It looks like they aren't sure which direction the travel might have gone:

"Our earliest estimated date of contact isad 1150 for Fatu Hiva, South Marquesas. This is close to the date estimated by radiocarbon dating for settlement of that island group13, raising the intriguing possibility that, upon their arrival, Polynesian settlers encountered a small, already established, Native American population. It was on the island of Fatu Hiva—the easternmost island in equatorial Polynesia—that Thor Heyerdahl hypothesized that Native American and Polynesian individuals might have contacted one another, based on islanders’ legends stating that their forefathers had come from the east39. The Marquesas lie at the latitude of Ecuador, and wind- and current-based simulations indicate that they are the islands most likely to be reached from South America via the strong east-to-west currents and winds at these equatorial latitudes4,40,41.

We cannot discount an alternative explanation: a group of Polynesian people voyaged to northern South America and returned42 together with some Native American individuals, or with Native American admixture, as speculated in ref. 10. We have dated the contact event to the time when Polynesian explorers were, according to some studies, making their longest-range voyages (the century surrounding ad 1200)—a time when these studies suggest that the Polynesian settlers discovered all remaining island groups in the Pacific, from Hawaii to New Zealand to Rapa Nui13,38,42. The Tuamotu Archipelago, which lies at the centre of the Polynesian islands in which we found a Native American component, is known to have been a Polynesian voyaging hub, and according to simulations it is the second most likely location to be reached when voyaging from South America4. Further population genetics collaborations with these genetically understudied island populations are needed to resolve these alternative hypotheses."

By "single contact event" I think they mean that all the contacts between Polynesia and South America happened around the same time period and stopped thereafter for some reason. So the contact could have been groups going in either (or both) direction around that time period.

Perhaps they lost their wayfinder before the knowledge was sufficiently passed on? [0]

[0]https://en.wikipedia.org/wiki/Mau_Piailug

That's an incredibly interesting link. Thanks for sharing!

Posts and comment threads like these are the reason why HN is so damn good

The most likely reason is that they found everything there was to find. This kind of exploration was a speculative search for new places to live, and as the returns diminished there would have been less and less motivation to head into the unknown.

And, presumably, once they hit the American continents and realized they were not uninhabited islands, they would have had no need to continue exploring to the east.

Thanks, that's interesting.

The great book Pathway of the Birds, about Polynesian voyaging, navigation and settlement, mentions the possibility of travel to the South American mainline. I don't remember the details, but the winds and currents support travel east and then north along the coast, then back west further north.

They can't distinguish at this point. I wonder if examining the Y DNA and mitochondrial DNA patterns of the same populations might shed light on the gender breakdown of the genes, which might be something that can be correlated with patterns of gender representation in migrations.

Interesting paper, but it seems to suggest that all the Native American Y-DNA on Rapa Nui is explainable by the 19th century Peruvian slave trade, not contact between Polynesians and South Americans centuries earlier.

The full article considers both possibilities, and doesn't settle on one of them as more likely.