8000 Years of morphometric evolution of sheep, goat and pig in the northwestern Mediterranean basin

Understanding how domestic mammal species evolved through time provides insight into the artificial and natural selection processes that have shaped the diversity of domestic animals. The focus of this article is the morphometric evolution of sheep, goats and suids in the Northwestern Mediterranean Basin over the last 8000 years, employing a 2D geometric morphometrics protocol applied to the third lower molars. Using a comprehensive dataset comprising 2798 archaeological specimens from 176 sites in Southern France and Spanish Catalonia, along with 1303 modern specimens, we aim to identify and contrast the environmental and anthropic factors influencing species evolution linked to past husbandry practices. Each of these three taxa follows its own evolutionary trajectory, exhibiting variations over time and across different regions. Notably, reduction in the centroid size of sheep molars between the Neolithic and the early Iron Age could potentially be associated with an increased demand for meat and/or shifts in male-to-female ratios. A clear geographical structuring of caprines between the Neolithic and Antiquity is observed, likely influenced by a combination of factors including artificial selection, environmental changes and socio-economic dynamics, as corroborated by previous studies. Moreover, a reduction in molar size during the Middle Ages is observed across all three species, possibly linked to extensive agropastoral practices. Furthermore, divergent processes of breed improvement and standardization are identified in pigs and caprines. This study highlights the complex nature of morphological variations in domestic species, emphasising the multifactorial influences involved. It underscores the importance of interdisciplinary approaches in understanding the factors contributing to morphological transformations over time.