Laughter in animals other than human

Human

Humans are the only living species in the Homo genus...

s describes animal behavior which resembles human laughter

Laughter

Laughing is a reaction to certain stimuli, fundamentally stress, which serves as an emotional balancing mechanism. Traditionally, it is considered a visual expression of happiness, or an inward feeling of joy. It may ensue from hearing a joke, being tickled, or other stimuli...

.

According to Dr. Brian Carroll, self awareness is conscious concomitant of the physiological processes involving laughter or smiling reflex (response) and its grades, degrees or spectrum varies according to phylogenetic development, with no clear cut demarcation. The emotional ingredients (such as contempt, hatred, ridicule, sarcasm, love, amusement etc.) are variable and involve different neurophysiological and physiological processes.

Non-human primates

Chimpanzee

Chimpanzee

Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...

s, gorillas, bonobo

Bonobo

The bonobo , Pan paniscus, previously called the pygmy chimpanzee and less often, the dwarf or gracile chimpanzee, is a great ape and one of the two species making up the genus Pan. The other species in genus Pan is Pan troglodytes, or the common chimpanzee...

s and orangutans show laughter-like vocalizations in response to physical contact, such as wrestling, play chasing, or tickling. This is documented in 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. 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. It is hard to tell, though, whether or not the chimpanzee is expressing joy. There are instances in which non-human primates have been reported to have expressed joy. One study analyzed and recorded sounds made by human babies and bonobos (also known as pygmy chimpanzees) when tickled. It found that although the bonobo’s laugh was a higher frequency, the laugh followed the same spectrographic 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. The enjoyment of tickling in chimpanzees does not diminish with age.

Research has noted the similarity in forms of laughter among humans and apes (chimpanzees, bonobos, gorillas, orangutans) when tickled, suggesting that laughter derived from a common origin among primate species, and has subsequently evolved

Evolution

Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

 prior to the origin of humans.

Rats

It has been discovered that rat

Rat

Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...

s emit long, high frequency, ultrasonic, socially induced vocalization during rough and tumble play and when tickled. The vocalization is described as distinct “chirping”. Humans cannot hear the "chirping" without special equipment. It was also discovered that like humans, rats have "tickle skin". These are certain areas of the body that generate more laughter response than others. The laughter is associated with positive emotional feelings and social bonding occurs with the human tickler, resulting in the rats becoming conditioned to seek the tickling. Additional responses to the tickling were those that laughed the most also played the most, and those that laughed the most preferred to spend more time with other laughing rats. This suggests a social preference to other rats exhibiting similar responses. However, as the rats age, there does appear to be a decline in the tendency to laugh and respond to tickle skin. The initial goal of Jaak Panksepp

Jaak Panksepp

Jaak Panksepp is an Estonian-born American psychologist, a psychobiologist, a neuroscientist, 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 Jeff Burgdorf’s research was to track the biological origins of joyful and social processes of the brain by comparing rats and their relationship to the joy and laughter commonly experienced by children in social play. Although, the research was unable to prove rats have a sense of humor, it did indicate that they can laugh and express joy. Chirping by rats is also reported in additional studies by Brian Knutson of the National Institutes of Health. Rats chirp when wrestling one another, before receiving morphine, or when mating. The sound has been interpreted as an expectation of something rewarding. High frequency ultrasonic vocalizations serve an important communicative function, namely to elicit social approach behavior in the recipient.

Dogs

A dog

Dog

The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...

 laugh sounds similar to a normal pant. By analyzing the pant using a sonograph, this pant varies with bursts of frequencies, resulting in a laugh. When this recorded dog-laugh vocalization is played to dogs in a shelter setting, it can initiate play, promote pro-social behavior, and decrease stress levels. In a study by Simonet, Versteeg, and Storie, 120 subject dogs in a mid-size county animal shelter were observed. Dogs ranging from 4 months to 10 years of age were compared with and without exposure to a dog-laugh recording. The stress behaviors measured included panting, growling, salivating, pacing, barking, cowering, lunging, play-bows, sitting, orienting and lying down. The study resulted in positive findings when exposed to the dog laughing: significantly reduced stress behaviors, increased tail wagging and the display of a play-face when playing was initiated, and the increase of pro-social behavior such as approaching and lip licking were more frequent. This research suggests exposure to dog-laugh vocalizations can calm the dogs and possibly increase shelter adoptions.

External links

• Simonet 2005 (includes a sample of dog laughter).
• Goodall 1968 & Parr 2005 (a sample of chimpanzee laughter).