Summary
Terrestrial mammals use pheromones to effectively trigger or block conspecific aggression. Here we tested whether hexadecanal (HEX), a human body-volatile implicated as a mammalian-wide social odor, impacts human aggression. Using validated behavioral paradigms, we observed a remarkable dissociation: sniffing HEX blocked aggression in men, but triggered aggression in women. Next, using functional brain imaging, we uncovered a pattern of brain activity mirroring behaviour: In both men and women, HEX increased activity in the left angular gyrus, an area implicated in perception of social cues. Hex then modulated functional connectivity between the angular gyrus and a brain network implicated in social appraisal (temporal pole) and aggressive execution (amygdala and orbitofrontal cortex) in a sex-dependent manner consistent with behaviour: increasing connectivity in men, but decreasing connectivity in women. These findings implicate HEX as a human pheromone, whose sex-specific brain processing is at the mechanistic heart of human aggressive behavior.
Competing Interest Statement
The Office of Technology Licensing at the Weizmann Institute of Science is filing for patent on the compound.