Big science news, and it's not COVID-19 related!
Conclusive genetic evidence that Polynesians intermingled with native South Americans around 1150.
The evidence shows that South American genes ended up in Polynesian islands, but could have gotten there several ways. South Americans could have been there first, and were overrun by Polynesians so they left only a genetic trace. They could have arrived after the Polynesians, sailing on their own. They could have been transported there by the Polynesians, as guests or otherwise. It's even possible that Polynesians visited or settled the Pacific coast of the Americas and some of them returned bringing half-american offspring back with them.
The spread of sweet potatoes from South America is one of the things that suggested this in the past, but it's difficult to prove without genetic results.
Because of the way we shuffle our chromosomes, the length of the Native American sequences in the DNA tells us how many generations ago the addition happened. This lets them filter out more recent additions of DNA from the Americas.
Very, very cool. It seemed unlikely that Polynesians could pinpoint navigate to small islands across the south Pacific but never managed to reach South America. Nice to see proof that they made it (or that native Colombians reached them).