Pan paniscus

The bonobo (/bəˈnoʊboʊ, ˈbɒnəboʊ/; Pan paniscus), also historically called the pygmy chimpanzee and less often, the dwarf or gracile chimpanzee, is an endangered great ape and one of the two species making up the genus Pan; the other being the common chimpanzee (Pan troglodytes). Although bonobos are not a subspecies of chimpanzee (Pan troglodytes), but rather a distinct species in their own right, both species are sometimes referred to collectively using the generalized term chimpanzees, or chimps. Taxonomically, the members of the chimpanzee/bonobo subtribe Panina (comprised entirely by the genus Pan) are collectively termed panins. The bonobo is distinguished by relatively long legs, pink lips, dark face and tail-tuft through adulthood, and parted long hair on its head. The bonobo is found in a 500,000 km2 (190,000 sq mi) area of the Congo Basin in the Democratic Republic of the Congo, Central Africa. The species is omnivorous and inhabits primary and secondary forests, including seasonally inundated swamp forests. Political instability in the region and the timidity of bonobos has meant there has been relatively little field work done observing the species in its natural habitat. Along with the common chimpanzee, the bonobo is the closest extant relative to humans. As the two species are not proficient swimmers, the formation of the Congo River 1.5–2 million years ago possibly led to the speciation of the bonobo. Bonobos live south of the river, and thereby were separated from the ancestors of the common chimpanzee, which live north of the river. There are no concrete data on population numbers, but the estimate is between 29,500 and 50,000 individuals. The species is listed as Endangered on the IUCN Red List and is threatened by habitat destruction and human population growth and movement, though commercial poaching is the most prominent threat. They typically live 40 years in captivity; their lifespan in the wild is unknown. Despite the alternative common name 'pygmy chimpanzee', the bonobo is not especially diminutive when compared to the common chimpanzee, with exception of its head. The appellative 'pygmy' is instead owed to its namer, Ernst Schwarz, who classified the species after observing a previously mislabeled bonobo cranium, due to the diminutive size compared to the chimpanzee's counterpart. The name 'bonobo' first appeared in 1954, when Eduard Paul Tratz and Heinz Heck proposed it as a new and separate generic term for pygmy chimpanzees. The name is thought to be a misspelling on a shipping crate from the town of Bolobo on the Congo River near the location from which the first bonobo specimens were collected in the 1920s. Fossils of Pan species 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. However, Pan fossils have now been reported from Kenya. This would indicate that both humans and members of the Pan clade were present in the East African Rift Valley during the Middle Pleistocene. According to A. Zihlman, bonobo body proportions closely resemble those of Australopithecus, leading evolutionary biologist Jeremy Griffith to suggest that bonobos may be a living example of our distant human ancestors. German anatomist Ernst Schwarz is credited with being the first Westerner to recognise the bonobo as being distinctive, in 1928, based on his analysis of a skull in the Tervuren museum in Belgium that previously had been thought to have belonged to a juvenile chimpanzee. Schwarz published his findings in 1929. In 1933, American anatomist Harold Coolidge offered a more detailed description of the bonobo, and elevated it to species status. The American psychologist and primatologist Robert Yerkes was also one of the first scientists to notice major differences between bonobos and chimpanzees. These were first discussed in detail in a study by Eduard Paul Tratz and Heinz Heck published in the early 1950s. The first official publication of the sequencing and assembly of the bonobo genome became publicly available in June 2012. It was deposited with the International Nucleotide Sequence Database Collaboration (DDBJ/EMBL/GenBank) under the EMBL accession number AJFE01000000 after a previous analysis by the National Human Genome Research Institute confirmed that the bonobo genome is about 0.4% divergent from the chimpanzee genome. In addition, as of 2011 Svante Pääbo's group at the Max Planck Institute for Evolutionary Anthropology were sequencing the genome of a female bonobo from the Leipzig zoo. Studies showed that chimpanzees and bonobos are more closely related to humans than to gorillas. In the crucial Nature paper reporting on initial genome comparisons, researchers identified 35 million single-nucleotide changes, five million insertion or deletion events, and a number of chromosomal rearrangements which constituted the genetic differences between the two Pan species and humans, covering 98% of the same genes. While many of these analyses have been performed on the common chimpanzee rather than the bonobo, the differences between the two Pan species are unlikely to be substantial enough to affect the Pan-Homo comparison significantly.