Mastication in goats shows a chewing side preference

Developmental instability theory suggests that variation in some body parts in part can reflect the ability to buffer development from key environmental and genetic perturbations. Support for this approach comes mainly from assessment of fluctuating asymmetry, or deviations from symmetry of body features that are symmetric at the population level. In order to study dental asymmetry in domestic goats, we sampled 22 adult goat skulls. Bucco-palatine and mesio-distal distances (width and length) of the second molar on each side for each skull, on their occlusal aspect, were measured and compared using standard lineal methods. There was evidence of directional asymmetry, that is, unilateral mastication habits, being the left teeth of the arch slightly but systematically longer than the right. This directional change supported a right chewing side preference in the sample. It is important to highlight that the sample comes from non-pathological specimens. Therefore, it does depict the sample population of animals used in general. The observed asymmetries was not associated with any other cranio-facial abnormalities.Authors wish to acknowledge the help of Josué Sabaté for allowing the study of his private collection of White Rasquera skulls. The rest of skulls are stored in the bone collection of the Department of Animals Science of the University of Lleida, Catalonia, Spain