The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of
great ape
The Hominidae (), whose members are known as the great apes or hominids (), are a taxonomic family of primates that includes eight extant species in four genera: '' Pongo'' (the Bornean, Sumatran and Tapanuli orangutan); ''Gorilla'' (the ...
tropical Africa
Although tropical Africa is mostly familiar to the West for its rainforests, this biogeographic realm of Africa is far more diverse. While the tropics are thought of as regions with hot moist climates, which are caused by latitude and the trop ...
. It has four confirmed subspecies and a fifth proposed subspecies. 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
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
human
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...
s' 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
Robustness is the property of being strong and healthy in constitution. When it is transposed into a system, it refers to the ability of tolerating perturbations that might affect the system’s functional body. In the same line ''robustness'' ca ...
than the bonobo, weighing for males and for females and standing .
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
Hunting is the human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products ( fur/ hide, bone/tusks, horn/antler, ...
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
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
as an
endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...
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. They are sometimes kept as pets, though their strength, aggressiveness, and unpredictability makes them dangerous in this role. Some hundreds have been kept in laboratories for research, especially in America. Many attempts have been made to teach languages such as American Sign Language to chimpanzees, with limited success.
Etymology
The English word ''chimpanzee'' is first recorded in 1738. It is derived from Vili ''ci-mpenze'' or
Tshiluba language
Luba-Kasai, also known as Western Luba, ''Bena-Lulua, Cilubà/Tshilubà'', ''Luba-Lulua'' or ''Luva'', is a Bantu language ( Zone L) of Central Africa and a national language of the Democratic Republic of the Congo, alongside Lingala, Swahil ...
''chimpenze'', with a meaning of "
ape
Apes (collectively Hominoidea ) are a clade of Old World simians native to sub-Saharan Africa and Southeast Asia (though they were more widespread in Africa, most of Asia, and as well as Europe in prehistory), which together with its sister g ...
". The colloquialism "chimp" was most likely coined some time in the late 1870s. The genus name ''Pan'' derives from the
Greek god
The following is a list of gods, goddesses, and many other divine and semi-divine figures from ancient Greek mythology and ancient Greek religion.
Immortals
The Greeks created images of their deities for many purposes. A temple would house the ...
, while the specific name ''troglodytes'' was taken from the
Troglodytae
The Troglodytae ( el, , ''Trōglodytai''), or Troglodyti (literally "cave goers"), were people mentioned in various locations by many ancient Greek and Roman geographers and historians, including Herodotus (5th century BCE), Agatharchides (2nd c ...
, a mythical race of cave-dwellers.
Taxonomy and genetics
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
Jacobus Bontius (Jacob de Bondt) (1592, in Leiden – 30 November 1631, in Batavia, Dutch East Indies) was a Dutch physician and a pioneer of tropical medicine. He is known for the four-volume work ''De medicina Indorum''. His 1631 work "Historiae ...
. In 1641, the Dutch anatomist
Nicolaes Tulp
Nicolaes Tulp (9 October 1593 – 12 September 1674) was a Dutch surgeon and mayor of Amsterdam. Tulp was well known for his upstanding moral character and as the subject of Rembrandt's famous painting ''The Anatomy Lesson of Dr. Nicolaes Tulp' ...
applied the name to a chimpanzee or bonobo brought to the Netherlands from Angola. Another Dutch anatomist,
Peter Camper
Petrus Camper FRS (11 May 1722 – 7 April 1789), was a Dutch physician, anatomist, physiologist, midwife, zoologist, anthropologist, palaeontologist and a naturalist in the Age of Enlightenment. He was one of the first to take an interest ...
, 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
Johann Friedrich Blumenbach (11 May 1752 – 22 January 1840) was a German physician, naturalist, physiologist, and anthropologist. He is considered to be a main founder of zoology and anthropology as comparative, scientific disciplines. He ...
classified the chimpanzee as ''Simia troglodytes'' by 1775. Another German naturalist,
Lorenz Oken
Lorenz Oken (1 August 1779 – 11 August 1851) was a German naturalist, botanist, biologist, and ornithologist.
Oken was born Lorenz Okenfuss (german: Okenfuß) in Bohlsbach (now part of Offenburg), Ortenau, Baden, and studied natural history ...
, coined the genus ''Pan'' in 1816. The bonobo was recognised as distinct from the chimpanzee by 1933.
Evolution
Despite a large number of ''
Homo
''Homo'' () is the genus that emerged in the (otherwise extinct) genus '' Australopithecus'' that encompasses the extant species ''Homo sapiens'' ( modern humans), plus several extinct species classified as either ancestral to or closely relat ...
'' 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
The Chibanian, widely known by its previous designation of Middle Pleistocene, is an age in the international geologic timescale or a stage in chronostratigraphy, being a division of the Pleistocene Epoch within the ongoing Quaternary Period. Th ...
.
DNA evidence suggests the bonobo and chimpanzee species separated from each other less than one million years ago (similar in relation between ''Homo sapiens'' and
Neanderthal
Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ago. While the ...
s). A 2017 genetic study suggests ancient gene flow ( introgression) between 200 and 550 thousand years ago from the bonobo into the ancestors of central and eastern chimpanzees. The chimpanzee line
split
Split(s) or The Split may refer to:
Places
* Split, Croatia, the largest coastal city in Croatia
* Split Island, Canada, an island in the Hudson Bay
* Split Island, Falkland Islands
* Split Island, Fiji, better known as Hạfliua
Arts, entertai ...
from the last common ancestor of the human line around six million years ago. Because no species other than ''Homo sapiens'' has survived from the human line of that branching, both chimpanzee species are the closest living relatives of humans; the lineage of humans and chimpanzees diverged from
gorilla
Gorillas are herbivorous, predominantly ground-dwelling great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or fi ...
s (genus ''Gorilla'') about seven million years ago. A 2003 study argues the chimpanzee should be included in the human branch as ''Homo troglodytes'' and notes "experts say many scientists are likely to resist the reclassification, especially in the emotionally-charged and often disputed field of anthropology".
