Digit ratio (2D:4D) – A forensic marker for sexual dimorphism in North Indian population

Abstract

BackgroundIn the analysis of mutilated remains encountered in case of war or in case of natural or unnatural calamities, the assessment of sex is foremost vital element when rendering identity profile of an individual. 2D:4D digit ratio (2D=index finger, 4D=the ring finger) has been proposed as sexually dimorphic phenotypic trait. The paucity of literature on the issue of sexual dimorphism from digit ratio (2D:4D) has prompted the author to conduct the research work. AimThe purpose of the study is to determine sexual dimorphism from digit ratio (2D:4D) in North Indian population. Materials and methods300 participants (141 males & 159 females) of North Indian population specifically from Kumaon region of Uttarakhand were recruited for the research study. Participants ranged in age from 18 to 60years. Index finger length (2D), ring finger length (4D), 2D:4D digit ratio (2D/4D) and sectioning point were estimated for both the right and left hands. SPSS statistical software was used for data interpretation. ResultsMales have significantly longer index and ring finger length than females. Sex differences in the length of ring finger are larger than index finger. Again Males show significantly lower mean 2D:4D digit ratio (0.968) as compared to females (1.014). With respect to handedness sex differences were found slightly higher for right hand than left hand. The study suggests that ratio below and equal to 0.99 is suggestive of male sex for both hands, while a ratio of more than 0.99 is suggestive female sex for both the hands. This cut-off accurately determines 93% males and 90% females for right hand and 87% males and 84% females for left hand. The study shows precisely very large sex effect with d values=−1.81(right hand), thus 2D:4D proves to be appropriate for sex determination in medicolegal investigations. ConclusionThis research study proves beneficial for identity authentication, for criminal investigation and a powerful forensic tool for medico – legal cases. This will help in the advancement of technology which will prove beneficial for the welfare of indigenous population of India. Also the data so collected can be useful as forensic anthropology population data.