How Did the Chicken Cross the Ocean?

At some point in the last few thousand years, someone in India or Southeast Asia decided to try catching one of the wild fowl than ran through the jungles and roosted up in the trees. We don’t know exactly what that person was intending, but the bird probably wasn’t destined to be stuffed and roasted or battered and fried. Archaeological evidence suggests that the birds were first caught for cockfighting (pit matches between wild partridges and quails were already common), and the idea of eating them didn’t come until later. Whatever the purpose, jungle fowl were brought into villages in droves, and eventually domesticated.

The common barnyard chicken we know and love around the world today is the hybrid descendant of two of these wild junglefowl species—the red junglefowl and the grey junglefowl—which went global with the movement of people. We have a pretty good handle on when and how they got to Europe and Africa, but exactly who brought them to the New World and when is murky, and even a little controversial.

Getting to the Other Side

For a long time the conventional wisdom said Europeans brought domestic chickens to the Americas as they established colonies in the wake of Christopher Columbus’ journey. The catch, though, is that when the Spanish conquistador Francisco Pizarro arrived in the cities of the Incan empire (in what is now Peru) in 1532, domestic chickens were already well integrated into the local culture, being both eaten and used in religious ceremonies. The birds certainly seemed to have been there longer than the few decades since the first European contact, but the idea of pre-Columbian New World chickens was roundly dismissed and forgotten for almost 500 years.

In 2002, archaeologists discovered chicken bones at a pre-Columbian site along the coast of Chile, allowing the age and origin of New World chickens to be studied. An international team of scientists, led by Australian Alice Storey, got a hold of the bones in 2007, radiocarbon-dated one of them, and ran DNA sequences. Their tests suggested that the bone had been there since sometime between 1304 and 1424, well before Europeans even had a whiff of the Americas.

But then how did they get there from Asia? They can’t fly, and not all of them take to swimming as well as this guy. The ancient chicken’s DNA included a unique genetic sequence identical to ones from prehistoric chickens dug up in Tonga and Samoa, suggesting that maybe the chickens had come to South America with early Polynesian explorers some 70 years or more before Europeans “discovered” America.

Polynesian Chicken?

Just a year after Storey’s team published their study, another international group of researchers, led by Australian Jaime Gongora, published another chicken study in the same journal. This group questioned Storey’s conclusions and, after conducting their own DNA analysis, couldn’t find any support for the Polynesian chicken conclusion. They showed that the genetic mutation that linked the ancient Polynesian and South American chickens was actually fairly common in different breeds of the bird worldwide. The South American chickens could have come Polynesia or from almost anywhere else in the world that already had chickens at the time, and extensive genetic surveys of modern South American chickens led back to exclusively European origins. Gongora’s team also questioned Storey’s dating of the bone; the site where it was found, El Arenal, is just a few miles from the ocean, so it’s possible that carbon from the ocean could have found its way into the chicken’s diet and skewed the dating.

Storey’s team conceded that the mutation they found may not have been unique, but they said the genetics were irrelevant if their carbon dating was right. Any chicken bones that fell in the date range of 1000 to 1400 fit within the era of eastward Polynesian exploration, and there was no evidence that any other Asian peoples had reached South America at that time or before. They went back to the bones again and recently published the results of their second carbon dating test.

This time around they used three bones instead of just one, and checked for any evidence of seafood or marine plants in the chickens’ diets that could cause a carbon problem. The new dating suggested that the bones were from 1304 at the earliest and 1459 at the latest, possibly more recent than they had first thought, but still ahead of the Europeans. The dates, combined with other evidence of Polynesian contact with the Americas - the appearance of South American sweet potatoes in the Pacific pre-European contact and a similarity in the Quechua and Polynesian names for the vegetable (kumar and kumara) -  suggest that it was Polynesians in wooden rafts who dragged the chicken, kicking and clucking, into the age of exploration and beat Columbus to the New World.