Posted on 09/23/2009 5:45:59 PM PDT by BGHater
The mixing of two distinct lineages led to most modern-day Indians.
The population of India was founded on two ancient groups that are as genetically distinct from each other as they are from other Asians, according to the largest DNA survey of Indian heritage to date. Nowadays, however, most Indians are a genetic hotchpotch of both ancestries, despite the populous nation's highly stratified social structure.
"All Indians are pretty similar," says Chris Tyler-Smith, a genome researcher at the Wellcome Trust Sanger Institute near Cambridge, UK, who was not involved in the study. "The population subdivision has not had a dominating effect."
India makes up around one-sixth of the world's population, yet the South Asian country has been sorely under-represented in genome-wide studies of human genetic variation. The International HapMap Project, for example, includes populations with African, East Asian and European ancestry — but no Indians. The closest the Human Genome Diversity Cell Line Panel of 51 global populations comes is Pakistan, India's western neighbour. The Indian Genome Variation database was launched in 2003 to fill the gap, but so far the project has studied only 420 DNA-letter differences, called single nucleotide polymorphisms (SNPs), in 75 genes1. Caste divisions
Now, a team led by David Reich of the Broad Institute in Cambridge, Massachusetts, and Lalji Singh of the Centre for Cellular and Molecular Biology in Hyderabad, India, has probed more than 560,000 SNPs across the genomes of 132 Indian individuals from 25 diverse ethnic and tribal groups dotted all over India.
The researchers showed that most Indian populations are genetic admixtures of two ancient, genetically divergent groups, which each contributed around 40-60% of the DNA to most present-day populations. One ancestral lineage — which is genetically similar to Middle Eastern, Central Asian and European populations — was higher in upper-caste individuals and speakers of Indo-European languages such as Hindi, the researchers found. The other lineage was not close to any group outside the subcontinent, and was most common in people indigenous to the Andaman Islands, a remote archipelago in the Bay of Bengal.
The researchers also found that Indian populations were much more highly subdivided than European populations. But whereas European ancestry is mostly carved up by geography, Indian segregation was driven largely by caste. "There are populations that have lived in the same town and same village for thousands of years without exchanging genes," says Reich. Number puzzle
Indian populations, although currently huge in number, were also founded by relatively small bands of individuals, the study suggests. Overall, the picture that emerges is of ancient genetic mixture, says Reich, followed by fragmentation into small, isolated ethnic groups, which were then kept distinct for thousands of years because of limited intermarriage — a practice also known as endogamy.
This genetic evidence refutes the claim that the Indian caste structure was a modern invention of British colonialism, the authors say. "This idea that caste is thousands of years old is a big deal," says Nicole Boivin, an archaeologist who studies South Asian prehistory at the University of Oxford, UK. "To say that endogamy goes back so far, and that genetics shows it, is going to be controversial to many anthropologists." Boivin fears that the study might be 'spun' by politicians seeking to maintain caste structures in India, and she calls on social scientists and geneticists to collaborate on such "highly politicized" issues.
Beyond the study's social repercussions, the low rates of genetic mingling "could have important implications for biomedical studies of Indian populations", notes Sarah Tishkoff, a human geneticist at the University of Pennsylvania in Philadelphia who was not involved in the research. The partitioned population structure will need to be taken into account in any efforts to map disease genes, she says.
The small numbers of founders of each Indian group also have clinical consequences, says Reich. "There will be a lot of recessive diseases in India that will be different in each population and that can be searched for and mapped genetically," he says. "That will be important for health in India."
The evidence that most Indians are genetically alike, even though anthropological data show that Indian groups tend to marry within their own group, is "very puzzling", says Aravinda Chakravarti, a human molecular geneticist at the Johns Hopkins University School of Medicine in Baltimore, Maryland, who wrote an accompanying News & Views article3. For example, Chakravarti notes that the study can't establish a rough date for when the ancient mixing between the two ancestral populations took place. "There are very curious features of the data that are hard to explain," he says, adding: "This is not the end of the story."
* References
1. Indian Genome Variation Consortium J. Genet. 87, 3-20 (2008).
2. Reich, D. et al. Nature 461, 489-494 (2009).
3. Chakravarti, A. Nature 461, 487-488 (2009).
I really can’t imagine who would think it was invented by the Brits.
Ignorant leftists.
Higher than average levels of blood type B in India.
They also used MUSEUM SAMPLES (of questionable provinence I might add).
Article we are discussing is quite recent and is based on thousands of samples taken recently.
I think the old conclusions have been overturned.
BTW, the discovery that the San people are apparantly the source of the most ancient lineages for Europeans and Chinese (and everybody else outside of Africa) is NEW STUFF.
Nils Vander Post suggested as much 3/4 of a century ago.
Their culture is extremely primitive, being hunting-gathering. They can't even make fire, but carry around something already burning (e.g. ignited by lightning strikes).
Genetic studies often seem to me to conflict with each other.
As to San being ancestral to us honkies, see my post about the Venus of Willendorf.
They still had tropical proportions but were roughly as tall as modern Negro people in Africa ~ and were clearly NOT white folk!
Remember, during the period of maximum glaciation in an ice age you have recurring periods of warmer weather where the ice may well melt allowing plants and animals to return.
Our early European ancestors supposedly walked into Europe about 35,000 years ago, just about when many of those cave paintings were being made. It is entirely possible that other people had gotten to Europe earlier, while the descendants of the San people in Africa (guys with the straight hair) simply arrived later.
I think you are correct. It would be hard to live as a Dalit or in a caste society generally.
self-ping
The cave paintings I have seen pictures of are superb mostly realistic art. Nothing remotely comparable to them is being made by San or Andamanese hunter-gatherers.
Way back when I studied genetics in college, my genetics prof told us there were only two races that he knew of, those who couldn’t breed at sea level and those who couldn’t breed at high altitudes. The rest were just skeletal / appearance differences.
ping
Of course not ~ you must first find a cave.....
That sounds like a lot of hooey with a political agenda.
It’s more than just the lack of caves. Bushmen, Andamanese, and other nomadic hunter-gatherers produce hardly any art above ground. They are stuck in the Paleolithic. Remember, these guys can’t even make fire!
There appears to be a lot of work to be done on this subject. It's interesting that at one time in the distant past there was a lot of intermarriage, but that stopped with the advent of the caste system. So, what changed? Why didn't the invaders from the North start a caste system right away?
Caste is very much alive among Muslims and Christians in India. Its a social system not religious.
The Europeans didn't even bring hanta virus with them ~ it was indigenous and is still a risk to everybody living in the Western hemisphere.
The primary reason Europeans purchased slaves from Africans was to REPOPULATE the agricultural regions in South and Central America as rapidly as possible to create wealth.
Those regions were not pristine jungle that'd never known the plough. Most of it had been good farmland and it was returned to that purpose through the hard work of African people who could resist the heat, humidity and to some degree the diseases (e.g. malaria).
BTW, that's just the most recent European migration. The people who became the Sa'ami and the Berbers in the old world were migrating to North America as early as 17,000 years ago when there were still vast Ice sheets over the continent and the ocean was hundreds of feet lower. They created the Clovis culture.
Now, in India, the Indo-European invaders arrived much earlier than is generally thought ~ and became part of the founding population, not just an add on. That's why it's so difficult to identify the Persian invaders of the Vedic period ~ they were simply the same folks as an earlier group.
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