Pacific Migration

People have traveled far across the oceans in search of greener pastures. Polynesians journeyed thousands of miles, hopping from island to island as they expanded eastward. And one period of expansion might have been triggered by big changes in the Pacific Ocean.

That period began about a thousand years ago. People were well entrenched in Western Polynesia—islands such as Tonga and Samoa. But they quickly turned up in Eastern Polynesia—Tahiti and surrounding islands—journeys of up to 1500 miles or longer across open ocean.

A recent study looked at climate conditions across Polynesia at the time. Researchers gathered deep sediments from several locations. They used sophisticated lab techniques to analyze the fat in leaves preserved in the soil. That revealed how rainy the climate was at the time the plants were growing.

The scientists combined that with other climate information, and ran it all through models of the climate at the time. They found that the rain began to dry up in Western Polynesia. But it got heavier in Eastern Polynesia.

That probably was the result of a change in the South Pacific Convergence Zone—a wide region that produces heavy rains during the summer. Changes in ocean temperatures pushed the zone eastward. The change also would have made the winds more favorable for moving eastward. So the people of Western Polynesia could have headed out—looking for greener pastures far across the Pacific.