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
Thor Heyerdahl then arrived in British Columbia. Heyerdahl called contemporary tribes of British Columbia, such as the Tlingit and Haida, descendants of these migrants. Heyerdahl claimed that cultural and physical similarities existed between these British Columbian tribes, Polynesians, and the Old World source. Heyerdahl's claims aside, however, there is no evidence that the Tlingit, Haida or other British Columbian tribes have an affinity with Polynesians. Heyerdahl's theory of Polynesian origins has not gained acceptance among anthropologists. Physical and cultural evidence had long suggested that Polynesia was settled from west to east, migration having begun from the Asian mainland, not South America. In