Europeans beat Polynesians to South America, says chicken DNA

One way to study ancient human migrations is to examine the genes of the animals with which humans typically travel.

To study Pacific migration, researchers looked at the genes of ancient and modern chickens. In doing so they overturned an earlier hypothesis that Polynesians had traveled to South America before Europeans arrived.

According to a study published in the Proceedings of the National Academy of Sciences titled "Using ancient DNA to study the origins and dispersal of ancestral Polynesian chickens across the Pacific," native South American chickens are genetically distinct from those found in Micronesia or Polynesia, suggesting that it was Columbus, not Polynesians, who 'discovered' the New World.

After sequencing mitochondrial DNA extracted from the feathers of modern chickens living on South Pacific islands and from chicken bones excavated from archaeological sites from islands including Hawaii, Rapa Nui (Easter Island), and Niue, the researchers found, "connections between chickens in the Micronesian and Bismarck Islands, but no evidence these were involved in dispersals further east. We also find clues about the origins of Polynesian chickens in the Philippines."

The results of this new study contradicts a study carried out in 2007 by Alice Storey (who was then a PhD student at the University of Auckland) and her team, who after examining a single chicken bone recovered from an archaeological site in Chile had suggested pre-Columbian introduction of chickens to the Americas from Polynesia.

"We were able to re-examine bones used in previous studies that had linked ancient Pacific and South American chickens, suggesting early human contact, and found that some of the results were contaminated with modern chicken DNA, which occurs at trace levels in many laboratory components," said project leader Alan Cooper, Director of the Australian Centre for Ancient DNA (ACAD). "We were able to show that the ancient chicken DNA provided no evidence of any pre-Columbian contact between these areas."

Dr. Storey remains skeptical of these recent findings. "In chickens in particular we know that mitochondrial DNA doesn't tell us anything about the past," she told the Australian Broadcasting Corporation. She further added, "People move around chickens all the time. Modern chicken DNA is this huge hodge podge mix of stuff. You might get some Aboriginal DNA but it's not going to tell you much about the Aboriginal settlement of Australia."

Keith Dobney, an Aberdeen University Scientist and co-author on the paper, says that the accuracy of the results depend on where the modern mitochondrial DNA samples are coming from. "The remoter the place (especially remote Islands), the more likely your are to find earlier lineages surviving and not swamped out by later introductions. That's what we found," he told the Monitor. "But I'd agree, we wouldn't have found them in modern day Sydney!"