A new study from Tom Bozza’s lab in the journal Nature reveals something new about our sense of smell—that individual genes matter. The research led by postdoctoral fellow Adam Dewan and graduate student Rodrigo Pacifico shows that removing one olfactory receptor gene called TAAR4 from mice can have a profound effect on their behavior. The gene encodes a receptor that responds to a chemical that is enriched in the urine of carnivores. While normal mice innately avoid the scent marks of predators, mice lacking the TAAR4 receptor do not. The lab is using this as a lead to understand neuronal circuits that give rise to hardwired, instinctual behaviors in mammals.