Apes are a branch of Old World tailless simians native to Africa and Southeast Asia. They are the sister group of the Old World monkeys, they are distinguished from other primates by a wider degree of freedom of motion at the shoulder joint as evolved by the influence of brachiation. In traditional and non-scientific use, the term "ape" excludes humans, is thus not equivalent to the scientific taxon Hominoidea. There are two extant branches of the superfamily Hominoidea: lesser apes; the family Hylobatidae, the lesser apes, include four genera and a total of sixteen species of gibbon, including the lar gibbon and the siamang, all native to Asia. They are arboreal and bipedal on the ground, they have lighter smaller social groups than great apes. The family Hominidae, the great apes, includes three extant species of orangutans and their subspecies, two extant species of gorillas and their subspecies, two extant species of chimpanzees and their subspecies, one extant species of humans in a single extant subspecies.
Except for gorillas and humans, hominoids are agile climbers of trees. Apes eat a variety of plant and animal foods, with the majority of food being plant foods, which can include fruit, stalks and seeds, including nuts and grass seeds. Human diets are sometimes different to that of other apes due in part to the development of technology and a wide range of habitation. Humans are by far the most numerous of the ape species, in fact outnumbering all other primates by a factor of several thousand to one. Most non-human hominoids are rare or endangered; the chief threat to most of the endangered species is loss of tropical rainforest habitat, though some populations are further imperiled by hunting for bushmeat. The great apes of Africa are facing threat from the Ebola virus. Considered to be the greatest threat to survival of African apes, Ebola is responsible for the death of at least one third of gorillas and chimpanzees since 1990. "Ape", from Old English apa, is a word of uncertain origin. The term has a history of rather imprecise usage -- and of punning usage in the vernacular.
Its earliest meaning was of any non-human anthropoid primate, as is still the case for its cognates in other Germanic languages. After the term "monkey" had been introduced into English, "ape" was specialized to refer to a tailless primate. Thus, the term "ape" obtained two different meanings, as shown in the 1911 Encyclopædia Britannica entry: it could be used as a synonym for "monkey" and it could denote the tailless humanlike primate in particular. Some, or all, hominoids are called "apes", but the term is used broadly and has several different senses within both popular and scientific settings. "Ape" has been used as a synonym for "monkey" or for naming any primate with a human-like appearance those without a tail. Biologists have traditionally used the term "ape" to mean a member of the superfamily Hominoidea other than humans, but more to mean all members of Hominoidea. So "ape"—not to be confused with "great ape"—now becomes another word for hominoid including humans; the term hominoid is not to be confused with the family of great apes.
The distinction between apes and monkeys is complicated by the traditional paraphyly of monkeys: Apes emerged as a sister group of Old World Monkeys in the catarhines, which are a sister group of New World Monkeys. Therefore, apes and related contemporary extinct groups such as Parapithecidaea are monkeys as well, for any consistent definition of "monkey". "Old World Monkey" may legitimately be taken to be meant to include all the catarrhines, including apes and extinct species such as Aegyptopithecus, in which case the apes and Aegyptopithecus emerged within the Old World Monkeys. The primates called "apes" today became known to Europeans after the 18th century; as zoological knowledge developed, it became clear that taillessness occurred in a number of different and otherwise distantly related species. Sir Wilfrid Le Gros Clark was one of those primatologists who developed the idea that there were trends in primate evolution and that the extant members of the order could be arranged in an "..
Ascending series", leading from "monkeys" to "apes" to humans. Within this tradition "ape" came to refer to all members of the superfamily Hominoidea except humans; as such, this use of "apes" represented a paraphyletic grouping, meaning that though all species of apes were descended from a common ancestor, this grouping did not include all the descendant species, because humans were excluded from being among the apes. The cladogram of the superfamily Hominoidae shows the descendant relationships of the extant hominoids that are broadly accepted today. For each clade, it is indicated how many million of years ago newer extant clades radiated. Traditionally, humans were considered neither apes nor great apes, but today they are recognized as having emerged deep in the phylogenetic tree of apes. Thus, there are at least three common, or traditional, uses of the term "ape": non-specialists may not distinguish between "monkeys" and "apes", that is, they may use the two terms interchangeably. Modern biologists and primatologists use monophyletic groups for taxonomic classification.
