Evolution of the cerebellum in hominoids: From macro to micro

The evolutionary expansion of the lateral cerebellum in humans and other hominoids has been suggested to provide the neuroanatomical basis for refined motor behaviors and higher cognitive functions. Functional interpretations of this evolutionary pattern typically assume cytoarchitectural uniformity across species. However, this assumption of absolute cerebellar uniformity has recently been challenged. Here, we discuss how variation in cerebellar microstructural features may refine our understanding of cerebellar evolution and the cerebellum's contribution to the evolution of hominoid cognition. We approach this exploration by examining the apparent mismatch between evolutionary size expansion of the lateral cerebellum and prefrontal cortex in the human lineage. We identify which cerebellar microstructural features would be most useful and feasible to incorporate into evolutionary studies.