Subspecies and population status
Four subspecies of the chimpanzee have been recognised, with the possibility of a fifth:
* Central chimpanzee or the tschego (''Pan troglodytes troglodytes''), found in
Cameroon
Cameroon (; french: Cameroun, ff, Kamerun), officially the Republic of Cameroon (french: République du Cameroun, links=no), is a country in west-central Africa. It is bordered by Nigeria to the west and north; Chad to the northeast; the C ...
, the
Central African Republic
The Central African Republic (CAR; ; , RCA; , or , ) is a landlocked country in Central Africa. It is bordered by Chad to the north, Sudan to the northeast, South Sudan to the southeast, the DR Congo to the south, the Republic of th ...
Gabon
Gabon (; ; snq, Ngabu), officially the Gabonese Republic (french: République gabonaise), is a country on the west coast of Central Africa. Located on the equator, it is bordered by Equatorial Guinea to the northwest, Cameroon to the nort ...
Democratic Republic of the Congo
The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...
, with about 140,000 individuals existing in the wild.
*
Western chimpanzee
The western chimpanzee, or West African chimpanzee, (''Pan troglodytes verus'') is a Critically Endangered subspecies of the common chimpanzee. It inhabits western Africa, specifically Côte d'Ivoire, Guinea, Liberia, Mali, Senegal, Ghana, ...
Mali
Mali (; ), officially the Republic of Mali,, , ff, 𞤈𞤫𞤲𞥆𞤣𞤢𞥄𞤲𞤣𞤭 𞤃𞤢𞥄𞤤𞤭, Renndaandi Maali, italics=no, ar, جمهورية مالي, Jumhūriyyāt Mālī is a landlocked country in West Africa. Mal ...
,
Sierra Leone
Sierra Leone,)]. officially the Republic of Sierra Leone, is a country on the southwest coast of West Africa. It is bordered by Liberia to the southeast and Guinea surrounds the northern half of the nation. Covering a total area of , Sierr ...
,
Guinea-Bissau
Guinea-Bissau ( ; pt, Guiné-Bissau; ff, italic=no, 𞤘𞤭𞤲𞤫 𞤄𞤭𞤧𞤢𞥄𞤱𞤮, Gine-Bisaawo, script=Adlm; Mandinka: ''Gine-Bisawo''), officially the Republic of Guinea-Bissau ( pt, República da Guiné-Bissau, links=no ), ...
Ghana
Ghana (; tw, Gaana, ee, Gana), officially the Republic of Ghana, is a country in West Africa. It abuts the Gulf of Guinea and the Atlantic Ocean to the south, sharing borders with Ivory Coast in the west, Burkina Faso in the north, and To ...
with about 52,800 individuals still in existence.
*
Nigeria-Cameroon chimpanzee
The Nigeria-Cameroon chimpanzee (''Pan troglodytes ellioti'') is a subspecies of the common chimpanzee which inhabits the rainforest along the border of Nigeria and Cameroon. Male Nigeria-Cameroon chimpanzees can weigh up to 70 kilos with a bo ...
(''P. troglodytes ellioti'' (also known as ''P. t. vellerosus'')), that live within forested areas across
Nigeria
Nigeria ( ), , ig, Naìjíríyà, yo, Nàìjíríà, pcm, Naijá , ff, Naajeeriya, kcg, Naijeriya officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf o ...
and Cameroon, with 6000–9000 individuals still in existence.
*
Eastern chimpanzee
The eastern chimpanzee (''Pan troglodytes schweinfurthii'') is a subspecies of the common chimpanzee. It is native to the Central African Republic, South Sudan, the Democratic Republic of the Congo, Uganda, Rwanda, Burundi, and Tanzania.
Taxono ...
(''P. troglodytes schweinfurthii''), found in the Central African Republic,
South Sudan
South Sudan (; din, Paguot Thudän), officially the Republic of South Sudan ( din, Paankɔc Cuëny Thudän), is a landlocked country in East Africa. It is bordered by Ethiopia, Sudan, Central African Republic, Democratic Republic of the ...
, the Democratic Republic of the Congo,
Uganda
}), is a landlocked country in East Africa. The country is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the south by Tanzania. The sou ...
Tanzania
Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands ...
, and
Zambia
Zambia (), officially the Republic of Zambia, is a landlocked country at the crossroads of Central, Southern and East Africa, although it is typically referred to as being in Southern Africa at its most central point. Its neighbours are t ...
, with approximately 180,000–256,000 individuals still existing in the wild.
* 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'', but it is not recognised by the IUCN.
Genome
A draft version of the chimpanzee genome was published in 2005 and encodes 18,759 proteins, (compared to 20,383 in the human proteome). 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
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
homologs
A couple of homologous chromosomes, or homologs, are a set of one maternal and one paternal chromosome that pair up with each other inside a cell during fertilization. Homologs have the same genes in the same loci where they provide points alon ...
differ in an average of only two
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
s. About 30% of all human proteins are identical in sequence to the corresponding chimpanzee protein. Duplications of small parts of
chromosome
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
s 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.
Characteristics
Adult chimpanzees have an average standing height of . Wild adult males weigh between with females weighing between . In exceptional cases, certain individuals may considerably exceed these measurements, standing over on two legs and weighing up to in captivity.
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 thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost digit. The Medical Latin English noun for thumb ...
. 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
The brow ridge, or supraorbital ridge known as superciliary arch in medicine, is a bony ridge located above the eye sockets of all primates. In humans, the eyebrows are located on their lower margin.
Structure
The brow ridge is a nodule or crest ...
. It has forward-facing eyes, a small nose, rounded non-lobed ears, 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.
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. The skin may range from pale to dark, though females develop swelling pink skin when in oestrus.
