Investigating turkey (Meleagris gallopavo) domestication in the Southwest United States through ancient DNA analysis

As one of the New World’s few animal domesticates, the turkey (Meleagris gallopavo) represented an important resource for the Ancestral Puebloans of the Southwest United States. Despite the rich database of Southwest archaeology, several questions concerning the domestication and use of turkeys remain unanswered, including the geographic origin of turkey domestication, the pre-contact flock management and breeding practices, and the changing roles of wild and domestic turkeys through time. In order to address these outstanding issues, this study applied ancient DNA analysis to 193 archaeological turkey bones, from 43 archaeological sites ranging in time from AD600 to AD1880. The authenticity of the ancient DNA data was secured through multiple criteria, including: the use of dedicated ancient DNA facilities; the inclusions of blank extracts and PCR negative controls; and repeat extractions and amplifications. Mitochondrial DNA analysis of the archaeological remains revealed a strong genetic bottleneck within the pre-contact Southwest turkey population, reflective of human selection and breeding. The genetic differences between the Southwest turkeys and modern commercially-raised turkeys point to two geographically distinct turkey domestication events in North America: one involving M. g. silvestris and/or intermedia with a subsequent trade of domestic stocks into the Southwest proper, and the other involving M. g. gallopavo in south-central Mexico. The broad distribution of a genetically uniform stock throughout the Southwest suggests that turkeys were traded within and between cultural traditions, and that a single lineage of turkey was used for ritual purposes, feather production, and for food. While the archaeological and genetic evidence point to the intensification of domestic turkey husbandry through time, the recovery of M. g. merriami haplotypes in the archaeological remains indicates that some local birds were exploited in conjunction with the imported domestic lineage. In addition to hunted wild birds, the osteological and genetic data point to the incorporation of wild individuals into domestic flocks, and/or hybridization of wild toms and domestic hens. This study, integrating genetic, osteometric and archaeological data offers an exclusive snapshot into the complexities of the domestication process, and the dynamic human-animal interactions of the past.