Life in a group entails a major risk: that of being exposed to contagious pathogens. To counter this danger, different strategies have evolved in social species. In the case of rodents, specific olfactory signals emitted by sick individuals induce avoidance behavior among their peers. The team of Ivan Rodriguez, professor at the Faculty of Science of the University of Geneva (UNIGE), Switzerland, unveils the neural mechanisms underlying this behavior, in a study published in the journal Current Biology. The researchers found that the vomeronasal system, specialized in detecting pheromones, identifies signs of disease and plays a key role in the avoidance response of the mouse. These findings reveal a novel function played by this neural system.