Laughter in apes

Young chimpanzees playing

Laughter might not be confined or unique to humans. The differences between chimpanzee and human laughter may be the result of adaptations that have evolved to enable human speech. Self-awareness of one's situation as seen in the mirror test, or the ability to identify with another's predicament (see mirror neurons), are prerequisites for laughter, so animals may be laughing in the same way that humans do.

Chimpanzees, gorillas, and orangutans show laughterlike vocalizations in response to physical contact, such as wrestling, play chasing, or tickling. This is documented in wild and captive chimpanzees. Common 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. There are instances in which non-human primates have been reported to have expressed joy. One study analysed and recorded sounds made by human babies and Bonobos when tickled. It found, that although the Bonobo's laugh was a higher frequency, the laugh followed a pattern similar to that of human babies and included 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.^[31

Scientists have long been fascinated with the studies of language, believing it to be a unique human cognitive ability. To test this hypothesis, scientists have attempted to teach human language to several species of great apes. One early attempt by Allen and Beatrice Gardner in the 1960s involved spending 51 months teaching American Sign Language to a chimpanzee named Washoe. The Gardners reported that Washoe learned 151 signs, and that he had spontaneously taught them to other chimpanzees.^[26] Over a longer period of time, Washoe learned over 800 signs.^[27]

There is ongoing debate among some scientists, notably Noam Chomsky and David Premack, about non-human great apes' ability to learn language. Since the early reports on Washoe, numerous other studies have been conducted with varying levels of success^[28], including one involving a chimpanzee named Nim Chimpsky trained by Herbert Terrace of Columbia University. Although his initial reports were quite positive, in November of 1979, Terrace and his team re-evaluated the videotapes of Nim with his trainers, analyzing them frame by frame for signs as well as for exact context (what was happening both before and after Nim’s signs). In the re-analysis, Terrace concluded that Nim’s utterances could be explained merely as prompting on the part of the experimenters, as well as mistakes in reporting the data. “Much of the apes’ behavior is pure drill,” he said. “Language still stands as an important definition of the human species.” In this reversal, Terrace now argued that Nim’s use of ASL was not like human language acquisition. Nim never initiated conversations himself, rarely introduced new words, and simply imitated what the humans did. Nim’s sentences also did not grow in length, unlike human children whose vocabulary and sentence length show a strong positive correlation.

Recent studies have shown that chimpanzees engage in apparently altruistic behaviour within groups,^[21][22] but are indifferent to the welfare of unrelated group members.^[23]

Evidence for "chimpanzee spirituality" includes display of mourning, "incipient romantic love", "rain dance", appreciation of natural beauty such as a sunset over a lake, curiosity and respect towards wildlife (such as the python, which is neither a threat nor a food source to chimpanzees), empathy toward other species (such as feeding turtles) and even "animism" or "pretend play" in chimps cradling and grooming rocks or sticks.^[24] However, whether or not these behaviors are best explained with reference to spirituality is still debated.^{[citation needed]}

Chimpanzee, sometimes colloquially known as a chimp, is the common name for the two extant species of ape in the genus Pan where the Congo River forms the boundary between the native habitat of the two species:[2]

Common Chimpanzee, Pan troglodytes: the better known chimpanzee lives primarily in West and Central Africa.
Bonobo, Pan paniscus: also known as the "Pygmy Chimpanzee", this species is found in the forests of the Democratic Republic of the Congo.
Chimpanzees are members of the Hominidae family, along with gorillas, humans, and orangutans. Chimpanzee are thought to have split from human evolution about 6 million years ago and thus the two chimpanzee species are the closest living relatives to humans; all being members of the Hominini tribe (along with extinct species of Hominina subtribe). Chimpanzees are the only known members of the Panina subtribe. The two Pan species split only about one million years ago. Around 94% of human and chimpanzee DNA sequences are the same.[3]