The aim of this paper is to examine the relationship between occlusal surface wear and approximal facet length in a North American archaeological sample of modern human hunter–gatherers (n = 111) and agriculturalists (n = 123).
First maxillary molars (M1) were selected. The approximal wear facet was measured on the mesial surface of each M1 at the widest breadth using needle tipped digital callipers. Digital images were taken of the occlusal surface and wear was recorded as the percentage of dentine exposed to the total occlusal surface. Independent age estimate was based on age-related changes, (pubic symphysis and auricular surface). Results show the hunter–gatherers had a significantly faster rate of wear on both tooth surfaces compared to the agriculturalists in each of the four age groups. Both lifeway groups showed a positive correlation between the two tooth surfaces during the early stages of tooth wear (less than 25% occlusal wear), where the percentage of occlusal wear and the length of the approximal facet increased at a similar rate. During the middle and final stages of tooth wear (occlusal wear greater than 35%) there was a strong negative correlation between the two surfaces in both groups. It is suggested this pattern is due to the shape and function of the M1. Both correlations were more extreme in the hunter–gatherers than the agriculturalists. When the per cent of occlusal wear exceeded 35% the length of the approximal facet started to decrease, and it is therefore recommended studies that include approximal wear exclude molars with heavy occlusal wear. Copyright © 2010 John Wiley & Sons, Ltd.