Polynesian navigation snow. In the mid-20th century, Thor Heyerdahl proposed a new theory of Polynesian origins (one which did not win general acceptance), arguing that the Polynesians had migrated from South America on balsa-log boats. The presence in the Cook Islands of sweet potato that is a plant native to the Americas (called "kūmara" in Māori), which have been radiocarbon-dated to 1000 CE, has been cited as evidence that Americans could have traveled to Oceania. The current thinking is that sweet potato was brought to central Polynesia circa 700 CE and spread across Polynesia from there, possibly by Polynesians who had traveled
Kon-Tiki expedition Raft Across the South Seas", later reprinted as "Kon-Tiki: Across the Pacific in a Raft". It appeared with great success in English in 1950, also in many other languages. A documentary motion picture about the expedition, also called "Kon-Tiki", was produced from a write-up and expansion of the crew's filmstrip notes and won an Academy Award in 1951. It was directed by Thor Heyerdahl and edited by Olle Nordemar. The voyage was also chronicled in the documentary TV-series "The Kon-Tiki Man: The Life and Adventures of Thor Heyerdahl", directed by Bengt Jonson. The original "Kon-Tiki" raft is now on display