Early Polynesians didn’t go to Americas, chicken DNA hints

Poultry genetics undermines claims of ancient cross-sea trips to South America

Ancient Polynesians probably didn’t reach the shores of South America, an analysis of ancient chicken DNA from islands dotting the Pacific suggests.

Between about 3,400 and 700 years ago, Polynesians settled the islands of the Pacific, carrying plants and food animals with them. Researchers have used DNA from pigs, chickens and rats to help trace the people’s island-hopping path.  

One study of chicken DNA had suggested that Polynesians reached South America sometime before Columbus. Now Vicki Thomson of the University of Adelaide in Australia and colleagues question that report. Contamination of ancient DNA samples with modern chicken DNA misled the researchers, Thomson’s group reports March 17 in the Proceedings of the National Academy of Sciences.

The team studied maternally inherited mitochondrial DNA from 22 ancient chicken bones and 122 modern chickens’ feathers, collected from islands in the Pacific and Southeast Asia. They also cleaned up ancient chicken samples used in the earlier study and found that the Pacific island samples aren’t the type found in South America. That finding suggests that Polynesians’ journeys did not take them to the Americas.

The analysis also revealed that some ancient chicken breeds are still alive on remote Pacific islands, such as Marquesas, Vanuatu and the Santa Cruz and Solomon islands.

Tina Hesman Saey is the senior staff writer and reports on molecular biology. She has a Ph.D. in molecular genetics from Washington University in St. Louis and a master’s degree in science journalism from Boston University.

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