NEW YORK (GenomeWeb) – A sequencing study of Y chromosomes from Aboriginal Australians suggests that today's indigenous people are genetically connected to the people who settled the continent 50,000 years ago, challenging a previous assumption about the history of Australia linking Aboriginal Australians to a prehistoric migration from India between 4,000 and 5,000 years ago.
Researchers from the Wellcome Trust Sanger Institute and La Trobe University in Melbourne published the results of the study today in Current Biology.
The team first analyzed SNP data from 144 Aboriginal Australian men who had volunteered to participate in the Genographic Project. Of those, the researchers looked for men whose Y chromosome SNP data indicated they belonged to an indigenous haplogroup. Thirteen agreed to further studies and the researchers sequenced their genomes on the Illumina HiSeq instrument.
After sequencing, the researchers aligned reads that mapped to the Y chromosome then used sequence data from 1,244 samples from the 1,000 Genomes Project to generate a phylogenetic tree.
The tree revealed "deep divergences" between Y chromosomes indigenous to Sahul — the ancient continent that included Australia and New Guinea — and all other populations, the authors wrote. And that divergence occurred around 54,000 years ago.
There is archeological evidence that humans lived in Australia as early as 47,000 years ago, but previous genetic studies had traced Aboriginal Australians to South Asian populations that migrated 4,000 years ago. In addition, other evidence found the arrival of the dingo at that time along with substantial language and cultural changes.
However, those previous genetic studies relied on Y-STR analysis to trace the genetic ancestry, a method that is not as high resolution as NGS. Using NGS, the researchers were able to get a more detailed view of the Y chromosome, finding that the Aboriginal Australian Y chromosomes were clearly distinct from Indian Y.
"These results refute the previous Y chromosome study, thus excluding this part of the puzzle as providing evidence for a prehistoric migration from India," first author Anders Bergstrom said in a statement. Nonetheless, the arrival of the dingo in Australia 4,000 years ago provides some evidence that was contact between Australia and South Asia at that time, the authors wrote.
Lesley Williams, a cultural advisor and community elder who worked as a liaison between the researchers and Aboriginal community said in a statement that the "results confirmed what our ancestors have taught us over many generations."
"The disparity between our findings and the earlier report can be attributed to improvements in technology, as none of the methods previously used to study the history of the paternal lineage offered the level of phylogenetic or dating precision afforded by complete Y chromosome sequencing," the authors wrote in the study.