Authors : Hengameh Alibeik and S. Abdolhamid Angaji
Abstract: It has been reported the coexistence of both right and left-handed individuals at least since the Upper Paleolithic. There is still today a polymorphism of handedness in humans, in all populations. Left-handers are in the minority and left-handedness seems to be associated with several fitness costs, such as poorer health, lower height or reduced longevity. In this context, the persistence of the polymorphism is interesting and suggests that left-handedness must be associated with enhanced abilities. In humans, it has been proposed that the polymorphism of handedness is maintained by negative frequency-dependent selection (advantage being greater when the frequency of a trait is lower). The frequency-dependent advantage of left-handers in physical fights is strongly suggested by both the study of interactive sports in industrialized societies and a cross-cultural comparison of traditional societies. In western societies, left-handers are supposed to have a socio-economic status advantage. The differences between right and lefthanders socio-economic statuses could be related to their reproductive success, though the importance of socio-economic status in human mate choice directly benefits the offspring.
Hengameh Alibeik and S. Abdolhamid Angaji, 2010. Evolutionary Back Grounds of Human Left Handedness. Research Journal of Biological Sciences, 5: 36-41.