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Chimpanzee

February 16, 2024

"Chimp" redirects here. For other uses, see Chimpanzee (disambiguation) and Chimp (disambiguation).

The chimpanzee (/tʃɪmpænˈzi/; Pan troglodytes), also known as simply the chimp, is a species of great ape native to the forests and savannahs of tropical Africa. It has four confirmed subspecies and a fifth proposed one. When its close relative the bonobo was more commonly known as the pygmy chimpanzee, this species was often called the common chimpanzee or the robust chimpanzee. The chimpanzee and the bonobo are the only species in the genus Pan. Evidence from fossils and DNA sequencing shows that Pan is a sister taxon to the human lineage and is humans' closest living relative. The chimpanzee is covered in coarse black hair, but has a bare face, fingers, toes, palms of the hands, and soles of the feet. It is larger and more robust than the bonobo, weighing 40–70 kg (88–154 lb) for males and 27–50 kg (60–110 lb) for females and standing 150 cm (4 ft 11 in).

Chimpanzee[1]
Temporal range: 4–0 Ma
↓
[2]
P. t. schweinfurthii in Kibale National Park, Uganda
CITES Appendix I (CITES)[4]
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Suborder: Haplorhini
Infraorder: Simiiformes
Family: Hominidae
Subfamily: Homininae
Tribe: Hominini
Genus: Pan
Species:
P. troglodytes
Binomial name
Pan troglodytes
(Blumenbach, 1775)
Subspecies
Distribution of subspecies
  1.      Pan troglodytes verus
  2.      P. t. ellioti
  3.      P. t. troglodytes
  4.      P. t. schweinfurthii
Synonyms
  • Simia troglodytes Blumenbach, 1775
  • Troglodytes troglodytes (Blumenbach, 1776)
  • Troglodytes niger E. Geoffroy, 1812
  • Pan niger (E. Geoffroy, 1812)
  • Anthropopithecus troglodytes (Sutton, 1883)

The chimpanzee lives in groups that range in size from 15 to 150 members, although individuals travel and forage in much smaller groups during the day. The species lives in a strict male-dominated hierarchy, where disputes are generally settled without the need for violence. Nearly all chimpanzee populations have been recorded using tools, modifying sticks, rocks, grass and leaves and using them for hunting and acquiring honey, termites, ants, nuts and water. The species has also been found creating sharpened sticks to spear small mammals. Its gestation period is eight months. The infant is weaned at about three years old but usually maintains a close relationship with its mother for several years more.

The chimpanzee is listed on the IUCN Red List as an endangered species. Between 170,000 and 300,000 individuals are estimated across its range. The biggest threats to the chimpanzee are habitat loss, poaching, and disease. Chimpanzees appear in Western popular culture as stereotyped clown-figures and have featured in entertainments such as chimpanzees' tea parties, circus acts and stage shows. Although many chimpanzees have been kept as pets, their strength, aggressiveness, and unpredictability makes them dangerous in this role. Some hundreds have been kept in laboratories for research, especially in the United States. Many attempts have been made to teach languages such as American Sign Language to chimpanzees, with limited success.

Etymology

 
Relationships among apes. The branch lengths are a measure of evolutionary distinctness. Based on genome sequencing by The Chimpanzee Sequencing and Analysis Consortium. Figure from Yousaf et al. 2021,[5] adapted from Prado-Martinez et al. 2013.[6]

The English word chimpanzee is first recorded in 1738.[7] It is derived from Vili ci-mpenze[8] or Tshiluba language chimpenze, with a meaning of "ape",[9] or "mockman".[10] The colloquialism "chimp" was most likely coined some time in the late 1870s.[11] The genus name Pan derives from the Greek god, while the specific name troglodytes was taken from the Troglodytae, a mythical race of cave-dwellers.[12][13]

Taxonomy

The first great ape known to Western science in the 17th century was the "orang-outang" (genus Pongo), the local Malay name being recorded in Java by the Dutch physician Jacobus Bontius. In 1641, the Dutch anatomist Nicolaes Tulp applied the name to a chimpanzee or bonobo brought to the Netherlands from Angola.[14] Another Dutch anatomist, Peter Camper, dissected specimens from Central Africa and Southeast Asia in the 1770s, noting the differences between the African and Asian apes. The German naturalist Johann Friedrich Blumenbach classified the chimpanzee as Simia troglodytes by 1775. Another German naturalist, Lorenz Oken, coined the genus Pan in 1816. The bonobo was recognised as distinct from the chimpanzee by 1933.[12][13][15]

Evolution

Further information: Chimpanzee–human last common ancestor

Despite a large number of Homo fossil finds, Pan fossils were not described until 2005. Existing chimpanzee populations in West and Central Africa do not overlap with the major human fossil sites in East Africa, but chimpanzee fossils have now been reported from Kenya. This indicates that both humans and members of the Pan clade were present in the East African Rift Valley during the Middle Pleistocene.[16]

According to studies published in 2017 by researchers at George Washington University, bonobos, along with chimpanzees, split from the human line about 8 million years ago; then bonobos split from the common chimpanzee line about 2 million years ago.[17][18] Another 2017 genetic study suggests ancient gene flow (introgression) between 200,000 and 550,000 years ago from the bonobo into the ancestors of central and eastern chimpanzees.[19]

Subspecies and population status

Four subspecies of the chimpanzee have been recognised,[20][21] with the possibility of a fifth:[19][22]

Genome

Main article: Chimpanzee genome project
Genomic information
NCBI genome ID202
Ploidydiploid
Genome size3,323.27 Mb
Number of chromosomes24 pairs

A draft version of the chimpanzee genome was published in 2005 and encodes 18,759 proteins,[29][30] (compared to 20,383 in the human proteome).[31] The DNA sequences of humans and chimpanzees are very similar and the difference in protein number mostly arises from incomplete sequences in the chimp genome. Both species differ by about 35 million single-nucleotide changes, five million insertion/deletion events and various chromosomal rearrangements.[32] Typical human and chimpanzee protein homologs differ in an average of only two amino acids. About 30% of all human proteins are identical in sequence to the corresponding chimpanzee protein. Duplications of small parts of chromosomes have been the major source of differences between human and chimpanzee genetic material; about 2.7% of the corresponding modern genomes represent differences, produced by gene duplications or deletions, since humans and chimpanzees diverged from their common evolutionary ancestor.[29][32]

Characteristics

 
Skeleton

Adult chimpanzees have an average standing height of 150 cm (4 ft 11 in).[33] Wild adult males weigh between 40 and 70 kg (88 and 154 lb)[34][35][36] with females weighing between 27 and 50 kg (60 and 110 lb).[37] In exceptional cases, certain individuals may considerably exceed these measurements, standing over 168 cm (5 ft 6 in) on two legs and weighing up to 136 kg (300 lb) in captivity.[a]

The chimpanzee is more robustly built than the bonobo but less than the gorilla. The arms of a chimpanzee are longer than its legs and can reach below the knees. The hands have long fingers with short thumbs and flat fingernails. The feet are adapted for grasping, and the big toe is opposable. The pelvis is long with an extended ilium. A chimpanzee's head is rounded with a prominent and prognathous face and a pronounced brow ridge. It has forward-facing eyes, a small nose, rounded non-lobed ears and a long mobile upper lip. Additionally, adult males have sharp canine teeth. Chimpanzees lack the prominent sagittal crest and associated head and neck musculature of gorillas.[15][40]

 
Chimpanzee hand (left) compared to human hand

Chimpanzee bodies are covered by coarse hair, except for the face, fingers, toes, palms of the hands, and soles of the feet. Chimpanzees lose more hair as they age and develop bald spots. The hair of a chimpanzee is typically black but can be brown or ginger. As they get older, white or grey patches may appear, particularly on the chin and lower region.[15][40] Chimpanzee skin that is covered with body hair is white, while exposed areas vary: white which ages into a dark muddy colour in eastern chimpanzees, freckled on white which ages to a heavily mottled muddy colour in central chimpanzees, and black with a butterfly-shaped white mask that darkens with age in western chimpanzees.[41][42] Facial pigmentation increases with age and exposure to ultraviolet light. Females develop swelling pink skin when in oestrus.[15][40]

Chimpanzees are adapted for both arboreal and terrestrial locomotion. Arboreal locomotion consists of vertical climbing and brachiation.[43][44] On the ground, chimpanzees move both quadrupedally and bipedally. These movements appear to have similar energy costs.[45] As with bonobos and gorillas, chimpanzees move quadrupedally by knuckle-walking, which probably evolved independently in Pan and Gorilla.[46] Their muscles are 50% stronger per weight than those of humans due to higher content of fast twitch muscle fibres, one of the chimpanzee's adaptations for climbing and swinging.[47] According to Japan's Asahiyama Zoo, the grip strength of an adult chimpanzee is estimated to be 200 kg (440 lb),[48] while other sources claim figures of up to 330 kg (730 lb).[b]

Ecology

 
Overnight nest in a tree

The chimpanzee is a highly adaptable species. It lives in a variety of habitats, including dry savanna, evergreen rainforest, montane forest, swamp forest, and dry woodland-savanna mosaic.[51][52] In Gombe, the chimpanzee mostly uses semideciduous and evergreen forest as well as open woodland.[53] At Bossou, the chimpanzee inhabits multistage secondary deciduous forest, which has grown after shifting cultivation, as well as primary forest and grassland.[54] At Taï, it is found in the last remaining tropical rain forest in Ivory Coast.[55] The chimpanzee has an advanced cognitive map of its home range and can repeatedly find food.[56] The chimpanzee builds a sleeping nest in a tree in a different location each night, never using the same nest more than once. Chimpanzees sleep alone in separate nests except for infants or juvenile chimpanzees, which sleep with their mothers.[57]

