Evolutionary perspectives on the development of the mammalian cerebellum: From cellular diversity to gene regulatory programs.

During mammalian evolution, the cerebellum has diversified in size and morphology and broadened its roles from motor control to higher-order cognitive and emotional processing. To understand how cerebellar form and function have evolved, it is critical to investigate the underlying molecular and developmental mechanisms. Recent advances in single-cell genomics now allow high-resolution tracking of cellular dynamics, gene expression, and regulatory programs in complex tissues. This presents an opportunity to integrate genome-wide data to the long tradition of research on development and evolution of the cerebellum, started by the foundational comparative histological work of Ramón y Cajal on brain cell types and Olof Larsell on cerebellar anatomy. Focusing on single-cell genomics approaches, this chapter explores emerging insights into how cerebellar cell types and their developmental programs have evolved across mammals. While the emphasis is mammalian, key insights from other vertebrates are included to provide evolutionary context.