Common chimpanzee

The chimpanzee (Pan troglodytes), also known as the common chimpanzee, robust chimpanzee, or simply 'chimp', is a species of great ape native to the forests and savannahs of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. The chimpanzee and the closely related bonobo (sometimes called the 'pygmy chimpanzee') are classified in the genus Pan. Evidence from fossils and DNA sequencing shows that Pan is a sister taxon to the human lineage and are humans' closest living relatives. The chimpanzee is covered in coarse black hair, but has a bare face, fingers, toes, palms of the hands, and soles of the feet. It is larger and more robust than the bonobo, weighing 40–60 kg (88–132 lb) for males and 27–50 kg (60–110 lb) for females and standing 100 to 170 cm (3.3 to 5.6 ft). 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. It lives in groups which 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 acquiring honey, termites, ants, nuts and water. The species has also been found creating sharpened sticks to spear small mammals. 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. They are sometimes kept as pets, though their strength and aggressiveness 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; for example, sentences do not grow in length with more training. The English name 'chimpanzee' is first recorded in 1738. It is derived from Vili ci-mpenze or Tshiluba language chimpenze, with a meaning of 'ape'. The colloquialism 'chimp' was most likely coined some time in the late 1870s. The genus name Pan derives from the Greek god, while the specific name troglodytes was taken from the Troglodytae, a mythical race of cave-dwellers. The first great ape known to Western science in the 17th century was the 'orang-outang' (genus Pongo), the local Malay name being recorded in Java by the Dutch physician Jacobus Bontius. In 1641, the Dutch anatomist Nicolaes Tulp applied the name to a chimpanzee or bonobo brought to the Netherlands from Angola. Another Dutch anatomist, Peter Camper, dissected specimens from Central Africa and Southeast Asia in the 1770s, noting the differences between the African and Asian apes. The German naturalist Johann Friedrich Blumenbach classified the common chimpanzee as Simia troglodytes by 1775. Another German naturalist, Lorenz Oken, coined the genus Pan in 1816. The bonobo was recognised as distinct from the common chimpanzee by 1933. Despite a large number of Homo fossil finds, Pan fossils were not described until 2005. Existing chimpanzee populations in West and Central Africa do not overlap with the major human fossil sites in East Africa, but chimpanzee fossils have now been reported from Kenya. This indicates that both humans and members of the Pan clade were present in the East African Rift Valley during the Middle Pleistocene. DNA evidence suggests the bonobo and common 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 common 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'.