It all adze up: Stone tool traveled the Pacific

Tool found in Polynesia came from Kahoolawe

The Polynesian oral histories are correct.

Hawaiian lore has long held that ancient voyagers came to Hawaii from what is now French Polynesia and then returned, time and again. In fact, a point on the island of Kahoolawe, named Kealaikahiki -- "the way to Tahiti" -- is believed to have been a popular starting point for the voyage back south.

Now, for the first time, scientists have found hard evidence that ancient Hawaiians returned to the Tuamotu Archipelago, a group of islands on the way to Tahiti. Studying the chemistry of ancient basalt adzes found in the Tuamotus in the 1930s, scientists from the University of Queensland in Australia have definitively traced one of them to the island of Kahoolawe.

Their research appears in the current issue of the journal Science.

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COURTESY BETTY LOU KAM / BISHOP MUSEUM This late prehistoric, fine-grained basalt adze was collected from the island of Napuka in central Polynesia. Isotope and trace element data indicates that the source rock for this adze is from Kahoolawe.

Sophisticated chemical analysis of an adze found in French Polynesia in the 1930s shows that it came from the island of Kahoolawe, proving for the first time that ancient Polynesian voyagers made the return trip from Hawaii.

Proof of multidirectional voyages, supported by Polynesian oral histories, came when new technology was applied to a collection of prehistoric tools stored for decades at the Bishop Museum.

The adze, a rock tool used for hollowing out tree trunks into canoes, was among 19 collected in the Tuamotu Archipelago by noted Bishop Museum anthropologist Kenneth Emory.

Because they were made of the volcanic rock basalt, the adzes were clearly not from the Tuamotus, which are low-lying islands long past their period of volcanism.

But the mystery of just where they came from remained unsolved until now.

Writing in the current issue of the journal Science, two scientists from the University of Queensland in Australia report that one of the adzes bears the unmistakable geochemical signature of basalt from Kahoolawe.

"The rock from which it was made was transported a minimum distance of (2,500 miles) from its source on Kahoolawe in the Hawaiian chain," says the article, "Stone Adze Compositions and the Extent of Ancient Polynesian Voyaging and Trade."

Kenneth Collerson and former Bishop Museum researcher Marshall Weisler, both with the University of Queensland, report that the adze known as C-7727, which was collected on the Tuamotu island of Napuka, matches basalt rocks from Kahoolawe across a wide array of chemical yardsticks. Specific characteristics differentiate it from similar basalts on Lanai and the other Hawaiian islands, the scientists said.

Two other adzes were traced to their origins, one to Pitcairn Island, made famous by mutineers of the HMS Bounty, and the other to Rurutu in the Austral Islands.

Their analysis looked at lead and other trace elements and isotopes -- cousins in the same elemental family that differ in atomic weight due to natural radioactive decay.

In an accompanying article, Ben Finney, a University of Hawaii anthropologist, said the technique should now be turned to artifacts found in South America to determine of Polynesians made it that far, as many scientists suspect.

"A bone of a Polynesian chicken excavated in Chile has recently provided archaeological support for Polynesians having reached South America in pre-Columbian times," Finney said. "Now we need to look for Polynesian basalt adzes there."