Origins Of Pacific Islanders

February 2008 - Research published in PLoS Genetics throws new light on long-standing controversies surrounding the origins and genetic relationships of Pacific Islanders. A comprehensive genetic study of nearly1000 individuals from 41 populations has found that Polynesians and Micronesians have almost no genetic relation to Melanesians, and that Island Melanesian communities are among the most diverse known.

The study involved researchers from Temple University, University of Maryland, Yale, Binghamton University, the Marshfield Clinic Research Foundation, Victoria University in New Zealand, Mackay Memorial Hospital in Taiwan, and the Institute for Medical Research in Papua New Guinea.

Researchers analyzed more than 800 genetic markers (highly informative microsatellites) in their subjects, comparing the results with earlier conflicting findings based on small-scale mitochondrial DNA or Y chromosome studies.

Lead author Jonathan Friedlaender, professor emeritus of anthropology at Temple said:

"The first settlers of Australia, New Guinea, and the large islands just to the east arrived between 50 000 and 30 000 years ago, when Neanderthals still roamed Europe. These small groups were isolated and became extremely diverse during the following tens of thousands of years. Then, a little more than 3000 years ago, the ancestors of the Polynesians and Micronesians, with their excellent sailing outrigger canoes, appeared in the islands of Melanesia, and during the following centuries settled the islands in the vast unknown regions of the central and eastern Pacific."

"Over the last 20 years there have been many hypotheses concerning where the ancestors of the Polynesians came from in Asia, how long it took them to develop their special seafaring abilities in Island Melanesia, and how much they interacted with the native Melanesian peoples there before they commenced their remarkable Diaspora across the unexplored islands in the Pacific."

Researchers explain that the "fast train hypothesis", supported by mitochondrial evidence, suggests that ancestors of the Polynesians originated in Taiwan, moved through Indonesia to Island Melanesia, and then out into the islands of the Pacific without having any significant contact with the Island Melanesians. The "slow boat hypothesis," supported by Y chromosome evidence, suggests that the ancestors of the Polynesians were primarily Melanesians, and that there was very little Asian or Taiwanese influence. Finally, the "entangled bank hypothesis" suggests these ancient migrations cannot be accurately reconstructed by researching the genetics of contemporary populations, even in association with archaeological evidence.

The new analysis is consistent with the first of these hypotheses, suggesting that the ancestors of Polynesians moved through Island Melanesia relatively quickly with little intermixing with indigenous populations. Researchers also conclude that their findings consolidate previous studies suggesting that Island Melanesians are among the most genetically diverse people on the planet, with this diversity "neatly organized by island, island size, topography and language families".

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