How did the sweet potato reach Polynesia before European contact?

The presence of the sweet potato in Polynesia during pre-European times is considered the most concrete evidence of contact between the Pacific islands and the American continent. While scholars reject theories suggesting that Oceanic peoples originated in the Americas, they acknowledge that eastern-voyaging Polynesians could well have reached the American continent and subsequently returned to the islands, facilitating the introduction of the plant.1

The sweet potato is native to tropical South America and spread through most of Polynesia in the pre-European era. Notably, it reached Polynesia much earlier than it reached the Highlands of New Guinea, where it only arrived approximately 300 to 400 years ago. Despite the significance of this botanical evidence, researchers emphasize that theories of trans-Pacific contact must be treated with caution, as other claims of cultural or linguistic connections between the regions lack scientific credibility.2341