Diet

 
A mother with young eating Ficus fruit in Kibale National Park, Uganda

The chimpanzee is an omnivorous frugivore. It prefers fruit above all other food items but also eats leaves, leaf buds, seeds, blossoms, stems, pith, bark, and resin.[58][59] A study in Budongo Forest, Uganda found that 64.5% of their feeding time concentrated on fruits (84.6% of which being ripe), particularly those from two species of Ficus, Maesopsis eminii, and Celtis gomphophylla. In addition, 19% of feeding time was spent on arboreal leaves, mostly Broussonetia papyrifera and Celtis mildbraedii.[60] While the chimpanzee is mostly herbivorous, it does eat honey, soil, insects, birds and their eggs, and small to medium-sized mammals, including other primates.[58][61] Insect species consumed include the weaver ant Oecophylla longinoda, Macrotermes termites, and honey bees.[62][63] The red colobus ranks at the top of preferred mammal prey. Other mammalian prey include red-tailed monkeys, infant and juvenile yellow baboons, bush babies, blue duikers, bushbucks, and common warthogs.[64]

Despite the fact that chimpanzees are known to hunt and to collect both insects and other invertebrates, such food actually makes up a very small portion of their diet, from as little as 2% yearly to as much as 65 grams of animal flesh per day for each adult chimpanzee in peak hunting seasons. This also varies from troop to troop and year to year. However, in all cases, the majority of their diet consists of fruits, leaves, roots, and other plant matter.[59][65] Female chimpanzees appear to consume much less animal flesh than males, according to several studies.[66] Jane Goodall documented many occasions within Gombe Stream National Park of chimpanzees and western red colobus monkeys ignoring each other despite close proximity.[57][67]

Chimpanzees do not appear to directly compete with gorillas in areas where they overlap. When fruit is abundant, gorilla and chimpanzee diets converge, but when fruit is scarce gorillas resort to vegetation.[68] The two apes may also feed on different species, whether fruit or insects.[62][63][69] Interactions between them can range from friendly and even stable social bonding,[70] to avoidance,[68][71] to aggression and predation on part of chimpanzees.[72]

Mortality and health

 
Chimpanzee named "Gregoire" on 9 December 2006, born in 1944 (Jane Goodall sanctuary of Tchimpounga, Republic of the Congo)

The average lifespan of a chimpanzee in the wild is relatively short, usually less than 15 years, although individuals that reach 12 years may live an additional 15 years. On rare occasions, wild chimpanzees may live nearly 60 years. Captive chimpanzees tend to live longer than most wild ones, with median lifespans of 31.7 years for males and 38.7 years for females.[73] The oldest-known male captive chimpanzee to have been documented lived to 66 years,[74] and the oldest female, Little Mama, was over 70 years old.[75]

Leopards prey on chimpanzees in some areas.[76][77] It is possible that much of the mortality caused by leopards can be attributed to individuals that have specialised in chimp-killing.[76] Chimpanzees may react to a leopard's presence with loud vocalising, branch shaking, and throwing objects.[76][78] There is at least one record of chimpanzees killing a leopard cub after mobbing it and its mother in their den.[79] Four chimpanzees could have fallen prey to lions at Mahale Mountains National Park. Although no other instances of lion predation on chimpanzees have been recorded, lions likely do kill chimpanzees occasionally, and the larger group sizes of savanna chimpanzees may have developed as a response to threats from these big cats. Chimpanzees may react to lions by fleeing up trees, vocalising, or hiding in silence.[80]

 
The chimpanzee louse Pediculus schaeffi is closely related to the human body louse P. humanus.

Chimpanzees and humans share only 50% of their parasite and microbe species. This is due to the differences in environmental and dietary adaptations; human internal parasite species overlap more with omnivorous, savanna-dwelling baboons. The chimpanzee is host to the louse species Pediculus schaeffi, a close relative of P. humanus, which infests human head and body hair. By contrast, the human pubic louse Pthirus pubis is closely related to Pthirus gorillae, which infests gorillas.[81] A 2017 study of gastrointestinal parasites of wild chimpanzees in degraded forest in Uganda found nine species of protozoa, five nematodes, one cestode, and one trematode. The most prevalent species was the protozoan Troglodytella abrassarti.[82]

Behaviour

Recent studies have suggested that human observers influence chimpanzee behaviour. One suggestion is that drones, camera traps, and remote microphones should be used to record and monitor chimpanzees rather than direct human observation.[83]

Group structure

 
Group in Uganda

Chimpanzees live in communities that typically range from around 15 to more than 150 members but spend most of their time traveling in small, temporary groups consisting of a few individuals. These groups may consist of any combination of age and sexes. Both males and females sometimes travel alone.[57] This fission-fusion society may include groups of four types: all-male, adult females and offspring, adults of both sexes, or one female and her offspring. These smaller groups emerge in a variety of types, for a variety of purposes. For example, an all-male troop may be organised to hunt for meat, while a group consisting of lactating females serves to act as a "nursery group" for the young.[84]

At the core of social structures are males, which patrol the territory, protect group members, and search for food. Males remain in their natal communities, while females generally emigrate at adolescence. Males in a community are more likely to be related to one another than females are to each other. Among males, there is generally a dominance hierarchy, and males are dominant over females.[85] However, this unusual fission-fusion social structure, "in which portions of the parent group may on a regular basis separate from and then rejoin the rest,"[86] is highly variable in terms of which particular individual chimpanzees congregate at a given time. This is caused mainly by the large measure of individual autonomy that individuals have within their fission-fusion social groups.[40] As a result, individual chimpanzees often forage for food alone, or in smaller groups, as opposed to the much larger "parent" group, which encompasses all the chimpanzees which regularly come into contact with each other and congregate into parties in a particular area.[84]

 
Alpha male chimpanzee at Kibale National Park, Uganda.

Male chimpanzees exist in a linear dominance hierarchy. Top-ranking males tend to be aggressive even during dominance stability.[87] This is probably due to the chimpanzee's fission-fusion society, with male chimpanzees leaving groups and returning after extended periods of time. With this, a dominant male is unsure if any "political maneuvering" has occurred in his absence and must re-establish his dominance. Thus, a large amount of aggression occurs within five to fifteen minutes after a reunion. During these encounters, displays of aggression are generally preferred over physical attacks.[87][88]

Males maintain and improve their social ranks by forming coalitions, which have been characterised as "exploitative" and based on an individual's influence in agonistic interactions.[89] Being in a coalition allows males to dominate a third individual when they could not by themselves, as politically apt chimpanzees can exert power over aggressive interactions regardless of their rank. Coalitions can also give an individual male the confidence to challenge a dominant or larger male. The more allies a male has, the better his chance of becoming dominant. However, most changes in hierarchical rank are caused by dyadic interactions.[87][90] Chimpanzee alliances can be very fickle, and one member may suddenly turn on another if it is to his advantage.[91]

 
Mutual grooming, removing lice

Low-ranking males frequently switch sides in disputes between more dominant individuals. Low-ranking males benefit from an unstable hierarchy and often find increased sexual opportunities if a dispute or conflict occurs.[89][91] In addition, conflicts between dominant males cause them to focus on each other rather than the lower-ranking males. Social hierarchies among adult females tend to be weaker. Nevertheless, the status of an adult female may be important for her offspring.[92] Females in Taï have also been recorded to form alliances.[93] While chimpanzee social structure is often referred to as patriarchal, it is not entirely unheard of for females to forge coalitions against males.[94] There is also at least one recorded case of females securing a dominant position over males in their respective troop, albeit in a captive environment.[95] Social grooming appears to be important in the formation and maintenance of coalitions. It is more common among adult males than either between adult females or between males and females.[90]

 
Males in Mahale National Park, Tanzania

Chimpanzees have been described as highly territorial and will frequently kill other chimpanzees,[96] although Margaret Power wrote in her 1991 book The Egalitarians that the field studies from which the aggressive data came, Gombe and Mahale, used artificial feeding systems that increased aggression in the chimpanzee populations studied. Thus, the behaviour may not reflect innate characteristics of the species as a whole.[97] In the years following her artificial feeding conditions at Gombe, Jane Goodall described groups of male chimpanzees patrolling the borders of their territory, brutally attacking chimpanzees that had split off from the Gombe group. A study published in 2010 found that the chimpanzees wage wars over territory, not mates.[98] Patrols from smaller groups are more likely to avoid contact with their neighbours. Patrols from large groups even take over a smaller group's territory, gaining access to more resources, food, and females.[91][99] While it was traditionally accepted that only female chimpanzees immigrate and males remain in their natal troop for life, there are confirmed cases of adult males safely integrating themselves into new communities among West African chimpanzees, suggesting they are less territorial than other subspecies.[100]

Mating and parenting

 
Infant and mother

Chimpanzees mate throughout the year, although the number of females in oestrus varies seasonally in a group.[101] Female chimpanzees are more likely to come into oestrus when food is readily available. Oestrous females exhibit sexual swellings. Chimpanzees are promiscuous: during oestrus, females mate with several males in their community, while males have large testicles for sperm competition. Other forms of mating also exist. A community's dominant males sometimes restrict reproductive access to females. A male and female can form a consortship and mate outside their community. In addition, females sometimes leave their community and mate with males from neighboring communities.[102][103]

These alternative mating strategies give females more mating opportunities without losing the support of the males in their community.[103] Infanticide has been recorded in chimpanzee communities in some areas, and the victims are often consumed. Male chimpanzees practice infanticide on unrelated young to shorten the interbirth intervals in the females.[104][105] Females sometimes practice infanticide. This may be related to the dominance hierarchy in females or may simply be pathological.[92]

Copulation is brief, lasting approximately seven seconds.[106] The gestation period is eight months.[40] Care for the young is provided mostly by their mothers. The survival and emotional health of the young is dependent on maternal care. Mothers provide their young with food, warmth, and protection, and teach them certain skills. In addition, a chimpanzee's future rank may be dependent on its mother's status.[107][108] Male chimpanzees continue to associate with the females they impregnated and interact with and support their offspring.[109] Newborn chimpanzees are helpless. For example, their grasping reflex is not strong enough to support them for more than a few seconds. For their first 30 days, infants cling to their mother's bellies. Infants are unable to support their own weight for their first two months and need their mothers' support.[110]

When they reach five to six months, infants ride on their mothers' backs. They remain in continual contact for the rest of their first year. When they reach two years of age, they are able to move and sit independently and start moving beyond the arms' reach of their mothers. By four to six years, chimpanzees are weaned and infancy ends. The juvenile period for chimpanzees lasts from their sixth to ninth years. Juveniles remain close to their mothers, but interact an increasing amount with other members of their community. Adolescent females move between groups and are supported by their mothers in agonistic encounters. Adolescent males spend time with adult males in social activities like hunting and boundary patrolling.[110] A captive study suggests males can safely immigrate to a new group if accompanied by immigrant females who have an existing relationship with this male. This gives the resident males reproductive advantages with these females, as they are more inclined to remain in the group if their male friend is also accepted.[111]

Communication

 
Pant-hoot call
Pant-hoot call made by an adult male, demonstrating the introduction, build-up, climax, and let-down phases.[112]
Problems playing this file? See media help.

