Polynesians Descended From Taiwanese, Other East Asians
for National Geographic News
|January 17, 2008|
The ancestors of today's Polynesians and Micronesians were probably East Asians who quickly island-hopped through Near Oceania—what is now Australia, New Guinea, and the Solomon Islands—a new genetic study suggests.
Jonathan Friedlaender and colleagues found that the two modern-day groups show little genetic relation to the indigenous peoples of Near Oceania. (See an Oceania map.)
The finding supports theories that Polynesians instead descended from East Asians and aboriginal Taiwanese who apparently raced through the region.
"They left very few genes behind," said Friedlaender, a professor emeritus of anthropology at Temple University in Philadelphia, Pennsylvania.
"And they incorporated very few genes from the people in this region of Near Oceania, [although] they stayed for three or four hundred years before moving on to explore the central Pacific islands, where they became Polynesians and Micronesians," added Friedlaender, whose project was funded in part by the National Geographic Society's Committee for Research and Exploration. (The National Geographic Society owns National Geographic News.)
The study also reveals that Melanesian peoples (those from Vanuatu, the Solomon Islands, Papua New Guinea, and Fiji) harbor incredible genetic diversity—evidence of tens of thousands of years of relative isolation and a series of small migrations from Asia.
"There's more population divergence in these islands than you see across all of Europe," Friedlaender said. "You can really tell by the way people look, and now genetically, what island they are from."
Archaeologist Patrick Kirch said, "It's what you'd expect over a long time period like that.
"You see the same complexity in languages. New Guinea alone has something like 900 languages in its interior. That's probably the highest density of language differential per square mile in the world," said Kirch, of the University of California, Berkeley.
The new research appears in the January issue of the journal PLoS Genetics.
Archaeologists, linguists, and geneticists have spent decades pondering how humans settled the Pacific islands.
Commonly held theories suggest that Near Oceania was colonized first, between about 30,000 and 50,000 years ago. According to these theories, humans reached Australia, New Guinea, and the Bismarck and Solomon Islands at a time when Neandertals still lived in Europe.
(Related: "Pig DNA Study Suggests New Path of Pacific Human Migration" [March 20, 2007].)
The newcomers arrived in small numbers. In succeeding centuries their populations became isolated in a way that few people have anywhere in the world.
But between 3,000 and 3,500 years ago, a new migration occurred, featuring an influx of peoples from Asia called the Lapita—the ancestors of those who would go on populate distant Polynesia and Micronesia.
Previous studies of genetics, pottery styles, and the shared family of Austronesian languages suggested that the Lapita's most likely origin was Taiwan and East Asia—but opinions diverge concerning the history of these people.
Friedlaender's study supports an "express train" theory—the idea that they plied the waters in outrigger vessels and inhabited offshore islands and coastal areas not heavily populated with indigenous Melanesians.
"Maybe they were scared of going inland," he suggested. "There was continuous feuding in this area, and it may have been a pretty [dangerous] thing to go inland."
Some scientists, however, hold firm to the "slow boat" theory—the idea that Polynesians had Melanesian ancestors on their family tree.
Melanesian Melting Pot
Some interaction between the Lapita and Melanesian peoples is evident.
Lapita pottery, for instance, originated in Southeast Asia but underwent distinct changes in Near Oceania. Crops from Melanesia were adopted by the Lapita and carried to the far Pacific. Linguistic patterns also suggest some significant intermixing.
The critical question for scientists is the extent of this commingling.
Geneticist Spencer Wells is a National Geographic Society explorer-in-residence and director of the society's Genographic Project.
Wells thinks that the genetic data may show that Polynesians and Micronesians are a mix of Taiwanese aborigines, East Asians, and Melanesians.
"I certainly don't think the data refute a slow-boat model," he said.
He pointed out that the mitochondrial DNA evidence—which is passed down from females—tends to support the express-train theory. But the Y-chromosome, or male, evidence supports a slow-boat process, he said.
This "suggests something interesting is going on, perhaps with different male and female migration patterns, which we see in other regions of the world," he said.
UC Berkeley's Kirch, however, believes that Friedlaender's genetic studies dovetail nicely with other evidence in favor of the express-train theory.
"I think now the biological evidence comes in very strongly in line with the picture that we've seen [in archaeology and linguistics]. Given that these are three independent lines of evidence and sources of data, that makes the [theory] stronger in my view."
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