September 27, 2007
Early Polynesians sailed thousands of miles for exploration and trade, suggests a new study of early stone woodworking tools.The analysis confirms traditional tales of vast ocean voyages and hints that a trading network existed between Hawaii and Tahiti as early as a thousand years ago. (See a photo gallery of the artifacts and early voyages.)
The work also bolsters research suggesting that the Polynesians were skillful sailors who rapidly expanded across the Pacific and journeyed as far as South America by the 1400s A.D.
Kenneth Collerson and Marshall Weisler of the University of Queensland in Australia studied 19 adzes—bladed tools used to shape wood—that were collected early last century.
The tools were found on nine islands in the Tuamotu Group, which is located more than 1,000 miles (1,600 kilometers) southeast of Tahiti in eastern Polynesia.
The adzes were made from basalt, a volcanic rock not found naturally on the Tuamotus, confirming they must have arrived with pre-European explorers or traders.
By comparing the trace elements and isotopes in the tools with basalt sources throughout the Pacific, the scientists were able to trace the artifacts to islands such as Pitcairn and the Marquesas.
But it was an adze known only as C7727—collected from the tiny atoll of Napuka—that gave the pair their greatest surprise.
C7727 was hewn from a fine-grained basalt known as hawaiite. The stone is unique to the Hawaiian island Kaho'olawe, located some 2,500 miles (4,000 kilometers) to the northwest of Napuka—a distance roughly the size of Western Europe.
"Until our discovery, there was no object found in southeast Polynesia that we could link back to a source in Hawaii," Collerson said. "That's the real magic of this discovery."
Collerson said the findings corroborate Hawaiian oral tradition that recounts canoe journeys over the vast southeastern Pacific—the last region on Earth colonized by humans."This 4,000-kilometer [2,500-mile] journey now stands as the longest uninterrupted maritime voyage in human prehistory," he said. The find also coincides with a "pulse of migration into southeast Polynesia about 900 A.D.," Collerson added.
The traditions tell of voyagers pausing before setting out on their epic voyages at a headland on the westernmost tip of Kaho'olawe—a place called Lae o Kealaikahiki, meaning "cape or headland of the way to Tahiti."
The ratio of thorium and uranium to lead in a core sample of C7727 left "a very distinctive isotopic fingerprint of the source region," which confirmed that the tool could only have come from a few sites along the coast of Kaho'olawe.
One such site lies very close Lae o Kealaikahiki, suggesting that sailors may have collected the rocks immediately prior to departure as ballast for their canoes. The stones were probably turned into tools or given as gifts or mementos to distant trading partners later.
The Tuamotu group was likely a center of trade, Collerson added. "It was probably the Singapore of the Pacific."
His study appears in this week's issue of the journal Science.
Voyages No Accident
Ben Finney, a professor emeritus of anthropology at the University of Hawaii, welcomed the findings as further evidence that early Polynesian voyages were far from accidental, as past academics often claimed.
Rather, the journeys were carefully planned and skillfully conducted, he said, with a thorough understanding of the geography of island archipelagoes.
In 1976 Finney and a Polynesian crew sailed a traditional twin-hulled canoe from Hawaii to Tahiti and back "as proof of a concept."
The team used traditional navigation techniques on the journey, such as consulting star and wind compasses, watching migrating birds, and maintaining a bearing relative to prevailing sea swells.
Such voyages would initially have been exploratory, and canoes would have been laden with tools, provisions, and a crew of men and women carefully selected to establish new colonies, Finney said.
The journeys would have been meticulously timed to exploit favorable trade winds, which would have eased return journeys.
"I'm delighted that [Collerson and Weisler] are at last getting some hard evidence for us," Finney said. "We can now get a handle on back-and-forth voyaging."
The challenge now lies in determining the true extent of Polynesian colonization, Finney added.
"Now that we've found a chicken bone in South America, the job is to find those adzes."
Lead study author Collerson agreed, saying the analysis technique has "opened up a Pandora's box of opportunities. We can now track down [the source of stone artifacts] throughout Polynesia."
But further mysteries about the Polynesians remain, he added. While navigational knowledge would have grown as it passed down through hundreds of generations, voyaging in the southeastern Pacific mysteriously ended around A.D. 1450.
"Perhaps that knowledge was lost," Collerson said, "or climate change influenced weather patterns that made sailing more difficult."