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 color from reddish to blonde. In contrast, most of the Polynesians had golden-brown skin, raven-black hair, and rather flat noses. Heyerdahl claimed that when Jakob Roggeveen first discovered Easter Island in 1722, he supposedly noticed that many of the natives were white-skinned. Heyerdahl claimed that these people could count their ancestors who were "white-skinned" right back to the time of Tiki and Hotu Matua, when they first came sailing across the sea "from a mountainous land in the east which was scorched by the sun". The ethnographic evidence for these claims is outlined in Heyerdahl's book "Aku-Aku: The Secret of