An archaeological conundrum may have been solved by DNA analyses carried out by a team of Stanford Medicine scientists led by Alexander Ioannidis that indicates Native Americans and Polynesians came into contact centuries before the arrival of the first Europeans.
In 1947, a young Thor Heyerdahl and five like-minded explorers set sail from Peru on a primitive balsa raft on an epic 101-day journey across 6,900 km (4,300 mi) of open sea to Raroia in the Tuamotus in Polynesia. The purpose of this dramatic experiment was to answer a question that had puzzled scholars for decades. Why were there so many similarities in some words, works of art, and even crops between the native peoples of the west coast of South America and those of Polynesia?
The Polynesians and the South Americans are unrelated, with the South Americans believed to be descended from people who migrated down from North America, while the Polynesians migrated much later across the Pacific from Southeast Asia. However, some works of Polynesian art resemble those found in the Andean civilizations of South America, and some Andean and Polynesian words sound very similar, but the biggest puzzle was that the Polynesians cultivated sweet potatoes – a plant native to South America. Even more intriguing are similarities between the word for sweet potato in Polynesian and various Andean languages.
The problem was that the two peoples were separated by thousands of miles of open ocean. The Polynesians had great voyaging canoes, but the winds and currents would have prevented them from reaching South America except by a rough upwind tack, and while the South Americans had winds and currents in their favor to drift west, their seacraft were limited to fragile coastal rafts made out of balsa wood.
The purpose of Heyerdahl's voyage was to reveal whether the South Americans could have sailed or drifted to Polynesia. Despite ending up on a reef, the Kon Tiki voyage was successful. However, it only proved that such a trip could be made, not that it did happen.
The Stanford study aimed at gathering direct evidence that Polynesians and Native Americans not only did meet, but that they also had offspring, which would be reflected in modern populations. These would be revealed by deep-genome analysis, which involves sequencing genomes in search of snippets characteristic of each population and segments that were inherited from the same ancestor generations ago.
According to Stanford, this isn't the first time that DNA has been brought to bear on the problem. Early genetic tests focused on sweet potatoes and how or if the ones grown in Polynesia are related to the ones in South America, but the genetic origins of the sweet potato were too complex to provide a definitive answer.
Instead, Ioannidis's team focused on 807 samples from people on 17 Polynesian islands and from 15 Native American groups along the Pacific coast of the Americas from Mexico to Chile. Modern DNA samples were preferred because, as is notorious in the tropics, samples from archaeological sites were too degraded. From there, they were able to trace common genetic signatures of Native American and Polynesian DNA back centuries to about 1200 CE, which Ioannidis says is "around the time that these islands were originally being settled by native Polynesians” and is over 200 years before the first Europeans reached South America.
According to Ioannidis, the DNA points to a genetic mingling of people from Polynesia and what is now Columbia due to Polynesians landing either by design or accident in South America at least once, though it is also possible that a Columbian raft was caught in a storm and drifted west, which could also explain the sweet potato's migration as opposed to their floating on a natural vegetable mat.
"If you think about how history is told for this time period, it’s almost always a story of European conquest, and you never really hear about everybody else," says Ioannidis. "I think this work helps piece together those untold stories – and the fact that it can be brought to light through genetics is very exciting to me."
The research was published in Nature.
Source: Stanford Medicine
