Exploring dental macrowear in a Sambaqui population from Encosta da Lagoa (southern Brazil): variation patterns and an extreme case of molar wear verticalization

Shell mound (Sambaqui) societies of coastal Brazil are traditionally interpreted as marine-oriented fisher-hunter-gatherer groups; however, the extent to which intra-community behavioural variability structured daily activities remains insufficiently explored. This study presents a dental analysis of the human assemblage from the Encosta da Lagoa site (Santa Catarina, Brazil), a Holocene shell mound dated between 3126 +/- 35<^>14C years BP (3385-3206 cal BP) and 3045 +/- 35<^>14C years BP (3345-3066 cal BP). The sample set includes a minimum of 24 adults and 17 subadults recovered from a mixed funerary context for age and sex. In fact, anthropological and proteomic analyses confirm the presence of both sexes. Dental pathology and wear patterns were examined macroscopically and microscopically to assess dietary and behavioural factors. Caries prevalence is low (2.45%), whereas dental calculus is highly frequent (52.09%), consistent with protein-rich coastal diets typical of Sambaqui populations. Most individuals exhibit moderate to severe generalized tooth wear. However, a small subset displays unusual morphological patterns, including molar verticalization, lingual tilting, interproximal spacing, root incorporation into the occlusal plane, and hypercementosis. One adult male (30-35 years) shows near-complete reorientation of the mandibular molars along their long axis. Microscopic analysis reveals wear features compatible with controlled, repetitive extramasticatory mechanical activities. Cultural explanations such as labret use are unsupported, and dietary abrasiveness alone cannot explain the localized distribution of these features. Instead, the evidence suggests prolonged extra-masticatory use of posterior teeth, plausibly related to repetitive manipulation of fibrous materials, likely related to coastal production activities. These results indicate behavioural specialization within the community, highlighting differentiated labour practices in Sambaqui societies.