The surprisingly versatile code by which chemical cues help trigger some of the most basic behaviors in mice has been deciphered by scientists. The findings shed light on the evolution of mammalian behaviors -- which include human behaviors -- and their underlying brain mechanisms. They also challenge the traditional view of how pheromones work in animals such as mice. These compounds have until now been thought to trigger behaviors very directly and simply -- one compound, when detected, triggers one behavior -- so that behaviors critical for survival and reproduction don’t have to be learned.