Laughter in animals other than humans describes animal behavior which resembles human laughter.
Several non-human species demonstrate vocalizations that sound similar to human laughter. A significant proportion of these species are mammals, which suggests that the neurological functions occurred early in the process of mammalian evolution. [1] Laughter as communication is found in over 60 species. [2]
Chimpanzees, gorillas and orangutans show laughter-like vocalizations in response to physical contact such as wrestling, play chasing or tickling. Some orangutans also react with laughter at magic tricks performed by humans. [3] [4] This behavior is documented in both wild and captive chimpanzees. Chimpanzee laughter is not readily recognizable to humans as such, because it is generated by alternating inhalations and exhalations that sound more like breathing and panting. [5] It sounds similar to screeching. The differences between chimpanzee and human laughter may be the result of adaptations that have evolved to enable human speech. One study analyzed sounds made by human babies and bonobos when tickled. It found that although the bonobo's laugh was a higher frequency, the laugh followed the same sonographic pattern of human babies to include as similar facial expressions. Humans and chimpanzees share similar ticklish areas of the body such as the armpits and belly. [6]
Research has noted the similarity in forms of laughter among humans and other apes (chimpanzees, gorillas and orangutans) when tickled, suggesting that laughter derived from a common origin among primate species, and therefore evolved prior to the origin of humans. [7] [8]
Rats emit long, 50-kHz ultrasonic calls that are induced during rough and tumble play, and when tickled by humans. The vocalization is described as distinct "chirping". Like humans, rats have "tickle skin", areas of the body that generate greater laughter responses than others. Rats that laugh the most also play the most and prefer to spend more time with other laughing rats. It has been reported that there is no decline in the tendency to laugh and respond to tickle skin as rats age, however, it has also been reported that in females, brain maturation after puberty appears to redefine tickling as aversive, leading to avoidance rather than appetitive responses. [9] Further studies show that rats chirp when wrestling one another, before receiving morphine, or when mating. The sound has been interpreted as an expectation of something rewarding. [10] High frequency ultrasonic vocalizations are important in rat communication and function to elicit approach behavior in the recipient. [11]
The initial goal of research by Jaak Panksepp and Jeff Burgdorf was to track the biological origins of how the brain processes emotions and social behavior. They compared rat vocalizations during social interactions to the joy and laughter commonly experienced by children in social play. They concluded that the 50-kHz rat vocalizations might reflect positive affective states (feelings or emotions), analogous to those experienced by children laughing during social play. [12]
More recent studies have investigated the emotional states of rats after being tickled. An animal's optimism or pessimism can be assessed by cognitive bias studies. After being tickled, rats are more optimistic, indicating the interaction invokes a positive affective state. [13] Furthermore, rats self-administer playback of the 50-kHz trill calls and avoid playback of 22-kHz calls. [14]
When rats are given naloxone (an opioid antagonist), tickling no longer evokes the 50-kHz vocalisation[ citation needed ] which indicates that the rewarding properties of tickling are modulated by endogenous opioids.
Dogs sometimes pant in a manner that sounds like a human laugh. By analyzing the pant using a sonograph, this pant varies with bursts of frequencies. When this vocalization is played to dogs in a shelter setting, it can initiate play, promote pro-social behavior, and decrease stress levels. One study compared the behaviour of 120 dogs with and without exposure to a recorded "dog-laugh". Playback reduced stress-related behaviors, increased tail wagging, the display of a "play-face" when playing was initiated, and pro-social behavior such as approaching and lip licking. [15]
In 2004, researchers who were studying dolphins in Sweden noticed a particular set of sounds that they had not heard before. [16] These sounds consisted of a short burst of pulses, followed by a whistle. After further observations the researchers discovered that these signals were only being made by dolphins during play-fighting, and never during aggressive confrontations. Their conclusion was that these sounds were being made by the dolphins to indicate that the situation was pleasant and/or non-threatening, and to help prevent it escalating into something like a real fight. This, according to psychologists, is the reason why laughter exists in the first place, suggesting these noises were the dolphin equivalent of a human laugh. [17]
Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genus Pongo, orangutans were originally considered to be one species. From 1996, they were divided into two species: the Bornean orangutan and the Sumatran orangutan. A third species, the Tapanuli orangutan, was identified definitively in 2017. The orangutans are the only surviving species of the subfamily Ponginae, which diverged genetically from the other hominids between 19.3 and 15.7 million years ago.
