Some reasons for the fear of public speaking include a fear of being singled out and excessive adrenaline. Public speaking ranks as one of the most prominent social phobias, famously shown to be more widely feared than death itself.
Many psychologists suggest that the fear of public speaking traces back to primal instincts from humanity’s cave-dwelling days. A public-speaking situation essentially places the speaker apart from a group, bearing all the attention of an audience. In humanity’s hunting and gathering era, being singled out or set apart from a group meant reduced safety and a lesser chance for survival. Therefore, the ingrained fear of public speaking may, in some sense, be an instinctive reaction to being taken away from the safety of the group. The fear of rejection due to poor public speaking is also a primal fear since being rejected from a group in primitive times meant being forced to survive alone.
For many people, a public-speaking engagement is one of the most dramatic and important experiences in daily life, the modern-day equivalent of a caveman hunting a mammoth. The body understands the importance of the situation, so it generates excess adrenaline, helping the brain and body work faster to succeed. The problem is that while adrenaline was useful for cavemen to perform physical tasks like hunting, it doesn’t do much for verbal tasks, including public speaking. This is what leads to fast talking, increased heartbeat, a racing mind and all the other tics that people associate with public speaking. These physical effects occur because the body doesn’t know what to do with its excess adrenaline.