It is generally assumed that the expansion of AMH from Africa (or Africarabia) reached S-E Asia around 70,000 years ago and Australia some 40,000 – 50,000 years ago. The Australian population then remained virtually isolated until quite recently. But a new genome-wide study suggests that there was migration from India to Australia some 4,200 years ago during the Holocene and that they brought stone-tools and the ancestor of the dingo with them. The study suggests that after the first migrants originally arrived in Sahul, the Australian, New Guinea and Mamanwa populations split from each other some 36,000 years ago. But by – an as yet unknown route – migrants from India arrived in Australia between 4,000 and 5,000 years ago.
Though this coincides with the height of the Indus Valley civilization in 2600 BC, I think it is more likely that any ocean-based, island-hopping migration at this time would have started – at least geographically – from S-E India rather than from the Indus Valley civilization in N-W India. But coastal navigation around the Indian coastline of that time would have been well within the capabilities of the Indus valley inhabitants. This is also the period when proto-Dravidian was the language across most of India (including in the Indus valley civilization) and it would be interesting if there are any traces in language which match this genetic data.
Genome-wide data substantiate Holocene gene flow from India to Australia, by Irina Pugach, Frederick Delfin, Ellen Gunnarsdóttir, Manfred Kayser, and Mark Stoneking, Proceedings of the National Academy of Sciences,
Abstract:The Australian continent holds some of the earliest archaeological evidence for the expansion of modern humans out of Africa, with initial occupation at least 40,000 y ago. It is commonly assumed that Australia remained largely isolated following initial colonization, but the genetic history of Australians has not been explored in detail to address this issue. Here, we analyze large-scale genotyping data from aboriginal Australians, New Guineans, island Southeast Asians and Indians. We find an ancient association between Australia, New Guinea, and the Mamanwa (a Negrito group from the Philippines), with divergence times for these groups estimated at 36,000 y ago, and supporting the view that these populations represent the descendants of an early “southern route” migration out of Africa, whereas other populations in the region arrived later by a separate dispersal. We also detect a signal indicative of substantial gene flow between the Indian populations and Australia well before European contact, contrary to the prevailing view that there was no contact between Australia and the rest of the world. We estimate this gene flow to have occurred during the Holocene, 4,230 y ago. This is also approximately when changes in tool technology, food processing, and the dingo appear in the Australian archaeological record, suggesting that these may be related to the migration from India.
“For a long time, it has been commonly assumed that following the initial colonization, Australia was largely isolated as there wasn’t much evidence of further contact with the outside world,” explained Prof Mark Stoneking, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
“It is one of the first dispersals of modern humans – and it did seem a bit of a conundrum that people who got there this early would have been so isolated.”
To study the early origins of Australia’s population, the team compared genetic material from Aboriginal Australians with DNA from people in New Guinea, South East Asia and India.
By looking at specific locations, called genetic markers, within the DNA sequences, the researchers were able to track the genes to see who was most closely related to whom.
They found an ancient genetic association between New Guineans and Australians, which dates to about 35,000 to 45,000 years ago. At that time, Australia and New Guinea were a single land mass, called Sahul, and this tallies with the period when the first humans arrived.
But the researchers also found a substantial amount of gene flow between India and Australia.
Prof Stoneking said: “We have a pretty clear signal from looking at a large number of genetic markers from all across the genome that there was contact between India and Australia somewhere around 4,000 to 5,000 years ago.”
He said the genetic data could not establish the route the Indians would have taken to reach the continent, but it was evidence that Australia was not as cut off as had been assumed.
“Our results show that there were indeed people that made a genetic contribution to Australians from India,” Prof Stoneking explained.
The researchers also looked at fossils and other archaeological discoveries that date to this period.
They said changes in tool technology and new animals could possibly be attributed to the new migrants.
Prof Stoneking said: “We don’t have direct evidence of any connection, but it strongly suggestive that microliths, dingo and the movement of people were all connected.”