Chimpanzees are adapted for both
arboreal
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose nu ...
and
terrestrial locomotion
Terrestrial locomotion has evolved as animals adapted from aquatic to terrestrial environments. Locomotion on land raises different problems than that in water, with reduced friction being replaced by the increased effects of gravity.
As viewe ...
. Arboreal locomotion consists of vertical climbing and brachiation. On the ground, chimpanzees move both quadrupedally and bipedally. These movements appear to have similar energy costs. As with bonobos and gorillas, chimpanzees move quadrupedally by
knuckle-walking
Knuckle-walking is a form of quadrupedal walking in which the forelimbs hold the fingers in a partially flexed posture that allows body weight to press down on the ground through the knuckles. Gorillas, bonobos, and chimpanzees use this style o ...
, which probably evolved independently in ''Pan'' and ''Gorilla''. The physical strength of chimps is around 1.5 times greater than humans due to higher content of fast twitch muscle fibres, one of the chimpanzee's adaptations for climbing and swinging. According to Japan's
Asahiyama Zoo
The is a municipal zoo that opened in July 1967 in Asahikawa, Hokkaidō, Japan, and is the northernmost zoo in the country. In August 2004, over 320,000 people had visited the zoo, the second highest number of visitors among all the zoos in Japan ...
, the grip strength of an adult chimpanzee is estimated to be 200 kg (441 lb), while other sources claim figures of up to 330 kg (727 lb).
Ecology
The chimpanzee is a highly adaptable species. It lives in a variety of habitats, including dry
savanna
A savanna or savannah is a mixed woodland- grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...
,
evergreen
In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...
rainforest,
montane forest
Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial ...
,
swamp forest
Freshwater swamp forests, or flooded forests, are forests which are inundated with freshwater, either permanently or seasonally. They normally occur along the lower reaches of rivers and around freshwater lakes. Freshwater swamp forests are found ...
, and dry
woodland
A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ''plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (se ...
-savanna mosaic. In Gombe, the chimpanzee mostly uses semideciduous and evergreen forest as well as open woodland. At
Bossou
Bossou is a town and sub-prefecture in the Lola Prefecture in the Nzérékoré Region of south-eastern Guinea. Much of the sub prefecture consists of the Mount Nimba Strict Nature Reserve. The Bossou Hills Reserve situated at the south-easter ...
, the chimpanzee inhabits multistage secondary
deciduous forest
In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...
, which has grown after
shifting cultivation
Shifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then abandoned while post-disturbance fallow vegetation is allowed to freely grow while the cultivator moves on to another plot. The period of cu ...
, as well as
primary forest
An old-growth forestalso termed primary forest, virgin forest, late seral forest, primeval forest, or first-growth forestis a forest that has attained great age without significant disturbance, and thereby exhibits unique ecological feature ...
and grassland. At
Taï
Taï is a town in southwestern Ivory Coast. It is a sub-prefecture of and the seat of Taï Department in Cavally Region, Montagnes District. Taï is also a commune. The town is between Taï National Park and the Cavally River. The river—which ...
, it is found in the last remaining tropical rain forest in Ivory Coast. The chimpanzee has an advanced
cognitive map
A cognitive map is a type of mental representation which serves an individual to acquire, code, store, recall, and decode information about the relative locations and attributes of phenomena in their everyday or metaphorical spatial environment. T ...
of its home range and can repeatedly find food. 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.
Diet
The chimpanzee is an
omnivorous
An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...
frugivore. It prefers fruit above all other food items but also eats leaves, leaf buds, seeds, blossoms, stems,
pith
Pith, or medulla, is a tissue in the stems of vascular plants. Pith is composed of soft, spongy parenchyma cells, which in some cases can store starch. In eudicotyledons, pith is located in the center of the stem. In monocotyledons, it ext ...
, bark, and
resin
In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on n ...
. 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
''Ficus'' ( or ) is a genus of about 850 species of woody trees, shrubs, vines, epiphytes and hemiepiphytes in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extendi ...
'', ''
Maesopsis eminii
''Maesopsis eminii'', the umbrella tree, is a species of tree in the family Rhamnaceae found in India and Africa. It is the only species in the genus ''Maesopsis''. It is often grown as a plantation tree, and as a shade tree in coffee plantation ...
'', and ''
Celtis gomphophylla
''Celtis gomphophylla'' is a species of flowering plant native to sub-Saharan Africa, Madagascar, and the Comoros.
Description
''Celtis gomphophylla'' is a tree, growing from 5 to 35 meters tall.
Range and habitat
''Celtis gomphophylla'' ranges ...
''. In addition, 19% of feeding time was spent on arboreal leaves, mostly ''
Broussonetia papyrifera
The paper mulberry (''Broussonetia papyrifera'', syn. ''Morus papyrifera'' L.) is a species of flowering plant in the family Moraceae. It is native to Asia,Celtis mildbraedii''. While the chimpanzee is mostly
herbivorous
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...
, it does eat honey, soil, insects, birds and their eggs, and small to medium-sized mammals, including other primates. Insect species consumed include the weaver ant '' Oecophylla longinoda'', ''
Macrotermes
''Macrotermes'' is a genus of termites belonging to the subfamily Macrotermitinae and widely distributed throughout Africa and South-East Asia. Well-studied species include ''Macrotermes natalensis'' and '' M. bellicosus.''
Like other genera i ...
''
termite
Termites are small insects that live in colonies and have distinct castes (eusocial) and feed on wood or other dead plant matter. Termites comprise the infraorder Isoptera, or alternatively the epifamily Termitoidae, within the order Blatto ...
s, and
honey bee
A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Afro-Eurasia. After bees spread naturally throughout Africa and Eurasia, humans became responsible for the current cosm ...
s. The
red colobus
Red colobuses are Old World monkeys of the genus ''Piliocolobus''. It was formerly considered a subgenus within the genus ''Procolobus'', which is now restricted to the olive colobus. They are closely related to the black-and-white colobus monke ...
ranks at the top of preferred mammal prey. Other mammalian prey include
red-tailed monkey
The red-tailed monkey (''Cercopithecus ascanius''), also known as the black-cheeked white-nosed monkey, red-tailed guenon, redtail monkey, or Schmidt's guenon, is a species of primate in the family Cercopithecidae.
