Humans may be able to communicate positive emotions like happiness through the smell of their sweat, according to a new research.

The findings suggest that we produce chemical compounds, or chemosignals, when we experience happiness that are detectable by others who smell our sweat.

While previous research has shown that negative emotions related to fear and disgust are communicated via detectable regularities in the chemical composition of sweat, few studies have examined whether the same communicative function holds for positive emotions.

“Our study shows that being exposed to sweat produced under happiness induces a simulacrum of happiness in receivers, and induces a contagion of the emotional state,” said psychological scientist Gun Semin of Utrecht University in the Netherlands, senior researcher on the study.

“This suggests that somebody who is happy will infuse others in their vicinity with happiness. In a way, happiness sweat is somewhat like smiling - it is infectious,” Semin said.

Semin and colleagues examined whether sweat taken from people in a happy state would influence behaviour, perception, and emotional state of people exposed to the sweat.

The researchers recruited 12 Caucasian males to provide the sweat samples for the study.

They watched a video clip intended to induce a particular emotional state (fear, happiness, neutral) and they also completed a measure of implicit emotion, in which they were asked to view Chinese symbols and rate how pleasant or unpleasant each one was.

For the second part of the study, the researchers recruited 36 Caucasian females.

The women were seated in a chair and placed their chins on a chin rest. The vial containing the sweat sample was placed in a holder attached to the chin rest and was opened immediately prior to the target task.

The women were exposed to a sweat sample of each type (fear, happiness, neutral), with a 5-minute break in between samples.

Initial data analyses confirmed that the videos did influence the emotional states of the male participants - men who watched the fear video showed predominantly negative emotion afterward and men who watched the happiness video showed predominantly positive emotion.

Researchers found that women who were exposed to “fear sweat” showed greater activity in the medial frontalis muscle, a common feature of fear expressions.

Women who were exposed to “happy sweat” showed more facial muscle activity indicative of a Duchenne smile, a common component of happiness expressions.

The sweat samples did not seem to impact the women’s ratings on the Chinese symbols task, suggesting that the sweat-based chemosignals did not bias their implicit emotional states.

The research was published in Psychological Science, a journal of the Association for Psychological Science.