| Summary: | Change in diet is thought to be the explanation for many evolutionary changes in the human face and jaws. Since tooth wear may be a record of foods, food consistency, or food preparation, it has been used as evidence for a number of "dietary hypotheses". However, acceptance of this evidence has been hampered by a lack of quantitative analysis. This study constructs an internally consistent model and provides methods of measurement for the interpretation of several specific features of tooth wear. Two long-st and ing problems of evolutionary interest are investigated: the effect of changes in food preparation technology on tooth wear and the determinants of features of tooth wear thought to be unique to humans, namely, high molar wear gradients and the helicoidal plane of occlusion. Five hunter-gatherer groups--Middle and Upper Paleolithic of Europe and Asia, Mesolithic Europeans, Archaic American Indians, recent Australian aborigines, and pre-contact Eskimos--are contrasted with five agriculturalist groups--Neolithic Europeans, prehistoric and early historic Nubians, early historic British, Mississippian American Indians, and Puebloan American Indians. Comparisons with wild-shot chimpanzees place human tooth wear in larger perspective. Agriculturalists differ from hunter-gatherers in systematic fashion, consistent with the model that the former have significantly reduced food "toughness" by changes in food sources and food preparation. Compared to hunter-gatherers, agriculturalists show: less anterior versus posterior dental attrition, more oblique wear planes on molar occlusal surfaces, a faster rate of change of angle of molar wear, higher expression of the helicoidal plane, differences in frequencies of location of wear on molars and incisors, later retention of overbite and overjet at central incisors, and less relative mesial migration of m and ibular first molar. All these differences are obscured if teeth are not first matched for overall degree of occlusal surface wear. In addition, the axial inclination ...
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