The Pacific Ocean covers almost one-third of the Earth's surface, yet centuries ago, Polynesian navigators were skilled enough to find and populate most of the habitable islands scattered between Oceana and the Americas. Now a new genetic analysis is revealing more about their incredible journeys—and the people they met along the way.
A provocative new study argues Polynesians and Native Americans made contact some 800 years ago. That date would place their first meeting before the arrival of Europeans in the Americas and before the settlement of Easter Island (Rapa Nui), which has been suggested as the site of such an initial encounter.
Researchers, published in Nature, sampled genes of modern peoples living across the Pacific and along the South American coast and the results suggest that voyages between eastern Polynesia and the Americas happened around the year 1200, resulting in a mixture of those populations in the remote South Marquesas archipelago. It remains a mystery whether Polynesians, Native Americans, or both peoples undertook the long journeys that would have led them together. The findings could mean that South Americans, hailing from what’s now coastal Ecuador or Columbia, ventured to East Polynesia. Alternatively, Polynesians could have arrived in the Marquesas alone having already mixed with those South American people—but only if they’d first sailed to the American continent to meet them.
Alexander Ioannidis, who studies genomics and population genetics at Stanford University, co-authored the new study in Nature. “The genes show that the Native Americans who contributed came from the coastal regions of Ecuador and Columbia,” he says. “What they can’t show, and we don’t know, is where exactly it first took place—on a Polynesian island or the coast of the Americas.”
Launching one of history’s great eras of exploration, Polynesians journeyed by canoe across the vast Pacific Ocean. During several centuries of voyaging to the east they found and settled the tiny islands scattered across 16 million square miles from New Zealand to Hawaii, reaching the most distant, like Easter Island (Rapa Nui) and the Marquesas, by perhaps 1200 A.D., They left no written history to chronicle these voyages, but scientists have retraced the trips using various lines of evidence. Striking similarities in languages exist across widely separated island groups, for example, and the remains of structures and stones offer clues to who erected them. Even the spread of foodstuffs like the sweet potato—of American origin but found across the Pacific and nowhere else—could offer evidence of the skills and nerve by which people eventually populated the Pacific (though some scientists suggest that the sweet potato was dispersed naturally.)
Most recently, scientists have tried to chart the paths of these ancient voyagers through the genes of their descendants. "We recapitulate, with genetic evidence, a prehistoric event that left no conclusive trace, except for the one recorded in the DNA of those who had contact 800 years ago in one of the most remote places on Earth,” explains co-author Andres Moreno Estrada, with the National Laboratory of Genomics for Biodiversity (Mexico). For this study Estrada and colleagues did a genome-wide analysis for more than 800 present-day individuals, who hail from 17 islands across the Pacific and also from peoples up and down the Pacific coast of South America, looking for evidence of mixing between the two populations. They added a handful of pre-Columbian, South American DNA samples to help confirm that any indigenous signals identified hadn’t been created by later mixing after European contact.
Their findings revealed a Native American genetic signature among people on some of Polynesia’s easternmost islands. Not only did this signature indicate a common source among Colombia’s indigenous peoples, but it also showed that the people who carry it on different islands shared the same Native American ancestors.
“It is fascinating new evidence,” says Pontus Skoglund, who leads the ancient genomics lab at the Francis Crick Institute and wasn’t involved in the research. Skoglund was particularly intrigued by the evidence that Native Americans would’ve encountered Polynesians before they encountered Europeans, contrary to what some previous studies have shown. “This suggests that the Native American ancestry is not due to events in more recent colonial history where trans-Pacific travel was documented.”
Who met whom
If Native Americans had reached these remote islands by around 1200 they likely did so by following the prevailing currents and winds. In 1947, explorer Thor Heyerdahl famously demonstrated that it was possible to travel the Pacific by drifting on winds and currents on a raft when his famed Kon-Tiki journeyed more than 4,300 miles from South America to Raroia Atoll. Those islands lie in the same region that the genetic study suggests as the likely point of contact between Polynesian and Native American peoples.
“That’s where the winds and currents will take you if you’re drifting,” Ioannidis says. “If people in boats plying coastal trade routes were blown off course or drifting to sea, those same currents and winds might have taken them to these Pacific Islands.”
Paul Wallin, an archaeologist at Uppsala University, Sweden who wasn’t involved in the research, thinks this study may confirm a Native South American contact into the Pacific. “[That’s] the same area DNA studies of sweet potato have indicated, [so] this early mix may explain the existence of sweet potato in East Polynesia,” Wallin says. The date is so early that the Native South Americans may have come to the South Marquesas just before the Polynesians did, he adds.
Despite Heyerdahl’s success, most scientists have pushed back against his ideas that Native Americans settled Polynesian islands in this manner. However, this new DNA research could also support an alternate explanation that some of those dissenting scientists favor: that Polynesians might have sailed to the Americas.
“We can speculate that possibly the Polynesians found the Americas, and there was some interaction with Native Americans,” Ioannidis says. “Then as they go and settle the last of these most remote islands, including Easter Island, they take that genetic ancestry with them because they themselves now carry part of that Native American ancestry.”
There’s little doubt that the Polynesians—gifted mariners who used the night sky, the sun, birds, clouds, and the reading of ocean swells—had the oceanic skills necessary to reach the Americas. As Ioannidis notes, we know they reached Easter Island. “They made it well to the east of where North America begins, although they were in the Southern Hemisphere,” he says. “If they could have made it there, they could have made it all the way. And why would they have stopped?”
David Burley, an archaeologist at Simon Fraser University not involved in the study, finds the explanation of Polynesians visiting America far more likely. "A North American group from Colombia making it to the southern Marquesas and interbreeding with Polynesians seems a stretch,” he says. “Polynesian seafarers had well developed maritime technologies and were quite capable of reaching the Americas. Not sure that is at all the case for Colombia.”
Mysteries of Easter Island
The new study’s genetic results also offer clues to possibly unraveling the history behind Easter Island (Rapa Nui), whose inhabitants erected the famed Moai monoliths before their civilization collapsed. Some researchers have pointed to the island as a possible landing point for any South American peoples venturing into the Pacific, as it is the closest inhabited island to South America’s Pacific Coast, though it lies 2,200 miles away.
Previous studies that sought to untangle the history of Polynesian settlement haven't been conclusive. A 2017 Current Biology study (co-authored by Pontus Skogland) sampled human remains dating from before Europeans reached the island in 1722 and found only Polynesian DNA. However, the study included only five individuals, meaning other ancestries might have been present on the island but not represented in the group. A 2014 paper sampled 27 modern inhabitants and found that they had a significant amount of Native American DNA (about 8 percent). It concluded that Native Americans may have journeyed, alone or with Polynesians, to Easter Island before 1500—before Europeans ventured there.
As part of their new study, Ioannidis and colleagues sampled DNA from 166 inhabitants of Easter Island. They determined that admixture between Native American and Polynesian peoples didn't occur here until around 1380 though the island was settled by at least 1200, perhaps by a Polynesian group that hadn’t had any contact with Native Americans.
“The surprising thing is that the Rapa Nui admixture happened later, although the cultural impact might have been stronger there than in other parts of East Polynesia,” Paul Wallin says. He stresses that it’s too early to make too many sweeping conclusions about this phase of the island’s history. We know South Americans and Polynesians have a shared history on the Pacific Ocean. The exact wheres and whens are mysteries still to be solved.