Bony labyrinth taxonomic identification and long-term evolution of livestock in the Southwest and Central Asia

Abstract

Abstract Southwest and Central Asia were pivotal regions for the domestication and dispersal of domestic herbivores. Here we investigate long-term variation in bony labyrinth morphology of domestic bovids (sheep, goats and cattle) across the last 10 000 years. We focused on the osseous cavity of the inner ear, located within the petrous bone. We analysed semicircular canal (SC) size and shape using micro-computed tomography and geometric morphometrics (GMM) on 78 modern reference specimens and 234 archaeological petrous bones from 51 sites spanning the Iranian Plateau, Central Asia, the Caucasus and the Indus Valley. Bony labyrinth morphometrics yielded a strong taxonomic signal, enabling species-level identification of 228 out of 234 specimens and revealing greater diversity than anticipated. Comparative analyses further documented contrasting, nonlinear diachronic trajectories in SC size and shape among sheep, goats and cattle, reflecting species-specific responses to domestication and long-term herd management. Together, these results demonstrate that bony labyrinth GMM provides a robust, non-destructive framework for taxonomic identification and evolutionary inference and underscore how long-term, interdisciplinary approaches can capture the complex, nonlinear dynamics of animal domestication across the longue durée.