Fear, a fundamental human emotion, serves as a critical survival tool, alerting us to potential hazards. However, some individuals lack this capacity, a consequence of rare medical conditions.
Jordie Sarnik from Britain was diagnosed with Cushing’s syndrome in 2005. This condition causes the body to overproduce cortisol, a stress hormone. After undergoing treatment involving adrenal gland removal, Sarnik experienced a complete absence of fear. He rode rollercoasters, jumped from planes, and rappelled from heights without feeling any fear, with his heart rate remaining normal and no signs of anxiety.
In the United States, a woman identified as S.M. presents another case. She suffers from Urbach-Wiethe disease, a rare genetic disorder also known as lipoid proteinosis. This disease destroys the amygdala, the part of the brain that governs fear. Scientists conducted experiments on S.M., exposing her to scary movies, haunted houses, and dangerous animals like snakes and spiders. Despite the frightening stimuli, she never showed fear; instead, she often approached the perceived threats.
S.M.’s behavior is unusual. She tends to get very close to people, including strangers. In an experiment, when asked how close she felt comfortable being to someone, she replied with just 0.34 meters (about one foot), far less than the typical comfort zone. This shows how fear helps regulate social interactions.
S.M. has faced threats involving weapons, but she has never perceived the danger, which sometimes resulted in precarious situations.
Scientists explain that fear functions in two distinct ways: one related to external threats (e.g., a predator) and another related to internal threats (e.g., suffocation). The amygdala is critical for recognizing external dangers, but the brainstem controls internal anxieties, such as the distress caused by carbon dioxide buildup. When S.M. was exposed to carbon dioxide, she experienced intense fear, demonstrating that fear is not exclusively dependent on the amygdala.
Feinstein suggests that an animal without an amygdala would likely die quickly in the wild because it couldn’t recognize dangers. However, S.M. has lived for over 50 years without one. These cases demonstrate that fear protects us from harm while also profoundly impacting our social and emotional behaviors.