How did the alert posture of Thomson’s gazelles become a more visible signal?

The alert posture of Thomson’s gazelles (Gazella thomsoni) evolved from a simple "freeze reflex" used when the animal detects a suspicious sound. This behavior, which involves stopping foraging, raising the head high, and staring toward the potential threat, serves as a cue for nearby individuals to prepare for flight.

Through a process known as ritualization, this original survival behavior was amplified to function as a more effective signal. Specifically, the evolution of distinct black-and-white stripes along the gazelle’s face and body has made this head-high staring posture significantly more conspicuous to other members of the herd. By enhancing the visibility of this posture, the gazelle ensures that the alert signal is easily detected and interpreted by others, facilitating a coordinated group response to danger.1