The most common specific phobia is acrophobia, also known as the fear of heights (Zutt, 1952). It is no wonder that acrophobia is the most common specific phobia, as almost everyone has a fear of heights when they start crawling as an infant. This natural fear of heights that develops when an infant starts to crawl is protective to the infant, as crawling to the edge of a sharp drop-off induces significant anxiety to prevent the infant from falling.
Reference:
[Acrophobia, the most common phobia]. Zutt J. J Nerv Ment Dis. 1952 Dec;116(6):789-93.
