Behavioral and neuroanatomical correlates of white matter asymmetries in chimpanzees (Pan troglodytes).

Although behavioral and brain asymmetries have been documented in non-human primates, lateralization in cortical connectivity as reflected in white matter has not been described in any species, despite the intrinsic theoretical interest in white matter expansion during primate brain evolution. Here we report evidence of population-level leftward asymmetries in the white matter of chimpanzees. We further report that lateralization in white matter correlates with their handedness as well as neuroanatomical asymmetries in the precentral gyrus. These findings suggest that chimpanzees show asymmetries in cortical connectivity and these may serve as the foundation for morphological and behavioral laterality in primates, including humans.