Genetic influence on the expression of hand preferences in chimpanzees (Pan troglodytes): Evidence in support of the right-shift theory and developmental instability

Genetic mechanisms have been proposed to explain the pervasive representati on of right-handedness in humans, whereas random, nongenetic factors have b een posited to explain the lack of population-level right-handedness in non human primates. We report evidence that hand preferences in chimpanzees are heritable, even among related individuals raised in different environments . Furthermore, we report that the degree of heritability is modified by fac tors associated with developmental instability, notably, offspring parity. The data are interpreted to reconcile both genetic models for handedness an d hypotheses suggesting that developmental instability influences variation in handedness.