Social behavior is common throughout the tree of life, and many animals benefit from living in groups. Large bird flocks and fish schools are prime examples, where many individuals act together in ways that can seem almost choreographed.
This coordination depends on the exchange of information among group members. By observing and responding to one another, animals can quickly adjust their movements and behavior. The process becomes especially important during an attack, when a rapid, unified response can make the difference between escape and capture.
The result is a "social brain" that allows individuals to pool sensory inputs and react as a collective, turning many separate animals into a single, responsive unit.