Controlled and Natural Ingestion of Exogenous Mineral Particles: Impact on Dental Microwear Textures in Pigs

Abstract

The selective pressures of exogenous mineral particles on dental innovations have been a long-standing debate in paleontology and evolutionary biology. However, the relationship between exogenous abrasives and dental wear remains unclear, questioning our ability to detect the consumption of such particles in past records. This issue is also of crucial interest when investigating ancient pig husbandry systems, since anthropogenic food supply and penning can reduce soil ingestion associated with rooting. Here, we explore the effect of different mineral particles on dental microwear of control-fed domestic pigs (Sus scrofa). We conducted dental microwear texture analysis (DMTA) on four groups of six pigs: a control group fed only with cereal flour, and three groups fed with the same diet and supplemented with 4% kaolin, 4% fine-to-medium sand (diameter between 0.1 and 0.3 mm), or 4% medium-to-coarse sand (diameter between 0.5 and 1 mm). Our study shows that different mineral particles generate different microwear textures that are distinct from those of control pigs. Clay consumption produces a polishing effect, whereas larger-sized sand generates a trend toward more abrupt relief changes. Regardless of particle type, microwear textures tend to show lower values in heterogeneity of complexity. Aiming at cross-checking these results, we observe that captive boars with and without natural soil ingestion tend to reflect the same trends, notably showing less rough and more homogeneous surfaces following soil ingestion. This study contributes to better understanding how exogenous abrasives impact dental microwear and reinforces the potential of DMTA in detecting soil ingestion in past records or the feeding on dust-rich vegetation in arid environments.