By analyzing the DNA of 1,245 sweet potato varieties from Asia and the Americas, researchers have found a genetic smoking gun that proves the root vegetable made it all the way to Polynesia from the Andes — nearly 400 years before Inca gold was a twinkle in Ferdinand and Isabella’s eyes.

The findings, published in the Proceedings of the National Academy of Sciences, offer more evidence that ancient Polynesians may have interacted with people in South America long before the Europeans stepped foot on the continent.

“There’s been many kinds of evidence – linguistic and archaeological – for contact between these two people,” Caroline Rouiller, an evolutionary biologist at the Center for Functional and Evolutionary Ecology in France who led the study, tells The Salt. “But the sweet potato is the most compelling.”

Sweet potatoes originated in Central and South America. But archaeologists have found prehistoric remnants of sweet potato in Polynesia from about A.D. 1000 to A.D. 1100, according to radiocarbon dating. They’ve hypothesized that those ancient samples came from the western coast of South America. Among the clues: One Polynesian word for sweet potato — “kuumala” — resembles “kumara,” or “cumal,” the words for the vegetable in Quechua, a language spoken by Andean natives.

From NPR. Click on the title to read more.