There is No Sex-, Handedness-, and Hand Grip Strengthrelated Dimorphism in Digit Ratio in both Sedentary and Athletic African Young People
Author(s): Abdulhakim Masari Aminu, Chidinma Nmesoma Udeze, Hauwa Samaila, Nabila Danzaria Yahya, Mariam Salako, Senol Dane*
Introduction: The ratio of second-to-fourth digit length (2D:4D) is sexually dimorphic and is generally higher in females compared to males. Digit ratio is believed to be a marker of prenatal testosterone exposure, and is related to physical strength. Lower 2D:4D is associated with greater physical strength, better sporting performance and a propensity towards jobs demanding greater physical ability. Very recently, emerging data have shown absence of digit ratio in some ethnicities and geographical regions of the world. However, there is lack of data about digit ratio in African population. To this end, we investigated the sex- and handedness differences in digit ratio in African people.
Methods: 233 healthy young participants volunteered for the study. Of them, 125 were males (average age-19.31 years) and 108 were females (average age-17.79 years) with all between ages 16 and 25 years. Handedness was determined using the Edinburgh Handedness Inventory. The lengths of the 2nd and 4th fingers were determined using electronic digital caliper. Hand grip muscle strength was recorded using electronic dynamometer of PowerLab 26T (AD Instruments, Bella Vista, Australia).
Results: There was no significant sex and handedness related difference in both right and left hand digit ratios. Athletes had no significantly lower digit ratio than sedentary subjects and there was no significant correlation between digit ratios.
Conclusion: Sexual dimorphism and handedness related differences in digit ratio are not universal in humans.