One particular group of hormones released from the body selectively triggers our sense of smell. These pheromones cause the brain to process body odors differently than other smells. Instead of simply activating the olfactory bulb — the group of neurons that integrate smell — body odors also trigger the emotional and attentional circuits in the peripheral areas of the brain. Now, Bettina Pause’s lab at the University of Dusseldorf has uncovered evidence that the clusters of neurons activated by body odors depends on what made the person sweat in the first place.

By placing cotton balls under the armpits of college-age volunteers, the Pause Lab collected sweat samples from a group of participants while they prepared for a stressful school exam (anxiety condition) on one day or while they pedaled effortlessly on a stationary bicycle (passive exercise condition) on another.

Both experimental conditions made the volunteers sweat, yet completely changed the way certain hormones were released into the body. During the anxiety condition, cortisol and testosterone levels spiked. Mindlessly pedaling on a bike was somewhat calming, causing both testosterone and cortisol levels to drop.

Cortisol and testosterone are two particularly important hormones during competition. Their levels fluctuate depending on an athlete’s state of mind, and they may even predict the winner before the competition begins.

Researchers collected the sweat from the cotton balls and gave a different group of participants a whiff. Most of the time, the subjects didn’t notice any sort of smell, yet their brains told a different story.

When people sniffed the sweat from anxious volunteers, fMRI scans revealed that certain areas of the brain activated, areas believed to be responsible for empathy — the notion of identifying with someone else’s emotional experience. Conversely, when the subjects smelled the sweat of leisurely exercising volunteers, the empathetic centers of the brain were silent.

Taken together, these results suggest that the cortisol- and testosterone-laden sweat from nervous colleagues may have subconsciously primed the emotional areas of another person’s brain, without them even knowing it.

While this study is preliminary, one can speculate on the consequences of empathizing with a competitor’s anxiety during competition. Other studies have shown that when someone experiences empathy, there’s a large increase in the release of yet another hormone, oxytocin. The poster-child, feel-good hormone for explaining everything from parent-child bonds to the more general ideals of human social connections, oxytocin is often called the “trust hormone.”

In humans, increased oxytocin levels have been correlated to altruistic competition and
increased generosity, both characteristics of good sportsmanship. Though the participants still fiercely competed with each other, there was no “offensive aggression” displayed toward rival groups.

So next time you’re watching a classic fight, think how the smell of victory really can lead to the agony of defeat.

Citation: Prehn-Kristensen, A., Wiesner, C., Bergmann, T., Wolff, S., Jansen, O., Mehdorn, H., Ferstl, R., & Pause, B. (2009) Induction of Empathy by the Smell of Anxiety. PLoS ONE, 4(6), e5987. DOI: 10.1371/journal.pone.0005987

Photo: Flickr/polinasergeeva, CC

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Authors: Brian Mossop

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