Animals not only are what they eat, but also wear what they eat — into their tooth enamel. Scientists from a group of institutions are using scanning confocal microscopy and specialized software to analyze the pits and grooves on teeth caused by various diets. By comparing samples of dental deterioration in modern primates — whose diets are known — with teeth from early humans, physical anthropologists are gaining insight into what our ancestors dined upon.It seems that Australopithecus africanus preferred tough fibrous leaves while Paranthropus robustus had a predilection for crunchier stuff. But both ate a mixed diet, especially when their favorite foods were scarce. This could be evidence that they adapted to seasons or surroundings in their food choices.At the core of the research is software called scale-sensitive fractal analysis. Developed at the University of Arkansas, Fayetteville, and at Worcester Polytechnic Institute in Massachusetts, the programming measures relative roughness of surfaces and creates analyses similar to topographical maps. A repeatable approach to quantifying complexity and directionality of surface aberrations, it allows documentation of much subtler diet distinctions, and it is much faster than previous methods of analyzing dental defects. It could facilitate profiles of diet and subsistence in extinct species and archaeological samples.It also could be applied by engineers for investigating wear and tear on metal surfaces or for monitoring clean surfaces on a microscopic scale.Perhaps it even could be refined to help answer that favorite question of mothers: But did you brush?