Polynesia of the plant in the Cook Islands have been radiocarbon-dated to 1000, and current thinking is that it was brought to central Polynesia c. 700 and spread across Polynesia from there, possibly by Polynesians who had traveled to South America and back. Thor Heyerdahl proposed in the mid-20th century that the Polynesians had migrated from the northwest coast of Canada by large whale-hunting dugouts, and from South America on balsa-log boats. Many anthropologists have criticised Heyerdahl's theory, including Wade Davis in his book "The Wayfinders". Davis says that Heyerdahl "ignored the overwhelming body of linguistic, ethnographic, and ethnobotanical evidence, augmented
Kon-Tiki expedition Heyerdahl tested more than twenty different composites before settling on one that proved an effective compromise between bulk and torsional rigidity. No metal was used in the construction. "Kon-Tiki" carried of drinking water in 56 water cans, as well as a number of sealed bamboo rods. The purpose stated by Heyerdahl for carrying modern and ancient containers was to test the effectiveness of ancient water storage. For food "Kon-Tiki" carried 200 coconuts, sweet potatoes, bottle gourds and other assorted fruit and roots. The U.S. Army Quartermaster Corps provided field rations, tinned food and survival equipment. In return, the "Kon-Tiki" explorers