Gorillas exhibit a range of interesting behaviors. Among these, chest beating stands out as one of the most iconic. Why do they do it?
Gorilla Communication
Gorillas are highly intelligent primates with sophisticated methods of communication. They have a repertoire of sounds, including grunts, hoots, and roars, to indicate a variety of emotions. Physical gestures and postures—like eye contact, facial expressions, and body positions—also play roles in conveying messages.
The primary reason that gorillas beat their chests is to assert dominance and establish territory. Chest beating conveys strength, warns rivals, and is also used in courtship. The sound resonates through the forest, signaling to other males to respect their space and avoid confrontation. This behavior helps maintain hierarchies without resorting to physical violence, conserving energy and reducing the risk of injury.
At the center of the gorilla social structure is the silverback, the dominant male who leads the group. He is responsible for protection, decision-making, and conflict resolution. The silverback’s beats its chest to reinforce his position and keep younger males in check. His leadership ensures group cohesion and the safety of all members.
Do Only Silverbacks Beat Their Chest?
No. Non-alpha males, including younger males and even females and juveniles, also engage in chest beating. However, the context and intention behind their chest beating differ from those of the dominant silverback.
Chest beating can be a way to express excitement, frustration, or nervousness. In these cases, it’s a spontaneous reaction to stimuli rather than a deliberate challenge to the silverback. The chest beating of non-alpha males is typically less intense and shorter in duration compared to that of the silverback. Alongside chest beating, gorillas use body language to assume submissive or neutral postures. The dominant male recognizes these subtleties and understands that their displays aren’t meant as a threat.
Young gorillas often beat their chests during play. This behavior is a form of learning and practicing the social cues they’ll need as adults. It’s not meant to disrespect authority.
If a non-alpha male begins to chest beat with increased intensity, coupled with aggressive body language and vocalizations, it may signal a challenge. In such cases, the silverback will respond to reaffirm his dominance.
Chest beating from males outside the group is more likely to be perceived as a threat.
The Mechanics of Chest Beating
When a gorilla beats its chest, it uses open, cupped hands to rapidly strike the chest area. This technique creates a drumming sound amplified by the gorilla’s large chest cavity. The strong pectoral muscles and large rib cage enhance the impact and resonance of the chest beat. The size of the male’s hands and the shape of his chest also contribute to the volume.
An international study published in Scientific Reports found there is a significant correlation between the body size of gorillas and the frequency of their chest beats. Larger and more competitive males produce lower frequency, deeper chest beats. These acoustic signals serve as indicators of the gorillas’ physical stature to both their social groups and neighboring populations.
Additionally, variations in chest beat characteristics suggest the presence of individual signatures. Therefore, each gorilla’s chest beat has unique characteristics, allowing individuals to recognize each other from a distance.
Do Any Other Animals Beat Their Chest?
Chest beating requires specific physical adaptations to produce noticeable sounds or movements. Most animals do not have the anatomy to perform effective chest-beating. Even among primates, chest beating is relatively rare, but there are a few other species besides gorillas that exhibit similar behaviors.
Orangutans beat their chest for communication. It is typically done among males to establish dominance, to establish territory boundaries, and to attract females.
Humans sometimes display chest beating. It’s possible that this is a vestige of ancestral primate behaviors. In modern humans, this gesture has been repurposed as an emotional expression of excitement or triumph rather than an assertion of dominance. It’s worth noting that humans don’t often engage in chest beating as part of their behavioral repertoire. Instead, humans use a wide range of verbal and non-verbal communication methods.
Chimpanzees and bonobos do not engage in chest beating. Instead, they use a variety of other display behaviors such as pant-hoots, facial expressions, and aggressive postures to communicate.
