|Year : 2019 | Volume
| Issue : 4 | Page : 173-176
Sexual dimorphism in right and left orbital fossa measurements from adult human skulls from an eastern Indian population
Ritwik Ghosh1, Soumeek Chowdhuri2, Somnath Maity3
1 Calcutta National Medical College, Kolkata, West Bengal, India
2 Department of Forensic and State Medicine, Calcutta National Medical College, Kolkata, West Bengal, India
3 Department of Forensic and State Medicine, Midnapore Medical College, Midnapore, West Bengal, India
|Date of Submission||20-Jul-2019|
|Date of Decision||09-Sep-2019|
|Date of Acceptance||25-Oct-2019|
|Date of Web Publication||11-Dec-2019|
Department of Forensic and State Medicine, Calcutta National Medical College, Kolkata, West Bengal
Source of Support: None, Conflict of Interest: None
In forensic anthropology, the pelvis is the most reliable indicator of sex, followed by the skull, with several studies having used the morphometry of the orbital aperture of dry skulls to estimate sex. However, age, sex, ancestry, and evolutionary periods cause variations in orbital characteristics. In this study, we analyzed measurements of orbital fossa from adult human craniums and employed discriminant function analysis to establish a model to predict sex. A manual Vernier caliper was used to obtain measurements of the left and right orbital fossa. On comparing the measurements (including mean, minimum, and maximum), we found that all the dimensions were greater in males than in females. Wilks' lambda for the sex-discriminating model was 0.533, signifying a moderate discriminating power. The discriminant function equation was: df = −10.274 × right orbit width + 13.44 × left orbit width − 7.982 × right orbit height + 7.694 × left orbit height − 12.234 (constant). The cutoff point was (90.567− [−1.512])/2 = 1.0395. Therefore, above this value of 1.0395, cases were predicted to be male, while below it, they were predicted to be female. Orbital aperture measurements can play an important role in estimating sex from dry craniums. Orbital measurements could be a useful adjunctive test for sex estimation in forensic practice.
Keywords: Anthropology, forensic, orbital fossa, sex
|How to cite this article:|
Ghosh R, Chowdhuri S, Maity S. Sexual dimorphism in right and left orbital fossa measurements from adult human skulls from an eastern Indian population. J Forensic Sci Med 2019;5:173-6
|How to cite this URL:|
Ghosh R, Chowdhuri S, Maity S. Sexual dimorphism in right and left orbital fossa measurements from adult human skulls from an eastern Indian population. J Forensic Sci Med [serial online] 2019 [cited 2020 Jul 3];5:173-6. Available from: http://www.jfsmonline.com/text.asp?2019/5/4/173/272720
| Introduction|| |
In forensic anthropology, the identification of sex from skeletal remains can be a very important task. While the pelvis is the most reliable indicator of sex, previous studies indicate that it is followed by the skull.,,,
Traditionally, sex estimation from skeletal remains depends on visual assessments of sexually dimorphic traits. Using visual morphological traits, Rogers determined sex in a historic skeletal collection with 89.1% accuracy. According to Krogman andIscan, the skull can be used to accurately identify the sex of an individual in 90% of cases, while the use of both the pelvis and the skull resulted in 98% of cases being accurately classified.
Several studies have used orbital aperture morphometry to estimate the sex of dry skulls.,,,,,,,, The orbit is a structure that is superficially accessible and easy to measure. Orbits show significant sexual dimorphism among parts of the skull, with male orbits being characteristically squarer and relatively smaller, while female orbits are rounder and comparatively larger.,, However, age, sex, ancestry, and evolutionary periods cause variation in the orbital characteristics.,,,
Discriminant analysis of skeletal measurements requires high measurement precision. However, the accurate measurement of the skull is quite difficult. For these reasons, we attempted to conduct discriminant function analysis on the dimensions of right and left orbital fossa of adult skulls, to determine sexual dimorphism in an eastern Indian population.
| Methodology|| |
This study was conducted at the Department of Forensic and State Medicine, Calcutta National Medical College (CNMC) and Midnapore Medical College. This study was performed on a collection of skulls prepared from individuals belonging to the same geographical area and of the same ethnical lineage. The study samples consisted of 99 crania (72 males and 27 females) from the collection housed at the Museum of Department of Forensic and State Medicine, CNMC and Midnapore Medical College. The skull bones from both sexes were kept separate, as sexual determination was performed beforehand and confirmed by forensic experts. The crania used in this research were chosen for the following criteria: all were complete, with visible sutures, and determined to be of adults. Crania with broken bones and other malformations were excluded.
