Incisor microwear of Sumatran anthropoid primates.

Several studies have suggested that incisor microwear reflects diet and feeding adaptations of anthropoids. However, such studies have been largely qualitative, and interpretations have relied on anecdotal references to diet and tooth use reported in the socioecology literature. The current study relates incisor microwear in four anthropoid primates to specific ingestive behaviors and food types. Central incisor casts of wild-shot museum specimens of Hylobates lar, Macaca fascicularis, Pongo pygmaeus, and Presbytis thomasi were examined by scanning electron microscopy, and analyzed using a semiautomated image analysis procedure. Microwear patterns were used to generate predictions regarding diet and anterior tooth use. These predictions were evaluated using data collected during a 1 year study of feeding behavior of these same taxa in the wild (Ungar, 1992, 1994a,b). Results suggest that (1) enamel prism relief is associated with the effectiveness of etching reagents in foods, (2) dental calculus buildup results from a lack of incisor use and perhaps the ingestion of sugar-rich foods, (3) striation density varies with degree of anterior tooth use in the ingestion of abrasive food items, (4) striation breadth is proposed to relate to the ratio of exogenous grit to phytoliths consumed; and (5) preferred striation orientation indicates the direction that food items are pulled across the incisors during ingestion. It is concluded that incisor microwear studies can contribute to the understanding of diets and feeding behaviors of extinct primates.