Chicken DNA Challenges Theory That Polynesians Beat Europeans to Americas

So why did the chicken cross the Pacific? Well, apparently it didn't. At least not all the way.

Scientists looking into the DNA of ancient and modern chicken breeds found throughout Micronesia and Polynesia have determined that they are genetically distinct from those found in South America. The research runs counter to a popular theory that Polynesian seafarers might have reached the coast of South America hundreds of years ago, before European explorers.

Among the intriguing indications that contact might have been made between Polynesians and the native peoples of South America was the supposed pre-Columbian presence of non-native chickens, allegedly introduced to the continent by seafarers from South Pacific islands. More evidence comes from the ubiquity of the sweet potato, a South American native, in the South Pacificit was already widespread throughout the islands by the time James Cook sailed into the region in 1770. (See National Geographic's South Pacific photos.)

Now it appears the chicken link, at least, may be severed, according to Alan Cooper, director of the Australian Centre for Ancient DNA, a co-author of the study published this week in the Proceedings of the National Academy of Sciences.

Researchers sequenced mitochondrial DNA from 22 chicken bones found at Polynesian archaeological sites and 122 feathers from modern chickens living on islands across the South Pacific. They used an enzyme to remove any contamination by modern DNA that may have clouded the results of earlier studies. When the team compared the "cleaned-up" DNA of Polynesian chickens with that of ancient and modern South American chickens, they found the two groups were genetically distinct.

The chicken DNA does not support a connection between the peoples separated by the Pacific, Cooper said. "Indeed, the lack of the Polynesian sequences [of DNA] in modern South American chickens ... would argue against any trading contact as far as chickens go."

Cooper and his colleagues were able to trace the origins of Polynesian chickens back in time and across the Pacific, following the lines of what must rank as one of the boldest, most romantic, and least understood human migrations of all timethe peopling of the tropical islands of the South Seas.

"We can show [from chicken DNA] that the trail heads back into the Philippines," Cooper said. "We're currently working on tracing it farther northward from there. However, we're following a proxy, rather than the actual humans themselves."

Tahitians sail and paddle rafts in an engraving done a few years after Captain James Cook explored Polynesia and Tahiti, then called Otaheite.

ILLUSTRATION BY SSPL, GETTY

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Chicken DNA Challenges Theory That Polynesians Beat Europeans to Americas