Another factor might be a surprising one. According to a recent small study, published in the journal Science Advances, people who had an instant personal connection also shared similar body odors. “Non-human terrestrial mammals sniff themselves and each other to decide who is friend or foe,” says study author Inbal Ravebry, one of the researchers in an olfaction lab at the Weizmann Institute of Science in Israel. “Humans also sniff themselves and each other, but the function of this is unknown.” Since humans seek friends who are similar to themselves, the researchers hypothesized that humans may smell themselves and others to subconsciously estimate body-odor similarity, which in turn may promote friendship.
How Smell Helps Us “Click”
The study involved 20 friendship pairs who said they instantly “clicked”. The researchers found that each person’s body odor was closer to their friend’s than they would expect to be the case purely by chance. Each friendship pair followed a regimen well-practised in the field of human body odor research—cutting out foods like onions and garlic (which affect body odor) for a few days, and ditching aftershave and deodorant. They also bathed with an unscented soap provided by the lab and slept in a fresh, clean T-shirt (also provided by the lab). The T-shirts were then returned to the researchers for testing. Using a device that acted like a nose (an eNose), the researchers assessed the odor-causing volatile compounds coming from each T-shirt, with the help of 25 other volunteers to assess the similarity of the smells. The researchers were interested to find that “click” friends have similar body odor and that it was possible to predict clicking by body odor similarity with 71% accuracy (77% when there was a mutual click and 68% when there wasn’t). “This is important because it implies that we may be more like other terrestrial mammals in this respect than we typically appreciate,” Ravebry says. Theresa L. White, PhD, Professor and Chair in the department of psychology at Le Moyne College, New York, says the study is high quality, although she points out that it doesn’t necessarily apply to other types of same-sex friendships (i.e. non “click” connections), opposite-sex friendships, or romantic relationships. And while the eNose machine thought that “click” friends smelled more similarly to each other than they did to other people in the study, the machine and the people seem to be using different aspects of the body odor as the basis of their decisions. “So, the machine can do what we do, but it does it in a different way,” White says.
What Is Subconscious Smelling?
The study also notes that people subconsciously smell each other. “When we encounter other people, we use all of the information that we have available to make decisions about others,” White explains. “Body odor is one source of information, even if we’re not consciously aware that we’re smelling it.” Each person has a unique personal odor that is influenced by genetics, as well as environmental factors such as the food that they typically eat. “Both aspects influence the way that we think of a person, and we can even use that odor as a cue to a person’s identity,” says White, who co-authored a paper showing that first impressions are altered through the environmental odors associated with people. Evidence from previous studies suggests that people’s moods and emotions, including how they can be highly affected by odor. “It definitely has an effect on our perception of an individual (even if we are not consciously aware of the effect) and can also affect our emotional response as measured on independent judgments of the emotional or compentency states of others,” says Pamela Dalton, PhD, MPH, an experimental psychologist and faculty member at Monell Chemical Senses Center. The bottom line of this evidence is that the people around us are constantly giving their emotional/health body states via low level body volatiles and that many people are able to perceive these sensory signals, Dalton explains. “However, being able to perceive these sensory signals at a less than conscious level means that behavior may change without conscious perception,” she adds.
Friendships and Mental Health
Friends play a crucial part in protecting our mental heath and wellbeing. “Friendships are crucial to good mental health. Our friends give us a sense of belonging and help us combat loneliness,” says Amy Morin, LCSW, psychotherapist and Editor-in-Chief of Verywell Mind. Not only can friends help us be happier, they can help us find more meaning in life and support us during our times of need. “Spending time with people who care about us helps us feel better. It can give us reassurance that we can get through tough times because we have people who will be with us,” says Morin. “Friends may also encourage our healthy habits and may even help us live longer.” Dalton notes that humans are social animals and require companionship from others. “Subconscious signals that indicate a person is more similar to our lifestyle than others may be a quick prejudicial way to effect an introduction to a friendship,” she says.
