Morphological and anatomical variations in subcortical anatomy between humans and chimpanzees associated with...

There has been significant research on cortical reorganization in human evolution, but much less is known about the reorganization of subcortical circuits, key partners of the cortex. Here, using advanced image analysis and comparative neuroimaging, we systematically map organizational differences in striatal, pallidal, and thalamic anatomy between humans and chimpanzees. We relate interspecies differences-proxies for evolutionary change-to genetics and behavioral correlates in humans. We show highly heritable morphological measures are expanded across species, contrasting previous cortical findings. Multivariate techniques identified morphological-cognitive latent variables linked to striatal expansion and affective variables specifically associated with conserved thalamic and pallidal regions. Our results confirm that regions tied to higher-order cognitive functions are expanded in humans, whereas regions linked to lower-order limbic functions are conserved. These findings provide new insights into subcortical architecture. Additionally, we developed tools to map neuroimaging data across species, a prerequisite for quantitatively translating animal neuroanatomy to humans.