and they were the greatest navigators of their era," said Peter Vitousek, a professor of biological sciences at Stanford University and lead author of the Science study. "But another way they were equally great was that they were fantastic farmers. They were able to develop and sustain intensive agricultural systems in tropical environments that are very difficult to farm."

Volcanic history

The idea that volcanoes played a crucial role in early Hawaiian agriculture should come as no surprise. After all, the Hawaiian archipelago is actually a chain of volcanoes that has been forming for more than 30 million years.

The volcanic islands are created when the Pacific tectonic plate slowly passes over a region of hot magma located deep in the Earth's mantle. As a result, the islands get progressively younger as you move from west to east. Kauai, in the western end of the chain, emerged some 4.7 million years ago, followed by O'ahu, Moloka'i, Maui and the newest island, Hawai'i, where the magma hotspot continues to produce lava from Kilauea Volcano.

Spectacular rainfall

In the Science study, Vitousek and his co-authors focused on Kohala a comparatively young volcano on the northwest tip of the island of Hawaii. Early Polynesians created a vast agricultural complex on the volcano's southwest flank, where they raised sweet potatoes and other dryland crops. Remnants of long-abandoned fields including rows of earthen walls once used as windbreaks are still visible on the 25-square-mile site, most of which is now on private ranchland.

Kohalas last eruption occurred about 150,000 years ago long before the Polynesians arrived. "Human settlement and farming in the region began [around] 1200 to 1300 A.D, and the most intensive farming probably took place in 1400 to 1800 A.D," the authors wrote. Standing nearly 5,400 feet above sea level, Kohala Volcano is a place of extremes, experiencing "what may be the most
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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
10-Jun-2004

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