HUGE News: Basalt tools in Tahiti from Hawaii = 4,000 km ancient voyage

http://www.nature.com/news/2007/070924/full/070924-9.html;jsessionid=7D2B7F4BC6D10F2057EB74EEE540441A

27 September 2007
Stone tool reveals lengthy Polynesian voyage
Adzes form the first hard evidence of two-way travel between Hawaii and Tahiti.

The discovery of an adze fashioned from Hawaiian basalt on a Tuamotu atoll in French Polynesia provides the first material evidence that ancient voyagers made an 8,000-kilometre round trip from the South Pacific to Hawaii and back again.

More than 2,000 years ago, seafarers from Samoa and Tonga ventured eastward to settle on more remote archipelagos in the Pacific Ocean, including the Cook Islands, Tahiti, and the Marquesas Islands, colonizing most of these places by 900 AD. Eventually, the travelers set foot on Hawaii.

Scientists have long thought that these journeys must have been accidental or one-time events, but recent research has hinted that these peoples were capable of greater feats of navigation than previously suspected. .....

Hawaiian oral histories point to voyages to and from Tahiti, but in the absence of evidence these feats have remained the stuff of legends.

Kenneth Collerson and Marshall Weisler at the University of Queensland, Australia realized that one way to test this possibility was to trace the origins of 19 adzes — axe-like tools made from stone that were used for carving canoes and other wooden objects — that had been recovered from coral atolls in the Tuamotus in the late 1930s.........

Sweet potatoes, native to South America, have been documented archaeologically in Polynesian sites.

There's also some debate about the origins of the Chumash sewn-plank canoe, which some scholars think, along with the word the Chumash use for the canoe, is evidence of Polynesian contact (other scholars think that it's a case of independent invention).