Thousands of years of human-dog relationships: uncovering adaptation to dietary changes of dogs, resulting from the transition to farming

International audience

English. Following its domestication, the dog experienced the growing impact of humans on their environment and has witnessed the gradual evolution of their lifestyle. Dog is therefore a unique model that allows studying the biological changes resulting from the adaptation to cultural changes. A change in diet was a major shift during the Neolithic transition. By living so close to humans, we hypothesize that dogs were also impacted by this dietary transition. Here, we investigate the effect of dietary changes resulting from the transition to farming on the evolution of dogs at the genomic, morphological and functional levels. We targeted 86 dogs and 9 wild-canid ancient samples (mandibles and coprolites) coming from Paleolithic to late chalcolithic Romanian sites. The morphological study of the mandibles suggests that archaeological dogs may have had a jaw system optimized for hard biting at shallow gape angles. We performed isotopic analysis suggesting that Chalcolithic dogs are at a lower trophic level compared to the Mesolithic canids. High-throughput sequencing of ancient DNA extracted from the dental pulp and the coprolites allowed us to study modification in digestive microbiota composition. We detected oral pathogens and typical gut bacteria, and showed that ancient dental pulp is a valid source of DNA from microbes responsible for local and systemic infections. Finally, mitochondrial genome captures were performed on all samples together with nuclear DNA capture targeting 4000 variant sites with ancestry and functional relevance. It allowed to reconstruct population history and to detect genomic variations that may have been selected troughout the Neolithic transition.