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 the French schooner "Tamara", with the salvaged "Kon-Tiki" in tow. Heyerdahl believed that the original inhabitants of Easter Island were migrants from Peru. He argued that the monumental statues known as moai resembled sculptures more typical of pre-Columbian Peru than any Polynesian designs. He believed that the Easter Island myth of a power struggle between two peoples called the Hanau epe and Hanau momoko was a memory of conflicts between the original inhabitants of the island and a later wave of Native Americans from the Northwest coast, eventually leading to the annihilation of the Hanau epe and the destruction of