Chimpanzees use facial expressions, postures, and sounds to communicate with each other. Chimpanzees have expressive faces that are important in close-up communications. When frightened, a "full closed grin" causes nearby individuals to be fearful, as well. Playful chimpanzees display an open-mouthed grin. Chimpanzees may also express themselves with the "pout", which is made in distress, the "sneer", which is made when threatening or fearful, and "compressed-lips face", which is a type of display. When submitting to a dominant individual, a chimpanzee crunches, bobs, and extends a hand. When in an aggressive mode, a chimpanzee swaggers bipedally, hunched over and arms waving, in an attempt to exaggerate its size.[113] While travelling, chimpanzees keep in contact by beating their hands and feet against the trunks of large trees, an act that is known as "drumming". They also do this when encountering individuals from other communities.[114]

Vocalisations are also important in chimpanzee communication. The most common call in adults is the "pant-hoot", which may signal social rank and bond along with keeping groups together. Pant-hoots are made of four parts, starting with soft "hoos", the introduction; that gets louder and louder, the build-up; and climax into screams and sometimes barks; these die down back to soft "hoos" during the letdown phase as the call ends.[112][114] Grunting is made in situations like feeding and greeting.[114] Submissive individuals make "pant-grunts" towards their superiors.[92][115] Whimpering is made by young chimpanzees as a form of begging or when lost from the group.[114] Chimpanzees use distance calls to draw attention to danger, food sources, or other community members.[116] "Barks" may be made as "short barks" when hunting and "tonal barks" when sighting large snakes.[114]

 
Adult male eastern chimpanzee snatches a dead bushbuck antelope from a baboon in Gombe Stream National Park.

Hunting

When hunting small monkeys such as the red colobus, chimpanzees hunt where the forest canopy is interrupted or irregular. This allows them to easily corner the monkeys when chasing them in the appropriate direction. Chimpanzees may also hunt as a coordinated team, so that they can corner their prey even in a continuous canopy. During an arboreal hunt, each chimpanzee in the hunting groups has a role. "Drivers" serve to keep the prey running in a certain direction and follow them without attempting to make a catch. "Blockers" are stationed at the bottom of the trees and climb up to block prey that takes off in a different direction. "Chasers" move quickly and try to make a catch. Finally, "ambushers" hide and rush out when a monkey nears.[117] While both adults and infants are taken, adult male colobus monkeys will attack the hunting chimps.[118] Male chimpanzees hunt more than females. When caught and killed, the meal is distributed to all hunting party members and even bystanders.[117]

Intelligence

Further information: Primate cognition
 
Human and chimpanzee skull and brain. Diagram by Paul Gervais from Histoire naturelle des mammifères (1854).

Chimpanzees display numerous signs of intelligence, from the ability to remember symbols[119] to cooperation,[120] tool use,[121] and perhaps language.[122] They are among species that have passed the mirror test, suggesting self-awareness.[123] In one study, two young chimpanzees showed retention of mirror self-recognition after one year without access to mirrors.[124] Chimpanzees have been observed to use insects to treat their own wounds and those of others. They catch them and apply them directly to the injury.[125] Chimpanzees also display signs of culture among groups, with the learning and transmission of variations in grooming, tool use and foraging techniques leading to localized traditions.[126]

A 30-year study at Kyoto University's Primate Research Institute has shown that chimpanzees are able to learn to recognise the numbers 1 to 9 and their values. The chimpanzees further show an aptitude for eidetic memory, demonstrated in experiments in which the jumbled digits are flashed onto a computer screen for less than a quarter of a second. One chimpanzee, Ayumu, was able to correctly and quickly point to the positions where they appeared in ascending order. Ayumu performed better than human adults who were given the same test.[119]

In controlled experiments on cooperation, chimpanzees show a basic understanding of cooperation, and recruit the best collaborators.[120] In a group setting with a device that delivered food rewards only to cooperating chimpanzees, cooperation first increased, then, due to competitive behaviour, decreased, before finally increasing to the highest level through punishment and other arbitrage behaviours.[127]

Great apes show laughter-like vocalisations 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 recognisable to humans as such, because it is generated by alternating inhalations and exhalations that sound more like breathing and panting. Instances in which nonhuman primates have expressed joy have been reported. 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.[128]

Chimpanzees have displayed different behaviours in response to a dying or dead group member. When witnessing a sudden death, the other group members act in frenzy, with vocalisations, aggressive displays, and touching of the corpse. In one case chimpanzees cared for a dying elder, then attended and cleaned the corpse. Afterward, they avoided the spot where the elder died and behaved in a more subdued manner.[129] Mothers have been reported to carry around and groom their dead infants for several days.[130]

Experimenters now and then witness behaviour that cannot be readily reconciled with chimpanzee intelligence or theory of mind. Wolfgang Köhler, for instance, reported insightful behaviour in chimpanzees, but he likewise often observed that they experienced "special difficulty" in solving simple problems.[131] Researchers also reported that, when faced with a choice between two persons, chimpanzees were just as likely to beg food from a person who could see the begging gesture as from a person who could not, thereby raising the possibility that chimpanzees lack theory of mind.[132]

Tool use

Further information: Tool use by animals
Chimpanzees using twigs to dip for ants

Nearly all chimpanzee populations have been recorded using tools. They modify sticks, rocks, grass, and leaves and use them when foraging for termites and ants,[133] nuts,[133][134][135][136] honey,[137] algae[138] or water. Despite the lack of complexity, forethought and skill are apparent in making these tools.[121] Chimpanzees have used stone tools since at least 4,300 years ago.[139]

A chimpanzee from the Kasakela chimpanzee community was the first nonhuman animal reported making a tool, by modifying a twig to use as an instrument for extracting termites from their mound.[140][141] At Taï, chimpanzees simply use their hands to extract termites.[121] When foraging for honey, chimpanzees use modified short sticks to scoop the honey out of the hive if the bees are stingless. For hives of the dangerous African honeybees, chimpanzees use longer and thinner sticks to extract the honey.[142]

Chimpanzees also fish for ants using the same tactic.[143] Ant dipping is difficult and some chimpanzees never master it. West African chimpanzees crack open hard nuts with stones or branches.[121][143] Some forethought in this activity is apparent, as these tools are not found together or where the nuts are collected. Nut cracking is also difficult and must be learned.[143] Chimpanzees also use leaves as sponges or spoons to drink water.[144]

West African chimpanzees in Senegal were found to sharpen sticks with their teeth, which were then used to spear Senegal bushbabies out of small holes in trees.[145] An eastern chimpanzee has been observed using a modified branch as a tool to capture a squirrel.[146]

Whilst experimental studies on captive chimpanzees have found that many of their species-typical tool-use behaviours can be individually learnt by each chimpanzees,[147] a 2021 study on their abilities to make and use stone flakes, in a similar way as hypothesised for early hominins, did not find this behaviour across two populations of chimpanzees—suggesting that this behaviour is outside the chimpanzee species-typical range.[148]

Language

Main article: Great ape language
 
Hugo Rheinhold's Affe mit Schädel ("Ape with skull"), c. 1893

Scientists have attempted to teach human language to several species of great ape. One early attempt by Allen and Beatrix 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 had spontaneously taught them to other chimpanzees, including her adopted son, Loulis.[149] Over a longer period of time, Washoe was reported to have learned over 350 signs.[150]

Debate is ongoing among scientists such as David Premack about chimpanzees' ability to learn language. Since the early reports on Washoe, numerous other studies have been conducted, with varying levels of success.[122] One involved a chimpanzee jokingly named Nim Chimpsky (in allusion to the theorist of language Noam Chomsky), trained by Herbert Terrace of Columbia University. Although his initial reports were quite positive, in November 1979, Terrace and his team, including psycholinguist Thomas Bever, 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 reanalysis, Terrace and Bever 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' behaviour is pure drill", he said. "Language still stands as an important definition of the human species." In this reversal, Terrace now argued Nim's use of ASL was not like human language acquisition. Nim never initiated conversations himself, rarely introduced new words, and mostly imitated what the humans did. More importantly, Nim's word strings varied in their ordering, suggesting that he was incapable of syntax. Nim's sentences also did not grow in length, unlike human children whose vocabulary and sentence length show a strong positive correlation.[151]

Relations with humans

In culture

 
Chimpanzee mask, Gio tribe, Liberia

Chimpanzees are rarely represented in African culture, as people find their resemblance to humans discomforting. The Gio people of Liberia and the Hemba people of the Congo have created masks of the animals. Gio masks are crude and blocky, and worn when teaching young people how not to behave. The Hemba masks have a smile that suggests drunken anger, insanity or horror and are worn during rituals at funerals, representing the "awful reality of death". The masks may also serve to guard households and protect both human and plant fertility. Stories have been told of chimpanzees kidnapping and raping women.[152]

