Abstract
Frequency-dependent selection is an important process in the maintenance of genetic variation in fitness. In humans, it has been proposed that the polymorphism of handedness is maintained by negative frequency-dependent selection, through a strategic advantage of left-handers in fighting interactions. Using simple mathematical models, we explore: 1°) whether it is possible to predict the range of left-handedness frequencies observed in human populations by the frequency and the violence of fighting interactions; 2°) the consequences of the sex differences in the probability of transmission of hand preference to offspring. We show that a wide range of values of the frequency of lefthanders can be obtained with realistic changes of the parameters values. Our models reinforce the idea that negative frequency dependence may have played a role in maintaining left-handedness in human populations, and provide further support for the importance of fighting interactions in the evolution of hand preference. Moreover, they suggest an explanation for the occurrence of left-handedness among women in this context, namely an indirect selective advantage through their male offspring.