It is found in Angola, Cameroo ...
s, infant and juvenile
yellow baboon
The yellow baboon (''Papio cynocephalus'') is a baboon in the family of Old World monkeys. The species epithet means "dog-head" in Greek, due to the dog-like shape of the muzzle and head. Yellow baboons have slim bodies with long arms and legs, a ...
blue duiker
The blue duiker (''Philantomba monticola'') is a small antelope found in central, southern and eastern Africa. It is the smallest duiker. The species was first described by Swedish naturalist Carl Peter Thunberg in 1789. 12 subspecies are i ...
s,
bushbuck
The Cape bushbuck (''Tragelaphus sylvaticus'') is a common and a widespread species of antelope in sub-Saharan Africa.Wronski T, Moodley Y. (2009)Bushbuck, harnessed antelope or both? ''Gnusletter'', 28(1):18-19. Bushbuck are found in a wide ra ...
s, and
common warthog
The common warthog (''Phacochoerus africanus'') is a wild member of the pig family (Suidae) found in grassland, savanna, and woodland in sub-Saharan Africa. In the past, it was commonly treated as a subspecies of ''P. aethiopicus'', but today t ...
s.
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. Female chimpanzees appear to consume much less animal flesh than males, according to several studies.
Jane Goodall
Dame Jane Morris Goodall (; born Valerie Jane Morris-Goodall on 3 April 1934), formerly Baroness Jane van Lawick-Goodall, is an English primatologist and anthropologist. Seen as the world's foremost expert on chimpanzees, Goodall is best kn ...
documented many occasions within
Gombe Stream National Park
Gombe Stream National Park is a national park in Kigoma District of Kigoma Region in Tanzania, north of Kigoma, the capital of Kigoma Region.Tanzania National Parks“Gombe Stream National Park”, 2008. Established in 1968, it is one of the sm ...
of chimpanzees and western red colobus monkeys ignoring each other despite close proximity.
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. The two apes may also feed on different species, whether fruit or insects. Chimpanzees and gorillas usually ignore or avoid each other when feeding on the same tree, but coalitions of chimpanzees have been observed attacking families of gorillas including silverbacks and killing infants.
Mortality and health
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. The oldest known male captive chimpanzee to have been documented lived to 66 years, and the oldest female,
Little Mama Little Mama (born between 1937 and 1942, died on November 14, 2017) was a chimpanzee at Lion Country Safari in Loxahatchee (near West Palm Beach) in Palm Beach County, Florida. Her age was estimated at between 30 and 35 by primatologist Jane Good ...
, was over 70 years old.
Leopards prey on chimpanzees in some areas. It is possible that much of the mortality caused by leopards can be attributed to individuals that have specialised in chimp-killing. Chimpanzees may react to a leopard's presence with loud vocalising, branch shaking, and throwing objects. There is at least one record of chimpanzees killing a leopard cub after
mobbing
Mobbing, as a sociological term, means bullying of an individual by a group, in any context, such as a family, peer group, school, workplace, neighborhood, community, or online. When it occurs as physical and emotional abuse in the workplace, suc ...
it and its mother in their den. 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.
Chimpanzees and humans share only 50% of their
parasite
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...
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. A 2017 study of gastro
intestinal parasite
An intestinal parasite infection is a condition in which a parasite infects the gastro-intestinal tract of humans and other animals. Such parasites can live anywhere in the body, but most prefer the intestinal wall.
Routes of exposure and inf ...
s of wild chimpanzees in degraded forest in Uganda found nine species of protozoa, five nematodes, one cestode, and one
trematode
Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive h ...
. The most prevalent species was the protozoan ''Troglodytella abrassarti''.
Behaviour
Recent studies have suggested that human observers influence chimpanzee behaviour. One suggestion is that
drone
Drone most commonly refers to:
* Drone (bee), a male bee, from an unfertilized egg
* Unmanned aerial vehicle
* Unmanned surface vehicle, watercraft
* Unmanned underwater vehicle or underwater drone
Drone, drones or The Drones may also refer to:
...
s, camera traps, and remote microphones should be used to record and monitor chimpanzees rather than direct human observation.
Group structure
Chimpanzees live in communities that typically range from around 20 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. 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
Hunting is the human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/ hide, bone/tusks, horn/antler, e ...
for meat, while a group consisting of lactating females serves to act as a "nursery group" for the young.
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. 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," 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. 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.
Male chimpanzees exist in a linear dominance hierarchy. Top-ranking males tend to be aggressive even during dominance stability. 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.
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. 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. Chimpanzee alliances can be very fickle, and one member may suddenly turn on another if it is to his advantage.
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. 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. Females in Taï have also been recorded to form alliances. While chimpanzee social structure is often referred to as patriarchal, it is not entirely unheard of for females to forge coalitions against males. 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. 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.
Chimpanzees have been described as highly territorial and will frequently kill other chimpanzees, 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. 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. 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. 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.
Mating and parenting
Chimpanzees mate throughout the year, although the number of females in
oestrus
The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous ...
varies seasonally in a group. Female chimpanzees are more likely to come into oestrus when food is readily available. Oestrous females exhibit
sexual swelling
Sexual swellings are enlarged areas of genital and perineal skin occurring in some female primates that vary in size over the course of the menstrual cycle. Thought to be an honest signal of fertility, male primates are attracted to these swell ...
s. Chimpanzees are
promiscuous
Promiscuity is the practice of engaging in sexual activity frequently with different partners or being indiscriminate in the choice of sexual partners. The term can carry a moral judgment. A common example of behavior viewed as promiscuous by ma ...
