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
Thor Heyerdahl Madani Ait Ouhanni from Morocco. The boat became lost and was the subject of a United Nations search and rescue mission. The search included international assistance including people as far afield as Loo-Chi Hu of New Zealand. The boat reached Barbados, thus demonstrating that mariners could have dealt with trans-Atlantic voyages by sailing with the Canary Current. The "Ra II" is now in the Kon-Tiki Museum in Oslo, Norway. The book "The Ra Expeditions" and the film documentary "Ra" (1972) were made about the voyages. Apart from the primary aspects of the expedition, Heyerdahl deliberately selected a crew representing a