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
Mau Piailug prevent debate among scholars. Before the "Hōkūle‘a" voyage in 1976, academic debate about the settlement of Polynesia was divided between several schools of thought. Norwegian ethnographer Thor Heyerdahl hypothesized that the Pacific was settled by voyages from South America and set out to prove that with his "Kon-Tiki" expedition. Scholars did not take Heyerdahl's hypothesis seriously. New Zealander Andrew Sharp proposed the accidental voyaging hypothesis in 1957, which (erroneously) argued that Oceania was too vast to have been settled by intentional voyaging so migrations must have happened by accidental drift voyages. Sharp granted that Polynesians likely settled the Pacific from