Two issues long debated among Pacific and American prehistorians are ( i ) whether there was a pre-Columbian introduction of chicken ( Gallus gallus ) to the Americas and ( ii ) whether Polynesian contact with South America might be identified archaeologically, through the recovery of remains of unquestionable Polynesian origin. We present a radiocarbon date and an ancient DNA sequence from a single chicken bone recovered from the archaeological site of El Arenal-1, on the Arauco Peninsula, Chile. These results not only provide firm evidence for the pre-Columbian introduction of chickens to the Americas, but strongly suggest that it was a Polynesian introduction.

Data from morphology, linguistics, history, and archaeology have all been used to trace the dispersal of chickens from Asian domestication centers to their current global distribution. Each provides a unique perspective which can aid in the reconstruction of prehistory. This study expands on previous investigations by adding a temporal component from ancient DNA and, in some cases, direct dating of bones of individual chickens from a variety of sites in Europe, the Pacific, and the Americas. The results from the ancient DNA analyses of forty-eight archaeologically derived chicken bones provide support for archaeological hypotheses about the prehistoric human transport of chickens. Haplogroup E mtDNA signatures have been amplified from directly dated samples originating in Europe at 1000 B.P. and in the Pacific at 3000 B.P. indicating multiple prehistoric dispersals from a single Asian centre. These two dispersal pathways converged in the Americas where chickens were introduced both by Polynesians and later by Europeans. The results of this study also highlight the inappropriate application of the small stretch of D-loop, traditionally amplified for use in phylogenetic studies, to understanding discrete episodes of chicken translocation in the past. The results of this study lead to the proposal of four hypotheses which will require further scrutiny and rigorous future testing.

Direct evidence of the environmental impact of human colonization and subsequent human adaptational responses to new environments is extremely rare anywhere in the world. New Zealand was the last Polynesian island group to be settled by humans, who arrived around the end of the 13th century AD. Little is known about the nature of human adaptation and mobility during the initial phase of colonization. We report the results of the isotopic analysis (carbon, nitrogen and strontium) of the oldest prehistoric skeletons discovered in New Zealand to assess diet and migration patterns. The isotope data show that the culturally distinctive burials, Group 1, had similar diets and childhood origins, supporting the assertion that this group was distinct from Group 2/3 and may have been part of the initial colonizing population at the site. The Group 2/3 individuals displayed highly variable diets and likely lived in different regions of the country before their burial at Wairau Bar, supporting the archaeological evidence that people were highly mobile in New Zealand since the initial phase of human settlement.

Owing to exceptional biomolecule preservation, fossil avian eggshell has been used extensively in geochronology and palaeodietary studies. Here, we show, to our knowledge, for the first time that fossil eggshell is a previously unrecognized source of ancient DNA (aDNA). We describe the successful isolation and amplification of DNA from fossil eggshell up to 19 ka old. aDNA was successfully characterized from eggshell obtained from New Zealand (extinct moa and ducks), Madagascar (extinct elephant birds) and Australia (emu and owl). Our data demonstrate excellent preservation of the nucleic acids, evidenced by retrieval of both mitochondrial and nuclear DNA from many of the samples. Using confocal microscopy and quantitative PCR, this study critically evaluates approaches to maximize DNA recovery from powdered eggshell. Our quantitative PCR experiments also demonstrate that moa eggshell has approximately 125 times lower bacterial load than bone, making it a highly suitable substrate for high-throughput sequencing approaches. Importantly, the preservation of DNA in Pleistocene eggshell from Australia and Holocene deposits from Madagascar indicates that eggshell is an excellent substrate for the long-term preservation of DNA in warmer climates. The successful recovery of DNA from this substrate has implications in a number of scientific disciplines; most notably archaeology and palaeontology, where genotypes and/or DNA-based species identifications can add significantly to our understanding of diets, environments, past biodiversity and evolutionary processes.

This paper reintroduces the concept of mass migration into debates concerning the timing and nature of New Zealand's settlement by Polynesians. Upward revisions of New Zealand's chronology show that the appearance of humans on the landscape occurred extremely rapidly, and that within decades settlements had been established across the full range of climatic zones. We show that the rapid appearance of a strong archaeological signature in the early 14th century AD is the result of a mass migration event, not the consequence of gradual demographic growth out of a currently unidentified earlier phase of settlement. Mass migration is not only consistent with the archaeological record but is supported by recent findings in molecular biology and genetics. It also opens the door to a new phase of engagement between archaeological method and indigenous Maori and Polynesian oral history and tradition.