: during oestrus, females mate with several males in their community, while males have large testicles for
sperm competition
Sperm competition is the competitive process between spermatozoa of two or more different males to fertilize the same egg during sexual reproduction. Competition can occur when females have multiple potential mating partners. Greater choice and ...
. 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.
These alternative mating strategies give females more mating opportunities without losing the support of the males in their community.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. Females sometimes practice infanticide. This may be related to the dominance hierarchy in females or may simply be pathological.
Copulation
Sexual intercourse (or coitus or copulation) is a sexual activity typically involving the insertion and thrusting of the penis into the vagina for sexual pleasure or reproduction.Sexual intercourse most commonly means penile–vaginal penetra ...
is brief, lasting approximately seven seconds. The gestation period is eight months. 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. 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.
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. 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.
Communication
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. 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.
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. Grunting is made in situations like feeding and greeting. Submissive individuals make "pant-grunts" towards their superiors. Whimpering is made by young chimpanzees as a form of begging or when lost from the group. Chimpanzees use distance calls to draw attention to danger, food sources, or other community members. "Barks" may be made as "short barks" when hunting and "tonal barks" when sighting large snakes.
Hunting
When hunting small monkeys such as the
red colobus
Red colobuses are Old World monkeys of the genus ''Piliocolobus''. It was formerly considered a subgenus within the genus ''Procolobus'', which is now restricted to the olive colobus. They are closely related to the black-and-white colobus monke ...
, 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
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally, but others are exclusively arboreal. The habitats pose nu ...
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. While both adults and infants are taken, adult male colobus monkeys will attack the hunting chimps. Male chimpanzees hunt more than females. When caught and killed, the meal is distributed to all hunting party members and even bystanders.
Intelligence and cognition
Chimpanzees display numerous signs of intelligence, from the ability to remember symbols to cooperation, tool use, and perhaps language. They are among species that have passed the
mirror test
The mirror test—sometimes called the mark test, mirror self-recognition (MSR) test, red spot technique, or rouge test—is a behavioral technique developed in 1970 by American psychologist Gordon Gallup Jr. as an attempt to determine whether an ...
, suggesting self-awareness. In one study, two young chimpanzees showed retention of mirror self-recognition after one year without access to mirrors. 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. Chimpanzees also display signs of
culture
Culture () is an umbrella term which encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, and habits of the individuals in these groups ...
among groups, with the learning and transmission of variations in grooming, tool use and foraging techniques leading to localized traditions.
A 30-year study at Kyoto University's
Primate Research Institute is a Japanese research center for the study of primates. It was founded in 1967 by primatologists Kinji Imanishi and Junichiro Itani. The institute works toward understanding the biological, behavioral and socioecological aspects of primates, and ...
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
Eidetic memory ( ; more commonly called photographic memory or total recall) is the ability to recall an image from memory with high precision—at least for a brief period of time—after seeing it only onceThe terms ''eidetic memory'' and ''pho ...
, 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.
In controlled experiments on cooperation, chimpanzees show a basic understanding of cooperation, and recruit the best collaborators. 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.
Great apes show laughter-like vocalisations in response to physical contact, such as wrestling, play chasing, or
tickling
Tickling is the act of touching a part of a body in a way that causes involuntary twitching movements or laughter. The word evolved from the Middle English ''tikelen'', perhaps frequentative of ''ticken'', to touch lightly.
In 1897, psycholo ...
. 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.
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. Mothers have been reported to carry around and groom their dead infants for several days.
Experimenters now and then witness behaviour that cannot be readily reconciled with chimpanzee intelligence or
theory of mind
In psychology, theory of mind refers to the capacity to understand other people by ascribing mental states to them (that is, surmising what is happening in their mind). This includes the knowledge that others' mental states may be different fro ...
.
Wolfgang Köhler
Wolfgang Köhler (21 January 1887 – 11 June 1967) was a German psychologist and phenomenologist who, like Max Wertheimer and Kurt Koffka, contributed to the creation of Gestalt psychology.
During the Nazi regime in Germany, he prote ...
, for instance, reported insightful behaviour in chimpanzees, but he likewise often observed that they experienced "special difficulty" in solving simple problems. 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
In psychology, theory of mind refers to the capacity to understand other people by ascribing mental states to them (that is, surmising what is happening in their mind). This includes the knowledge that others' mental states may be different fro ...
.
Tool use
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, nuts, honey, algae or water. Despite the lack of complexity, forethought and skill are apparent in making these tools. Chimpanzees have used stone tools since at least 4,300 years ago.
A chimpanzee from the
Kasakela chimpanzee community
The Kasekela chimpanzee community (formerly spelled Kasakela) is a habituated community of wild eastern chimpanzees that lives in Gombe National Park near Lake Tanganyika in Tanzania. The community was the subject of Jane Goodall's pioneering s ...
was the first nonhuman animal reported making a tool, by modifying a twig to use as an instrument for extracting termites from their mound. At Taï, chimpanzees simply use their hands to extract termites. 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.
Chimpanzees also fish for ants using the same tactic. Ant dipping is difficult and some chimpanzees never master it. West African chimpanzees crack open hard nuts with stones or branches. 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. Chimpanzees also use leaves as sponges or spoons to drink water.
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. An eastern chimpanzee has been observed using a modified branch as a tool to capture a squirrel.
Whilst experimental studies on captive chimpanzees have found that many of their species-typical tool-use behaviours can be individually learnt by each chimpanzees, 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.
Language
Scientists have attempted to teach human
language
Language is a structured system of communication. The structure of a language is its grammar and the free components are its vocabulary. Languages are the primary means by which humans communicate, and may be conveyed through a variety of ...
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
Loulis (born May 10, 1978) is a chimpanzee who has learned to communicate in American Sign Language.
Loulis was named for two caregivers (Louise and Lisa) at the Yerkes Regional Primate Research Center in Atlanta, Georgia, where he was born. Afte ...
