, but instead is best described as many smaller isolated populations," said Dr Lalji Singh, one of the study leaders from the Centre for Cellular and Molecular Biology in Hyderabad, India.
     
  11. S.A.T.A

    S.A.T.A Senior Member Senior Member

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    While genetic data and evidence derived from it must be treated with great caution,because the results tend to be subjective to the sample population group the data is being taken from(and variation within it),these new findings however seem to lend greater credibility to the theory which has argued that the Indo-Aryans and Dravidian speaking population groups must have always been indigenous to the Indian subcontinent,remaining isolated from one another long enough to allow for distinct linguistic evolution and followed by centuries of extensive interaction enabling the extant common socio-cultural religious traits.


    Whatever this means to the AIT/AMT hypo
     
  12. Singh

    Singh Phat Cat Administrator

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    The Indian origin of paternal haplogroup R1a1* substantiates the autochthonous origin of Brahmins and the caste system
    ;

    Abstract

    Many major rival models of the origin of the Hindu caste system co-exist despite extensive studies, each with associated genetic evidences. One of the major factors that has still kept the origin of the Indian caste system obscure is the unresolved question of the origin of Y-haplogroup R1a1*, at times associated with a male-mediated major genetic influx from Central Asia or Eurasia, which has contributed to the higher castes in India. Y-haplogroup R1a1* has a widespread distribution and high frequency across Eurasia, Central Asia and the Indian subcontinent, with scanty reports of its ancestral (R*, R1* and R1a*) and derived lineages (R1a1a, R1a1b and R1a1c). To resolve these issues, we screened 621 Y-chromosomes (of Brahmins occupying the upper-most caste position and schedule castes/tribals occupying the lower-most positions) with 55 Y-chromosomal binary markers and seven Y-microsatellite markers and compiled an extensive dataset of 2809 Y-chromosomes (681 Brahmins, and 2128 tribals and schedule castes) for conclusions. A peculiar observation of the highest frequency (up to 72.22%) of Y-haplogroup R1a1* in Brahmins hinted at its presence as a founder lineage for this caste group. Further, observation of R1a1* in different tribal population groups, existence of Y-haplogroup R1a* in ancestors and extended phylogenetic analyses of the pooled dataset of 530 Indians, 224 Pakistanis and 276 Central Asians and Eurasians bearing the R1a1* haplogroup supported the autochthonous origin of R1a1 lineage in India and a tribal link to Indian Brahmins. However, it is important to discover novel Y-chromosomal binary marker(s) for a higher resolution of R1a1* and confirm the present conclusions.


    --------

    Conclusions

    The observation of R1a* in high frequency for the first time in the literature, as well as analyses using different phylogenetic methods, resolved the controversy of the origin of R1a1*, supporting its origin in the Indian subcontinent. Simultaneously, the presence of R1a1* in very high frequency in Brahmins, irrespective of linguistic and geographic affiliations, suggested it as the founder haplogroup for the population. The co-presence of this haplogroup in many of the tribal populations of India, its existence in high frequency in Saharia (present study) and Chenchu tribes, the high frequency of R1a* in Kashmiri Pandits (KPs—Brahmins) as well as Saharia (tribe) and associated phylogenetic ages supported the autochthonous origin and tribal links of Indian Brahmins, confronting the concepts of recent Central Asian introduction and rank-related Eurasian contribution of the Indian caste system.

    However, there is a scanty representation of Y-haplogroup R1a1 subgroups in the literature as well as in this study. The known subgroups (R1a1a, R1a1b and R1a1c), which are defined by binary markers M56, M157 or M87, respectively (Supplementary Figure 1), were not observed. In such a situation, it is likely that this haplogroup (R1a1*) is a polyphyletic (or paraphyletic) group of Y-lineages. It is, therefore, very important to discover novel Y chromosomal binary marker(s) for defining monophyletic subhaplogroup(s) belonging to Y-R1a1* with a higher resolution to confirm the present conclusion. Further, the under-representation of phylogenetic data of the population groups of North India in the literature and our observations hint at the immense need of phylogenetic explorations in the northern most Himalayan regions of India, which might have acted as an incubator of many ancient lineages, to obtain a clearer picture of the peopling of India and Eurasia.
     
  13. masterofsea

    masterofsea Regular Member

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    Who created the ancient Indus Valley civilization,indo-europeans or Dravidians?
     
  14. gokulakannan

    gokulakannan Regular Member

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  15. masterofsea

    masterofsea Regular Member

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    But dravidans now lived in south india.why they emigrated to south india from indus rivers basin?
     
  16. gokulakannan

    gokulakannan Regular Member

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    According to general Indian legend, the Aryans arrived in north India somewhere from Iran and southern Russia at around 1500 BC. Before the Aryans, the Dravidian people resided in India. The Aryans disregarded the local cultures. They began conquering and taking control over regions in north India and at the same time pushed the local people southwards or towards the jungles and mountains in north India. According to this historical fact the general division of Indian society is made. North Indians are Aryans and south Indians are Dravidians. But this division isn’t proper because of many reasons.

    Hope this link will help you..
    Who were aryans,dravidians? - Yahoo! Answers India
     
  17. S.A.T.A

    S.A.T.A Senior Member Senior Member

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    At best a popular myth.That Dravidians authored the Indus valley cultures is as speculative as the hypo that it was a product of the Indo-Aryans
     
  18. peacecracker

    peacecracker Regular Member

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    Recent days ,Indus Valley Civilization like remnants are found in Kerala state.
    Full Read:
    The Hindu : Front Page : Sign akin to Indus Valley’s found in Kerala

    http://news.outlookindia.com/item.aspx?666913
     
  19. S.A.T.A

    S.A.T.A Senior Member Senior Member

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    isolated cultural remnants of the Indus valley people have been found all over the world.An entire library of Indus valley seals where discovered in Mesopotamia and Bahrain.Indus seals were discovered at a BMAC site in Central Asia.Indus valley civilization was built around international trade these guys where everywhere,so does the evidence of these contacts.

    Recently in Tamil Nadu a stone Celt(a small hand held axe)was discovered and it appeared to have engravings similar to the IVC signs.Its a documented fact that many ornaments excavated in the IVC sites appear to contain signatures traces of gold mined in Kolar karnataka.harappan bronze have been discovered in AP.

    The absence of tell tale IVC habitation records at these sites of discovery indicate the isolated nature of the presence of these artifacts,probably indicating commercial contacts.
     

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