The Hominini, or hominins, form a taxonomic tribe of the subfamily Homininae. Hominini excludes the genus Gorilla; as of 2019, there is no consensus on whether it should include the genus Pan, the question being tied to the complex speciation process connecting humans and chimpanzees and the development of bipedalism in proto-humans. The tribe was introduced by John Edward Gray, long before any details on the speciation of Pan and Homo were known. Gray's tribe Hominini by definition includes both Homo; this definition is still adhered to in the proposal by Mann and Weiss, which divides Hominini into three subtribes, Panina and Australopithecina. Alternatively, Hominini is taken to exclude Pan. In this case, Panini may be used to refer to the tribe containing Pan as its only genus. Minority dissenting nomenclatures include Gorilla in Hominini and Pan in Homo, or both Pan and Gorilla in Homo. By convention, the adjectival term "hominin" refers to the tribe Hominini, while the members of the Hominina subtribe are referred to as "homininan".
This follows the proposal by Mann and Weiss, which presents tribe Hominini as including both Pan and Homo, placed in separate subtribes. The genus Pan is referred to subtribe Panina, genus Homo is included in the subtribe Hominina. However, there is an alternative convention which uses "hominin" to exclude members of Panina, i.e. either just for Homo or for both human and australopithecine species. This alternative convention is referenced in Dunbar. Potts in addition uses the name Hominini in a different sense, as excluding Pan, uses "hominins" for this, while a separate tribe for chimpanzees is introduced, under the name Panini. In this recent convention, contra Gray, the term "hominin" is applied to Homo, Australopithecus and others that arose after the split from the line that led to chimpanzees; this cladogram shows the clade of superfamily Hominoidea and its descendent clades, focussed on the division of Hominini. The family Hominidae comprises the tribes Ponginae and Hominini, the latter two forming the subfamily of Homininae.
Hominini is divided into Australopithecina. The Hominina are held to have emerged within the Australopithecina. Genetic analysis combined with fossil evidence indicates that hominoids diverged from the Old World monkeys about 25 million years ago, near the Oligocene-Miocene boundary; the most recent common ancestors of the subfamilies Homininae and Ponginae, lived about 15 million years ago. In the following cladogram, the approximate time the clades radiated newer clades indicated in millions of years ago. Both Sahelanthropus and Orrorin existed during the estimated duration of the ancestral chimpanzee-human speciation events, within the range of eight to four million years ago. Few fossil specimens have been found that can be considered directly ancestral to genus Pan. News of the first fossil chimpanzee, found in Kenya, was published in 2005. However, it is dated to recent times—between 545 and 284 thousand years ago; the divergence of a "proto-human" or "pre-human" lineage separate from Pan appears to have been a process of complex speciation-hybridization rather than a clean split, taking place over the period of anywhere between 13 million years ago and some 4 million years ago.
Different chromosomes appear to have split at different times, with broad-scale hybridization activity occurring between the two emerging lineages as late as the period 6.3 to 5.4 Mya, according to Patterson et al. This research group noted that one hypothetical late hybridization period was based in particular on the similarity of X chromosomes in the proto-humans and stem chimpanzees, suggesting the final divergence as recent as 4 Mya. Wakeley rejected these hypotheses. Most DNA studies find that humans and Pan are 99% identical, but one study found only 94% commonality, with some of the difference occurring in noncoding DNA, it is most that the australopithecines, dating from 3 to 4.4 Mya, evolved into the earliest members of genus Homo. In the year 2000, the discovery of Orrorin tugenensis, dated as early as 6.2 Mya challenged critical elements of that hypothesis, as it suggested that Homo did not in fact derive from australopithecine ancestors. All the listed fossil genera are evaluated for: 1) probability of being ancestral to Homo, 2) whether they are more related to Homo than to any other living primate—two traits that could identify them as hominins.
Some, including Paranthropus and Australopithecus, are broadly thought to be ancestral and related to Homo.
