The study of human migrations around the world, based on human genome, has established the fact that Australian aboriginals migrated to Australia from Papua- New Guinea, about 35000 to 40000 years ago. At that time, Australia and New Guinea were a single land mass, called Sahul.. This can be easily confirmed from the fact that ancient genetic association is found between New Guineans and Australians. The humans arrived there from the Indonesian archipelago after crossing the sea in small boats. Australia is thought to represent one of the earliest migrations for humans after they left Africa. The migration of modern humans around the earth, apparently proceeded via two routes: the northern route that gave rise to modern Asians 23,000-38,000 years ago and an earlier southern route, which followed the coast around the Arabian Peninsula and India to the Australian continent. It has been suggested that the ancestors of aboriginal Australians diverged from the ancestral Eurasian population 62,000-75,000 years ago and, based on archaeological evidence, reached Sahul ( Australia-New Guinea landmass ) by 35000 to 45,000 years ago. This group of humans on an early southward migration out of Africa, is believed to have diverged to Australia, New Guinea and Philippines about 36000 years ago.
So far it was thought that after this migration, the new inhabitants to Australia lived in perfect isolation there till Europeans arrived in late Nineteenth century. A new research article published in the science magazine Nature on 14 January 2013 and referring to a study outlined in the Proceedings of the National Academy of Sciences , claims that this was not so and aboriginal Australians did have a window of contact with outside world about 4000 years back. This study was carried out by researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany under leadership of Mark Stoneking, a geneticist at the Max Planck Institute. The team checked the entire genomes of 344 individuals, including aboriginal Australians from the Northern Territory, highlanders from Papua New Guinea, several populations from Southeast Asian and India and a handful of people from the United States and China and compared their genetic variations.
Perhaps the most interesting finding of this study is a curious fact that Australian aboriginal genome shows fair amount of mixing with Indian genes. Irina Pugach, a postdoctoral researcher in Mark Stoneking’s laboratory, discovered the signs of the Indian migration to Australia says that “ Some aboriginal Australians can trace as much as 11% of their genomes to migrants, who reached the island around 4,000 years ago from India. This genetic mixing, or gene flow, between the Indian and northern Australian populations; taking place around 141 generations ago, could not have occurred during the initial wave of migration into Australia because it is absent from New Guinean and Mamanwa (a Negrito group from the Philippines) genomes, and it is too uniformly spread across the northern Aboriginal genomes to have come from European colonists.” She says further; “ Our findings suggest substantial gene flow from India to Australia 4,230 years ago, well before European contact. Currently the accepted view is that Australia has been completely isolated for almost 45 thousand years following its initial colonization in the late 1800s. ”
This study brings up a totally new finding that there was an Indian migration to Australia around 4230 years ago. This date exactly matches with arrival of two more things in Australia, stone tools that formed the tips of weapons, called Microliths and a wild dog known as Dingo, which makes it’s first appearance in fossil records around this time.. This article says that the dingo, which most closely resembles Indian dogs, was probably brought in by the Indians along with their stone tools. Prof Stoneking adds: “We don’t have direct evidence of any connection, but it strongly suggestive that microliths, dingo and the movement of people were all connected.”
Another interesting finding is that, out of the populations considered in the study, Dravidian-speaking groups are the best match to be the source populations for this Indian migration to Australia. However, Ms. Pugach warns: “ This does not mean the ancestors of these groups actually were the source population. It is possible, that there is another group which we didn’t sample yet. Another possibility is that this group doesn’t even exist anymore.”
Regarding genetic mixing of up to 10% of Indian genome, she says: “We have estimated the amount of Indian contribution to Australian genomes at around 10%, but this number doesn’t tell us anything about how many individuals might have migrated. This number depends on the size of the Australian population at the time, and we don’t know how big it was. The amount of Indian ancestry could have become inflated through the process known as genetic drift, especially if the Australian population was small.”
I am quite sure that there would a large number of studies on this topic in future. What really baffles me is that this period of migration appears to be the same period in which Indus-Ghaggar civilization was at zenith in Indian sub continent, yet at the same time, a group of Indians from south, left Indian shores to migrate to a far off land to begin a new life. It has been found that people of Indus civilization knew how to build ships to cross the seas, as they had a flourishing trade with the middle east. We do not have to stretch our imagination too far to think, that an adventurous group of Indians sailors might have actually set their sails towards Australia and succeeded in landing there.