The Vomeronasal Organ is an olfactory structure in the nose, originally described in 1813 by the Danish court veterinarian Ludwig Jacobson. After some 150 years interest in it was reawakened, following the discovery of its key role in social and sexual responses. The organ serves to alert the emotional brain to the presence of specific semiochemicals, or signal molecules, which identify sex or status. Typically, such scents elicit responses at a non-conscious level — altering internal chemistry (hormones) in reaction to odours from the social environment (pheromones). The importance of...