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Out of India?

By Pat, 31 May 2013 News

Dingo drinking from a pool.

The strong flow of genes from India coincided with cultural changes, such as the arrival of the dingo and changes in tools and food processing.
Image: CSIRO/Willem van Aken

Aboriginal and Torres Strait Islander people have a long history with their land. They are one of the oldest continuous cultures in the world.

The ancestors of Aboriginal and Torres Strait Islander people first arrived in Australia more than 40 000 years ago as part of a migration out of Africa, through Asia into New Guinea and Australia. It was thought that the Aboriginal and Torres Strait Islander population then remained relatively isolated until the arrival of Europeans in the 17th century. Their genes tell a different story.

For many years, archeological evidence was used to work out the evolution and movement of human populations. Artefacts including pottery, tools and artworks, as well as ruins and human remains formed part of the jigsaw used to map the spread of human cultures. Similarities in artefacts from different cultures in different locations could suggest contact between populations. Techniques that date artefacts make it possible to work out which cultures developed first and where they spread.

While useful, the archeological record is patchy, plus it is possible for different cultures to have similarities, despite never coming in contact. For example, cultures in ancient Egypt and Central America both made pyramids, but it doesn’t mean there was contact between them.

Advances in DNA technology mean genetic information can help fill gaps in archeological evidence. Genomes include all of the genetic information of a person or organism. Similarities and differences in genomes can help reveal clues about different cultures. This includes how recently different populations split off from each other. Generally speaking, the more recent the split, the more similar the genomes. Mutations in DNA happen at a fairly regular rate, so by comparing genomes, it is possible to estimate a date when the split occurred.

A team of scientists compared the genomes of a number of populations, including some from the Northern Territory in Australia, Papua New Guinea, south-east Asia, India, China and Europe among others. The analysis indicates that Indigenous Australians split from New Guinea populations about 36 000 years ago. They also found a strong flow of genes from India to Australia around 4230 years ago.

This suggests contact between India and some areas of Australia’s Northern Territory thousands of years before Europeans arrived. Around this time, the archeological record shows changes in food processing, tools and the arrival of the dingo. Further genetic analysis could provide more pieces of this human puzzle.

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