In Western popular culture, chimpanzees have occasionally been stereotyped as childlike companions, sidekicks or clowns. They are especially suited for the latter role on account of their prominent facial features, long limbs and fast movements, which humans often find amusing. Accordingly, entertainment acts featuring chimpanzees dressed up as humans with lip-synchronised human voices have been traditional staples of circuses, stage shows and TV shows like Lancelot Link, Secret Chimp (1970-1972) and The Chimp Channel (1999).[153] From 1926 until 1972, London Zoo, followed by several other zoos around the world, held a chimpanzees' tea party daily, inspiring a long-running series of advertisements for PG Tips tea featuring such a party.[154][155] Animal rights groups have urged a stop to such acts, considering them abusive.[156]

 
Poster for the 1931 film Aping Hollywood. Media like this relied on the novelty of performing apes to carry their gags.[153]

Chimpanzees in media include Judy on the television series Daktari in the 1960s and Darwin on The Wild Thornberrys in the 1990s. In contrast to the fictional depictions of other animals, such as dogs (as in Lassie), dolphins (Flipper), horses (The Black Stallion) or even other great apes (King Kong), chimpanzee characters and actions are rarely relevant to the plot. Depictions of chimpanzees as individuals rather than stock characters, and as central rather than incidental to the plot can be found in science fiction. Robert A. Heinlein's 1947 short story "Jerry Was a Man" concerns a genetically enhanced chimpanzee suing for better treatment. The 1972 film Conquest of the Planet of the Apes, the third sequel of the 1968 film Planet of the Apes, portrays a futuristic revolt of enslaved apes led by the only talking chimpanzee, Caesar, against their human masters.[153]

As pets

Chimpanzees have traditionally been kept as pets in a few African villages, especially in the Democratic Republic of Congo. In Virunga National Park in the east of the country, the park authorities regularly confiscate chimpanzees from people keeping them as pets.[157] Outside their range, chimpanzees are popular as exotic pets despite their strength and aggression. Even in places where keeping non-human primates as pets is illegal, the exotic pet trade continues to prosper, leading to injuries from attacks.[158]

Use in research

See also: Countries banning non-human ape experimentation and Animal testing on non-human primates § Chimpanzees in the U.S.

Hundreds of chimpanzees have been kept in laboratories for research. Most such laboratories either conduct or make the animals available for invasive research,[159] defined as "inoculation with an infectious agent, surgery or biopsy conducted for the sake of research and not for the sake of the chimpanzee, and/or drug testing".[160] Research chimpanzees tend to be used repeatedly over decades for up to 40 years, unlike the pattern of use of most laboratory animals.[161] Two federally funded American laboratories use chimpanzees: the Yerkes National Primate Research Center at Emory University in Atlanta, Georgia, and the Southwest National Primate Center in San Antonio, Texas.[162] Five hundred chimpanzees have been retired from laboratory use in the US and live in animal sanctuaries in the US or Canada.[159]

A five-year moratorium was imposed by the US National Institutes of Health in 1996, because too many chimpanzees had been bred for HIV research, and it has been extended annually since 2001.[162] With the publication of the chimpanzee genome, plans to increase the use of chimpanzees in America were reportedly increasing in 2006, some scientists arguing that the federal moratorium on breeding chimpanzees for research should be lifted.[162][163] However, in 2007, the NIH made the moratorium permanent.[164]

 
Ham, the first great ape in space, before being inserted into his Mercury-Redstone 2 capsule on 31 January 1961

Other researchers argue that chimpanzees either should not be used in research, or should be treated differently, for instance with legal status as persons.[165] Pascal Gagneux, an evolutionary biologist and primate expert at the University of California, San Diego, argues, given chimpanzees' sense of self, tool use, and genetic similarity to human beings, studies using chimpanzees should follow the ethical guidelines used for human subjects unable to give consent.[162] A recent study suggests chimpanzees which are retired from labs exhibit a form of post-traumatic stress disorder.[166] Stuart Zola, director of the Yerkes laboratory, disagrees. He told National Geographic: "I don't think we should make a distinction between our obligation to treat humanely any species, whether it's a rat or a monkey or a chimpanzee. No matter how much we may wish it, chimps are not human."[162]

Only one European laboratory, the Biomedical Primate Research Centre in Rijswijk, the Netherlands, used chimpanzees in research. It formerly held 108 chimpanzees among 1,300 non-human primates. The Dutch ministry of science decided to phase out research at the centre from 2001.[167] Trials already under way were however allowed to run their course.[168] Chimpanzees including the female Ai have been studied at the Primate Research Institute of Kyoto University, Japan, formerly directed by Tetsuro Matsuzawa, since 1978. Some 12 chimpanzees are currently held at the facility.[169]

Two chimpanzees have been sent into outer space as NASA research subjects. Ham, the first great ape in space, was launched in the Mercury-Redstone 2 capsule on 31 January 1961, and survived the suborbital flight. Enos, the third primate to orbit Earth after Soviet cosmonauts Yuri Gagarin and Gherman Titov, flew on Mercury-Atlas 5 on 29 November of the same year.[170][171]

Field study

 
Feeding station at Gombe, where Jane Goodall used to feed and observe the chimpanzees

Jane Goodall undertook the first long-term field study of the chimpanzee, begun in Tanzania at Gombe Stream National Park in 1960.[172] Other long-term studies begun in the 1960s include Adriaan Kortlandt's in the eastern Democratic Republic of the Congo and Toshisada Nishida's in Mahale Mountains National Park in Tanzania.[173][174] Current understanding of the species' typical behaviours and social organisation has been formed largely from Goodall's ongoing 60-year Gombe research study.[97][175][176]

Attacks

Chimpanzees have attacked humans.[177][178] In Uganda, several attacks on children have happened, some of them fatal. Some of these attacks may have been due to the chimpanzees being intoxicated (from alcohol obtained from rural brewing operations) and becoming aggressive towards humans.[179] Human interactions with chimpanzees may be especially dangerous if the chimpanzees perceive humans as potential rivals.[180] At least six cases of chimpanzees snatching and eating human babies are documented.[181]

A chimpanzee's strength and sharp teeth mean that attacks, even on adult humans, can cause severe injuries. This was evident after the attack and near death of former NASCAR driver St. James Davis, who was mauled by two escaped chimpanzees (in the St. James Davis chimpanzee attack) while he and his wife were celebrating the birthday of their former pet chimpanzee.[182][183] Another example of chimpanzees being aggressive toward humans occurred in 2009 in Stamford, Connecticut, when a 90-kilogram (200 lb), 13-year-old pet chimpanzee named Travis attacked his owner's friend, who lost her hands, eyes, nose, and part of her maxilla from the attack.[184][185]

Human immunodeficiency virus

Two primary classes of human immunodeficiency virus (HIV) infect humans: HIV-1 and HIV-2. HIV-1 is the more virulent and easily transmitted, and is the source of the majority of HIV infections throughout the world; HIV-2 occurs mostly in west Africa.[186] Both types originated in west and central Africa, jumping from other primates to humans. HIV-1 has evolved from a simian immunodeficiency virus (SIVcpz) found in the subspecies P. t. troglodytes of southern Cameroon.[187][188] Kinshasa, in the Democratic Republic of Congo, has the greatest genetic diversity of HIV-1 so far discovered, suggesting the virus has been there longer than anywhere else. HIV-2 crossed species from a different strain of HIV, found in the sooty mangabey monkeys in Guinea-Bissau.[186]

Conservation

 
Cameroonian chimpanzee at a rescue centre after its mother was killed by poachers

The chimpanzee is on the IUCN Red List as an endangered species. Chimpanzees are legally protected in most of their range and are found both in and outside national parks. Between 172,700 and 299,700 individuals are thought to be living in the wild,[3] a decrease from about a million chimpanzees in the early 1900s.[189] Chimpanzees are listed in Appendix I of the Convention on International Trade in Endangered Species (CITES), meaning that commercial international trade in wild-sourced specimens is prohibited and all other international trade (including in parts and derivatives) is regulated by the CITES permitting system.[4]

The biggest threats to the chimpanzee are habitat destruction, poaching, and disease. Chimpanzee habitats have been limited by deforestation in both West and Central Africa. Road building has caused habitat degradation and fragmentation of chimpanzee populations and may allow poachers more access to areas that had not been seriously affected by humans. Although deforestation rates are low in western Central Africa, selective logging may take place outside national parks.[3]

Chimpanzees are a common target for poachers. In Ivory Coast, chimpanzees make up 1–3% of bushmeat sold in urban markets. They are also taken, often illegally, for the pet trade and are hunted for medicinal purposes in some areas. Farmers sometimes kill chimpanzees that threaten their crops; others are unintentionally maimed or killed by snares meant for other animals.[3]

Infectious diseases are a main cause of death for chimpanzees. They succumb to many diseases that afflict humans because the two species are so similar. As the human population grows, so does the risk of disease transmission between humans and chimpanzees.[3]

See also

Notes

  1. ^ One captive male, "Kermit", attained a height of 168 cm (5 ft 6 in) and a body weight of 82 kg (181 lb) when he was 11 years old.[38] As a fully grown adult, he weighed almost 136 kg (300 lb).[39]
  2. ^ According to A. S. Vanesyan's "Anthropology" (2015), a study by "Vorden" (probably 'Worden' or 'Warden') reported that a 54 kg (119 lb) male chimpanzee squeezed 330 kg (730 lb) on a dynamometer, while an angry female squeezed 504 kg (1,111 lb) with both hands. Of the hundreds of human students who also participated in the experiment, only one could squeeze more than 200 kg (440 lb) with both hands.[49] The source is said to be "Jan Dembowskiy, The Psychology of Monkeys."[50] This study is listed in: Dembowski, J. (1946). "Psychology of Monkeys". (PDF) (2nd ed.). Warsaw: Ksrazka. p. 359. Archived from the original (PDF) on 20 July 2021. Retrieved 19 March 2021.

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Literature cited

External links

 
Wikimedia Commons has media related to Pan troglodytes.
 
