New Delhi, Jan. 14: Indians migrated to Australia over 4,000 years ago and intermingled with the natives there, a genetic study has suggested, challenging the existing view that Australian Aboriginal populations remained largely isolated until the Europeans arrived in the late 18th century.
The international team of researchers that conducted the study said the migration seemed to coincide with changes in stone tool-making fashions and the introduction of wild dogs called "dingos" to Australia.
Scientists have known through earlier studies that modern humans dispersed out of Africa about 65,000 years ago and moved into India, the Andamans and Southeast Asian islands.
One such migratory wave some 40,000 years ago brought the ancestors of the Aborigines into Australia where, under prevailing ideas, they remained largely isolated till the British established settlements there in the 1780s.
The new study, published today in the US journal Proceedings of the National Academy of Sciences, has detected genetic evidence for a "substantial gene flow between Indian populations and Australia" long before the Europeans arrived.
"We've estimated the amount of Indian contribution to Australian genomes at about 10 per cent," said Irina Pugach, a scientist at the Max Planck Institute for Evolutionary Anthropology in Germany and the first author of the study.
"But this number doesn't tell us anything about how many individuals migrated," she told The Telegraph.
A number that would lead to the observed 10 per cent Indian contribution to the Australian genome would depend on the size of the Australian Aboriginal population at the time which, Pugach said, also remains unknown.
Pugach and her colleagues from institutions in Germany, Iceland, the Netherlands and the Philippines analysed genomic data from Aboriginal Australians, the highlanders of Papua New Guinea, 11 populations from Southeast Asian islands and 26 populations from India.
Their results suggest that the Indian migrants to Australia were closer to the ancestors of the present-day Dravidian-speaking Chenchu, Kurumba and non-tribal groups in southern India than to other Indian population groups.
The scientists used standard genetic techniques that help reconstruct ancient migrations and relationships between distant population groups. They repeated their analysis several times and each result pointed to a substantial gene flow from India to Australia about 141 generations ago --- or 4,230 years ago, assuming that one human generation lasts about 30 years.
The scientists say that archaeological records in Australia suggest that changes in stone tool-making fashions too occurred around the same time. Also, the dingo appears in the Australian fossil record for the first time around 4,000 years ago.
"It suggests that the appearance of the dingo could be potentially related to the migration," Pugach said.
"Although the dingo appears to have a Southeast Asian origin, (it) most closely resembles Indian dogs."
Vadlamudi Rao, professor of anthropology at the University of Delhi, said: "This study establishes a relatively modern connection between some of India's oldest tribal populations and Australian populations."
Rao, who was formerly with the Anthropological Survey of India, Calcutta, had earlier shown that tribal groups in Bastar and the Australian Aborigines have a shared genetic ancestry, both linked to the earliest wave of modern human migration out of Africa.
The India-to-Australia migration route remains unknown but researchers say it is likely that the movement took place with southeast Asian islands and Papua New Guinea as stepping stones towards Australia.