Love Stinks

Love Stinks (or at least smells) according to a study published in the Journal of Neuroscience. The scientists found that human social interactions are shaped by more than just words and gestures. Factors such as smell and proximity, and even temperature, all influence how people relate to one another and can affect their behavior. Our environmental surroundings appear to affect our judgments of both people and things. Previous work suggests smells are tied to behaviors. For instance, the cleaning smell of Windex has been found to be associated with virtuous behavior and purity (Virgos buy Windex by the case).

Scientists have long debated whether humans, like animals, use chemical signals called pheromones to communicate sexual interest to potential mates. Problem is, the effects of pheromones are thought to be subconscious — meaning that if we do communicate using them, we sure don't know it. It's also hard to know what these pheromones might be and how we sense them, so researchers understand little about them.

But if human pheromones are going to be anywhere, they're going to be in sweat. The psychologists devised an experiment to compare how women respond to different forms of male sweat — sweat produced in everyday situations versus that produced when a man is turned on. The researchers speculated that if humans do produce and respond to sweat pheromones, then a woman should respond to a guy's sexual sweat differently than she does to his normal sweat.

Twenty heterosexual guys were asked to stop wearing deodorant and scented products for a few days. Then were told to put small pads in their armpits as they watched pornographic videos and became aroused (the researchers confirmed, using electrodes, that the images did the job). Later, the guys were asked to exchange those pads for fresh pads to collect the sweat they produced when they weren't aroused.

Then the researchers recruited 19 brave women to smell the men's pads while undergoing brain scans. The investigators used functional magnetic resonance imaging (MRI), a technique that reveals the brain regions a person is using at any given time — even if their brain activity is subconscious.

Sure enough, the women's brains responded very differently depending on which sweat they sniffed. (And no, none of them passed out.) The sexual sweat, but not the normal sweat, activated the right orbitofrontal cortex and the right fusiform cortex, brain areas that help us recognize emotions and perceive things, respectively. Both regions are in the right hemisphere, which is generally involved in smell, social response, and emotion.

Our sexual intentions, in other words, may be a lot clearer than we ever intended them to be. That crush you have on your co-worker? She may already know — at least subconsciously. Although we might not be aware of it, smells appear to affect our behavior, and perhaps can even be used to communicate emotions, research suggests.

The study also showed women's brains respond differently to men's sweat depending on the circumstances under which the sweat was produced. If the sweat was generated while the men were aroused from watching erotic videos, the women's brains were activated in regions responsible for recognizing emotions. No such pattern was seen in women's brains when they smelled sweat produced under normal circumstances.

Other studies revealed that the amount of time couples are together might affect their ability to interpret such odor cues. A group of heterosexual couples, who had been together anywhere from one to seven years, watched videos meant to elicit certain emotions: comedies for happiness, horror films for fear, erotic videos for sexual arousal and documentaries for neural emotions. The subjects wore gauze under their arms to collect sweat while watching the videos.

They were then asked to smell three bottles of sweat. Two were produced during the neural video, and one from one of the three emotional videos. The subjects had to identify the odd one out (the scent produced during the emotional video). The participants were more likely to identify the emotional sweat when it was produced by their partner rather than a stranger. And the longer the couples were together, the higher the accuracy. The accumulating evidence suggests smell isn't just useful for detecting food, but also for perhaps detecting the fine nuances of human social behavior.

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