. Over a longer period of time, Washoe was reported to have learned over 350 signs.
Debate is ongoing among scientists such as
David Premack
David Premack (October 26, 1925 – June 11, 2015) was an American psychologist who was a professor of psychology at the University of Pennsylvania. He was educated at the University of Minnesota when logical positivism was in full bloom. The de ...
about chimpanzees' ability to learn language. Since the early reports on Washoe, numerous other studies have been conducted, with varying levels of success. One involved a chimpanzee jokingly named
Nim Chimpsky
Neam "Nim" Chimpsky (November 19, 1973 – March 10, 2000) was a chimpanzee and the subject of an extended study of animal language acquisition at Columbia University. The project was led by Herbert S. Terrace with the linguistic analysis head ...
(in allusion to the theorist of language
Noam Chomsky
Avram Noam Chomsky (born December 7, 1928) is an American public intellectual: a linguist, philosopher, cognitive scientist, historian, social critic, and political activist. Sometimes called "the father of modern linguistics", Chomsky i ...
), trained by Herbert Terrace of
Columbia University
Columbia University (also known as Columbia, and officially as Columbia University in the City of New York) is a private research university in New York City. Established in 1754 as King's College on the grounds of Trinity Church in Manhatt ...
. 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.
Relations with humans
In culture
Chimpanzees are rarely represented in
African culture
African or Africans may refer to:
* Anything from or pertaining to the continent of Africa:
** People who are native to Africa, descendants of natives of Africa, or individuals who trace their ancestry to indigenous inhabitants of Africa
*** Ethn ...
, as people find their resemblance to humans discomforting. The
Gio people
The Dan are a Mande ethnic group from northwestern Ivory Coast and neighboring Liberia. There are approximately 700,000 members of the group and their largest settlement is Man, Ivory Coast. Neighboring peoples include the Krahn, Kpelle and ...
of Liberia and the
Hemba people
The Hemba people (or ''Eastern Luba'') are a Bantu peoples, Bantu ethnic group in the Democratic Republic of the Congo (DRC).
History
The Hemba language belongs to a group of related languages spoken by people in a belt that runs from southern ...
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.
In Western
popular culture
Popular culture (also called mass culture or pop culture) is generally recognized by members of a society as a set of practices, beliefs, artistic output (also known as, popular art or mass art) and objects that are dominant or prevalent in a ...
, chimpanzees have occasionally been stereotyped as childlike companions,
sidekick
A sidekick is a slang expression for a close companion or colleague (not necessarily in fiction) who is, or is generally regarded as, subordinate to the one they accompany.
Some well-known fictional sidekicks are Don Quixote's Sancho Panza, ...
s or
clowns
A clown is a person who performs comedy and arts in a state of open-mindedness using physical comedy, typically while wearing distinct makeup or costuming and reversing folkway-norms.
History
The most ancient clowns have been found in t ...
. 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-sync
Lip sync or lip synch (pronounced , the same as the word ''sink'', short for lip synchronization) is a technical term for matching a speaking or singing person's lip movements with sung or spoken vocals.
Audio for lip syncing is generated th ...
hronised human voices have been traditional staples of
circus
A circus is a company of performers who put on diverse entertainment shows that may include clowns, acrobats, trained animals, trapeze acts, musicians, dancers, hoopers, tightrope walkers, jugglers, magicians, ventriloquists, and unicyclis ...
es,
stage show
A theatrical production is any work of theatre, such as a staged play, musical, comedy or drama produced from a written book or script. Theatrical productions also extend to other performance designations such as Dramatic and Nondramatic theatre, a ...
s and TV shows like ''
Lancelot Link, Secret Chimp
''Lancelot Link, Secret Chimp'' is an American action/adventure comedy series that originally aired Saturday mornings on ABC from September 12, 1970 to January 2, 1971 and rebroadcast the following season. The live-action film series featured a ...
'' (1970-1972) and ''
The Chimp Channel
''The Chimp Channel'' is an American sitcom which aired on TBS Superstation in 1999. Based on the '' Monkey-ed Movies'' interstitials that TBS aired one year prior, it is the network's first original sitcom. The series primarily consists of costum ...
'' (1999). 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.
Animal rights
Animal rights is the philosophy according to which many or all Animal consciousness, sentient animals have moral worth that is independent of their Utilitarianism, utility for humans, and that their most basic interests—such as avoiding s ...
groups have urged a stop to such acts, considering them abusive.
Chimpanzees in media include Judy on the television series ''
Daktari
''Daktari'' ( Swahili for "doctor") is an American family drama series that aired on CBS between 1966 and 1969. The series is an Ivan Tors Films Production in association with MGM Television starring Marshall Thompson as Dr. Marsh Tracy, a vete ...
'' in the 1960s and Darwin on ''
The Wild Thornberrys
''The Wild Thornberrys'' is an American animated television series created by Arlene Klasky, Gábor Csupó, Steve Pepoon, David Silverman, and Stephen Sustarsic for Nickelodeon. The series portrays an American family of wildlife documentary ...
'' in the 1990s. In contrast to the fictional depictions of other animals, such as dogs (as in '' Lassie''), dolphins ('' Flipper''), horses (''
The Black Stallion
The Black Stallion, known as the Black or Shêtân, is the title character from author Walter Farley's bestselling series about the Arab stallion and his young owner, Alec Ramsay. The series chronicles the story of a Sheikh's prized stallion a ...
'') or even other great apes (''
King Kong
King Kong is a fictional giant monster resembling a gorilla, who has appeared in various media since 1933. He has been dubbed The Eighth Wonder of the World, a phrase commonly used within the franchise. His first appearance was in the novelizat ...
''), 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
Science fiction (sometimes shortened to Sci-Fi or SF) is a genre of speculative fiction which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel uni ...
.
