Evolution

How do you tell when someone's afraid or disgusted? By their face, talking to them, perhaps a noise they've made? A new study suggests you might even be able to smell it.

Communication by scent and chemical signals is widespread in the animal kingdom, but odour has generally been assumed to have no role in human communication. However Gün Semin (Utrecht University, Netherlands) and his team devel

oped a different hypothesis - that bodily secretions (such as sweat) could contain chemicals that activated similar processes in both the sender of the signal and the receiver. In this way, someone could experience fear after exposure to chemosignals of someone already experiencing fear.

To test this hypothesis they collected sweat from two groups of men. One group had seen disgusting videos and the other group had watched scary videos. These men had followed a strict regime over the previous days to avoid contamination. 36 women were then unknowingly exposed to either fear or disgust sweat while doing a visual task (the study used women as receivers because previous research indicates women are more sensitive to a man's scent than vice versa). As predicted, those exposed to fear sweat produced a fearful facial expression and those exposed to disgust sweat pulled a disgusted face.

These findings do suggest that scent has a role in human communication, at least of some emotions. They also suggest we can become "emotional synchronized" with others without our awareness. The researchers wrote this finding could help explain how emotions spread in crowds.

Photo credit: Daniel Arsenault/Getty.

For more reading:
http://www.livescience.com/24578-humans-smell-fear.html

http://www.psychologicalscience.org/index.php/news/releases/the-knowing-nose-chemosignals-communicate-human-emotions.html