A study published in the journal Science Advances on Friday concluded that people who share similar body odors are more likely to become friends.
“Non-human terrestrial mammals constantly sniff each other and, accordingly, decide who their friends or enemies are,” wrote a group of researchers led by Inbal Raffrebi of the Weizmann Institute of Science in Israel.
Since humans are looking for friends who are similar to themselves, the team proceeded from the hypothesis that people smell to appreciate similar body odors and judge the possibility of amicable compatibility with others.
To verify this, the researchers collected samples of same-sex friends who were not in a romantic relationship and who said that they quickly developed a friendship.
They found 20 pairs of friends, divided equally between men and women, between the ages of 22 and 39.
To avoid any odor transmission, participants had to avoid certain foods and sleep away from their partner and pets, wearing the T-shirt provided by the study authors.
The shirts were collected and then analyzed using an electronic nose, a machine that analyzes chemical composition.
The researchers found that the scents of each pair of friends were generally more similar than the scents of pairs of non-friends chosen at random.
To see if the machine’s results match human perception, the team used the sense of smell of volunteers who had to smell two friends and a third, and were able to identify pairs of friends.
However, another hypothesis might explain this convergence in terms of smell: Friends spend a lot of time together, and they share common factors that affect their smell, such as where they live and the food they eat.
So the researchers wanted to determine if scent predicts the sympathy of two people who don’t know each other.
By using 17 unknown people, they found that the similarity of smells predicts good understanding between the two people in 77% of cases, or in return indicates a lack of chemistry between the two people in 68% of cases.
