The blood that can be felt and seen rushing to certain parts of the body, the heart rate speeding up and the pupils dilating – combined, these are very well known and clear signs that a person has aroused sex.
Now sex researchers from the Research Laboratory on Human Sexuality, or SexLab for short, at the University of Porto in Portugal, have come into fruitful contact with a group of researchers from the Max Planck Institute for Chemistry in Mainz and have learned something completely new about sex.
In the joint study, they found that a person’s sexual arousal can also be observed in another way: through breathing air. Jonathan Williams is actually an atmospheric chemist who checks the air in rainforests or large cities for various organic compounds.
But in 2018, Williams and his team, together with scientists from Johannes Gutenberg University in Mainz, published a study in which they measured the concentration of a specific molecule, isoprene, in the air of movie theaters. The concentration of this substance increases in the air that people breathe, especially when they are afraid.
“The study got a lot of attention,” Williams told DW with a laugh.
And she was honored with the Ig Nobel Prize in Chemistry in 2021. Since at least then, the researcher has also taken an interest in the chemistry of emotions.
The chemistry of sexual arousal
It’s just a small pilot study where 12 men and 12 women were placed in front of a screen at SexLab at the University of Porto. Watch different 10-minute videos in random order: a nature documentary, a horror movie, a soccer game, and an adult movie.
While sex researchers measured arousal in the genitals using various sensors, atmospheric chemists analyzed the people’s exhaled air.
Levels of key chemical components of breathing, such as acetone or methanol, did not change regardless of the emotional state in which participants were placed by the film clips.
“Instead, it was some of the trace elements that were highly volatile,” Williams says. “Although sexual arousal is of course very individual, we did find some very clear chemical signals that increase in focus when someone is feeling happy.”
These substances are called phenol, cresol and indole. They are metabolites of the amino acid tryptophan, which in turn is a precursor to the neurotransmitter serotonin, which affects mood, performance and well-being.
the smell of lust
Williams found the rise in indole to be particularly interesting. “At higher concentrations, this is what causes stool odor,” Williams says. However, in small doses, such as those found in human breath, this so-called heterocyclic compound smells like flowers and is therefore often a component of perfumes. The chemist explains, “In perfumes, it’s an ingredient that’s supposed to give a fragrance an alluring touch.”
In contrast, levels of isoprene, the odor of fear identified by Williams and colleagues in the cinema study, decreased significantly while the participants watched the sex movie. “It’s like people are freezing,” Williams says.
Can I smell the excitement on my partner’s breath?
In general, breath analysis was more pronounced in men than in women, according to the study. The increase in signs of chemical arousal in breathing was less pronounced in women, and reproductive measurements indicated that some women did not find the sex film quite as inspirational as the male participants.
“It’s a study too small to draw general conclusions from,” Williams says. However, it is promising enough to be followed up by more studies – with 1,000 or more participants. The chemist says the colleagues at SexLabs were thrilled.
“It’s not easy to find subjects for sex research because a lot of people don’t want to have sensors on their genitals.” Breath analysis can be a more comfortable alternative.
Perhaps follow-up studies could also answer the “golden question,” the big question, as Williams calls it: Can I perceive my peer’s sexual arousal through the air I breathe?
Williams thinks this is entirely possible. “We know that people respond to messages through chemicals in the air. And the smell of pizza can make your stomach growl.”
However, it has not yet been investigated whether the chemical signals we emit have an effect on the people around us.
As long as we don’t know if we’re blowing up our emotional state in a way that everyone can see, the following applies: Keep breathing quietly.