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 Museum and the National Library of Norway in Oslo. Heyerdahl was born in Larvik, Norway, the son of master brewer Thor Heyerdahl (1869–1957) and his wife, Alison Lyng (1873–1965). As a young child, Heyerdahl showed a strong interest in zoology, inspired by his mother who had a strong interest in Charles Darwin's theory of evolution. He created a small museum in his childhood home, with a common adder ("Vipera berus") as the main attraction. He studied zoology and geography at the faculty of biological science at the University of Oslo. At the same time, he privately studied Polynesian culture and