Sex-specific asymmetries in communication sound perception are not related to hand preference in an early primate

Background  

Left hemispheric dominance of language processing and handedness, previously thought to be unique to humans, is currently under debate. To gain an insight into the origin of lateralization in primates, we have studied gray mouse lemurs, suggested to represent the most ancestral primate condition. We explored potential functional asymmetries on the behavioral level by applying a combined handedness and auditory perception task. For testing handedness, we used a forced food-grasping task. For testing auditory perception, we adapted the head turn paradigm, originally established for exploring hemispheric specializations in conspecific sound processing in Old World monkeys, and exposed 38 subjects to control sounds and conspecific communication sounds of positive and negative emotional valence.