Animal is known that body signals in the form of fleeting fabrics play an important role in communication. Many species, including insects, influence the behavior of their peers via so -called pheromones. In the meantime, it is known that our Riech brain is also receptive to subliminal messages of fellow human beings. But the knowledge is still limited. A team led by the odor researcher Noam Sobel from the Weizmann Institute of Science in Israel has now shown that a fleeting molecule that is separated from human skin, breathing air and faeces has a direct influence on our brain and our aggression level. It can be found on the scalp of newborns and possibly offered a survival advantage.
First, the researchers invited 127 subjects (67 of them women) to a behavioral experiment: they were supposed to play with another subject on the computer. The first part aimed to create frustration among the participants (the "other player" pockets the majority of the profit); the second part is about triggering aggression. Here, the volunteers were allowed to take revenge by hitting the "other player" with a caustic tone at the push of a button. During the experiment, an odor sample was attached under her nose: one half of the group got to smell the pure carrier substance, the other half additionally hexadecanal. However, neither produced a perceptible odor impression.
Surprisingly, there was a clear gender effect: the women reacted more aggressive under the influence of hexadecanal (turning the sound louder), but the men seemed to appease it. In order to examine the underlying processes in the brain, the team carried out an FMRI experiment with another 49 participants (including 24 women). While they were in the scanner tube, they completed a similar aggression paradigm as the group before. It was either supplied with a hexadis or only with a carrier substance enriched air via a breathing mask.
The analysis showed that hexadecanal activated a region central to social cognition in both men and women, namely the angular gyrus. But the links to areas related to social evaluation and the regulation of aggression were strengthened in men under the influence of the signaling molecule, but decreased in women.
According to Eva Mishor, first author of the study, the volatile substance may be a cool-down signal for men, but at the same time it causes aggressive behavior in women. "In the animal kingdom, male aggression often translates into aggression towards newborns. Female aggression, on the other hand, is usually directed at the defense of the offspring, "says the neuroscientist. From an evolutionary point of view, sniffing at the back of a baby's head makes sense.