Wikispecies has information related to Pan troglodytes.
  • Chimpanzee Genome resources
  • Primate Info Net Pan troglodytes Factsheets 13 January 2008 at the Wayback Machine
  • U.S. Fish & Wildlife Service Species Profile
  • View the Pan troglodytes genome in Ensembl
  • Genome of Pan troglodytes (version Clint_PTRv2/panTro6), via UCSC Genome Browser
  • Data of the genome of Pan troglodytes, via NCBI
  • Data of the genome assembly of Pan troglodytes Clint_PTRv2/panTro6, via NCBI
  • Human Timeline (Interactive) – Smithsonian, National Museum of Natural History (August 2016).

February 16, 2024
chimpanzee, chimp, redirects, here, other, uses, disambiguation, chimp, disambiguation, chimpanzee, troglodytes, also, known, simply, chimp, species, great, native, forests, savannahs, tropical, africa, four, confirmed, subspecies, fifth, proposed, when, close. Chimp redirects here For other uses see Chimpanzee disambiguation and Chimp disambiguation The chimpanzee tʃ ɪ m p ae n ˈ z i Pan troglodytes also known as simply the chimp is a species of great ape native to the forests and savannahs of tropical Africa It has four confirmed subspecies and a fifth proposed one When its close relative the bonobo was more commonly known as the pygmy chimpanzee this species was often called the common chimpanzee or the robust chimpanzee The chimpanzee and the bonobo are the only species in the genus Pan Evidence from fossils and DNA sequencing shows that Pan is a sister taxon to the human lineage and is humans closest living relative The chimpanzee is covered in coarse black hair but has a bare face fingers toes palms of the hands and soles of the feet It is larger and more robust than the bonobo weighing 40 70 kg 88 154 lb for males and 27 50 kg 60 110 lb for females and standing 150 cm 4 ft 11 in Chimpanzee 1 Temporal range 4 0 Ma PreꞒ Ꞓ O S D C P T J K Pg N 2 P t schweinfurthii in Kibale National Park UgandaConservation statusEndangered IUCN 3 1 3 CITES Appendix I CITES 4 Scientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataClass MammaliaOrder PrimatesSuborder HaplorhiniInfraorder SimiiformesFamily HominidaeSubfamily HomininaeTribe HomininiGenus PanSpecies P troglodytesBinomial namePan troglodytes Blumenbach 1775 SubspeciesPan troglodytes verusPan troglodytes elliotiPan troglodytes troglodytesPan troglodytes schweinfurthiiDistribution of subspecies Pan troglodytes verus P t ellioti P t troglodytes P t schweinfurthiiSynonymsSimia troglodytes Blumenbach 1775Troglodytes troglodytes Blumenbach 1776 Troglodytes niger E Geoffroy 1812Pan niger E Geoffroy 1812 Anthropopithecus troglodytes Sutton 1883 The chimpanzee lives in groups that range in size from 15 to 150 members although individuals travel and forage in much smaller groups during the day The species lives in a strict male dominated hierarchy where disputes are generally settled without the need for violence Nearly all chimpanzee populations have been recorded using tools modifying sticks rocks grass and leaves and using them for hunting and acquiring honey termites ants nuts and water The species has also been found creating sharpened sticks to spear small mammals Its gestation period is eight months The infant is weaned at about three years old but usually maintains a close relationship with its mother for several years more The chimpanzee is listed on the IUCN Red List as an endangered species Between 170 000 and 300 000 individuals are estimated across its range The biggest threats to the chimpanzee are habitat loss poaching and disease Chimpanzees appear in Western popular culture as stereotyped clown figures and have featured in entertainments such as chimpanzees tea parties circus acts and stage shows Although many chimpanzees have been kept as pets their strength aggressiveness and unpredictability makes them dangerous in this role Some hundreds have been kept in laboratories for research especially in the United States Many attempts have been made to teach languages such as American Sign Language to chimpanzees with limited success Contents 1 Etymology 2 Taxonomy 2 1 Evolution 2 2 Subspecies and population status 2 3 Genome 3 Characteristics 4 Ecology 4 1 Diet 4 2 Mortality and health 5 Behaviour 5 1 Group structure 5 2 Mating and parenting 5 3 Communication 5 4 Hunting 6 Intelligence 6 1 Tool use 6 2 Language 7 Relations with humans 7 1 In culture 7 2 As pets 7 3 Use in research 7 4 Field study 7 5 Attacks 7 6 Human immunodeficiency virus 8 Conservation 9 See also 10 Notes 11 References 11 1 Literature cited 12 External linksEtymology nbsp Relationships among apes The branch lengths are a measure of evolutionary distinctness Based on genome sequencing by The Chimpanzee Sequencing and Analysis Consortium Figure from Yousaf et al 2021 5 adapted from Prado Martinez et al 2013 6 The English word chimpanzee is first recorded in 1738 7 It is derived from Vili ci mpenze 8 or Tshiluba language chimpenze with a meaning of ape 9 or mockman 10 The colloquialism chimp was most likely coined some time in the late 1870s 11 The genus name Pan derives from the Greek god while the specific name troglodytes was taken from the Troglodytae a mythical race of cave dwellers 12 13 TaxonomyThe first great ape known to Western science in the 17th century was the orang outang genus Pongo the local Malay name being recorded in Java by the Dutch physician Jacobus Bontius In 1641 the Dutch anatomist Nicolaes Tulp applied the name to a chimpanzee or bonobo brought to the Netherlands from Angola 14 Another Dutch anatomist Peter Camper dissected specimens from Central Africa and Southeast Asia in the 1770s noting the differences between the African and Asian apes The German naturalist Johann Friedrich Blumenbach classified the chimpanzee as Simia troglodytes by 1775 Another German naturalist Lorenz Oken coined the genus Pan in 1816 The bonobo was recognised as distinct from the chimpanzee by 1933 12 13 15 Evolution Further information Chimpanzee human last common ancestor Despite a large number of Homo fossil finds Pan fossils were not described until 2005 Existing chimpanzee populations in West and Central Africa do not overlap with the major human fossil sites in East Africa but chimpanzee fossils have now been reported from Kenya This indicates that both humans and members of the Pan clade were present in the East African Rift Valley during the Middle Pleistocene 16 According to studies published in 2017 by researchers at George Washington University bonobos along with chimpanzees split from the human line about 8 million years ago then bonobos split from the common chimpanzee line about 2 million years ago 17 18 Another 2017 genetic study suggests ancient gene flow introgression between 200 000 and 550 000 years ago from the bonobo into the ancestors of central and eastern chimpanzees 19 Subspecies and population status Four subspecies of the chimpanzee have been recognised 20 21 with the possibility of a fifth 19 22 Central chimpanzee or the tschego Pan troglodytes troglodytes found in Cameroon the Central African Republic Equatorial Guinea Gabon the Republic of the Congo and the Democratic Republic of the Congo with about 140 000 individuals existing in the wild 23 Western chimpanzee P troglodytes verus found in Ivory Coast Guinea Liberia Mali Sierra Leone Guinea Bissau Senegal and Ghana with about 52 800 individuals still in existence 24 25 Nigeria Cameroon chimpanzee P troglodytes ellioti also known as P t vellerosus 20 that live within forested areas across Nigeria and Cameroon with 6000 9000 individuals still in existence 26 27 Eastern chimpanzee P troglodytes schweinfurthii found in the Central African Republic South Sudan the Democratic Republic of the Congo Uganda Rwanda Burundi Tanzania and Zambia with approximately 180 000 256 000 individuals still existing in the wild 28 Southeastern chimpanzee P troglodytes marungensis in Burundi Rwanda Tanzania and Uganda Colin Groves argues that this is a subspecies created by enough variation between the northern and southern populations of P t schweinfurthii 22 but it is not recognised by the IUCN 3 Genome Main article Chimpanzee genome project Genomic informationNCBI genome ID202PloidydiploidGenome size3 323 27 MbNumber of chromosomes24 pairs A draft version of the chimpanzee genome was published in 2005 and encodes 18 759 proteins 29 30 compared to 20 383 in the human proteome 31 The DNA sequences of humans and chimpanzees are very similar and the difference in protein number mostly arises from incomplete sequences in the chimp genome Both species differ by about 35 million single nucleotide changes five million insertion deletion events and various chromosomal rearrangements 32 Typical human and chimpanzee protein homologs differ in an average of only two amino acids About 30 of all human proteins are identical in sequence to the corresponding chimpanzee protein Duplications of small parts of chromosomes have been the major source of differences between human and chimpanzee genetic material about 2 7 of the corresponding modern genomes represent differences produced by gene duplications or deletions since humans and chimpanzees diverged from their common evolutionary ancestor 29 32 Characteristics nbsp SkeletonAdult chimpanzees have an average standing height of 150 cm 4 ft 11 in 33 Wild adult males weigh between 40 and 70 kg 88 and 154 lb 34 35 36 with females weighing between 27 and 50 kg 60 and 110 lb 37 In exceptional cases certain individuals may considerably exceed these measurements standing over 168 cm 5 ft 6 in on two legs and weighing up to 136 kg 300 lb in captivity a The chimpanzee is more robustly built than the bonobo but less than the gorilla The arms of a chimpanzee are longer than its legs and can reach below the knees The hands have long fingers with short thumbs and flat fingernails The feet are adapted for grasping and the big toe is opposable The pelvis is long with an extended ilium A chimpanzee s head is rounded with a prominent and prognathous face and a pronounced brow ridge It has forward facing eyes a small nose rounded non lobed ears and a long mobile upper lip Additionally adult males have sharp canine teeth Chimpanzees lack the prominent sagittal crest and associated head and neck musculature of gorillas 15 40 nbsp Chimpanzee hand left compared to human handChimpanzee bodies are covered by coarse hair except for the face fingers toes palms of the hands and soles of the feet Chimpanzees lose more hair as they age and develop bald spots The hair of a chimpanzee is typically black but can be brown or ginger As they get older white or grey patches may appear particularly on the chin and lower region 15 40 Chimpanzee skin that is covered with body hair is white while exposed areas vary white which ages into a dark muddy colour in eastern chimpanzees freckled on white which ages to a heavily mottled muddy colour in central chimpanzees and black with a butterfly shaped white mask that darkens with age in western chimpanzees 41 42 Facial pigmentation increases with age and exposure to ultraviolet light Females develop swelling pink skin when in oestrus 15 40 Chimpanzees are adapted for both arboreal and terrestrial locomotion Arboreal locomotion consists of vertical climbing and brachiation 43 44 On the ground chimpanzees move both quadrupedally and bipedally These movements appear to have similar energy costs 45 As with bonobos and gorillas chimpanzees move quadrupedally by knuckle walking which probably evolved independently in Pan and Gorilla 46 Their muscles are 50 stronger per weight than those of humans due to higher content of fast twitch muscle fibres one of the chimpanzee s adaptations for climbing and swinging 47 According to Japan s Asahiyama Zoo the grip strength of an adult chimpanzee is estimated to be 200 kg 440 lb 48 while other sources claim figures of up to 330 kg 730 lb b Ecology nbsp Overnight nest in a treeThe chimpanzee is a highly adaptable species It lives in a variety of habitats including dry savanna evergreen