Dogs greet other dogs' noses first, sniffing(嗅) each other from head to tail. People are not so open about the process of sniffing, but smell is important in human relations, too. There is also evidence that humans can infer relationship and emotional states and even discover disease through smell.
Now, Inbal Ravreby, Kobi Snitz and Noam Sobel of the Weizmann Institute of Science have gone a step further. As they report in Science Advances, the three researchers started their first experiment by testing the smells of 20 pairs of familiar and same-sex friends. They employed an electronic nose (e-nose) and two groups of human "smellers".
The e-nose used a set of gas sensors to assess T-shirts worn by participants. One group of human smellers were given pairs of these shirts and asked to rate how similar they smelt. Those in the other group were asked to rate the smells of individual T-shirts on five dimensions (维度): pleasantness, intensity, attractiveness, competence and warmth. Both approaches produced the same result. The T-shirts of friends smelt more similar to each other than did the T-shirts of strangers.
Does friendship cause similarity of smell, or does similarity of smell cause friendship? The three researchers investigated whether there were positive interactions between strangers by using the e-nose measurement. They collected the smells of another 17 volunteers with e-nose, and then asked the participants to play a mirroring game.
That game involved silently mirroring another individual's hand movements, Participants were paired up by chance and their reactions were recorded. After each interaction, they demonstrated how close they felt to their fellow gamer by overlapping two circles (one representing themselves, the other their partner). The more similar the two electronic smell signatures were, the greater the overlap. Participants also rated the quality of their interaction in the game along 12 dimensions of feelings that define friendship, Similar smells were consistent with positive ratings for nine of these dimensions. However, two participants smelling alike did not mean they were any more accurate at the mirroring game than others.
Why smell might play a role in forming friendships remains obscure. Other qualities related to being friends, including age, appearance, and education, are either immediately obvious or rapidly become so. But while some individuals have strong body smell, many do not. It is present. But it is subliminal(潜意识的). Dr Ravreby guesses that there may be "an evolutionary advantage in having friends that are genetically similar to us". Body smell is known to be linked with genetic make-up. Smelling similar to others may thus allow subliminal inferences about genetic similarity to be drawn.
