Eur J Anat, 17 (4): 243-249 (2013)

Effect of hand preference on second to fourth digit ratio and its role in sexual dimorphism: a study in 300 Haryanvi Brahmins and 300 Kashmiri Pandits

Shveta Swami¹, Tarsem Kumar², Deepak Sharma³ and Subhash Kaushal²

¹Department of Anatomy, BPS Government Medical College for Women, Khanpur Kalan, Dist Sonepat, ²Department of Anatomy, M.M. Institute of Medical Sciences and Research, Mullana (Ambala) and ³Department of Pediatric and Preventive Dentistry, M.M. College of Dental Sciences and Research, Mullana (Ambala), Haryana, India

ABSTRACT The 2nd to 4th digit ratio (2D:4D) is a sexually dimorphic biometric marker, related to prenatal estrogen and testosterone levels in-utero and determined genetically by HOX genes. The prenatal effects of testosterone on development of brain hemispheres are considered as a key factor in etiology of left-handedness. Besides sexual dimorphism, 2D:4D ratio shows significant ethnic and population differences. The aim of the present study is to provide an authentic database on right and left 2D:4D ratios in two different ethnic groups of a particular age and sex, and study its correlation with handedness and sexual dimorphism. The study was conducted on 300 Haryanvi Brahmins (150 each of either sex) and 300 Kashmiri Pandits (150 each of either sex) of the age group of 18 years and above. The values for 2D:4D ratio was calculated for both the hands. Hand preference was established according to Edinburgh Inventory and five hand-preference determination groups were constituted after calculation of laterality score. The results were tabulated and subjected to statistical analysis. Mean values for 2D:4D ratio in both the ethnic groups were found to be higher in females than in males. When the values of 2D:4D ratio were assessed by sex, the values were found to be statistically significant (p<0.001). When relationship between laterality score (indicator of hand preference) and 2D:4D were examined, the values were found to be significant only in Haryanvi Brahmins (males) on the right side.

Keywords: Digit ratio, 2D:4D, Sexual dimorphism, Hand preference