The brown rat, also known as the common rat, street rat, sewer rat, wharf rat, Hanover rat, Norway rat and Norwegian rat, is a widespread species of common rat. One of the largest muroids, it is a brown or grey rodent with a body length of up to 28 cm (11 in) long, and a tail slightly shorter than that. It weighs between 140 and 500 g. Thought to have originated in northern China and neighbouring areas, this rodent has now spread to all continents except Antarctica, and is the dominant rat in Europe and much of North America. With rare exceptions, the brown rat lives wherever humans live, particularly in urban areas.
Laughter is a pleasant physical reaction and emotion consisting usually of rhythmical, often audible contractions of the diaphragm and other parts of the respiratory system. It is a response to certain external or internal stimuli. Laughter can rise from such activities as being tickled, or from humorous stories, imagery, videos or thoughts. Most commonly, it is considered an auditory expression of a number of positive emotional states, such as joy, mirth, happiness, or relief. On some occasions, however, it may be caused by contrary emotional states such as embarrassment, surprise, or confusion such as nervous laughter or courtesy laugh. Age, gender, education, language, and culture are all indicators as to whether a person will experience laughter in a given situation. Other than humans, some other species of primate show laughter-like vocalizations in response to physical contact such as wrestling, play chasing or tickling.
Tickling is the act of touching a part of a body in a way that causes involuntary twitching movements or laughter. The word evolved from the Middle English tikelen, perhaps frequentative of ticken, to touch lightly.
Animal cognition encompasses the mental capacities of non-human animals including insect cognition. The study of animal conditioning and learning used in this field was developed from comparative psychology. It has also been strongly influenced by research in ethology, behavioral ecology, and evolutionary psychology; the alternative name cognitive ethology is sometimes used. Many behaviors associated with the term animal intelligence are also subsumed within animal cognition.
Animal languages are forms of non-human animal communication that show similarities to human language. Animals communicate through a variety of signs, such as sounds or movements. Signing among animals may be considered a form of language if the inventory of signs is large enough. The signs are relatively arbitrary, and the animals seem to produce them with a degree of volition. In experimental tests, animal communication may also be evidenced through the use of lexigrams by chimpanzees and bonobos.
Research into great ape language has involved teaching chimpanzees, bonobos, gorillas and orangutans to communicate with humans and each other using sign language, physical tokens, lexigrams, and imitative human speech. Some primatologists argue that the use of these communication methods indicate primate "language" ability, though this depends on one's definition of language.
Human–animal communication is the communication observed between humans and other animals, ranging from non-verbal cues and vocalizations to the use of language.
Emotion is defined as any mental experience with high intensity and high hedonic content. The existence and nature of emotions in non-human animals are believed to be correlated with those of humans and to have evolved from the same mechanisms. Charles Darwin was one of the first scientists to write about the subject, and his observational approach has since developed into a more robust, hypothesis-driven, scientific approach. Cognitive bias tests and learned helplessness models have shown feelings of optimism and pessimism in a wide range of species, including rats, dogs, cats, rhesus macaques, sheep, chicks, starlings, pigs, and honeybees. Jaak Panksepp played a large role in the study of animal emotion, basing his research on the neurological aspect. Mentioning seven core emotional feelings reflected through a variety of neuro-dynamic limbic emotional action systems, including seeking, fear, rage, lust, care, panic and play. Through brain stimulation and pharmacological challenges, such emotional responses can be effectively monitored.
Animal culture can be defined as the ability of non-human animals to learn and transmit behaviors through processes of social or cultural learning. Culture is increasingly seen as a process, involving the social transmittance of behavior among peers and between generations. It can involve the transmission of novel behaviors or regional variations that are independent of genetic or ecological factors.
Knismesis and gargalesis are the scientific terms, coined in 1897 by psychologists G. Stanley Hall and Arthur Allin, used to describe the two types of tickling. Knismesis refers to the light, feather-like type of tickling. This type of tickling generally does not induce laughter and is often accompanied by an itching sensation. Gargalesis refers to harder, laughter-inducing tickling, and involves the repeated application of high pressure to sensitive areas.
