The mysterious contents of the skull have long captivated their owners.
Ancient Egyptians treated brain injuries by pouring milk in both ears. Aristotle believed the brain was a cooling unit for the heart. Galen, the leading physician of the Roman Empire, claimed that “animal spirits” imbued the brain with its abilities.
These ideas were a product of limited tools and unscientific preconceptions. As scientists have developed more sophisticated methods and ideas, their understanding of how the brain works has shifted too.