Microwear patterns from Natufian hunter-gatherers (12,500–10,250 bp) and early Neolithic (10,250–7,500 bp) farmers from northern Israel are correlated with location on facet nine and related to an archaeologically suggested change in food preparation. Casts of permanent second mandibular molars are examined with a scanning electron microscope at a magnification of 500×. Digitized micrographs are taken from the upper and lower part of facet nine. Microwear patterns are recorded with an image-analysis computer program and compared within and between samples, using univariate and multivariate analyses. Comparisons within samples reveal a greater frequency of pits on the lower part of the facet among the farmers, compared to the upper part. Microwear does not vary over the facet among the hunter-gatherers. Comparisons between samples reveal larger dental pits (length and width) and wider scratches among the farmers at the bottom of the facet, compared to the hunter-gatherers. Microwear does not vary between samples at the top of the facet. The microwear patterns suggest that the Natufian to early Neolithic development led to a harder diet, and this is related to an archaeologically suggested change in food processing. The harder diet of the early farmers may have required higher bite forces that were exerted at the bottom of facet nine, in the basin of the tooth. Am J Phys Anthropol, 2006. © 2006 Wiley-Liss, Inc.