The question of whether dolphins laugh compels us to examine the intricate relationship between animal emotion and communication. Humans often project familiar behaviors, like laughter, onto intelligent species, especially those displaying complex social lives. Determining if a dolphin vocalization is truly analogous to human laughter requires scientists to look beyond the sound itself and analyze its social context and function. This investigation is complicated because dolphins, as highly cognitive and social marine mammals, possess a communication system vastly different from our own.
Defining Laughter and Emotion in Animals
Scientists rarely look for a sound that acoustically matches a human’s sharp expulsion of breath when investigating animal laughter. Instead, the focus is on a functional equivalent—a specific vocalization tied to social play and non-aggression. This “play vocalization” acts as a signal to an interaction partner that rough-and-tumble actions, like chasing or mock-biting, are not serious threats. The inability to directly measure subjective emotional states, such as a feeling of humor or joy, makes this functional approach necessary for researchers.
Vocal play signals are documented in over 65 species, primarily mammals, suggesting an ancient evolutionary origin for this type of social cue. Primates, like chimpanzees, produce a panting sound during tickling and wrestling that serves this purpose, while rats emit an ultrasonic chirp when engaging in rough play. These vocalizations work to reinforce social bonds and prevent playful sparring from escalating into actual conflict. The existence of these signals in other intelligent mammals provides a framework for seeking a comparable, context-specific sound within the dolphin’s repertoire.
The Actual Sounds Dolphins Produce
Dolphins utilize a varied acoustic repertoire, which can be categorized into three primary types: clicks, signature whistles, and burst-pulse sounds.
Clicks
Clicks are rapid, broadband pulses of sound primarily used for echolocation. This biological form of sonar helps dolphins navigate and locate prey. The rate of these clicks increases as the dolphin approaches an object of interest, essentially creating an acoustic map of its environment.
Signature Whistles
Signature whistles are narrowband, frequency-modulated sounds that function like individual names, unique to each dolphin. They are used for identification and social contact over long distances. Dolphins develop this distinct whistle early in life and maintain it throughout their long lifespan. Studies have shown dolphins can even mimic the signature whistle of a companion, effectively calling them by their “name.”
Burst-Pulse Sounds
Burst-pulse sounds are the third category, consisting of high-repetition-rate packets of clicks that are heard as buzzing, squawking, or barks to the human ear. These are generally associated with close-proximity social interactions and are the most common type of signal used in social settings. The complex, varied nature of burst-pulse sounds suggests they carry the bulk of the dolphins’ emotional and contextual communication.
Interpreting Playful Dolphin Vocalizations
Dolphins do not possess the vocal apparatus necessary to produce a sound that physically matches human laughter. However, they use specific vocalizations and visual cues that serve the same social function as laughter in other species. The squawks and whistles emitted by bottlenose dolphins during vigorous play are recognized as a form of play vocalization. These high-frequency sounds signal a non-aggressive intent during activities that might otherwise be mistaken for fighting.
Beyond the vocalizations, dolphins utilize a visual signal that is considered a direct analogue to the “play face” of primates and the human smile. During social play, dolphins frequently display an “open-mouth” posture, which quickly communicates a playful mood to their partner. This visual signal prevents playful actions, such as mock-chasing or biting, from escalating into genuine aggression. The open-mouth display and the accompanying high-intensity burst-pulse sounds together function as the dolphin’s method of communicating pleasure and reinforcing social cohesion.