Handedness, Eyedness, Footedness, Crossed Dominance and Digit Ratio in Nigerian People
Author(s): Nuhu M Abubakar, Fatima T Nasir, Oluwaferanmi H Lojede, Jamila Adamu, Aisha M Zagi, Uduakobong A Nyong, Muhammed J Saka, Senol Dane*
Background: Proxy measures of cerebral lateralization such as handedness, eyedness, footedness and crossed dominance are associated with digit ratio. Cerebral lateralization and digit ratio are believed to serve as potential biomarkers of effectiveness of performance in several spheres of human endeavors, and are also related to development of certain diseases that affect mankind. Both cerebral lateralization and digit ratio vary with different genders, ethnic groups and geographical locations. There is lack of data on digit ratio and cerebral lateralization among the Nigerian people. Furthermore, gender differences in digit ratio and cerebral lateralization are not known in the Nigerian population. The aim of this study was to investigate the gender differences in handedness, footedness, eyedness, and digit ratio among young Nigerian people. The effects of crossed dominance on digit ratio for right and left hands were also investigated.
Methods: A total of 107 Nigerians (52 males and 55 females, age range: 17-27 years) volunteered for the study.
Results: The percentage of left handedness was higher in males, whereas females had higher percentage of right handedness. There was no gender difference in eyedness, footedness and digit ratio. Digit ratio for the right hand was higher in subjects having crossed hand-eye dominance, while the left hand digit ratio was higher in subjects having crossed handfoot dominance.
Conclusions: Among the proxy measures of cerebral lateralization, Nigerians showed gender variation for handedness only. Gender differences in digit ratio and cerebral lateralization are not universal across nationalities or geographical regions.