Tool use by non-humans is a phenomenon in which a non-human animal uses any kind of tool in order to achieve a goal such as acquiring food and water, grooming, combat, defence, communication, recreation or construction. Originally thought to be a skill possessed only by humans, some tool use requires a sophisticated level of cognition. There is considerable discussion about the definition of what constitutes a tool and therefore which behaviours can be considered true examples of tool use. A wide range of animals, including mammals, birds, fish, cephalopods, and insects, are considered to use tools.
Jaak Panksepp was an Estonian-American neuroscientist and psychobiologist who coined the term "affective neuroscience", the name for the field that studies the neural mechanisms of emotion. He was the Baily Endowed Chair of Animal Well-Being Science for the Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology at Washington State University's College of Veterinary Medicine, and Emeritus Professor of the Department of Psychology at Bowling Green State University. He was known in the popular press for his research on laughter in non-human animals.
A talking animal or speaking animal is any non-human animal that can produce sounds or gestures resembling those of a human language. Several species or groups of animals have developed forms of communication which superficially resemble verbal language, however, these usually are not considered a language because they lack one or more of the defining characteristics, e.g. grammar, syntax, recursion, and displacement. Researchers have been successful in teaching some animals to make gestures similar to sign language, although whether this should be considered a language has been disputed.
Primate cognition is the study of the intellectual and behavioral skills of non-human primates, particularly in the fields of psychology, behavioral biology, primatology, and anthropology.
Cognitive bias in animals is a pattern of deviation in judgment, whereby inferences about other animals and situations may be affected by irrelevant information or emotional states. It is sometimes said that animals create their own "subjective social reality" from their perception of the input. In humans, for example, an optimistic or pessimistic bias might affect one's answer to the question "Is the glass half empty or half full?"
Theory of mind in animals is an extension to non-human animals of the philosophical and psychological concept of theory of mind (ToM), sometimes known as mentalisation or mind-reading. It involves an inquiry into whether non-human animals have the ability to attribute mental states to themselves and others, including recognition that others have mental states that are different from their own. To investigate this issue experimentally, researchers place non-human animals in situations where their resulting behavior can be interpreted as supporting ToM or not.
Ultrasonic vocalizations (USVs) occur at frequencies ranging from approximately 20–100 kHz. They are emitted by animals such as bats and rodents, and have been extensively studied in rats and mice. As opposed to sonic vocalizations, ultrasonic vocalizations cannot be detected by the human ear. USVs serve as social signals, and are categorized according to their frequency. Different categories of USVs are elicited in response to different situations and varying affective states. The behavioural functions of USVs vary as a rat or mouse pup reaches the juvenile/adult stage of their development. The brain mechanisms behind calling behaviour have also been studied, and some studies have used pharmacological manipulation.
The cooperative pulling paradigm is an experimental design in which two or more animals pull rewards toward themselves via an apparatus that they cannot successfully operate alone. Researchers use cooperative pulling experiments to try to understand how cooperation works and how and when it may have evolved.
Inequity aversion in animals is the willingness to sacrifice material pay-offs for the sake of greater equality, something humans tend to do from early age. It manifests itself through negative responses when rewards are not distributed equally between animals. In controlled experiments it has been observed, to varying degrees, in capuchin monkeys, chimpanzees, macaques, marmosets, dogs, wolves, rats, crows and ravens. No evidence of the effect was found in tests with orangutans, owl monkeys, squirrel monkeys, tamarins, kea, and cleaner fish. Based on mixed results in experimental studies it may be concluded that some bonobos, baboons, gibbons, and gorillas are inequity averse. Disadvantageous inequity aversion, which occurs when the animal protests as it gets a lesser reward than another animal, is most common. But advantageous inequity aversion has been observed as well, in chimpanzees, baboons and capuchins: the animal protests when it gets a better reward. Scientists believe that sensitivity to inequity co-evolved with the ability to cooperate, as it helps to sustain benefitting from cooperation. There is little evidence for inequity aversion in non-cooperative species.