In their habitat in the forests of Central Africa, chimpanzees spend most of their days in the treetops. When they do come down to earth, chimps usually travel on all fours, though they can walk on their legs like humans for as far as a mile. They use sticks to fish termites out of mounds and bunches of leaves to sop up drinking water.
Despite our shared lineage, humans are pushing chimpanzees toward extinction. Chimps have already disappeared completely from four countries and are under tremendous pressure everywhere else they live.
Poaching is another prominent threat. Bushmeat has always been a primary food source in Central and West Africa, but in recent years poaching has become commercialized to satisfy the appetites of wealthy urban residents. Infant chimpanzees are frequently taken alive and sold in cities as pets.
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.
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 Neanderthals). 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 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 gorillas (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".
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 rearrangements. 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.
Adult chimpanzees have an average standing height of 150 cm (4 ft 11 in). Wild adult males weigh between 40 and 70 kg (88 and 154 lb) with females weighing between 27 and 50 kg (60 and 110 lb). 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]
Chimpanzees are adapted for both arboreal and terrestrial locomotion. 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, 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 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).[b]
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. In Gombe, the chimpanzee mostly uses semideciduous and evergreen forest as well as open woodland. At Bossou, the chimpanzee inhabits multistage secondary deciduous forest, which has grown after shifting cultivation, as well as primary forest and grassland. At Taï, it is found in the last remaining tropical rain forest in Ivory Coast. The chimpanzee has an advanced cognitive map 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.
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 documented many occasions within Gombe Stream National Park 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.
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, 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 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 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 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.
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.
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. 2b1af7f3a8