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SYFY WIRE chemistry

Your nose knows similarly scented people and wants you to be friends

We're basically dogs sniffing one another.

By Cassidy Ward
Nose smelling

In the classic Christmas story Rudolph the Red Nosed Reindeer, the titular reindeer has trouble making friends at the North Pole, as a consequence of his unusually red nose. You’ve heard the story before, know all the words to the song, and have seen the Rankin/Bass TV movie. What you may not know is that there’s some very real science which supports the relationship between our noses and our friends. The key, however, isn’t the way our noses look, but what they smell.

Inbal Ravreby from the Azrieli National Institute for Human Brain Imaging and Research and the Department of Brain Research at the Weizmann Institute for Science, and colleagues, studied the effects of subliminal body odors on the way we make friends. Their findings were published in the journal Science Advances.

“I wondered for many years why we sometimes just feel like there’s chemistry between us. It’s almost magical. Out of nowhere you just click with someone. You feel like you’ve known them forever and you’re on the same wavelength. I wondered what could explain this and thought there must be some biological mechanism,” Ravreby told SYFY WIRE.

Anyone who has spent any time with a dog knows that smell is an important factor of interpersonal relationships in many mammal species. A walk down the sidewalk might suddenly pause so two dogs can sniff one another and make an assessment. Previous research has shown that mammals use their own body odor as a reference and compare it to the body odor of others in order to decide if they are friends or enemies. It was unclear, however, if a similar mechanism was at work in humans.

“Friends tend to be similar in many ways. Their visual appearance, their personality, values, and even their brain response and genetics. We thought maybe body odor is also a factor on this list,” Ravreby said.

To find out, they put a few dozen participants through a series of lab experiments which compared their body odor to their social interactions. Researchers collected body odor samples by asking participants to sleep two consecutive nights in a t-shirt provided to them. They were also asked to avoid any particularly pungent foods like garlic or onion, take a shower with an unscented soap, and abstain from any odor modifiers like perfume, deodorant, or body lotion.

After two nights, the shirts were analyzed using an electronic nose with an array of 10 sensors. They where then compared to determine how similar or different each of them were. When that data was bounced up against the existing relationships of study participants, researchers found that those friends who self-reported having a “click” friendship — one in which they felt immediate chemistry upon meeting — had body odors more similar than others.

That told scientists there was at least a correlation between friendship and similar body smell, but it wasn’t clear that it was causal. Close friends tend to live in the same places, eat the same foods, and be exposed to the same things. Similar body odor might be a symptom of friendship, not the cause. To really find an answer, researchers needed to know if they could predict friendship among strangers, using body odor alone.

“To test the question, we asked participants to come to the lab after donating their body odor. In each session, we asked the participants to play the mirror game. They had to move their hands together, as coordinated as they could, while standing half a meter apart. This enabled them to subconsciously smell the body odor of each other. We then asked them to indicate whether they clicked with each other or not,” Ravreby said.

Participants were also asked to rate their partner on 13 metrics measuring how they experienced their social interaction. Questions included how much they liked each other, if there was chemistry between them, and whether or not they thought they could be friends. Meanwhile, researchers used the electronic nose to analyze their body odor samples and make predictions. They found that using only body odor similarity, they could predict whether or not two people would click with 71% accuracy.

It seems clear that similarity of body odor is an important factor in whether or not you will immediately like someone upon meeting them. What’s less clear is whether or not it’s an indication of a long-lasting friendship or if other factors like shared interests, or the lack thereof, will win out over time.

When you’re out there meeting new people, if something smells off about them, it’s probably best to trust your nose. The science tells us that relationship is likely doomed to fail before it starts.

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