Investigating the global dispersal of chickens in prehistory using ancient mitochondrial DNA signatures

Abstract

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.

Figure 1. A close up of the E and D branches of a Maximum Parsimony Network showing the affinities of ten of the eleven, non-continuiously numbered, ancient haplogroups detected in our 48 samples with those previously defined by Liu et al. .

Ancient haplotypes are identified in red bold text and occur in haplogroups D and E. The full network showing the B branch is available as Figure S1.

Figure 2. Map showing the relative proportions of haplogroups sequenced from archaeologically derived remains.

Each pie represents 100% of the sequences obtained and the numbers inside each pie refer to the legend which details the geographic provenience and the number of samples from each area. Each colour represents one of three distinct haplogroups. The natural range of Red Junglefowl is outlined in red and represents the area in which initial domestication events must have occurred , . The red shaded area in northern China represents an area in which G. gallus bones have been recovered from archaeological sites older than 5000 BC. This has led to debate about whether the natural range of Red Junglefowl in prehistory extended further north , , .