Robert A. Heinlein
Robert Anson Heinlein (; July 7, 1907 – May 8, 1988) was an American science fiction author, aeronautical engineer, and naval officer. Sometimes called the "dean of science fiction writers", he was among the first to emphasize scientific accu ...
Conquest of the Planet of the Apes
''Conquest of the Planet of the Apes'' is a 1972 American science fiction film directed by J. Lee Thompson and written by Paul Dehn. It is the fourth of five films in the original ''Planet of the Apes'' series produced by Arthur P. Jacobs. The ...
'', the third sequel of the 1968 film ''
Planet of the Apes
''Planet of the Apes'' is an American science fiction media franchise consisting of films, books, television series, comics, and other media about a world in which humans and intelligent apes clash for control. The franchise is based on Frenc ...
'', portrays a futuristic revolt of enslaved apes led by the only talking chimpanzee,
Caesar
Gaius Julius Caesar (; ; 12 July 100 BC – 15 March 44 BC), was a Roman general and statesman. A member of the First Triumvirate, Caesar led the Roman armies in the Gallic Wars before defeating his political rival Pompey in a civil war, an ...
, against their human masters.
As pets
Chimpanzees have traditionally been kept as pets in a few African villages, especially in the
Democratic Republic of Congo
The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...
. In
Virunga National Park
, iucn_category = II
, iucn_ref =
, location = Democratic Republic of the Congo
, map = Democratic Republic of the Congo
, relief = 1
, coordinates =
, area =
, established =
, nearest_city = Goma
, photo =Virunga National Park-107997 ...
in the east of the country, the park authorities regularly confiscate chimpanzees from people keeping them as pets. Outside their range, chimpanzees are popular as
exotic pet
An exotic pet is a pet which is relatively rare or unusual to keep, or is generally thought of as a wild species rather than as a domesticated pet. The definition varies by culture, location, and over time—as animals become firmly enough est ...
s despite their strength and aggression. Even where keeping non-human primates as pets is illegal, the exotic pet trade continues to prosper, leading to injuries from attacks.
Use in research
Hundreds of chimpanzees have been kept in laboratories for research. Most such laboratories either conduct or make the animals available for invasive research, 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". Research chimpanzees tend to be used repeatedly over decades for up to 40 years, unlike the pattern of use of most laboratory animals. Two federally funded American laboratories use chimpanzees: the
Yerkes National Primate Research Center
The Emory National Primate Research Center (formerly known as Yerkes National Primate Research Center) located in Atlanta, Georgia, owned by Emory University, is a center of biomedical and behavioral research, is dedicated to improving human and a ...
at
Emory University
Emory University is a private research university in Atlanta, Georgia. Founded in 1836 as "Emory College" by the Methodist Episcopal Church and named in honor of Methodist bishop John Emory, Emory is the second-oldest private institution of ...
in Atlanta, Georgia, and the Southwest National Primate Center in San Antonio, Texas. Five hundred chimpanzees have been retired from laboratory use in the U.S. and live in animal sanctuaries in the U.S. or Canada.
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. With the publication of the
chimpanzee genome
The Chimpanzee Genome Project was an effort to determine the DNA sequence of the chimpanzee genome. Sequencing began in 2005 and by 2013 twenty-four individual chimpanzees had been sequenced. This project was folded into the Great Ape Genome Pro ...
, 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. citing However, in 2007, the NIH made the moratorium permanent.
Other researchers argue that chimpanzees either should not be used in research, or should be treated differently, for instance with legal status as persons. Pascal Gagneux, an evolutionary biologist and primate expert at the
University of California, San Diego
The University of California, San Diego (UC San Diego or colloquially, UCSD) is a public land-grant research university in San Diego, California. Established in 1960 near the pre-existing Scripps Institution of Oceanography, UC San Diego is t ...
, 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. A recent study suggests chimpanzees which are retired from labs exhibit a form of
posttraumatic stress disorder
Post-traumatic stress disorder (PTSD) is a mental and behavioral disorder that can develop because of exposure to a traumatic event, such as sexual assault, warfare, traffic collisions, child abuse, domestic violence, or other threats ...
. 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."
Only one European laboratory, the
Biomedical Primate Research Centre
The Biomedical Primate Research Centre (BPRC) is Europe's largest primate animal testing research centre. It is a scientific research institute that performs research that contributes to the identification and development of new medicines against ...
in
Rijswijk
Rijswijk (), formerly known as Ryswick ( ) in English, is a city and municipality in the western Netherlands, in the province of South Holland. Its population was in , and it has an area of , of which is water.
The municipality also includes t ...
, 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. Trials already under way were however allowed to run their course. Chimpanzees including the female Ai have been studied at the
Primate Research Institute is a Japanese research center for the study of primates. It was founded in 1967 by primatologists Kinji Imanishi and Junichiro Itani. The institute works toward understanding the biological, behavioral and socioecological aspects of primates, and ...
Tetsuro Matsuzawa
is a primatologist who was a past director of the Primate Research Institute of Kyoto University. He graduated from Kyoto University with a B.A. degree in 1974, a Psy.M. degree in 1976 and a Ph.D. degree in Science in 1989.
Matsuzawa is know ...
, since 1978. Some 12 chimpanzees are currently held at the facility.
Two chimpanzees have been sent into outer space as
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...
research subjects.
Ham
Ham is pork from a leg cut that has been preserved by wet or dry curing, with or without smoking."Bacon: Bacon and Ham Curing" in ''Chambers's Encyclopædia''. London: George Newnes, 1961, Vol. 2, p. 39. As a processed meat, the term "ham ...
, the first great ape in space, was launched in the
Mercury-Redstone 2
Mercury-Redstone 2 (MR-2) was the test flight of the Mercury-Redstone Launch Vehicle just prior to the first crewed American space mission in Project Mercury. Carrying a chimpanzee named Ham on a suborbital flight, Mercury spacecraft Number 5 w ...
capsule on 31 January 1961, and survived the suborbital flight.
