Dental asymmetry as a measure of environmental stress in the Ticuna Indians of Colombia.

The magnitude of fluctuating dental asymmetry is reported for a marginally Westernized, horticultural Indian group, the Ticuna of the Region Amazonas, Colombia. Asymmetry is lower than in other Amerindian and Eskimo groups reported to date, which accords with the adequacy and reliability of traditional food sources and complements the claim that protein intake is at or above minimum requirements. Partitioning the variation by sex, arcade, dimension, and tooth discloses several statistically significant effects. Among these: 1) females are proportionately more asymmetric than males; 2) maxillary teeth are more asymmetric than their mandibular counterparts; 3) the mesiodistal dimension is less canalized than buccolingual width in the maxilla, but is more asymmetric in the mandible; and 4) the pattern of asymmetry corresponds closely with the morphogenetic gradients within each tooth field, suggesting that bilaterality provides an additional measure for disclosing underlying genetic and ontogenetic patterns in the dentition.