The Miocene is the first geological epoch of the Neogene Period and extends from about 23.03 to 5.333 million years ago. The Miocene was named by Charles Lyell; the Miocene is followed by the Pliocene. As the earth went from the Oligocene through the Miocene and into the Pliocene, the climate cooled towards a series of ice ages; the Miocene boundaries are not marked by a single distinct global event but consist rather of regionally defined boundaries between the warmer Oligocene and the cooler Pliocene Epoch. The Apes first evolved and diversified during the early Miocene, becoming widespread in the Old World. By the end of this epoch and the start of the following one, the ancestors of humans had split away from the ancestors of the chimpanzees to follow their own evolutionary path during the final Messinian stage of the Miocene; as in the Oligocene before it, grasslands continued to forests to dwindle in extent. In the seas of the Miocene, kelp forests made their first appearance and soon became one of Earth's most productive ecosystems.
The plants and animals of the Miocene were recognizably modern. Mammals and birds were well-established. Whales and kelp spread; the Miocene is of particular interest to geologists and palaeoclimatologists as major phases of the geology of the Himalaya occurred during the Miocene, affecting monsoonal patterns in Asia, which were interlinked with glacial periods in the northern hemisphere. The Miocene faunal stages from youngest to oldest are named according to the International Commission on Stratigraphy: Regionally, other systems are used, based on characteristic land mammals. Of the modern geologic features, only the land bridge between South America and North America was absent, although South America was approaching the western subduction zone in the Pacific Ocean, causing both the rise of the Andes and a southward extension of the Meso-American peninsula. Mountain building took place in western North America and East Asia. Both continental and marine Miocene deposits are common worldwide with marine outcrops common near modern shorelines.
Well studied continental exposures occur in Argentina. India continued creating dramatic new mountain ranges; the Tethys Seaway continued to shrink and disappeared as Africa collided with Eurasia in the Turkish–Arabian region between 19 and 12 Ma. The subsequent uplift of mountains in the western Mediterranean region and a global fall in sea levels combined to cause a temporary drying up of the Mediterranean Sea near the end of the Miocene; the global trend was towards increasing aridity caused by global cooling reducing the ability of the atmosphere to absorb moisture. Uplift of East Africa in the late Miocene was responsible for the shrinking of tropical rain forests in that region, Australia got drier as it entered a zone of low rainfall in the Late Miocene. During the Oligocene and Early Miocene the coast of northern Brazil, south-central Peru, central Chile and large swathes of inland Patagonia were subject to a marine transgression; the transgressions in the west coast of South America is thought to be caused by a regional phenomenon while the rising central segment of the Andes represents an exception.
While there are numerous registers of Oligo-Miocene transgressions around the world it is doubtful that these correlate. It is thought that the Oligo-Miocene transgression in Patagonia could have temporarily linked the Pacific and Atlantic Oceans, as inferred from the findings of marine invertebrate fossils of both Atlantic and Pacific affinity in La Cascada Formation. Connection would have occurred through narrow epicontinental seaways that formed channels in a dissected topography; the Antarctic Plate started to subduct beneath South America 14 million years ago in the Miocene, forming the Chile Triple Junction. At first the Antarctic Plate subducted only in the southernmost tip of Patagonia, meaning that the Chile Triple Junction lay near the Strait of Magellan; as the southern part of Nazca Plate and the Chile Rise became consumed by subduction the more northerly regions of the Antarctic Plate begun to subduct beneath Patagonia so that the Chile Triple Junction advanced to the north over time.
The asthenospheric window associated to the triple junction disturbed previous patterns of mantle convection beneath Patagonia inducing an uplift of ca. 1 km that reversed the Oligocene–Miocene transgression. Climates remained moderately warm, although the slow global cooling that led to the Pleistocene glaciations continued. Although a long-term cooling trend was well underway, there is evidence of a warm period during the Miocene when the global climate rivalled that of the Oligocene; the Miocene warming b
The eastern gorilla is a critically endangered species of the genus Gorilla and the largest living primate. At present, the species is subdivided into two subspecies. Grauer's gorilla known as the eastern lowland gorilla is more populous, at about 3,800 individuals; the mountain gorilla has only about 1000 individuals. The International Union for the Conservation of Nature mentioned illegal hunting in its assessment of threats to the species. There are two recognised subspecies of eastern gorilla: the mountain gorilla of the volcanic slopes of Rwanda and eastern Democratic Republic of Congo. Grauer's gorillas and mountain gorillas were thought to be two of the three subspecies of one single species, the gorilla. However, genetic research has shown that the two eastern subspecies are far more related than the western subspecies: the western lowland gorilla, which justified the separate classification; the two eastern subspecies are now classified as G. beringei. The eastern gorilla is a large hominid with a large head, broad chest, long arms.
