Nature has given chimpanzees the ability to express themselves and communicate with one another through a variety of means, including 30 recorded vocalizations. A wide range of emotions are expressed through these calls. Notably, chimpanzees elicit different warning calls in association with specific predators.

Out of all their vocalizations, the “pant-hoot” is perhaps the one that most of us human primates associate with chimpanzees. This structurally complex, long-distance call is a sequence of shrieks and roars. It begins softly, almost tentatively, gradually building in intensity with in-and-out pants, culminating in a series of frenetic, high-pitched screams, before gradually quieting. Pant-hoot calls carry a distance up to 1.2 mi (2 km). Both males and females engage in the pant hoot, though it is more commonly heard from a group of adult males, collectively pant-hooting in chorus.

The pant hoot call serves multiple purposes. Chorusing among males is thought to cultivate “brotherly” friendships. High-ranking males emit pant-hoots to proclaim their dominance or strength over other group members. An individual who comes upon a tree laden with fruit announces his find to fellow members with a pant-hoot call. Pant hoot calls are also used by individuals to communicate their location to one another while foraging.

While the pant-hoot is certainly impressive, it’s their facial expressions, hand gestures, and postures that most often indicate what’s on their mind. In fact, an international team of researchers found that wild chimpanzees communicate through hand gestures in a manner that follows human linguistic rules. They posit that despite chimpanzees’ inability to speak human language, the foundations of the two species’ respective communications systems follow the same basic mathematical principles. Human speech may have evolved from gesturing! Researchers have stated that the communication systems of human toddlers and chimpanzees are remarkably similar.

Chimpanzees do not have a poker face. Stink eye, maybe. This penetrating stare is meant as a threat. When angry or threatened, they curl their wide lips apart into what appears to be a smile. But this “fear smile” (as it is colloquially referred to by wildlife biologists) is not indicative of happiness or contentment. When they wish to intimidate a potential predator, chimpanzees flash their giant, fearsome fangs. This toothy threat might be accompanied by slapping the ground or raising the arms overhead while standing fully upright. In a phenomenon described as “piloerection,” the hairs on an individual’s body bristle to stand on end, making the chimpanzee appear larger than his actual size and, hence, a greater threat. (We may have witnessed this occurrence in dogs. When fearful or angry, the hairs around a dog’s neck bristle and stand up. We call these hairs “hackles.” In human vernacular, we might warn someone against “raising our hackles,” which means “you better not anger me, or else. . .”).

In chimpanzee culture, foot stomping is an overture of randy males directed at a particular female with whom they wish to mate. Or a male might engage in more subtle flirtation by tearing strips of leaves with his teeth to get a female’s attention. Chimpanzees are known to greet and comfort one another with an embrace. They kiss, hold hands, and even tickle one another.

Lip smacking or teeth clacking can be heard by an individual who is lost in the Zen of grooming another. Like other nonhuman primates, mutual grooming is an important daily activity for Nigeria-Cameroon chimpanzees. This activity serves a greater purpose than just picking parasites off of one another; “allogrooming” helps to instill and strengthen social bonds and establish trust among group members. Scratching one’s own body part in the presence of another is an invitation to be groomed. A mother who wishes to invite her little one to hop onto her back will present her rear end and extend her foot, exposing the sole.

Communication studies of captive chimpanzees leave no doubt as to their exceptional intelligence. Researchers have taught these chimpanzees to communicate through American Sign Language. Other captive chimpanzees have been taught to remember and apply abstract mathematical principles (symbols, shapes, sizes). An indication of self-awareness, chimpanzees recognize their reflection in a mirror.