rainforest montane forest swamp forest and dry woodland savanna mosaic 51 52 In Gombe the chimpanzee mostly uses semideciduous and evergreen forest as well as open woodland 53 At Bossou the chimpanzee inhabits multistage secondary deciduous forest which has grown after shifting cultivation as well as primary forest and grassland 54 At Tai it is found in the last remaining tropical rain forest in Ivory Coast 55 The chimpanzee has an advanced cognitive map of its home range and can repeatedly find food 56 The chimpanzee builds a sleeping nest in a tree in a different location each night never using the same nest more than once Chimpanzees sleep alone in separate nests except for infants or juvenile chimpanzees which sleep with their mothers 57 Diet nbsp A mother with young eating Ficus fruit in Kibale National Park UgandaThe chimpanzee is an omnivorous frugivore It prefers fruit above all other food items but also eats leaves leaf buds seeds blossoms stems pith bark and resin 58 59 A study in Budongo Forest Uganda found that 64 5 of their feeding time concentrated on fruits 84 6 of which being ripe particularly those from two species of Ficus Maesopsis eminii and Celtis gomphophylla In addition 19 of feeding time was spent on arboreal leaves mostly Broussonetia papyrifera and Celtis mildbraedii 60 While the chimpanzee is mostly herbivorous it does eat honey soil insects birds and their eggs and small to medium sized mammals including other primates 58 61 Insect species consumed include the weaver ant Oecophylla longinoda Macrotermes termites and honey bees 62 63 The red colobus ranks at the top of preferred mammal prey Other mammalian prey include red tailed monkeys infant and juvenile yellow baboons bush babies blue duikers bushbucks and common warthogs 64 Despite the fact that chimpanzees are known to hunt and to collect both insects and other invertebrates such food actually makes up a very small portion of their diet from as little as 2 yearly to as much as 65 grams of animal flesh per day for each adult chimpanzee in peak hunting seasons This also varies from troop to troop and year to year However in all cases the majority of their diet consists of fruits leaves roots and other plant matter 59 65 Female chimpanzees appear to consume much less animal flesh than males according to several studies 66 Jane Goodall documented many occasions within Gombe Stream National Park of chimpanzees and western red colobus monkeys ignoring each other despite close proximity 57 67 Chimpanzees do not appear to directly compete with gorillas in areas where they overlap When fruit is abundant gorilla and chimpanzee diets converge but when fruit is scarce gorillas resort to vegetation 68 The two apes may also feed on different species whether fruit or insects 62 63 69 Interactions between them can range from friendly and even stable social bonding 70 to avoidance 68 71 to aggression and predation on part of chimpanzees 72 Mortality and health nbsp Chimpanzee named Gregoire on 9 December 2006 born in 1944 Jane Goodall sanctuary of Tchimpounga Republic of the Congo The average lifespan of a chimpanzee in the wild is relatively short usually less than 15 years although individuals that reach 12 years may live an additional 15 years On rare occasions wild chimpanzees may live nearly 60 years Captive chimpanzees tend to live longer than most wild ones with median lifespans of 31 7 years for males and 38 7 years for females 73 The oldest known male captive chimpanzee to have been documented lived to 66 years 74 and the oldest female Little Mama was over 70 years old 75 Leopards prey on chimpanzees in some areas 76 77 It is possible that much of the mortality caused by leopards can be attributed to individuals that have specialised in chimp killing 76 Chimpanzees may react to a leopard s presence with loud vocalising branch shaking and throwing objects 76 78 There is at least one record of chimpanzees killing a leopard cub after mobbing it and its mother in their den 79 Four chimpanzees could have fallen prey to lions at Mahale Mountains National Park Although no other instances of lion predation on chimpanzees have been recorded lions likely do kill chimpanzees occasionally and the larger group sizes of savanna chimpanzees may have developed as a response to threats from these big cats Chimpanzees may react to lions by fleeing up trees vocalising or hiding in silence 80 nbsp The chimpanzee louse Pediculus schaeffi is closely related to the human body louse P humanus Chimpanzees and humans share only 50 of their parasite and microbe species This is due to the differences in environmental and dietary adaptations human internal parasite species overlap more with omnivorous savanna dwelling baboons The chimpanzee is host to the louse species Pediculus schaeffi a close relative of P humanus which infests human head and body hair By contrast the human pubic louse Pthirus pubis is closely related to Pthirus gorillae which infests gorillas 81 A 2017 study of gastrointestinal parasites of wild chimpanzees in degraded forest in Uganda found nine species of protozoa five nematodes one cestode and one trematode The most prevalent species was the protozoan Troglodytella abrassarti 82 BehaviourRecent studies have suggested that human observers influence chimpanzee behaviour One suggestion is that drones camera traps and remote microphones should be used to record and monitor chimpanzees rather than direct human observation 83 Group structure nbsp Group in UgandaChimpanzees live in communities that typically range from around 15 to more than 150 members but spend most of their time traveling in small temporary groups consisting of a few individuals These groups may consist of any combination of age and sexes Both males and females sometimes travel alone 57 This fission fusion society may include groups of four types all male adult females and offspring adults of both sexes or one female and her offspring These smaller groups emerge in a variety of types for a variety of purposes For example an all male troop may be organised to hunt for meat while a group consisting of lactating females serves to act as a nursery group for the young 84 At the core of social structures are males which patrol the territory protect group members and search for food Males remain in their natal communities while females generally emigrate at adolescence Males in a community are more likely to be related to one another than females are to each other Among males there is generally a dominance hierarchy and males are dominant over females 85 However this unusual fission fusion social structure in which portions of the parent group may on a regular basis separate from and then rejoin the rest 86 is highly variable in terms of which particular individual chimpanzees congregate at a given time This is caused mainly by the large measure of individual autonomy that individuals have within their fission fusion social groups 40 As a result individual chimpanzees often forage for food alone or in smaller groups as opposed to the much larger parent group which encompasses all the chimpanzees which regularly come into contact with each other and congregate into parties in a particular area 84 nbsp Alpha male chimpanzee at Kibale National Park Uganda Male chimpanzees exist in a linear dominance hierarchy Top ranking males tend to be aggressive even during dominance stability 87 This is probably due to the chimpanzee s fission fusion society with male chimpanzees leaving groups and returning after extended periods of time With this a dominant male is unsure if any political maneuvering has occurred in his absence and must re establish his dominance Thus a large amount of aggression occurs within five to fifteen minutes after a reunion During these encounters displays of aggression are generally preferred over physical attacks 87 88 Males maintain and improve their social ranks by forming coalitions which have been characterised as exploitative and based on an individual s influence in agonistic interactions 89 Being in a coalition allows males to dominate a third individual when they could not by themselves as politically apt chimpanzees can exert power over aggressive interactions regardless of their rank Coalitions can also give an individual male the confidence to challenge a dominant or larger male The more allies a male has the better his chance of becoming dominant However most changes in hierarchical rank are caused by dyadic interactions 87 90 Chimpanzee alliances can be very fickle and one member may suddenly turn on another if it is to his advantage 91 nbsp Mutual grooming removing liceLow ranking males frequently switch sides in disputes between more dominant individuals Low ranking males benefit from an unstable hierarchy and often find increased sexual opportunities if a dispute or conflict occurs 89 91 In addition conflicts between dominant males cause them to focus on each other rather than the lower ranking males Social hierarchies among adult females tend to be weaker Nevertheless the status of an adult female may be important for her offspring 92 Females in Tai have also been recorded to form alliances 93 While chimpanzee social structure is often referred to as patriarchal it is not entirely unheard of for females to forge coalitions against males 94 There is also at least one recorded case of females securing a dominant position over males in their respective troop albeit in a captive environment 95 Social grooming appears to be important in the formation and maintenance of coalitions It is more common among adult males than either between adult females or between males and females 90 nbsp Males in Mahale National Park TanzaniaChimpanzees have been described as highly territorial and will frequently kill other chimpanzees 96 although Margaret Power wrote in her 1991 book The Egalitarians that the field studies from which the aggressive data came Gombe and Mahale used artificial feeding systems that increased aggression in the chimpanzee populations studied Thus the behaviour may not reflect innate characteristics of the species as a whole 97 In the years following her artificial feeding conditions at Gombe Jane Goodall described groups of male chimpanzees patrolling the borders of their territory brutally attacking chimpanzees that had split off from the Gombe group A study published in 2010 found that the chimpanzees wage wars over territory not mates 98 Patrols from smaller groups are more likely to avoid contact with their neighbours Patrols from large groups even take over a smaller group s territory gaining access to more resources food and females 91 99 While it was traditionally accepted that only female chimpanzees immigrate and males remain in their natal troop for life there are confirmed cases of adult males safely integrating themselves into new communities among West African chimpanzees suggesting they are less territorial than other subspecies 100 Mating and parenting nbsp Infant and motherChimpanzees mate throughout the year although the number of females in oestrus varies seasonally in a group 101 Female chimpanzees are more likely to come into oestrus when food is readily available Oestrous females exhibit sexual swellings Chimpanzees are promiscuous during oestrus females mate with several males in their community while males have large testicles for sperm competition Other forms of mating also exist A community s dominant males sometimes restrict reproductive access to females A male and female can form a consortship and mate outside their community In addition females sometimes leave their community and mate with males from neighboring communities 102 103 These alternative mating strategies give females more mating opportunities without losing the support of the males in their community 103 Infanticide has been recorded in chimpanzee communities in some areas and the victims are often consumed Male chimpanzees practice infanticide on unrelated young to shorten the