You can usually tell when someone is happy based on seeing them smile, hearing them laugh or perhaps from receiving a big hug. But can you also smell their happiness? Surprising new research suggests that happiness does indeed have a scent, and that the experience of happiness can be transmitted through smell, reports Phys.org.

For the study, 12 young men were shown videos meant to induce a variety of emotions while researchers gathered sweat samples from them. All of the men were healthy and none of them were drug users or smokers, and all were asked to abstain from drinking, eating smelly foods or engaging in sexual activity during the study period. 

Those sweat samples were then given to 36 equally healthy young women to smell, while researchers monitored their reactions. Only women were selected to smell the samples, apparently because previous research has shown that women have a better sense of smell than men and are also more sensitive to emotional signaling — though it's unclear why only men were chosen to produce the scents. 

Researchers found that the behavior of the women after smelling the scents — particularly their facial expressions — indicated a correlation between the emotional states of the men who produced the sweat and the women who sniffed them. 

"Human sweat produced when a person is happy induces a state similar to happiness in somebody who inhales this odor," said study co-author Gun Semin, a professor at Koc University in Istanbul, Turkey, and the Instituto Superior de Psicologia Aplicada in Lisbon, Portugal.

This is an intriguing finding because it not only means that happiness does have a scent, but that the scent is capable of transmitting the emotion to others. The study also found that other emotions, such as fear, seem to carry a scent too. This corroborates previous research suggesting that some negative emotions have a smell, but it is the first time this has proved to be true of positive vibes.

Researchers have yet to isolate exactly what the chemical compound for the happiness smell is, but you might imagine what the potential applications for such a finding could be. Happiness perfumes, for instance, could be invented. Scent therapies could also be developed to help people through depression or anxiety.

Perhaps the most surprising result of the study, however, is our broadened understanding of how emotions get communicated, and also how our own emotions are potentially manipulated through our social context and the emotional states of those around us. 

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