Australia might not have been isolated for the 40,000 years before European colonisation, a latest study revealed recently.

The study, published in the journal PNAS (Proceedings of the National Academy of Sciences of the United States of America), has found evidence of substantial gene flow between Indian populations and Australia about 4000 years ago.

The researchers analysed large-scale genotyping data from Aboriginal Australians, New Guineans, island Southeast Asians and Indians that suggest a new possibility, and found a common origin for populations in Australia, New Guinea and the Mamanwa (a Negrito group from the Philippines) and estimated these groups split from each other about 36,000 years ago.

This evidence supports the view that these people represent the descendents of an ancient southwards migration out of Africa.

They also found a substantial gene flow from India to Australia 141 generations ago, or 4230 years ago assuming a generation span of 30 years.

"This is also approximately when changes in tool technology, food processing, and the dingo appear in the Australian archeological record, suggesting that these may be related to the migration from India," the study said.