Preliminary study on sexual dimorphism of metric traits of cranium and mandible in a modern Italian skeletal population and review of population literature

This study aims to assess the sexual dimorphism of skull in a modern skeletal collection through a direct anthropometric methodology by using a logistic regression analysis as statistical approach in order to provide specific regression formulae for the Italian population. Thirtyfour measurements (24 from cranium, 10 from mandible; 33 linear distances, one angle) were taken on 80 individuals (40 males, 40 females). A stepwise discriminant function analysis selected the combination of variables which best discriminated between sexes, and a cross-validation assessed the accuracy rate of the original sample. Most distances resulted longer in males than in females, but differences were statistically significant only for 12 and 6 out of respectively 24 cranium and 10 mandibular distances. Five combined cranium features returned a prediction accuracy of 88.6% (y = -81.01 + 0.14* Maximum cranial length + 0.16* Basion-bregma height -0.05* Cranial base length +0.20* Bizygomatic breadth +0.31* Nasal height; adjusted R-2 = 47.0%). Nine mandibular features were required to reach 74.7% accuracy (y = -93.08 + 0.19* Bigonial width +0.14* Bicondylar breadth +0.11* Mandibular length +0.18* Height of the mandibular body at mental foramen +0.21* Chin height -0.09* Mandibular angle -0.06* Minimum ramus breadth -0.05* Maximum ramus height -0.01* Maximum ramus breadth; adjusted R-2 = 23.92%). Current results and existing literature suggested that only few cranial measurements can be used for diagnosis of sex: the same variables showed similar accuracy in different ethnic contexts. In conclusion, some aspects of sexual dimorphism of skull seem to be independent from ancestry.