|But ancient chicken DNA obtained from Easter Island may represent a genetic signature of an early Polynesian dispersal of chickens.|
Did some native Amerindian breeds of chicken pre-date the arrival in the Americas of European chickens with the Spanish in the 15th century?
Many would like to think so. Such evidence is used to support ancient trading contact between Polynesian and South American Indians. Some have passionately argued the case for pre-Colombian chickens, citing in particular the unusual Chilean Araucana and Passion Fowl breeds.
The Araucana breed, for example, thought to be descended from indigenous Amerindian chickens, lays blue/green-shelled eggs and has distinctive plumage. Because features of its plumage are also found among Asian rather than Mediterranean chickens, it’s been hypothesized that the Araucana breed might have an Asian origin. A similar origin has been posited for Chile’s Passion Fowl. It is thought by some that these historic Chilean breeds could have arrived with early Polynesian or Dutch traders on the Pacific Coast of South America.
But a recent scientific paper published in the prestigious USA Proceedings of the National Academy of Sciences (29 July 2008) says that molecular evidence counters such an early introduction via Polynesia. Results of this research investigation into the putative ancient Polynesian lineage of Chile’s native chickens indicate an Indo-European genetic origin. This paper has generated a lively debate that is still on-going. (See, for example, the subsequent Letter to the Editor of PNAS from Storey.)
This molecular evolutionary genetic analysis of the origin of Chile’s native chickens was carried out by scientists working in nine institutes across the globe. Animal geneticists and archaeologists at four universities in Australia (Sydney, Adelaide, Queensland and the Australian National University) worked with archaeologists from the University of Durham (UK), medical biochemists and microbiologists from Uppsala University (Sweden), geneticists from Pontificia Universidad Catolica de Chile (which extracted the DNA samples) and livestock geneticists working at the Nairobi-based International Livestock Research Institute (ILRI) and a Beijing Joint Laboratory on Livestock and Forage Genetic Resources (JLLFGR) run jointly by ILRI and China’s Institute of Animal Sciences. ILRI and JLLFGR did the PCR and DNA sequencing work for this study. Researchers working in ILRI’s labs in Nairobi and Beijing are working to improve understanding of the diversity in backyard chicken populations and production systems so as to reduce chicken diseases and subsequent poverty in sub-Saharan Africa and Asia.
Interestingly, although this molecular evolutionary detective work provides no support for a pre-Colombian Polynesian introduction of chickens to South America, DNA sequences from ancient chicken remains obtained from two archaeological sites on Easter Island represent a genetic signature of an early Polynesian, rather than 15th century Spanish, introduction of chickens to the island.
The lineages of domestic plants and animals are often replaced by later introductions of the same domestic species with a different genetic heritage, thus erasing evidence of the initial dispersal. It is thus possible that the Indo-European chicken haplotypes found in Chile may have formed a more recent wave of dispersals, overwriting and removing earlier Indonesian sequences across western Polynesia but failing to do the same on distant Easter Island.
But at present, there is no evidence to support an ancient Asia Pacific route for the introduction of Indo-European chickens into Chile.
‘The origin of South America’s first chickens remains debatable today,’ says Han Jianlin, an author of this paper, who heads the ILRI-Chinese Joint Lab in Beijing. ‘But I predict that we will have the definitive answer within the next five years. That’s how fast this molecular detective work is moving.’
‘What is remarkable about this work,’ says Olivier Hanotte, another ILRI author of the paper, who leads an ILRI project to characterize indigenous animal genetic resources of the developing world, ‘is that it is allowing us to tackle major questions about human history that we would not have been able even to ask just 20 years ago.’
‘We didn’t set out in this research,’ says Hanotte, ‘to advance understanding of the history of the world’s farming societies. But that’s just where this research—conducted to characterize chicken genetic resources of and for the poor—has led us.~