Whether on the giving or the receiving end of a glance, nod, smile, or stare, we can all appreciate the power of visual communication. A look, as they say, is worth a thousand words. Adult male chacmas have earned a “tough guy” reputation. And while violent fights do occur, they can be costly. Injuries sustained during conflict may lead to infection and the inability to forage or travel, and could leave the troop more vulnerable to predators or rivals. Therefore, it is in the baboons’ best interest to avoid coming to blows. Visually assertive displays may serve to get a message across before the situation escalates into a physical brawl.
“Staring” sends a crystal-clear warning. In this penetrating glare, the baboon raises his eyebrows while keeping his eyes trained on his subject. To enhance the menacing effect, he will move his ears back so that the skin on his face and scalp is stretched taut, revealing a differently colored fur beneath his eyes. It is a signal that the recipient would be wise to heed.
A “canine display” is sometimes presented by a lower-ranking male to test a male of higher rank who is consorting with a female. A quick flash of the teeth serves as a threat and is often accompanied by “eyebrow raising,” which is viewed as an antagonistic gesture in itself. In order to avoid a scrap, a baboon on the receiving end of these visual cues may respond by “rapid glancing,” turning his head in the opposite direction and shifting his eyes to ease the tension of the situation. Another means to avert an aggressive encounter is through a “fear grimace,” in which the baboon retracts its lips and exposes its clenched teeth. This expression is usually accepted by the aggressor as a pacifying gesture.
But hostile displays aren’t only directed at troop-mates; they are also useful in defending the group. When a predator or rival troop approaches, an adult male is often effective in repelling them by opening his mouth widely in a “tension yawn,” fully revealing his formidable canine teeth.
Nonaggressive visual cues are also highly important in chacma society. “Social presenting” is a submissive act in which a female or juvenile exhibits their hindquarters to a higher-ranking male. A female may also present to a mother with an infant as a gesture of respect. She often embellishes this act by “lip smacking” to signal her affiliation with the troop. In this display of reassurance, the baboon protrudes and smacks its lips together repeatedly. Along with “teeth chattering,” this is also performed by a dominant male when a female or juvenile is presenting to him.