interbirth intervals in the females 104 105 Females sometimes practice infanticide This may be related to the dominance hierarchy in females or may simply be pathological 92 Copulation is brief lasting approximately seven seconds 106 The gestation period is eight months 40 Care for the young is provided mostly by their mothers The survival and emotional health of the young is dependent on maternal care Mothers provide their young with food warmth and protection and teach them certain skills In addition a chimpanzee s future rank may be dependent on its mother s status 107 108 Male chimpanzees continue to associate with the females they impregnated and interact with and support their offspring 109 Newborn chimpanzees are helpless For example their grasping reflex is not strong enough to support them for more than a few seconds For their first 30 days infants cling to their mother s bellies Infants are unable to support their own weight for their first two months and need their mothers support 110 When they reach five to six months infants ride on their mothers backs They remain in continual contact for the rest of their first year When they reach two years of age they are able to move and sit independently and start moving beyond the arms reach of their mothers By four to six years chimpanzees are weaned and infancy ends The juvenile period for chimpanzees lasts from their sixth to ninth years Juveniles remain close to their mothers but interact an increasing amount with other members of their community Adolescent females move between groups and are supported by their mothers in agonistic encounters Adolescent males spend time with adult males in social activities like hunting and boundary patrolling 110 A captive study suggests males can safely immigrate to a new group if accompanied by immigrant females who have an existing relationship with this male This gives the resident males reproductive advantages with these females as they are more inclined to remain in the group if their male friend is also accepted 111 Communication nbsp Pant hoot call source source Pant hoot call made by an adult male demonstrating the introduction build up climax and let down phases 112 Problems playing this file See media help Chimpanzees use facial expressions postures and sounds to communicate with each other Chimpanzees have expressive faces that are important in close up communications When frightened a full closed grin causes nearby individuals to be fearful as well Playful chimpanzees display an open mouthed grin Chimpanzees may also express themselves with the pout which is made in distress the sneer which is made when threatening or fearful and compressed lips face which is a type of display When submitting to a dominant individual a chimpanzee crunches bobs and extends a hand When in an aggressive mode a chimpanzee swaggers bipedally hunched over and arms waving in an attempt to exaggerate its size 113 While travelling chimpanzees keep in contact by beating their hands and feet against the trunks of large trees an act that is known as drumming They also do this when encountering individuals from other communities 114 Vocalisations are also important in chimpanzee communication The most common call in adults is the pant hoot which may signal social rank and bond along with keeping groups together Pant hoots are made of four parts starting with soft hoos the introduction that gets louder and louder the build up and climax into screams and sometimes barks these die down back to soft hoos during the letdown phase as the call ends 112 114 Grunting is made in situations like feeding and greeting 114 Submissive individuals make pant grunts towards their superiors 92 115 Whimpering is made by young chimpanzees as a form of begging or when lost from the group 114 Chimpanzees use distance calls to draw attention to danger food sources or other community members 116 Barks may be made as short barks when hunting and tonal barks when sighting large snakes 114 nbsp Adult male eastern chimpanzee snatches a dead bushbuck antelope from a baboon in Gombe Stream National Park Hunting When hunting small monkeys such as the red colobus chimpanzees hunt where the forest canopy is interrupted or irregular This allows them to easily corner the monkeys when chasing them in the appropriate direction Chimpanzees may also hunt as a coordinated team so that they can corner their prey even in a continuous canopy During an arboreal hunt each chimpanzee in the hunting groups has a role Drivers serve to keep the prey running in a certain direction and follow them without attempting to make a catch Blockers are stationed at the bottom of the trees and climb up to block prey that takes off in a different direction Chasers move quickly and try to make a catch Finally ambushers hide and rush out when a monkey nears 117 While both adults and infants are taken adult male colobus monkeys will attack the hunting chimps 118 Male chimpanzees hunt more than females When caught and killed the meal is distributed to all hunting party members and even bystanders 117 IntelligenceFurther information Primate cognition nbsp Human and chimpanzee skull and brain Diagram by Paul Gervais from Histoire naturelle des mammiferes 1854 Chimpanzees display numerous signs of intelligence from the ability to remember symbols 119 to cooperation 120 tool use 121 and perhaps language 122 They are among species that have passed the mirror test suggesting self awareness 123 In one study two young chimpanzees showed retention of mirror self recognition after one year without access to mirrors 124 Chimpanzees have been observed to use insects to treat their own wounds and those of others They catch them and apply them directly to the injury 125 Chimpanzees also display signs of culture among groups with the learning and transmission of variations in grooming tool use and foraging techniques leading to localized traditions 126 A 30 year study at Kyoto University s Primate Research Institute has shown that chimpanzees are able to learn to recognise the numbers 1 to 9 and their values The chimpanzees further show an aptitude for eidetic memory demonstrated in experiments in which the jumbled digits are flashed onto a computer screen for less than a quarter of a second One chimpanzee Ayumu was able to correctly and quickly point to the positions where they appeared in ascending order Ayumu performed better than human adults who were given the same test 119 In controlled experiments on cooperation chimpanzees show a basic understanding of cooperation and recruit the best collaborators 120 In a group setting with a device that delivered food rewards only to cooperating chimpanzees cooperation first increased then due to competitive behaviour decreased before finally increasing to the highest level through punishment and other arbitrage behaviours 127 Great apes show laughter like vocalisations 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 recognisable to humans as such because it is generated by alternating inhalations and exhalations that sound more like breathing and panting Instances in which nonhuman primates have expressed joy have been reported 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 128 Chimpanzees have displayed different behaviours in response to a dying or dead group member When witnessing a sudden death the other group members act in frenzy with vocalisations aggressive displays and touching of the corpse In one case chimpanzees cared for a dying elder then attended and cleaned the corpse Afterward they avoided the spot where the elder died and behaved in a more subdued manner 129 Mothers have been reported to carry around and groom their dead infants for several days 130 Experimenters now and then witness behaviour that cannot be readily reconciled with chimpanzee intelligence or theory of mind Wolfgang Kohler for instance reported insightful behaviour in chimpanzees but he likewise often observed that they experienced special difficulty in solving simple problems 131 Researchers also reported that when faced with a choice between two persons chimpanzees were just as likely to beg food from a person who could see the begging gesture as from a person who could not thereby raising the possibility that chimpanzees lack theory of mind 132 Tool use Further information Tool use by animals source source source source source source Chimpanzees using twigs to dip for antsNearly all chimpanzee populations have been recorded using tools They modify sticks rocks grass and leaves and use them when foraging for termites and ants 133 nuts 133 134 135 136 honey 137 algae 138 or water Despite the lack of complexity forethought and skill are apparent in making these tools 121 Chimpanzees have used stone tools since at least 4 300 years ago 139 A chimpanzee from the Kasakela chimpanzee community was the first nonhuman animal reported making a tool by modifying a twig to use as an instrument for extracting termites from their mound 140 141 At Tai chimpanzees simply use their hands to extract termites 121 When foraging for honey chimpanzees use modified short sticks to scoop the honey out of the hive if the bees are stingless For hives of the dangerous African honeybees chimpanzees use longer and thinner sticks to extract the honey 142 Chimpanzees also fish for ants using the same tactic 143 Ant dipping is difficult and some chimpanzees never master it West African chimpanzees crack open hard nuts with stones or branches 121 143 Some forethought in this activity is apparent as these tools are not found together or where the nuts are collected Nut cracking is also difficult and must be learned 143 Chimpanzees also use leaves as sponges or spoons to drink water 144 West African chimpanzees in Senegal were found to sharpen sticks with their teeth which were then used to spear Senegal bushbabies out of small holes in trees 145 An eastern chimpanzee has been observed using a modified branch as a tool to capture a squirrel 146 Whilst experimental studies on captive chimpanzees have found that many of their species typical tool use behaviours can be individually learnt by each chimpanzees 147 a 2021 study on their abilities to make and use stone flakes in a similar way as hypothesised for early hominins did not find this behaviour across two populations of chimpanzees suggesting that this behaviour is outside the chimpanzee species typical range 148 Language Main article Great ape language nbsp Hugo Rheinhold s Affe mit Schadel Ape with skull c 1893Scientists have attempted to teach human language to several species of great ape One early attempt by Allen and Beatrix 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 had spontaneously taught them to other chimpanzees including her adopted son Loulis 149 Over a longer period of time Washoe was reported to have learned over 350 signs 150 Debate is ongoing among scientists such as David Premack about chimpanzees ability to learn language Since the early reports on Washoe numerous other studies have been conducted with varying levels of success 122 One involved a chimpanzee jokingly named Nim Chimpsky in allusion to the theorist of language Noam Chomsky trained by Herbert Terrace of Columbia University Although his initial reports were quite positive in November 1979 Terrace and his team including psycholinguist Thomas Bever 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 reanalysis Terrace and Bever 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 behaviour is pure drill he said Language still stands as an important definition of the human species In this reversal Terrace now argued Nim s use of ASL was not like human language acquisition Nim never initiated conversations himself rarely introduced new words and mostly imitated what the humans did More importantly Nim s word strings varied in their ordering suggesting that he was incapable of syntax Nim s sentences also did not grow in length unlike human children whose vocabulary and sentence length show a