Sex determination using the mastoid process using South Indian skulls

 

Geethika. B¹, Dr. Thenmozhi²

¹BDS-I, Saveetha Dental College, Chennai.

²Head of Department, Department of Anatomy, Saveetha Dental College, Chennai.

 

ABSTRACT:

Sexual dimorphism plays an inevitable role in forensic science. Mastoid process shows evident difference between male and female skulls. This study aims to determine the sex of 50 dry South Indian skulls using mastoid process. Sexual dimorphism using skulls has been quite a task in forensic science. This study aims to contribute towards it.

 

 

 

INTRODUCTION:

Sexual dimorphism in human body composition is evident from fetal life, but emerges primarily during puberty (1). Sexual dimorphism is indispensable for the identification of an individual. Individual bones have been used for identifying sex of the individual 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 (2,3). Skull is the second best area for the determination of sex after pelvis. The skull can be used as a reliable source for determining the sex only after puberty. (4,5)

 

The mastoid process is a classically used indicator of sexual dimorphism in the area of bioarchaeology and forensic anthropology. Variation in size and shape of cranial elements, including the mastoid process, has been found to differ significantly between populations.

 

It is a favourable region for sex determination as its well protected, resistant to damage, and also due to its anatomical position at the base of the skull.(6)

 

Sexual dimorphism is prominent among different mammals, insects, and other species. In most of the species the dimorphism is in size. (7)

 

Determination of the race of the skull before identifying the sex of the skull aids in identifying the sex within that range. South Indian race is rich in ethnic and cultural diversity, and craniofacial growth is influenced by racial, ethnic, sexual and dietary differences.

 

The study aims to contribute the understanding of sexual dimorphism by analysing the dimorphism of the mastoid.

 

MATERIALS AND METHOD:

Fifty dry South Indian skulls of known sex were taken. Skulls that were damaged were excluded from the study. The sample for the study was examined from Department of Anatomy, Saveetha Dental College, Chennai. The measurements were recorded using a digital vernier calliper. The mastoid measurements taken from both sides were averaged and was considered for statistical analysis. The measurements were taken twice by a single observer to prevent errors.

 

Measuring the size of mastoid: (8)

Length x Breadth x Anteroposterior length / 100

 

1.   Mastoid length: The length is measured from an imaginary horizontal line from the lower margin of orbital opening and upper margin of external acoustic meatus known as Frankfort plane to the tip of the mastoid process.

2.   Mastoid breadth: The breadth is measured from the highest point on the medial surface to the point        along the same plane.

3.   Anteroposterior diameter: The Anteroposterior diameter is measured from anterior surface of the mastoid where the tympanic plate meets the mastoid process to the same level on the posterior surface.

 

RESULTS AND DISCUSSION:

The mean mastoid length was found to be 29.48, the breadth was found to be 11.40, the A-P diameter was found to be 18.20 in males.

 

In females, the mean mastoid length was 25.47, the mastoid breadth was 11.59, the A-P diameter was 17.84.

 

 

Table 1: Group statistics for mastoid measurements.

	MALE		FEMALE
	MEAN	S.D	MEAN	S.D	P-Value
MASTOID LENGTH	29.48	3.99	25.47	4.79	0.0682
MASTOID BREATH	11.40	1.70	11.59	3.53	0.8702
A-P DIAMETER	18.20	3.90	17.84	5.26	0.8594
SIZE OF MASTOID PROCESS	63.09	24.70	56.01	30.61	0.5904

 

 

P value and statistical significance:

The mean value of the overall size of the male skull mastoid process is 63.09 and the mean value of female skull mastoid process is 56.01 between the overall size equals to 0.5904.

 

This analysis shows the differences across various parameters with respect to the mastoid process of the different sex. The size calculated by the above formula shows that the male skull mastoid are bigger than the female skull mastoid.

 

CONCLUSION:

Sexual dimorphism is an inevitable parameter in forensics. Though these factors vary from race to race, records on this study adds to the existing evidence and will contribute towards the future studies which might cause a breakthrough in the field of forensics.

 

REFERENCES:

1.     Wells JC. Sexual dimorphism of body composition. Best Pract Res Clin Endocrinol Metab. 2007 Sep;21(3):415-30.

2.     Stone AC, et al. Sex determination of ancient human skeletons using DNA. Am J Phys Anthropol 1996; 99:231-8.

3.     Valdés CG. Antropologia Forense. Madrid: Taller Escuela Artes Gráficas, 1991:569-615.

4.     Ischan MY, Helmer RP. Forensic analysis of the skull in Morphologic and osteometric asses end of age, sex and race from the skull. John Wiley and sons Inc. Publication, New York 1933, p 81-3.

5.     Patil KR, Mody RN, Determination of sex by discrimination function analysis and stature by regression analysis a lateral cephalometric study. Forensic Sci Int. 2005 Jan; 147 (2-3): 175-80

6.     Saavedra de Paiva LA, Serge M. Sexing the human skulls through the mastoid process. Rev Hosp Clin Fac Med Sao Paulo. 2003 Jan-Feb; 58(1): 15-20.

7.     Ashok Samal, Vanitha Subramani, and David Marx. An Analysis of Sexual Dimorphism in the Human Face. Journal of Visual Communication and Image Representation 18 (2007), pp. 453-463; doi:10.1016/j.jvcir.2007.04.010

8.     Larnach SL, Mactonish NWG, The craniology of the aborigines of Coastal New South Wales. The Oceania Monographs. No. 13. 1966; 43-4.

 

 

Accepted on 07.10.2016        © RJPT All right reserved

Research J. Pharm. and Tech 2016; 9(11): 1869-1871