Figure S1: Distribution parameters for the length of the lower tooth row (#8 in Von den Driesch, 1976 [25]; mm) from Amy2B copy number variation reveals starch diet adaptations in ancient European dogs

Extant dog and wolf DNA indicates that dog domestication was accompanied by the selection of a series of duplications on the Amy2B gene coding for pancreatic amylase. In this study, we used a palaeogenetic approach to investigate the timing and expansion of the Amy2B gene in the ancient dog populations of Western and Eastern Europe and Southwest Asia. Quantitative PCR was used to estimate the copy numbers of this gene for 13 ancient dog samples, dated to between 15 000 and 4000 years before present (BP). This evidenced an increase of Amy2B copies in ancient dogs from as early as the 7th millennium BP in Southeastern Europe. We found that the gene expansion was not fixed across all dogs within this early farming context, with ancient dogs bearing between 2 and 20 diploid copies of the gene. The results also suggested that selection for the increased Amy2B copy number started 7000 years BP, at the latest. This expansion reflects a local adaptation that allowed dogs to thrive on a starch rich diet, especially within early farming societies, and suggest a biocultural coevolution of dog genes and human culture.