Humans are more likely to form friendships with people who have similar smells to them, according to a study published this Friday in Science Advances.
To be convinced of this, researchers from the Weizmann Institute of Science, in Israel, “recruited” twenty pairs of friends of the same sex and without romantic ties who had hooked from their first meeting.
They sampled their body odors with an electronic nose, a device that analyzes scents like a human would.
Result: the chemical signature of the odors was closer in the friends than in the randomly formed duos.
To ensure that the electronic nose has the same perception of similarities as us, the researchers asked 24 human "noses" to participate in several games, such as finding the odd one out in a trio, in other words, the individual who does not is not the friend of the other two.
These human “noses” easily found friends among the ten pairs of men and ten pairs of women, aged 20 to 39, who took part in the experiment.
As for the electronic nose, it was also able to guess when pairs associated at random would lead to friendships!
“By the similarity of chemical body odors alone, we could predict symbiosis between complete strangers with 71% accuracy,” enthuses Inbal Ravreby, a researcher at the Weizmann Institute of Science.
To propagate our genes?
As in other animals, alchemy between humans would therefore be a matter... of chemistry!
“Non-human land mammals sniff each other to decide who is friend or foe.
We make the assumption that humans establish a pattern from their own body odor and then subconsciously compare others to that pattern,” says Inbal Ravreby.
Previous studies suggest that humans use their own smell as a mediator, similar to what has been found in rodents and primates.
But then, what's the point of having friends who smell like us?
“I suspect that since body odor is correlated with genetic makeup, and in particular the immune system, smelling others gives us an indication of the degree of genetic similarity between us,” continues Inbal Ravreby.
What for ?
“One possible explanation, although this is only speculation, is that there is an evolutionary advantage to having friends who are genetically similar to us, and whose children are also relatively similar to us.
Thus, by helping friends, we would contribute to spreading our own genes.
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The scientist herself recognizes that new experiments are necessary to verify these suppositions.
His team is now trying to find out if the social areas of the brain are activated more in the presence of body odor similar to ours.