Temporal variations in basicranium dimorphism of North Indians.

In recent years, several investigations have documented notable secular changes in human skull morphology. The present study is the next link in the series, addressing its possible effects in the cranial base in North Indian populations. The present study aims to examine the sexual dimorphism in cranial base of two temporally different samples of North Indian population to provide updated population specific osteometric standards. The contemporary and the subrecent samples are comprised of 158 (M 110; F 48) and 325 adult crania (M 206; F 119), respectively. Five variables of cranial base were measured, and data were subjected to discriminant function analysis using SPSS 16.0. The t-tests between the two temporally different samples showed significant sexual dimorphism and population variation. Contemporary females showed comparatively greater dimensions than subrecent. Contemporary population exhibited less sexual dimorphism than subrecent population. Factors associated with the changes in sexual dimorphism are likely to be a consequence of improved nutrition and population admixture in last 50 years. The accuracy of sex prediction ranged from 48.1 to 70.0 % in contemporary sample and 60.9 % to 77.2 % in subrecent sample. Overall, these findings support the conclusion that sexual dimorphism shows variation within few decades, so sex discriminating osteometric standards must be updated regularly.