The ancestral relationships of people living in the widely scattered islands of the Pacific Ocean, long a puzzle to anthropologists, may have been solved by a new genetic study, researchers reported Thursday.
In an analysis of the DNA of 1,000 individuals from 41 Pacific populations, an international team of scientists found strong evidence showing that Polynesians and Micronesians in the central and eastern islands had almost no genetic relationship to Melanesians, in the western islands like Papua New Guinea and the Bismarck and Solomons archipelagos.
The researchers also concluded that the genetic data showed that the Polynesians and Micronesians were most closely related to Taiwan Aborigines and East Asians. They said this supported the view that these migrating seafarers originated in Taiwan and coastal China at least 3,500 years ago.
The findings were described in the online journal Public Library of Science Genetics (www.plosgenetics.org) by researchers led by Jonathan S. Friedlaender, professor emeritus of biological anthropology at Temple University. He was assisted in the data analysis by his wife, Françoise R. Friedlaender, an independent researcher. Other participants included scientists in the islands and at the Marshfield Clinic Research Foundation in Marshfield, Wis.
“Our analysis,” the scientists wrote, “indicates the ancestors of Polynesians moved through Melanesia relatively rapidly and only intermixed to a very modest degree with the indigenous populations there.”
Dr. Friedlaender of Temple said in an interview that the evidence was “substantial” and “solves a number of issues about the migration and settlement of Pacific people.”
In particular, he and other anthropologists not involved in the study said, the genetic research supported the “fast train” hypothesis. Increasing archaeological and linguistic evidence in recent years has suggested that ancestors of Micronesians and Polynesians had moved through Indonesia and Melanesia without having any significant contact there, culturally or genetically.
An alternative argument, the “slow boat” hypothesis, which had some support from male Y chromosome studies, raised the possibility that Polynesians were primarily Melanesians who had ventured on in their outrigger canoes. And a few anthropologists despaired of ever solving the mystery. Theirs was the “entangled bank” hypothesis.
The new genetic research, said Patrick V. Kirch, an anthropologist at the University of California, Berkeley, who is an authority on Pacific cultures, was “overwhelming biological evidence for a clear population movement out of Southeast Asia and Taiwan to Polynesia.”
Dr. Kirch, who did not participate in the genetic study, said that it reinforced research showing that Polynesian speech patterns were unrelated to Melanesian languages, suggesting — along with discoveries of the distinctive Lapita pottery across the Pacific — links to Taiwan and China, not Melanesia. “The combination of evidence shows we really can read this history,” he said.
As Dr. Friedlaender said, “If it wasn’t exactly an express train, it was pretty fast, and very few passengers climbed aboard or got off along the way.”
In the research, scientists examined more than 800 genetic markers known to be useful in distinguishing the ancestry of people. These involved mitochondrial DNA, passed down through females, and the Y chromosomes in males. Previous investigations along these lines had been conducted on a much smaller scale, Dr. Friedlaender said.
The new test results were repeatedly analyzed with a software program recently developed to classify genetic similarities and variations among different populations.
Primary support for the study was provided by the National Science Foundation, the Wenner-Gren Foundation of Anthropological Research, the National Geographic Society and the National Institutes of Health.
Further research to confirm the history of the Pacific diaspora, Dr. Friedlaender said, would require an expansion of genetic tests among people in the Philippines and Indonesia, regions that the migrants presumably passed through after leaving Taiwan more than 3,500 years ago, ultimately reaching as far as Hawaii and Easter Island. The Melanesians, on the other hand, probably arrived on their islands about 35,000 years ago, sometime later than the Aborigines reached Australia.
Years ago, a reporter who visited the Marshall Islands asked an aging Micronesian chief where his people came from long, long ago. “We have always been here,” he replied. Now, if it matters to them, his descendants have been given a more scientific answer.
