Abstract
Left-and right-handers have coexisted since the Palaeolithic age. Hand preference is heritable. Moreover, there is extensive evidence of an association between left-handedness and several fitness costs. In this context, the persistence of the polymorphism is interesting. Here, we explore the associations between socio-economic status and handedness, analysing data from two large cohorts of adult men and women. Such associations are relevant to an evolutionary approach, as the socio-economic and the reproductive value are related. Our results partly support the hypothesis that left-handers have a socio-economic status advantage, countervailing the health issues. Although the models explain a small proportion of the variance observed, the frequency of left-handedness is significantly higher: (1) among women of higher educational level; (2) among categories of higher income; and (3) among individuals who have a higher position in the company. The importance of these findings for the evolution of the polymorphism of handedness is discussed.