Variability of a dental morphological trait.

A study of morphologic variability was made for maxillary incisor lingual fossa depth. The problem of variability is discussed, and new methods for the statistical treatment of variability are presented. Possibly, the best procedure to express biologic variability is to present SDs, CVs, Xs, ranges, RCs, and the logarithmic graphic method of the relationship between CV and X. No sex differences in variability could be demonstrated. Maxillary centrals and laterals in the Eskimo were found to have relatively equal variability. This is seen in connection with the great functional demand on Eskimo incisors, giving less reduction of the laterals, a possible simultaneous commencement of calcification for I1sup and I2sup, and possible genetic drift. Comparison of variability for six populations shows no racial differences in variability. Variability is not found to increase with inbreeding. Population comparisons do not confirm little reduction in the Eskimo to be associated with high variability. Genetic drift might be the explanation of the homogeneity of maxillary incisor lingual fossa depth in East Greenland Eskimos.