Hitchhiking Adventures of Pre-Columbian Yeast


Contact between the people of the Western Hemisphere and Polynesia has been a subject of debate since long before Thor Heyerdahl sailed the Kon-Tiki from South America to the Tuamota Islands in the Pacific. Recently a humble microorganism may have added some evidence to the possibility of trans-Pacific contacts.

A particular strain of yeast was identified in three far flung corners of the globe: eastern Australia, Costa Rica and the Galapagos Islands. The yeast, a variety of Saccharomycopsis fodiens, was not found anywhere else, though microbiologists isolated thousands of different yeast strains growing on sap beetles, the microbes’ preferred habitat.

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How the S. fodiens strain got to such distant locales without leaving traces in between is a mystery. One possibility is that they hitched a ride with human travelers.

“The collection sites for S. fodiens are compatible with the hypothesis that ancient Polynesians migrated southward from Taiwan and then eastward across the Pacific and eventually South America carrying sweet potato plants, whose flowers carry similar insects and yeasts,” said Marc- André Lachance of Western Ontario University, who led the research, in a press release.

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A problem with that hypothesis is that the sweet potato is native to the Western Hemisphere, along with all of its spud relatives. But that doesn’t mean sweet potato plants and the beetles and yeast hitching a ride on them couldn’t have gone from South America out into the Pacific.

The Maori of New Zealand were growing a variety of sweet potato long before Europeans spread the plant around the world, as were other Polynesian people to the east. Radiocarbon dating of sweet potato remains on the Cook Islands found them to be approximately 1,000 years old.

Although Thor Heyerdahl proved people could travel west from South America into the Pacific with the potato in tow, it seems more likely that the Polynesians, with their mastery of long distance navigation, would have been the culture that made it across the Pacific to South America. The seafaring spud-bearers could have then turned back around and brought potatoes to the Pacific.

The Polynesians might not have been alone on their voyages. Some suggest that chickens made the crossing with them, then stayed in South America.

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Spanish invaders recorded seeing chickens in Peru in 1532 before they brought any of their own to the area. A study published in PNAS reported finding chicken bones that dated back to at least the 1400′s. That research also found genetic evidence of a link between the bone and Polynesian chickens. But another study of the mitochondrial DNA of the modern Araucana breed, a chicken thought to be a native of Chile, refuted the Polynesian poultry parentage hypothesis and suggested that the birds showed genetic links to birds most likely brought by the Spaniards.


Historical painting of a Polynesian ship (NOAA, Wikimedia Commons)

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