High in the mountains of Ethiopia lives a primate unlike any other. The Gelada may resemble a baboon, but it is not a baboon. It is the only primate that feeds almost entirely on grass, spending most of the day plucking blades with its nimble fingers on the cool alpine slopes.

Geladas live in complex societies where hundreds of individuals can share the same hillside. Keeping peace in such massive groups depends on constant communication. Instead of fighting, they use expressions and sounds to navigate daily life. A raised brow, a gentle grimace, or the famous lip flip can all shift the mood of the group in seconds.

The lip flip, where a male exposes his gums and long canines, is one of the Gelada’s displays. It is a clear warning meant to show dominance or ward off rivals. Often, it comes with a low, vibrating call known as a “wobble.” In Ethiopia’s Simien Mountains National Park, researchers found these displays often stop conflicts before they start, helping males keep control without fighting.

Each dominant male leads a small group of females and their young, while bachelor males form bands along the edges, watching for a chance to take over. Even with this competition, Gelada life is mostly calm.

Much of the day is spent grazing, grooming, and socializing. Scientists have identified over 30 distinct vocalizations, some with rhythmic patterns similar to human speech. Geladas combine facial and vocal signals to communicate in remarkably complex ways.

The bright red patch on a Gelada’s chest is another form of communication. In males, it becomes more vivid when testosterone levels rise, especially during mating season or after a show of dominance. In females, the patch changes shape and shade throughout their reproductive cycle, signaling fertility to nearby males.

Even while feeding, Geladas stay in contact through sound. They produce quiet grunts, coos, and squeaks as they graze, creating a steady hum across the grasslands. These gentle calls prevent tension and keep the group coordinated. While most primates vocalize mainly during alarm or conflict, Geladas talk almost constantly, using sound to hold their society together.

At night, the herds climb down cliffs to sleep safely on narrow ledges, far from leopards and hyenas. When morning light reaches the highlands, they return to the meadows to feed and reconnect through grooming and quiet chatter.