It has a flat nose with large nostrils. The face, hands and breast are bald; the fur is black, but adult males have a silvery "saddle" on their back. When the gorilla gets older, the hair on the saddle of the back becomes white, much like the gray hair of elderly people; this is. Grauer's gorilla has a shorter, deep black fur, while the mountain gorilla has a more bluish color; the mountain gorilla is smaller and lighter than Grauer's gorilla, but still larger and heavier than the western lowland gorilla and the Cross River gorilla. Males are much larger than females. A full-grown adult male Eastern gorilla weighs 140–205.5 kg and stands 1.7 m upright and a female weighs 90–100 kg and stands 1.5 m tall. The tallest silverback recorded was a 1.95-metre individual shot in Alimbongo, northern Kivu in May 1938. The heaviest gorilla recorded was a 1.83-metre silverback shot in Ambam, which weighed 267 kilograms, although the latter area is within the range of the western gorilla, far outside that of the eastern gorilla.
Mountain gorillas are restricted to the mountain rainforests and subalpine forests of eastern Democratic Republic of the Congo, southwestern Uganda and Rwanda. Grauer's gorilla occur across the forests of the Albertine Rift in eastern DRC. Eastern gorillas are herbivorous, with a foliage based diet, due to lack of available fruit in their habitats, they have smaller home ranges than western gorillas. They are diurnal but the majority of foraging occurs in the morning and late afternoon. At night, they build nests by folding over vegetation on the ground. Eastern gorillas live in cohesive family groups, led by a dominant silverback male. Eastern gorillas tend to have larger group sizes than their western relatives, numbering up to 35 individuals. There is no distinct breeding season and females give birth only once every 3–4 years due to the long period of parental care and a gestation period of 8.5 months. Newborn gorillas can crawl after 9 weeks. Males defend their females and offspring using their large size in intimidating displays involving charging and chest-beating.
The eastern gorilla has become endangered since the 1990s, the species was listed as critically endangered in September 2016 as its population continued to decrease. Illegal hunting for bushmeat and destruction of their habitat as a result of intensifying forestry and the development of agriculture form the most important threats for the species. Between 1996 and 2016, the eastern gorilla lost more than 70 percent of its population, by 2016 the total population was estimated to be less than 6,000; the only exception is the mountain gorilla subspecies, critically endangered but saw its population increase to about 880 individuals in 2016. In some national parks, viewing mountain gorillas is a popular tourist attraction; these national parks include Volcanoes National Park in Rwanda, Virunga National Park in the Democratic Republic of the Congo, Mgahinga Gorilla National Park and Bwindi Impenetrable National Park in Uganda. This has both disadvantages for the conservation of the gorillas. Unlike the western lowland gorilla, there are few eastern gorillas in zoos.
The Antwerp Zoo is the only zoo outside the native range of the species that has eastern lowland gorillas. Outside the native range, the mountain gorilla is not held in captivity at all. Small groups consisting of animals confiscated from poachers are kept in the Democratic Republic of Congo: Grauer's gorillas at the Gorilla Rehabilitation and Conservation Education center in Tayna Nature Reserve, mountain gorillas at the Senkwekwe Center in Virunga National Park. Animal Diversity Web: Gorilla beringei Eastern Gorilla: Mountain Gorilla and Grauer's Gorilla
In phylogenetics, the crown group of a collection of species consists of the living representatives of the collection together with their ancestors back to their most recent common ancestor as well as all of that ancestor's descendants. It is thus a group consisting of a species and all its descendants; the concept was developed by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms relative to their extinct relatives in his "Die Stammesgeschichte der Insekten", the "crown" and "stem" group terminology was coined by R. P. S. Jefferies in 1979. Though formulated in the 1970s, the term was not used until its reintroduction in 2000 by Graham Budd and Sören Jensen, it is not necessary for a species to have living descendants in order for it to be included in the crown group. Extinct side branches on the family tree that are descended from the most recent common ancestor of living members will still be part of a crown group. For example, if we consider the crown-birds, extinct side branches like the dodo or great auk are still descended from the most recent common ancestor of all living birds, so fall within the bird crown group.
