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 excavations at such prominent sites as Orongo and Poike. The expedition published two large volumes of scientific reports ("Reports of the Norwegian Archaeological Expedition to Easter Island and the East Pacific") and Heyerdahl later added a third ("The Art of Easter Island"). Heyerdahl's popular book on the subject, "Aku-Aku" was another international best-seller. In "Easter Island: The Mystery Solved" (Random House, 1989), Heyerdahl offered a more detailed theory of the island's history. Based on native testimony and archaeological research, he claimed the island was originally colonized by Hanau eepe ("Long Ears"), from South America, and that Polynesian Hanau momoko ("Short