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(ARCHIVE) VOL. XXII NO. 20, February 1-15, 2013
The story of migrations eastwards

Pramila Phatarphekar, the author of Old Dravida in New Guinea, wrote to Madras Musings contributor, K.V.S. Krishna, recently, "You should feel very proud today that Proceedings of the National Academy of Services, Australia, Nature and all prestigious magazines have confirmed your findings regarding the Indian migration into Australia and Papua New Guinea. Your observations predate the work done by the Max Planck Institute by several years!" Krishna has written several times in Madras Musings on this subject which figured in the headlines in mid-January.

Here are excerpts from the articles in Nature which highlighted these findings.

Ed Yong, writing in an article titled 'Genomes link aboriginal Australins to Indians', says, "Some aboriginal Australians can trace as much as 11 per cent of their genomes to migrants who reached the island around 4,000 years ago from India, a study suggests. Along with their genes, the migrants brought different tool-making techniques and the ancestors of the dingo, researchers say."

This scenario is the result of a large genetic analysis outlined in the Proceedings of the National Academy of Sciences. It contradicts a commonly held view that Australia had no contact with the rest of the world between the arrival of the first humans around 45,000 years ago and the coming of Europeans in the 18th Century.

"Australia is thought to represent one of the earliest migrations for humans after they left Africa 36,000 years ago, but it seemed pretty isolated after that," says Mark Stoneking, a geneticist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who led the study.

Irina Pugach, a postdoctoral researcher in Stoneking's laboratory, discovered signs of the Indian migration by comparing genetic variation across the entire genomes of 344 individuals, including aboriginal Australians from the Northern Territory, highlanders from Papua New Guinea, several populations from Southeast Asia and India and a handful of people from the United States and China.

Pugach found evidence of genetic mixing, or gene flow, between the Indian and northern Australian populations taking place around 141 generations ago. This gene flow could not have occurred during the initial wave of migration into Australia because it is absent from New Guinean and Mamanwa genomes, and it is too uniformly spread across the northern Aboriginal genomes to have come from European colonists.

The genetic mingling coincided with the arrival in Australia of microliths – small stone tools that formed the tips of weapons – and the first appearance in the fossil record of the dingo, which most closely resembles Indian dogs. All of these changes may be related to the same migration, the researchers say…

Sheila van Holst Pellekaan, a geneticist at the University of New South Wales, Australia, and a co-author of the earlier genome-wide study, welcomes the latest research, but warns that the finding is "definitely not representative of Australia", because it only looked at people from the Northern Territories. She believes that the Aboriginals' vast genetic diversity suggests that multiple waves of migration could have occurred, but that new genes would not always have dispersed through the pre-existing peoples…

Elie Dolgin adds in an article titled 'Indian ancestry revealed' that 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…

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 per cent 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…

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."…

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. For example, Chakravarti notes that the study can't establish a rough date as to 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."

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In this Issue

City roads taken over
Government flip-flop
Our power crisis
The story of migrations eastwards
Vignettes of the past – in pictures... & live
The view from the Mount
On the trail of judges & lawyers
Enjoying ourselves at the Book Fair

Our Regulars

Short 'N' Snappy
Our Readers Write
Quizzin' with Ram'nan
Dates for your Diary
Babu's Toon


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