One simplified cladogram for birds is shown below: In this diagram, the clade labelled "Neornithes" is the crown group of birds: it includes the most recent common ancestor of all living birds and its descendants, living or not. Although considered to be birds and other extinct groups are not included in the crown group, as they fall outside the Neornithes clade, being descended from an earlier ancestor. An alternative definition does not require any members of a crown group to be extant, only to have resulted from a "major cladogenesis event"; the first definition forms the basis of this article. The crown group is given the designation "crown-", to separate it from the group as defined. Both birds and mammals are traditionally defined by their traits, contain fossil members that lived before the last common ancestors of the living groups or, like the mammal Haldanodon, were not descended from that ancestor although they lived later. Crown-Aves and Crown-Mammalia therefore differ in content from the common definition of Aves and Mammalia.
This has caused some confusion in the literature. The cladistic idea of using the topology of the phylogenetic tree to define groups, necessitates other definitions than crown groups to adequately define discussed fossil groups like various Burgess Shale fauna. Thus, a host of prefixes have been defined to describe various branches of the phylogenetic tree relative to extant organisms. A pan-group or total group is the crown group and all organisms more related to it than to any other extant organisms. In a tree analogy, it is the crown group and all branches back to the split with the closest branch to have living members; the Pan-Aves thus contain the living birds and all organisms more related to birds than to crocodilians. The phylogenetic lineage leading back from Neornithes to the point where it merges with the crocodilian lineage, along with all side branches, constitutes pan-birds. In addition to non-crown group primitive birds like Archaeopteryx and Confuciusornis, pan-group birds would include all dinosaurs and pterosaurs as well as an assortment of non-crocodilian animals like Marasuchus.
Pan-Mammalia consists of all mammals and their fossil ancestors back to the phylogenetic split from the remaining amniotes. Pan-Mammalia is thus an alternative name for Synapsida. A stem group is a paraphyletic group composed of a pan-group or total group, minus the crown group itself; this leaves primitive relatives of the crown groups, back along the phylogenetic line to the last common ancestor of the crown group and their nearest living relatives. It follows from the definition; the "stem group" is the most used and most important of the concepts linked to crown groups, as it offers a purely phylogenetic route to classify fossils that otherwise do not fit into systematics based on living organisms. While attributed to Jefferies, Willmann traced the origin of the stem group concept to German systematist Othniel Abel, it was discussed and diagrammed in English as early as 1933 by A. S. Romer. Alternatively, the term "stem group" is sometimes used in a narrower sense to cover just the members of the traditional taxon falling outside the crown group.
Permian synapsids like Dimetrodon and Anteosaurus are stem mammals in the wider sense but not in the narrower one. Stem birds constitute the most cited example of a stem group, as the phylogeny of this group is well known; the following cladogram, based on Benton, illustrates the concept: The crown group here is Neornithes, all modern bird lineages back to their last common ancestor. The closest living relatives of birds are crocodilians. If we follow the phylogenetic lineage leading to Neornithes to the left, the line itself and all side branches belong to the stem birds until the lineage merges with that of the crocodilians. In addition to non-crown group primitive birds like Archaeopteryx and Confuciusornis, stem group birds include the dinosaurs and the pterosaurs; the last common ancestor of birds and crocodilians—the first crown group archosaur—was neither bird nor crocodilian and possessed none of the features unique to either. As the bird stem group evolved, distinctive bird features such as feathers and hollow
Cladistics is an approach to biological classification in which organisms are categorized in groups based on the most recent common ancestor. Hypothesized relationships are based on shared derived characteristics that can be traced to the most recent common ancestor and are not present in more distant groups and ancestors. A key feature of a clade is that all its descendants are part of the clade. All descendants stay in their overarching ancestral clade. For example, if within a strict cladistic framework the terms animals, bilateria/worms, fishes/vertebrata, or monkeys/anthropoidea were used, these terms would include humans. Many of these terms are used paraphyletically, outside of cladistics, e.g. as a'grade'. Radiation results in the generation of new subclades by bifurcation; the techniques and nomenclature of cladistics have been applied to other disciplines. Cladistics is now the most used method to classify organisms; the original methods used in cladistic analysis and the school of taxonomy derived from the work of the German entomologist Willi Hennig, who referred to it as phylogenetic systematics.
