History In Their Blood
DNA studies confirm Maori beliefs about their ancestors' origins
By SIMON ROBINSON/AUCKLAND

A battered double-hulled canoe fights through a foaming sea. A group of emaciated Polynesians lie exhausted and dying below a tattered sail. Suddenly, one man glimpses a speck of land off in the distance. Propping himself up in the prow, he points it out to the others. New Zealand's most famous painting, an 1898 work by Charles Goldie and Louis Steele called The Arrival of the Maoris in New Zealand, may be based on a European colonists' myth, but it remains a vivid reminder that, like the country's white settlers, Polynesians arrived in New Zealand from across the ocean.

But when, and from where? A new study of DNA taken from modern Maori confirms what Maori oral history has long maintained: that Polynesians from the Cook Islands area 3,000 km to New Zealand's northeast set off on deliberate voyages of discovery and found the uninhabited islands their descendants would call Aotearoa about 1,000 years ago. "Our oral history has often been criticized for being imprecise," says Professor Mason Durie, head of Maori Studies at Palmerston North's Massey University. "This is saying: Don't take our traditions too lightly."

The study, published in the July issue of U.S. journal Proceedings of the National Academy of Sciences, looked at segments of mitochondrial DNA from the hair or blood of 54 New Zealand Maori. The DNA blueprint in mitochondria, the energy factories of cells, is passed exclusively by mothers to their children. Though changes in it occur only by random mutation, they have taken place often enough over the past 500,000 years to serve as markers scientists can use to construct extended "family trees" and thus trace patterns of migration. In east Africa, where modern humans first appeared around 200,000 years ago, the mtDNA of the Turkana people has 44 mutations. But as humans left Africa and fanned out in successively smaller groups across Asia and the Pacific, that genetic diversity was gradually reduced. In New Zealand, the last major land mass to be populated, the mtDNA of the Maori volunteers showed just four mutations, all of which are also found in Polynesian populations like those of the Cook Islands.

By feeding the number of mtDNA mutations into computer-generated statistical models, the Massey team have conservatively estimated New Zealand's founding female population at between 50 and 100 women. Since mtDNA marks only the female line, the technique cannot determine the size of the original male population, but the number of female settlers sits easily with Maori tradition and should dispel the lingering notion that the country was settled accidentally, by Polynesian fishermen blown off course. "With 100 women you either had mighty big fishing boats manned by women," says Durie, "or the story that migration was accidental just doesn't hold water."

According to ethnographers, early Polynesian sailors crisscrossed the Pacific without instruments by reading the stars at night and swells by day, and fixed their canoe's position by mentally calculating time, speed and direction. They could detect islands up to 50 km away by observing birds, cloud changes or floating debris. Archaeologists and Polynesians have tested these navigational methods using a global positioning satellite device and found that "even on long journeys the old ways were very accurate," says Geoffrey Irwin, a professor of archaeology at the University of Auckland.

The discovery of New Zealand volcanic rocks in the Kermadec Islands, 750 km north of New Zealand, and Kermadec volcanic rocks on Norfolk Island, 800 km to the northeast, proves the Polynesians "were shuttling all over the place," says Irwin. "They didn't just come and stay." Plants like the taro, yam and cabbage tree, and animals like the Polynesian dog, which were all introduced to New Zealand, are further proof of planned voyages.

DNA research is filling in other prehistoric gaps. Over the past decade scientists have found genetic links between Polynesians and a people who lived in what is now eastern China and Taiwan around 5,000 years ago. "Once the migration got to the Marquesas [north of Tahiti] we think it split in two. Some went north to Hawaii, some south to New Zealand," says Australian National University professor Sue Serjeantson, who studied transplantation genes in Pacific islanders in the 1980s. Says Geoffrey Chambers, a reader in biological sciences at Victoria University and head of an unpublished study comparing Maori DNA with that of other Asia-Pacific groups: "There is an exact living record of these voyages of colonization preserved in the DNA of their modern-day descendants along the route."