strong positive correlation 151 Relations with humansIn culture nbsp Chimpanzee mask Gio tribe LiberiaChimpanzees are rarely represented in African culture as people find their resemblance to humans discomforting The Gio people of Liberia and the Hemba people of the Congo have created masks of the animals Gio masks are crude and blocky and worn when teaching young people how not to behave The Hemba masks have a smile that suggests drunken anger insanity or horror and are worn during rituals at funerals representing the awful reality of death The masks may also serve to guard households and protect both human and plant fertility Stories have been told of chimpanzees kidnapping and raping women 152 In Western popular culture chimpanzees have occasionally been stereotyped as childlike companions sidekicks or clowns They are especially suited for the latter role on account of their prominent facial features long limbs and fast movements which humans often find amusing Accordingly entertainment acts featuring chimpanzees dressed up as humans with lip synchronised human voices have been traditional staples of circuses stage shows and TV shows like Lancelot Link Secret Chimp 1970 1972 and The Chimp Channel 1999 153 From 1926 until 1972 London Zoo followed by several other zoos around the world held a chimpanzees tea party daily inspiring a long running series of advertisements for PG Tips tea featuring such a party 154 155 Animal rights groups have urged a stop to such acts considering them abusive 156 nbsp Poster for the 1931 film Aping Hollywood Media like this relied on the novelty of performing apes to carry their gags 153 Chimpanzees in media include Judy on the television series Daktari in the 1960s and Darwin on The Wild Thornberrys in the 1990s In contrast to the fictional depictions of other animals such as dogs as in Lassie dolphins Flipper horses The Black Stallion or even other great apes King Kong chimpanzee characters and actions are rarely relevant to the plot Depictions of chimpanzees as individuals rather than stock characters and as central rather than incidental to the plot can be found in science fiction Robert A Heinlein s 1947 short story Jerry Was a Man concerns a genetically enhanced chimpanzee suing for better treatment The 1972 film Conquest of the Planet of the Apes the third sequel of the 1968 film Planet of the Apes portrays a futuristic revolt of enslaved apes led by the only talking chimpanzee Caesar against their human masters 153 As pets Chimpanzees have traditionally been kept as pets in a few African villages especially in the Democratic Republic of Congo In Virunga National Park in the east of the country the park authorities regularly confiscate chimpanzees from people keeping them as pets 157 Outside their range chimpanzees are popular as exotic pets despite their strength and aggression Even in places where keeping non human primates as pets is illegal the exotic pet trade continues to prosper leading to injuries from attacks 158 Use in research See also Countries banning non human ape experimentation and Animal testing on non human primates Chimpanzees in the U S Hundreds of chimpanzees have been kept in laboratories for research Most such laboratories either conduct or make the animals available for invasive research 159 defined as inoculation with an infectious agent surgery or biopsy conducted for the sake of research and not for the sake of the chimpanzee and or drug testing 160 Research chimpanzees tend to be used repeatedly over decades for up to 40 years unlike the pattern of use of most laboratory animals 161 Two federally funded American laboratories use chimpanzees the Yerkes National Primate Research Center at Emory University in Atlanta Georgia and the Southwest National Primate Center in San Antonio Texas 162 Five hundred chimpanzees have been retired from laboratory use in the US and live in animal sanctuaries in the US or Canada 159 A five year moratorium was imposed by the US National Institutes of Health in 1996 because too many chimpanzees had been bred for HIV research and it has been extended annually since 2001 162 With the publication of the chimpanzee genome plans to increase the use of chimpanzees in America were reportedly increasing in 2006 some scientists arguing that the federal moratorium on breeding chimpanzees for research should be lifted 162 163 However in 2007 the NIH made the moratorium permanent 164 nbsp Ham the first great ape in space before being inserted into his Mercury Redstone 2 capsule on 31 January 1961Other researchers argue that chimpanzees either should not be used in research or should be treated differently for instance with legal status as persons 165 Pascal Gagneux an evolutionary biologist and primate expert at the University of California San Diego argues given chimpanzees sense of self tool use and genetic similarity to human beings studies using chimpanzees should follow the ethical guidelines used for human subjects unable to give consent 162 A recent study suggests chimpanzees which are retired from labs exhibit a form of post traumatic stress disorder 166 Stuart Zola director of the Yerkes laboratory disagrees He told National Geographic I don t think we should make a distinction between our obligation to treat humanely any species whether it s a rat or a monkey or a chimpanzee No matter how much we may wish it chimps are not human 162 Only one European laboratory the Biomedical Primate Research Centre in Rijswijk the Netherlands used chimpanzees in research It formerly held 108 chimpanzees among 1 300 non human primates The Dutch ministry of science decided to phase out research at the centre from 2001 167 Trials already under way were however allowed to run their course 168 Chimpanzees including the female Ai have been studied at the Primate Research Institute of Kyoto University Japan formerly directed by Tetsuro Matsuzawa since 1978 Some 12 chimpanzees are currently held at the facility 169 Two chimpanzees have been sent into outer space as NASA research subjects Ham the first great ape in space was launched in the Mercury Redstone 2 capsule on 31 January 1961 and survived the suborbital flight Enos the third primate to orbit Earth after Soviet cosmonauts Yuri Gagarin and Gherman Titov flew on Mercury Atlas 5 on 29 November of the same year 170 171 Field study nbsp Feeding station at Gombe where Jane Goodall used to feed and observe the chimpanzeesJane Goodall undertook the first long term field study of the chimpanzee begun in Tanzania at Gombe Stream National Park in 1960 172 Other long term studies begun in the 1960s include Adriaan Kortlandt s in the eastern Democratic Republic of the Congo and Toshisada Nishida s in Mahale Mountains National Park in Tanzania 173 174 Current understanding of the species typical behaviours and social organisation has been formed largely from Goodall s ongoing 60 year Gombe research study 97 175 176 Attacks Chimpanzees have attacked humans 177 178 In Uganda several attacks on children have happened some of them fatal Some of these attacks may have been due to the chimpanzees being intoxicated from alcohol obtained from rural brewing operations and becoming aggressive towards humans 179 Human interactions with chimpanzees may be especially dangerous if the chimpanzees perceive humans as potential rivals 180 At least six cases of chimpanzees snatching and eating human babies are documented 181 A chimpanzee s strength and sharp teeth mean that attacks even on adult humans can cause severe injuries This was evident after the attack and near death of former NASCAR driver St James Davis who was mauled by two escaped chimpanzees in the St James Davis chimpanzee attack while he and his wife were celebrating the birthday of their former pet chimpanzee 182 183 Another example of chimpanzees being aggressive toward humans occurred in 2009 in Stamford Connecticut when a 90 kilogram 200 lb 13 year old pet chimpanzee named Travis attacked his owner s friend who lost her hands eyes nose and part of her maxilla from the attack 184 185 Human immunodeficiency virus Two primary classes of human immunodeficiency virus HIV infect humans HIV 1 and HIV 2 HIV 1 is the more virulent and easily transmitted and is the source of the majority of HIV infections throughout the world HIV 2 occurs mostly in west Africa 186 Both types originated in west and central Africa jumping from other primates to humans HIV 1 has evolved from a simian immunodeficiency virus SIVcpz found in the subspecies P t troglodytes of southern Cameroon 187 188 Kinshasa in the Democratic Republic of Congo has the greatest genetic diversity of HIV 1 so far discovered suggesting the virus has been there longer than anywhere else HIV 2 crossed species from a different strain of HIV found in the sooty mangabey monkeys in Guinea Bissau 186 Conservation nbsp Cameroonian chimpanzee at a rescue centre after its mother was killed by poachersThe chimpanzee is on the IUCN Red List as an endangered species Chimpanzees are legally protected in most of their range and are found both in and outside national parks Between 172 700 and 299 700 individuals are thought to be living in the wild 3 a decrease from about a million chimpanzees in the early 1900s 189 Chimpanzees are listed in Appendix I of the Convention on International Trade in Endangered Species CITES meaning that commercial international trade in wild sourced specimens is prohibited and all other international trade including in parts and derivatives is regulated by the CITES permitting system 4 The biggest threats to the chimpanzee are habitat destruction poaching and disease Chimpanzee habitats have been limited by deforestation in both West and Central Africa Road building has caused habitat degradation and fragmentation of chimpanzee populations and may allow poachers more access to areas that had not been seriously affected by humans Although deforestation rates are low in western Central Africa selective logging may take place outside national parks 3 Chimpanzees are a common target for poachers In Ivory Coast chimpanzees make up 1 3 of bushmeat sold in urban markets They are also taken often illegally for the pet trade and are hunted for medicinal purposes in some areas Farmers sometimes kill chimpanzees that threaten their crops others are unintentionally maimed or killed by snares meant for other animals 3 Infectious diseases are a main cause of death for chimpanzees They succumb to many diseases that afflict humans because the two species are so similar As the human population grows so does the risk of disease transmission between humans and chimpanzees 3 See also nbsp Animals portal nbsp Mammals portal nbsp Primates portal nbsp Africa portalAnthropopithecus Obsolete primate taxon Bili ape Chimpanzees in the northern Democratic Republic of the Congo Chimpanzee 2012 documentary Gombe Chimpanzee War Conflict between groups of chimpanzees Great Ape Project International Primate Day List of individual apes List of notable non human apes Prostitution among animals Limited evidence for prostitution among non human animals One Small Step The Story of the Space Chimps 2008 documentary Primate archaeologyNotes One captive male Kermit attained a height of 168 cm 5 ft 6 in and a body weight of 82 kg 181 lb when he was 11 years old 38 As a fully grown adult he weighed almost 136 kg 300 lb 39 According to A S Vanesyan s Anthropology 2015 a study by Vorden probably Worden or Warden reported that a 54 kg 119 lb male chimpanzee squeezed 330 kg 730 lb on a dynamometer while an angry female squeezed 504 kg 1 111 lb with both hands Of the hundreds of human students who also participated in the experiment only one could squeeze more than 200 kg 440 lb with both hands 49 The source is said to be Jan Dembowskiy The Psychology of Monkeys 50 This study is listed in Dembowski J 1946 Psychology of Monkeys The Chimpanzee A Topical Bibliography PDF 2nd ed Warsaw Ksrazka p 359 Archived 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