Incidence and Prevalence of Left handedness in a Nigerian sub-population

Abstract

Left handedness is controlled by both genetic and environmental factors. Its occurrence has some advantages in the society. There is usually low prevalence of left handedness and variations exist in its frequency from different populations. The present survey is designed to examine the incidence and prevalence of left handedness among different age groups in two geopolitical zones in Nigeria. This study also presents information on difference in incidence between male and female Nigerians sub-population examined. We determine to extend current knowledge on how Nigerians sub-population varies genetically with regards to distribution of left-handedness alleles. A total of 2704 individuals participated in the survey and they include 450 families of which 250 were recruited from Kwara, North-central and 200 from Lagos South-west Nigeria participated in this study. Statistical Package Social Sciences software (SPSS) Version 16 was used to analyse data the overall incidence of left handedness in the two geopolitical zones studied was 12.2%. The incidence of left handedness in Lagos (20.1%) was almost four times higher than what was recorded in Kwara state (5.4%). In Kwara, incidence of left handedness in males (5.8%) was significantly higher than that of females (4.7%) (χ²= 0.706, df= 1 p= 0.401). Similar statistically significant findings was observed in Lagos where incidence of 21.9% and 18.4% were recorded for male and female respectively (χ²=2.32, df= 1 p= 0.128). The findings from this study provide information on left handedness in two geopolitical zones in Nigeria. It will be useful to population geneticists and anthropologists with respect to population studies.