This study demonstrates that dental topographic analysis can be used to document morphological differences between variably worn teeth. We expect that natural selection continues to act on individuals as their teeth wear and therefore should select for a morphology that will maintain chewing efficiency throughout the life of the tooth. Characteristics such as cusp slope, aspect, surface area, relief, and basin volume can be quantified using GIS algorithms. These may be of interest in assessing functional changes in chewing efficiency as teeth wear. Still, this list is certainly not exhaustive, and techniques described here may allow measurement of many other relevant attributes, such as the area of a polygon connecting the tips of the cusps, or the difference between the actual volume of the tooth and the "cylindrical" volume (measured as the product of tooth area in the x-y plane and height of the tallest cusp).

The delta slope results, although preliminary, are particularly intriguing. There is no apparent change in angularity of gorilla tooth surface from less to more worn specimens. This evidently reflects the steep walls of the occlusal pits that form as enamel gives way to softer dentin as the tooth wears. Such a phenomenon may be comparable to that seen in herbivorous ungulates that have complex infoldings and lophs designed to form sharp edges with dentin exposure for shearing and grinding tough foods. If so, it might provide evidence that thin tooth enamel in primate folivores, such as the gorilla, would lead to sharp edges at the sites of dentin exposure to improve shredding and slicing abilities of the tooth with wear (Kay 1981). Clearly, however, a comprehensive study of large numbers of individuals representing various folivorous taxa is needed to adequately test this hypothesis. Studies of food particle size in gut and fecal samples of younger and older individuals will provide an independent test of changes in chewing efficiency (e.g., Perez-Barberia and Gordon 1998).

This paper set out to demonstrate the potential of GIS to examine morphological changes in variably worn mammal teeth. The next phase of this research will involved a series of repeatability tests, followed by a temporal study of individual tooth wear. A temporal study will give us an idea of variation within species in tooth wear sequences, a necessary step if we are to use variably worn teeth of different individuals to construct a species-specific wear sequence. On the other hand, we are limited to variably worn teeth of different individuals in the fossil record, so such studies of extant groups will be needed to form an adequate baseline for comparison with extinct taxa.