New Study Suggests Polynesians and South Americans Met around 1200 CE

A new study published in Nature used DNA analysis to determine that South Americans and Polynesians made contact around 1200 CE and had children together. Alexander Ioannidis of Stanford led a team analyzing DNA from French Polynesia and South America, and they found indigenous South American DNA in Polynesia. Although Ioannidis believes that first contact likely happened when Polynesians reached South America, the evidence of Colombian DNA in Polynesia implies that the Americans sailed westward and landed in Polynesia, perhaps getting stranded there. According to Ioannidis, the evidence suggests a single contact event, since all of the Colombian DNA seems to derive from the same source (the Zenu people) at the same time.

Media reports announced this as a vindication for Thor Heyerdahl, who had made an epic voyage across the Pacific aboard the Kon Tiki in an attempt to prove that ancient Andean peoples had colonized Polynesia. The Nature study cites Heyerdahl as evidence that Polynesians discovered islands already colonized by South Americans.
 
However, the Nature study received criticism shorty after publication. Archaeologist Molle Guillaume, who specializes in the Pacific region, noted that the Nature authors based their analysis on Heyerdahl without deep engagement with archaeologists working in the region, or with biological anthropologists and geneticists who specialize in the Pacific region in general and French Polynesia specifically.

It based on modern genome analysis of individuals on today’s French Polynesia, Cook Is. and Rapa Nui. ADMIXTURE analyses show that many islanders appear to have a European component from colonial admixture, but also detect admixture in eastern Polynesia from Native American ind.

— Molle Guillaume (@molleguillaume) July 8, 2020

To be entirely honest, I don't really have a lot to add here. Regardless of the details, contact between Polynesia and South America has long been suspected, and the evidence suggests that it occurred late enough (c. 1200 CE) that it played no major role in the cultural development of the ancient cultures of either region. It is a great story about human accomplishment, but it does not imply anything about a lost civilization or any of the other wild claims that sprang up on the back of Heyerdahl's work.

Before I close today, I will also point out that I have posted a revised and expanded version of my recent long-form essay on Rebel without a Cause and midcentury moral panics in my Articles section.