For this study, a manual Vernier caliper was used, with an accuracy of within 1.0 mm. The orbit height and width (maximum) were measured from the left and right orbital fossa [Figure 1]. Ethical clearance was obtained from the Ethics Committee of Calcutta National Medical College. Data analysis was performed using SPSS software (IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp.).
|Figure 1: Image of a skull showing orbital height and width of the orbital fossa|
Click here to view
| Results|| |
Of the 99 skull bones analyzed, 72 were of male adults and 27 were of female adults. We found intra-observer error to be 0.96 and inter-observer error to be 0.93 (Cohen's Kappa). In males, the mean right orbit width was 4.2875, range 4–5; the mean left orbit width was 4.2875, range 4.0–4.8; the mean right orbit height was 3.675, range 3.2–4.1; and the mean left orbit height was 3.7125, range 3.1–4.1. In females, the mean right orbit width was 4.2, range 4.0–4.4; the mean left orbit width was 4.0667, range 3.8–4.4; the mean right orbit height was 3.6, range 3.4–3.8; and the mean left orbit height was 3.6333, range 3.4–4.0.
Comparisons of the measurements [mean, minimum, and maximum values; [Table 1] showed that all dimensions were greater in males than females. ANOVA tests showed no significant differences between left- and right-side dimensions.
|Table 1: Measurements of orbital height and width according to sex (n=99)|
Click here to view
Discriminant function analysis was performed on the study variables with sex as the grouping variable. Receiver operating characteristic curve analysis was first performed on the variables to determine their discriminating power. Wilks' lambda for the model was 0.533, signifying a moderate discriminating power, as shown in [Table 2]. The relative contribution of each variable to the discriminant equation is shown in [Table 3]. The discriminant function equation was: df = −10.274 × right orbit width + 13.44 × left orbit width − 7.982 × right orbit height + 7.694 × left orbit height − 12.234 (constant). The cutoff point was (0.567− [−1.512])/2 = 1.0395, as shown in [Table 4]. Therefore, above this value of 1.0395, cases would be classified as male, and below it, they would be classified as female. Overall 81.8% of the samples were correctly classified by the model, as shown in [Table 5]. Cross-validated results showed 81.8% of the cases to be correctly classified by this model. After the results were used to obtain a discriminant equation, the formula was used on a separate sample of 20 cases to validate the results.
| Discussion|| |
Measurements of orbital aperture can play an important role in cases of sex estimation. According to our results, the parameters used in our study showed similar usefulness to traditionally employed visual assessments, as they gave similar predictive values. At 81.8%, the accuracy of our study is quite high and is comparable with the 79% accuracy shown by Cunha and van Vark and the 84%–88% accuracy shown by Walker, as well as many other studies giving accuracy percentages ranging from the seventies to the mid-eighties. Our quantitative method is superior to subjective visual methods as it reduces the possibility of inter-observer variation. Therefore, it is more suitable for courtroom admissibility as expert witness testimony. Furthermore, the Vernier calipers needed for conducting these measurements are cheap and easy to use. Thus, this is an easily accessible and efficient method for determining sex from an unidentified human skull.
Our study showed that all the orbital dimensions measured were greater in males than in females. This is in congruence with the findings of Ghorai et al., except in the case of maximum height of the orbital aperture, which showed no significant between-gender difference in their study. Nitek et al. and Cheng et al. also concluded that the same dimensions were larger in males than in females in Polish and Chinese populations, respectively. To the contrary, Rajangam et al. reported no significant difference in height and breadth of the orbit between the two genders in an Indian population. Our findings are also similar to those of Rossi et al., who used the Caldwell radiographic technique to show that orbital width in a Brazilian population was larger in males than in females.
Adult skull bones from an eastern Indian population were used in our study, and the values of the study variables varied from those of other studies conducted in other ethnic populations. Fetouh and Mandour showed slight deviations from our study in an Egyptian population, although the variables were still efficient for sex discrimination purposes. In their study on an Egyptian population, the mean right orbital height was 35.68 mm, the mean left orbital height 34.99 mm, the mean right orbital width 43.19 mm, and the mean left orbital width 42.3 mm. In comparison with these findings, a study on a Sudanese population by Elzaki et al. showed mean right orbital height of 37.9 mm, mean left orbital height of 37.86 mm, mean right orbital width of 34.1 mm, and mean left orbital width of 34.06 mm. A study conducted by Ji et al. in a Chinese population found mean right orbital height of 33.45 mm, mean left orbital height of 33.28 mm, mean right orbital width of 39.1 mm, and mean left orbital width of 38.94 mm. When the parameters of the left and right orbits were used separately, the discriminating power of the model was significantly reduced, as seen from the value of Wilks' lambda and the cross-validation tables. Therefore, despite the left and right side measurements showing no significant differences, we used both to achieve better discriminating power in the predictive model. We conclude that orbital measurements can be a useful adjunctive test for sex estimation in forensic practice.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]