Posted on Wednesday 16 October 2002

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Ann Gibbons

Archaeologists, linguists, and geneticists struggle to understand the origins of the bold seafarers who settled the remote Pacific Islands

Polynesia, with its dramatic volcanic islands rising out of the South Pacific, was the last area of the world to be settled by people. The fossil and archaeological trail shows that humans first set foot in Fiji only 3000 years ago, then sailed on within 500 years to Samoa and Tonga, and later reached Easter Island, Hawaii, and the fringes of remote Oceania, exploring a realm stretching 4500 kilometers. But just who was in those outrigger canoes has long been a mystery. Even Captain James Cook mused about the islanders' origins on his last voyage from 1776 to 1780, noting the resemblance of language, customs, and appearance among the tall, fair Polynesians on such far­flung islands as New Zealand, Tahiti, and Easter Island. And he proposed his own theory that they had come from Malaysia or somewhere in the islands of Micronesia, such as the Marianas or Caroline Islands, where they had "affinities with some of the Indian tribes."

From such observations, Europeans such as French voyager Jules­Sebastien­Cesar Dumont d'Urville got the idea that these islanders could not be the descendants of the generally shorter, dark­skinned Melanesians living in islands of New Guinea, the Bismarck Archipelago, and the Solomon Islands. In 1832 Dumont d'Urville classified the people of the Pacific into three groups: Polynesians ("many islands"), the diverse Melanesians ("dark islands"), and Micronesians ("little islands"). This superficial classification stuck­­even though the geographic terminology eventually changed­­and ever since, many researchers have looked beyond the Melanesians of Near Oceania for the ancestors of the Polynesians who populate Remote Oceania (see map).

For example, until recently many geneticists and linguists have looked to the "express train" model. In this view, the ancestors of Polynesians came from Taiwan, where farmers speaking Austronesian languages set sail 3600 to 6000 years ago, largely bypassing the indigenous Papuan­speaking people of Melanesia as they swept out into the Pacific and left behind a trail of distinctly decorated pots.

Although this model was often touted as an interdisciplinary synthesis, in fact it is no favorite of archaeologists, many of whom have for years preferred a more "integrated" model, with at least some mixing between Melanesians and Austronesian speakers from Southeast Asia (a vast area that ranges from the coast of southern China to the islands of Indonesia and the Philippines). And now a flurry of studies of the Y chromosomes of Polynesians also favors the "slow boat" model, in which the ancestors of Polynesians originated in Asia but moved slowly through Melanesia, with time for genetic mixing among the peoples before the colonization of the rest of the Pacific. But even as these different kinds of data begin to point the same way, researchers are still groping for a true synthesis of the archaeological, linguistic, and genetic data. Each discipline tends to frame ideas in its own way, and at the moment each data set tends to favor a different homeland for the original voyagers. "I have to write a review myself of the spread of early farmers, and it's very difficult," says archaeologist Peter Bellwood of the Australian National University in Canberra. "It's the genetics that is causing headaches."

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