March 19, 2014
Polynesian Chickens May Have Flown The Coop, But They Didn’t Make It To South America: Study
Lawrence LeBlond for redOrbit.com - Your Universe Online
It is commonly agreed in the scientific community that Polynesians expanded their culture throughout the South Pacific some 3,000 years ago and later arrived in places like Tahiti and Hawaii. But did the Polynesians make it all the way to South America? And if they did, did they beat Columbus?
New evidence paints a pretty clear picture that Polynesians were in fact not the first to arrive in South America, and maybe never made the journey at all. This is based on an analysis of ancient DNA taken from chicken bones recovered in archaeological dig sites across the Pacific.
Researchers used the DNA to study the origins and dispersal of ancestral Polynesian chickens, reconstructing the early migrations of the people and the animals they carried with them.
The study, led by Prof Alan Cooper, of the University of Adelaide’s Australian Centre for Ancient DNA (ACAD) and published in the Proceedings of the National Academy of Sciences (PNAS), reveals that early Polynesians did not make contact with South America as previously reported. And any evidence showing that was likely based on contaminated results.
According to a report from National Geographic, there is some evidence, however, that does point to a Polynesian presence in South America.
In particular is a 2007 study that announced the discovery of chicken bones found at a dig site near Santiago, Chile that yielded radiocarbon dates to between 1321 and 1407 – long before the arrival of Europeans.
“The early dates, the location along the Pacific coast, and the presence in the bones of what appeared to have been a unique genetic mutation common to Polynesian chickens raised the tantalizing prospect that the meaty birds may have been introduced by South Pacific seafarers,” wrote NatGeo’s Roff Smith.
"It is the most likely explanation," said Alice Storey, an archaeologist with Archer CRM, who led the 2007 study in Chile. "I have investigated many other potential routes of introduction, and none of them are as likely as a Polynesian introduction."
However, those results were called into question within a year of publication and a subsequent analysis of the DNA by Cooper and his colleagues challenged the dates and suggested that the genetic mutation found in the chicken bones was a fairly common mutation found in chickens throughout the world. Those findings formed the basis of Cooper’s most recent research into the DNA of Polynesian chickens.
Storey stands behind her findings and argues that the DNA results in the latest study are Storey stands behind her findings and argues that the DNA results in the latest study are inconclusive.
"Indeed, the bulk of their research focuses on modern DNA," she told NatGeo’s Roff Smith. "Using modern DNA to understand what people were doing in the past is like sampling a group of commuters at a London Tube station at rush hour. The DNA you get is unlikely to provide much useful information on the pre-Roman population of London."
Still, Cooper’s study shows evidence that points to a unique genetic marker of Polynesian chickens only found in the Pacific and Southeast Asian islands.
The team used female-inherited mitochondrial DNA extracted from 22 chicken bones excavated from archaeological digs from Hawaii, Rapa Nui and Niue, as well as 122 feathers from modern chickens living on South Pacific islands.
According to National Geographic, the team used an enzyme to remove any contamination by modern DNA that may have clouded the results of earlier studies. When comparing the new DNA results with that of ancient and modern South American chickens, the team found the two groups were genetically different.
Their chicken DNA analysis doesn’t support a connection between Polynesia and South America, 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," he told Smith.
"We have identified genetic signatures of the original Polynesian chickens, and used these to track early movements and trading patterns across the Pacific," lead author Dr Vicki Thomson, of ACAD, said in a statement. "We were also able to trace the origins of these lineages back into the Philippines, providing clues about the source of the original Polynesian chicken populations."
"There are still many theories about where the early human colonists of the remote Pacific came from, which routes they followed and whether they made contact with the South American mainland. Domestic animals, such as chickens, carried on these early voyages have left behind a genetic record that can solve some of these long standing mysteries," Associate Professor Jeremy Austin, ACAD Deputy Director, said in a statement.
"Remarkably, our study also shows that the original Polynesian lineages appear to have survived on some isolated Pacific islands, despite the introduction of European domestic animals across the Pacific in the last couple of hundred years," Prof Cooper said. "These original lineages could be of considerable importance to the poultry industry which is concerned about the lack of genetic diversity in commercial stocks."
Interestingly, if the presence of pre-Columbian chickens is a good indicator that Polynesians succeeded in making contact with South America, then it would stand to reason that Rattus exulans, the Pacific rat, would have been widespread in South America. It is known that the Pacific rat had traveled everywhere that Polynesians had, establishing thriving habitats in those locations that exist until this day. However, there are no Pacific rats found in South America.
Regardless of the chicken DNA evidence, David Burley, an archaeologist at Simon Fraser University in Canada, said he has no doubt that Polynesians did in fact reach the New World.
"The evidence for Polynesian contact with the New World prior to Columbus is substantial," Burley told NatGeo. "We have the sweet potato, the bottle gourd, all this New World stuff that has been firmly documented as being out here pre-Columbian. If the Polynesians could find Easter Island, which is just this tiny speck, don't you think they could have found an entire continent?"