Anthropometric predictors for sexual dimorphism of skulls: A Comparative study
Abstract
Quantitative morphometric measurements with advanced analytical methods are emerging as reliable methods for sex differentiation of skeletal remnants. Aim of present study was to determine the difference in morphometric measurements in male and female skull and to determine the independents predictors and accuracy for sex differentiation using discriminant function analysis. A comparative observational study was conducted using 44 skull of known sex including 24skulls of males and 20 skulls of females. Various morphometric parameters are measured and analyzed using univariate, multivariate and discriminant function analysis. Cranial AP length, Bi Zygomatic diameter, Nasal Height, Nasal width and Mastoid length were found to be significantly higher in male skull. Discriminant function analysis predicted correctly the sex of skull with 79.5% accuracy. Morphometric measurement of cranium can be developed as objective method of sex determination with higher accuracy and repeatability and further enhanced by advanced statistical method like discriminant function analysis.
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Introduction
Anthropometry is a Greek word which means measurement of man: anthropos-man and metron-refers to the measurement. Anthropometry is a science which deals with the measurement of human beings, whether living or dead or of skeletal materials and constitutes a series of systematized measuring techniques of expressing quantitatively the form of the human body and skeleton. 1
Study of human skeleton for sex determination has been a topic of interest among researchers,2 as bones of the body are last to perish after death, next to enamel of teeth. Almost all bones of the human skeleton show some degree of sexual dimorphism. Sex of an individual can be identified accurately in 80% of cases using skull alone and in 98% cases using pelvis and skull together. The sex is best assessed from the pelvis but it is very often damaged. 3 Skull is the main reliable bone exhibiting sexually dimorphic traits, because skull is highly resistance to adverse environmental conditions over time, resulting in the greater stability of dimorphic features as compared to other skeletal bony pieces. 4 Skull requires the most frequent sexing in medico legal cases. 4
In the skull, Mastoid region is one of the most dimorphic traits; 5,6 the temporal bone is highly resistant to physical damage; thus it is commonly found as remainder in skeletons that are very old; of this, the petrous portion has been described as important for sex determination. Moreover, in case of burning, petrous part of temporal bone is generally preserved because of its compact structure and protected position at the base of skull. 7,8
Previous studies by non-metrical methods used morphological traits which were not reliable because these features varied with nutrition, race, geographical regions and observer variation. 9
Conclusion
Sex determination using morphometric measurement of cranium provides objectivity with higher accuracy and repeatability and advanced statistical method like discriminant function analysis further enhances it. The parameters like nasal height, nasal width and mastoid process length can be used as predictors to determine gender. Also gender differences in cranial morphology emphasize the significance of applying these data to an individual subject in a given population. Such knowledge is not only applicable to forensic scientists but also in plastic surgery and oral surgery with craniofacial deformity. Results of this study will be of immense use in forensic medicine and anthropology and will also serve as a future framework for estimating the craniofacial dimensions of other Indian population.