DNA reveals Pacific migration patterns
Tue, 23 Oct 2012 8:02a.m.
New Zealand's first Polynesian settlers likely came from a varied background rather than a tight-knit group, say scientists studying the DNA of remains unearthed in Marlborough.
University of Otago researchers have sequenced complete mitochondrial genomes for members of what was likely to be one of the first groups of Polynesians to settle New Zealand.
Four Rangitane iwi ancestors were buried at a large village on Marlborough's Wairau Bar more than 700 years ago. New techniques allowed the researchers to sequence the DNA, despite it being highly degraded.
Mitochondrial DNA is only inherited through the mother's side and can provide insights into ancient origins and migration routes.
"We found that three of the four individuals had no recent maternal ancestor in common, indicating that these pioneers were not simply from one tight-knit kin group, but instead included families that were not directly maternally related," said study director Professor Lisa Matisoo-Smith.
It gave a "fascinating new glimpse" into the social structure of the first New Zealanders and others in the final phases of the great Polynesian migration across the Pacific, she said.
Similar DNA detective work on modern and ancient Polynesian populations might now be able to clear up competing theories about the migration.
The researchers also discovered that at least one of the settlers carried a genetic mutation associated with insulin resistance, which leads to Type 2 diabetes.
Prof Matisoo-Smith said it was previously thought a lack of genetic diversity reflected uniformity in the founding population.
"Overall, our results indicate that there is likely to be significant mitochondrial DNA variation among New Zealand's first settlers."
Now that the researchers have identified several unique genetic markers in New Zealand's founding population, work can begin to obtain and sequence other ancient and modern DNA samples from Pacific islands and search for these same markers.
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