Why Do We Fear?

Fear is one of the earliest emotions to have evolved. Most vertebrates – and possibly some invertebrates – show fear when they are threatened. At its most core, fear keeps us alive, helping us flee from predators or avoid dangerous environments. But why does this process sometimes backfire, leaving us paralysed by otherwise harmless phobias? And why do so many people deliberately seek out fearful situations, from horror movies to parachute jumps, when instinct tells us to do the opposite? Can understanding the biology of fear help us conquer it, or simply make us more vulnerable to its impact?