Researchers show how the brain turns on innate behavior: "Innate or 'instinctive' behaviors are inborn and do not require learning or prior experience to be performed. Examples include courtship and sexual behaviors, escape and defensive maneuvers, and aggression.

Using the common fruit fly as a model organism, the researchers found through laboratory experiments that the innate behavior is initiated by a 'command' hormone that orchestrates activities in discrete groups of peptide neurons in the brain. Peptide neurons are brain cells that release small proteins to communicate with other brain cells and the body. "