Season of birth and handedness in Serbian high school students

We have investigated the effect of season of birth in an epidemiologically robust sample of randomly selected young people (n = 977), all born in the same year. A Kolmogorov-Smirnov type statistical test was used to determine season of birth.Neither the right-handed nor the non-right-handed groups demonstrated birth asymmetry relative to the normal population birth distribution. There was no between-group difference in the seasonal distribution of birth when comparing the right-handed to the non-right-handed groups.The present study failed to provide support for a season of birth effect on atypical lateralisation of handedness in humans.Functional dominance of the right hand is the norm across different populations, various geographical regions, and diverse cultures, with approximately 90% of humans exhibiting clear dominance of the right side of the body. This behavioural characteristic is considered as uniquely human, as there is no other species that displays such a large behavioural asymmetry at the population level. It is also widely accepted that this behavioural feature emerged at some point during the hominid evolution, and that this feature preceded the evolution of another uniquely human feature – language, and in particular, speech as its central component [1].The transmission of handedness over many generations of humans is widely believed to be under genetic control [2-4], rather than resulting from learning. Converging lines of evidence provide support for the genetic hypothesis, including imaging studies on twins [5], meta-analysis of handedness in twins [6], and molecular genetic studies [7,8]. To date, however, no gene for handedness has been identified. Genetic models of handedness [2,3] argue that the functional advantage of the right hand originates from a purely genetic effect, while left-handedness is a consequence of a random shift in hand dominance. Theory suggests that in individuals without the genetic disposition, both cerebral and hand do