NEW YORK (GenomeWeb News) – New research is casting doubt on the notion that there was extensive pre-Columbian trading between Polynesia and South America.
An international team of researchers sequenced mitochondrial DNA from 41 Chilean chickens and analyzed their phylogenetic relationships by comparing them with available ancient samples and with more than 1,000 modern domestic chickens from different parts of the world.
The results, appearing online this week in the Proceedings of the National Academy of Sciences, suggest that Chilean chickens share mitochondrial sequence with both Polynesian and European chickens, originating in the Indian subcontinent. As such, the new work fails to support — though it doesn’t disprove — the idea that there was pre-historic trade between early Polynesians and South Americans.
“Polynesians are known to have spread chickens across the Pacific at least as far as Easter Island, but were not thought to have introduced them to South America,” senior author Alan Cooper, director of the Australian Centre for Ancient DNA in Adelaide, explained in a statement.
But that didn’t stop some from speculating that there were chickens in America before the arrival of Spaniards in the 15th century. The presence of some unusual chicken breeds, including the Araucana and Passion Fowl, found in Chile fueled speculation that early Dutch or Polynesian traders had introduced chickens to the region before Columbus’ arrival.
And that theory was bolstered last year by research published in the Proceedings of the National Academy of Sciences linking chicken sequences at Chilean and Polynesian archeological sites. Based on their radiocarbon data and analyses of a short mitochondrial DNA control region, the researchers working on that paper concluded that there was a pre-Columbian introduction of chickens — originating in Polynesia — to the Arauco Peninsula in Chile.
For the latest study, Cooper and his team sequenced mitochondrial DNA from 41 different Chilean chicken breeds — 28 Araucanas, seven creole, one Japanese Long Tail, and five Passion Fowl — selected from a dozen sites within the country. They then compared these sequences with ancient Polynesian and Chilean chicken sequences and with roughly a thousand domestic chicken sequences.
When the researchers analyzed phylogenetic relationships between the birds, they found evidence that the proposed pre-Columbian chicken did share some sequence with Polynesian chickens. But, importantly, this sequence appears to have a worldwide distribution, removing genetic support for a direct relationship between Polynesian and South American birds.
“The results showed that the ancient Polynesian and Chilean chickens possessed a genetic sequence that is the most common in the world today, the so-called ‘KFC’ gene,” Cooper said. “This sequence would undoubtedly have been common in the early Spanish chickens, and therefore provides no evidence of Polynesian contact.”
In contrast, the team discovered an uncommon haplotype on Easter Island that is shared with chickens in the Indonesian islands and parts of Japan and the Philippines. So far, though, researchers have not detected the sequence representing that rare haplotype in Polynesia.
The team’s mitochondrial DNA analysis also provided evidence supporting the idea that European chickens originated in the Indian subcontinent and were dispersed to other parts of the world from there.
In the future, the team noted, more work will be necessary to determine the timing of chicken dispersal throughout and adaptation to the Americas and South East Asia. “Of particular interest will be chickens kept by some indigenous communities in the Amazon forest, the origins of which remain unclear,” they wrote.