The Smell of Fear

We all know of fear as an emotion, one that makes your heart race, your breath quicken, and your palms sweat. But a study in 2009 led by Lilianne Mujica-Parodi showed that others’ fear and stress can actually be detected from breathing in their sweat. In the study, sweat samples were taken from skydivers and were compared with the sweat from people in the control group who were simply running on the treadmill. The two different sweat samples were then given to 8 males and 8 females to smell while their brains were scanned using functional magnetic resonance imaging. 

The results showed that when smelling the skydivers’ sweat, the amygdala (the region of the brain associated with emotion) was more active. There was a subsequent study performed where participants smelled either the runners’ or the skydivers’ sweat and looked at pictures of faces, and it turned out that they were able to discriminate between neutral and angry faces better when exposed to the skydivers’ sweat. This is an indication of the amygdala being more vigilant toward potential threats when smelling the sweat from the skydivers, and that their sweat actually gives off stress signals that heightens the amygdala’s awareness.