Buccal microwear has been studied in a sample of 153 molar teeth from different modern hunter-gatherer, pastoralist, and agriculturalist groups, with different diets (Inuit, Fueguians, Bushmen, Australian aborigines, Andamanese, Indians from Vancouver, Veddahs, Tasmanians, Lapps, and Hindus), preserved at museum collections. Molds of an area of the buccal surface have been obtained and observed at 100x magnification in a scanning electron microscope (SEM). The length and orientation of each striation have been determined with a semiautomatic program of an image analyzer system (IBAS). Results show that intergroup variability is significantly higher than the intragroup variability. There exists a tendency toward fewer striations and a higher proportion of vertical striations in the carnivorous groups than in the vegetarian ones. This microwear pattern is concordant with biomechanics (predominantly vertical mandible movements in meat eaters) and phytolith content in plants (more abrasive particles in vegetarian diets). The variability found has been used in a multivariate analysis as a base to compare the microwear pattern of a sample of 20 Middle and Upper Pleistocene fossils, mainly from Europe, analyzed with the same methodology. The sample includes specimens usually classified as archaic H. sapiens (Broken Hill, Banyoles, Montmaurin, La Chaise-Suard, La Chaise-Bourgeios et Delaunay), Neanderthal (La Quina V, Gibraltar 2, Tabun 1 and 2, Amud 1, Malarnaud, St. Cesaire, Marillac), and anatomically modern H. sapiens (Skhül 4, Qafzeh 9, Cro-Magnon 4, Abri-Pataud, Veyrier, La Madelaine, Rond-du-Barry). Results indicate that some of the Neanderthal specimens have a microwear pattern close to that of the carnivorous groups (such as Inuit and Fueguians), suggesting that these individuals follow a hunter strategy. In contrast, archaic H. sapiens and H. sapiens sapiens seem to have a more abrasive diet, probably more depending on vegetable materials, than the Neanderthals.