Characteristics and significance of cerebellum`s evolutionary changes, as a part of central nervous system, during the evolution of the human brain:part 1

Abstract

Тhe evolution of the brain, particularly the cerebellum as a key component of the central nervous system, represents a critical focus in modern research across neuroscience, anthropology, psychology, and medicine. Special attention is given to the cerebellum’s role in shaping cognitive, emotional, and social functions, as well as its unique morphofunctional characteristics that have significantly transformed throughout Homo sapiens evolution. These evolutionary changes in the cerebellum enabled the emergence of new adaptive capacities, including optimization of social behavior, cognitive control, motor coordination, and sensory integration. Morphological studies have revealed the cerebellum's increasingly complex structure and functions, providing insight into the development of high-level cognition and behavior. Notably, investigations into HARs (human accelerated regions) suggest a strong genetic influence on cerebellar evolution, highlighting regulatory elements specific to Homo sapiens. The contemporary morphofunctional structure of the cerebellum demonstrates its intricate organization, consisting of multiple lobules and layers, each performing distinct functions. This organization allows the cerebellum to integrate sensorimotor signals, coordinate movement, maintain balance, and participate in non-motor functions such as speech, memory, social cognition, and emotions. Functional asymmetry and interactions with other brain regions are also crucial to understanding neuropsychological processes. Damage to the cerebellum manifests in a wide range of symptoms, from motor discoordination to emotional instability and social dysfunctions. In this context, studying cerebellar evolution holds not only academic but also practical value for diagnosing and treating neuropsychiatric and neurodegenerative disorders. A substantial portion of this study focuses on comparative analysis between the brains of Homo erectus—an important evolutionary link—and modern humans. Changes that occurred during brain globularization affected parietal and cerebellar protrusions, associated with advanced cognitive abilities such as abstract thinking, language, planning, and adaptation to changing environments. These characteristics differentiate Homo sapiens from Neanderthals and earlier hominins. The globular brain shape, which developed between 100,000 and 35,000 years ago, became a defining feature of modern human intellect. Moreover, the increased volume of the cerebellum and its numerous connections with other brain areas contributed to its functional complexity—from fine motor control to social bonding and communication. These aspects played a key role in the emergence of humans as social beings capable of self-awareness, abstraction, creativity, and cultural development. Thus, the cerebellum functions not only as a motor hub but also as a critical center for information integration, enabling cognitive complexity, social interaction, and emotional expression in Homo sapiens, and is essential for understanding the evolutionary roots of the human mind.