This study documents and interprets patterns of identity in relation to tooth ablation patterns at Yoshigo, a Late/Final Jomon period (3500–2500 yBP) site. Two patterns of tooth ablation are observed among the Yoshigo people: both (2) mandibular canines or four (4) mandibular incisors were extracted during life and formed a basis for identity differentiation. Three hypotheses are tested regarding these groups: (1) tooth ablation groups will be unrelated to postmarital residence; (2) tooth ablation groups will be associated with age-based achievements; (3) tooth ablation groups will be associated with occupational specialisation. Biodistance, demographic and stable isotope analyses were performed on skeletal remains recovered from Yoshigo (3500–2300 BP) to test these hypotheses. Within-group variation expressed by cranial and dental measurements was not significantly different between tooth ablation groups. This indicates that tooth ablation practices were not related to migration. Previous biodistance findings do, however, suggest that tooth ablation groups represent closely related individuals, possibly kin-based networks. Demographic analysis of age-at-death and tooth ablation suggests that tooth ablation styles were achieved at different ages. Stable isotope analysis indicates that the tooth ablation groups consumed similar foods. Based on isotopic findings from other sites and archaeological evidence for food sharing among Jomon people, these results suggest that dietary variability between tooth ablation groups was homogenised by cooperative food sharing. The totality of these findings support the hypothesis that the identities associated with tooth ablation were unrelated to migratory patterns, and instead, possibly reflect kin-based social units, where achievement or age acted as a determinant of membership. Copyright © 2010 John Wiley & Sons, Ltd.