The question of whether great apes laugh is central to understanding the evolutionary continuity of human emotion, behavior, and communication. For generations, scientists considered laughter a uniquely human expression, tied to complex cognitive functions like humor and language. However, comparative studies of our closest living relatives—chimpanzees, gorillas, bonobos, and orangutans—reveal that a homologous behavior exists, challenging the notion of human exclusivity. Investigating these vocalizations provides insight into the behavior of our shared ancestors, helping to chart the timeline for when this important social signal first emerged.
The Sound of Primate Amusement
Yes, great apes exhibit a behavior that scientists classify as laughter, typically triggered by physical interactions like tickling or rough-and-tumble play. This vocalization is often described as a breathy, rapid ‘pant-pant-pant’ sound, distinct from the clear, rhythmic vocal bursts of human laughter. Unlike human vocalizations, which are typically loud and voiced, ape laughter is more akin to a series of staccato grunts or panting noises, which is why the behavior is sometimes referred to as “play panting” in the scientific literature.
The physical manifestation of this amusement is consistent across the great ape species, signaling to a play partner that the interaction is non-aggressive. When tickled or engaged in mock fighting, apes often display a “play face,” characterized by an open mouth with the teeth covered by the lips. Acoustic analysis shows that chimpanzees and bonobos produce shorter, faster calls compared to the longer, slower grunts heard in orangutans. Observing this behavior in young apes, particularly in response to tickling, has been a primary method for comparing their amusement vocalizations with those of human infants.
Physiological Divergence from Human Laughter
The most significant distinction between ape and human laughter lies in the physiological mechanism of breath control, or respiratory regulation. Great apes produce their laughter-like vocalizations on both the inhalation and the exhalation, resulting in a continuous, breathy, alternating airflow. This means the sound is generated across the entire breathing cycle, leading to the characteristic ‘pant-pant-pant’ acoustic quality.
Human adult laughter, in contrast, is produced almost exclusively on a controlled exhalation, using a series of short, repeated vocal bursts, such as “ha-ha-ha.” This ability to precisely regulate the flow of air from the lungs, allowing for multiple sound elements on a single breath, is a specialized adaptation. This voluntary control over the respiratory system is thought to have been a prerequisite for the evolution of complex speech, allowing early humans to produce long, structured vocal sequences. The change from the ape’s ingressive-egressive pant-laugh to the human’s egressive vocal burst represents a major evolutionary shift in the control of the diaphragm and rib cage muscles.
Tracing the Evolutionary Timeline
Through a method known as phylogenetic analysis, scientists have reconstructed the timeline of laughter by mapping the acoustic similarities and differences across species onto the established hominid family tree. The consensus suggests that the proto-laughter behavior originated in the last common ancestor shared by all great apes and humans. This places the behavior’s genesis deep in primate history, with estimates ranging from 10 to 16 million years ago.
The fact that all four great ape species—orangutans, gorillas, chimpanzees, and bonobos—exhibit this tickle-induced vocalization provides strong evidence for a common origin. Acoustic data from these species, when analyzed, produce an evolutionary tree that closely matches the genetic relationships already established by DNA studies. This suggests that the behavior is homologous, meaning it was inherited from a single ancestral trait rather than evolving independently in different lineages. The acoustic differences seen today represent evolutionary modifications that occurred after the species diverged from that common ancestor.
The Social Function of Laughter
In both human and ape societies, the primary function of laughter is to act as a social signal, especially within the context of play. For great apes, the play panting serves as a metacommunicative tool, which essentially signals the intent of the interaction. By vocalizing, the ape confirms to its partner that the roughhousing, chasing, or mock aggression is entirely benign and not a real attack.
This signaling is instrumental in maintaining social cohesion and reducing the risk of a play session escalating into a genuine conflict. In chimpanzee groups, for example, the presence of laughter during play has been shown to prolong the interaction significantly. Furthermore, a phenomenon called “responsive laughter,” where one ape’s laughter triggers a similar vocalization in a playmate, helps to reinforce social bonds. This shared vocal expression builds trust and allows individuals to practice and explore social boundaries in a safe, low-stakes environment.