Enos Enos or Enosh (Hebrew: , Standard ''Enosh'', Tiberian ''ʼĔnôš''; "mortal man”) may refer to:
People in religious scripture
* Enos (biblical figure), a genealogical figure in the Bible.
* The Book of Enos, one of the books that make up the B ...
, the third primate to orbit Earth after Soviet cosmonauts
Yuri Gagarin
Yuri Alekseyevich Gagarin; Gagarin's first name is sometimes transliterated as ''Yuriy'', ''Youri'', or ''Yury''. (9 March 1934 – 27 March 1968) was a Soviet pilot and cosmonaut who became the first human to journey into outer space. T ...
and
Gherman Titov
Gherman Stepanovich Titov (russian: Герман Степанович Титов; 11 September 1935 – 20 September 2000) was a Soviet cosmonaut who, on 6 August 1961, became the second human to orbit the Earth, aboard Vostok 2, preceded by Y ...
, flew on
Mercury-Atlas 5
Mercury-Atlas 5 was an American spaceflight of the Mercury program. It was launched on November 29, 1961, with Enos, a chimpanzee, aboard. The craft orbited the Earth twice and splashed down about south of Bermuda, and Enos became the first pri ...
on 29 November of the same year.
Field study
Jane Goodall
Dame Jane Morris Goodall (; born Valerie Jane Morris-Goodall on 3 April 1934), formerly Baroness Jane van Lawick-Goodall, is an English primatologist and anthropologist. Seen as the world's foremost expert on chimpanzees, Goodall is best kn ...
undertook the first long-term field study of the chimpanzee, begun in Tanzania at
Gombe Stream National Park
Gombe Stream National Park is a national park in Kigoma District of Kigoma Region in Tanzania, north of Kigoma, the capital of Kigoma Region.Tanzania National Parks“Gombe Stream National Park”, 2008. Established in 1968, it is one of the sm ...
in 1960. Other long-term studies begun in the 1960s include A. Kortlandt's in the eastern
Democratic Republic of the Congo
The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...
and
Toshisada Nishida
Toshisada Nishida (3 March, 1941 – 7 June, 2011) was a Japanese primatologist who established one of the first long term chimpanzee field research sites. He was the first to discover that chimpanzees, instead of forming nuclear family-like ...
's in Mahale Mountains National Park in Tanzania. Current understanding of the species' typical behaviours and social organisation has been formed largely from Goodall's ongoing 60-year Gombe research study.
Attacks
Chimpanzees have attacked humans. 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. Human interactions with chimpanzees may be especially dangerous if the chimpanzees perceive humans as potential rivals. At least six cases of chimpanzees snatching and eating human babies are documented.
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
The National Association for Stock Car Auto Racing, LLC (NASCAR) is an American auto racing sanctioning and operating company that is best known for stock car racing. The privately owned company was founded by Bill France Sr. in 1948, and ...
driver St. James Davis, who was mauled by two escaped chimpanzees while he and his wife were celebrating the birthday of their former pet chimpanzee. Another example of chimpanzees being aggressive toward humans occurred in 2009 in Stamford, Connecticut, when a , 13-year-old pet chimpanzee named Travis attacked his owner's friend, who lost her hands, eyes, nose, and part of her
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...
from the attack.
Human immunodeficiency virus
Two primary classes of
human immunodeficiency virus
The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immun ...
(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 is largely confined to west Africa. Both types originated in west and central Africa, jumping from other primates to humans. HIV-1 has evolved from a
simian immunodeficiency virus
''Simian immunodeficiency virus'' (''SIV'') is a species of retrovirus that cause persistent infections in at least 45 species of non-human primates. Based on analysis of strains found in four species of monkeys from Bioko Island, which was iso ...
(SIVcpz) found in the subspecies ''P. t. troglodytes'' of southern
Cameroon
Cameroon (; french: Cameroun, ff, Kamerun), officially the Republic of Cameroon (french: République du Cameroun, links=no), is a country in west-central Africa. It is bordered by Nigeria to the west and north; Chad to the northeast; the C ...
. 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
Guinea-Bissau ( ; pt, Guiné-Bissau; ff, italic=no, 𞤘𞤭𞤲𞤫 𞤄𞤭𞤧𞤢𞥄𞤱𞤮, Gine-Bisaawo, script=Adlm; Mandinka: ''Gine-Bisawo''), officially the Republic of Guinea-Bissau ( pt, República da Guiné-Bissau, links=no ), ...
.
Status and conservation
The chimpanzee is on the
IUCN Red List
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
as an
endangered
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...
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, a decrease from about a million chimpanzees in the early 1900s. Chimpanzees are listed in Appendix I of the
Convention on International Trade in Endangered Species
CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...
(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.
The biggest threats to the chimpanzee are habitat destruction, poaching, and disease. Chimpanzee habitats have been limited by
deforestation
Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...
in both West and Central Africa. Road building has caused habitat degradation and fragmentation of chimpanzee populations and may allow
poacher
Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights.
Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set a ...
s 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.
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.
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 human populations grow, so does the risk of disease transmission between humans and chimpanzees.
Great Ape Project
The Great Ape Project (GAP), founded in 1993, is an international organization of primatologists, anthropologists, ethicists, and others who advocate a United Nations Declaration of the Rights of Great Apes that would confer basic legal right ...
Ensembl
Ensembl genome database project is a scientific project at the European Bioinformatics Institute, which provides a centralized resource for geneticists, molecular biologists and other researchers studying the genomes of our own species and other v ...
UCSC Genome Browser
The UCSC Genome Browser is an online and downloadable genome browser hosted by the University of California, Santa Cruz (UCSC). It is an interactive website offering access to genome sequence data from a variety of vertebrate and invertebrate spec ...
NCBI
The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The ...
NCBI
The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health (NIH). It is approved and funded by the government of the United States. The ...
National Museum of Natural History
The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7 ...