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
Frogner century Scandinavian sea vessels - including the fully intact Oseberg ship - which were used as high status tombs. A collection of Viking weapons, utensils and talismans, buried with the ships, is also on display. The Kon-Tiki Museum is named after the raft on which Norwegian adventurer Thor Heyerdahl crossed the Pacific Ocean in 1947. Alongside the raft, the museum houses various artefacts related to Heyerdahl's other expeditions and a changing program of temporary exhibitions explores his life and work. Oslo City Museum is situated at Frogner Manor in the Vigeland park (Frognerparken). It is a museum of cultural history