Cladistics in the original sense refers to a particular set of methods used in phylogenetic analysis, although it is now sometimes used to refer to the whole field. What is now called the cladistic method appeared as early as 1901 with a work by Peter Chalmers Mitchell for birds and subsequently by Robert John Tillyard in 1921, W. Zimmermann in 1943; the term "clade" was introduced in 1958 by Julian Huxley after having been coined by Lucien Cuénot in 1940, "cladogenesis" in 1958, "cladistic" by Cain and Harrison in 1960, "cladist" by Mayr in 1965, "cladistics" in 1966. Hennig referred to his own approach as "phylogenetic systematics". From the time of his original formulation until the end of the 1970s, cladistics competed as an analytical and philosophical approach to systematics with phenetics and so-called evolutionary taxonomy. Phenetics was championed at this time by the numerical taxonomists Peter Sneath and Robert Sokal, evolutionary taxonomy by Ernst Mayr. Conceived, if only in essence, by Willi Hennig in a book published in 1950, cladistics did not flourish until its translation into English in 1966.
Today, cladistics is the most popular method for constructing phylogenies from morphological data. In the 1990s, the development of effective polymerase chain reaction techniques allowed the application of cladistic methods to biochemical and molecular genetic traits of organisms, vastly expanding the amount of data available for phylogenetics. At the same time, cladistics became popular in evolutionary biology, because computers made it possible to process large quantities of data about organisms and their characteristics; the cladistic method interprets each character state transformation implied by the distribution of shared character states among taxa as a potential piece of evidence for grouping. The outcome of a cladistic analysis is a cladogram – a tree-shaped diagram, interpreted to represent the best hypothesis of phylogenetic relationships. Although traditionally such cladograms were generated on the basis of morphological characters and calculated by hand, genetic sequencing data and computational phylogenetics are now used in phylogenetic analyses, the parsimony criterion has been abandoned by many phylogeneticists in favor of more "sophisticated" but less parsimonious evolutionary models of character state transformation.
Cladists contend. Every cladogram is based on a particular dataset analyzed with a particular method. Datasets are tables consisting of molecular, ethological and/or other characters and a list of operational taxonomic units, which may be genes, populations, species, or larger taxa that are presumed to be monophyletic and therefore to form, all together, one large clade. Different datasets and different methods, not to mention violations of the mentioned assumptions result in different cladograms. Only scientific investigation can show, more to be correct; until for example, cladograms like the following have been accepted as accurate representations of the ancestral relations among turtles, lizards and birds: If this phylogenetic hypothesis is correct the last common ancestor of turtles and birds, at the branch near the ▼ lived earlier than the last common ancestor of lizards and birds, near the ♦. Most molecular evidence, produces cladograms more like this: If this is accurate the last common ancestor of turtles and birds lived than the last common ancestor of lizards and birds.
Since the cladograms provide competing accounts of real events, at most one of them is correct. The cladogram to the right represents the current universally accepted hypothesis that all primates, including strepsirrhines like the lemurs and lorises, had a common ancestor all of whose descendants were primates, so form a clade. Within the primates, all anthropoids are hypothesized to have had a common ancestor all of whose descendants were anthropoids, so they form the clade called Anthropoidea; the "prosimians", on the other hand, form a paraphyletic taxon. The name Prosimii is not used in phylogenetic nomenclature, whic
The bonobo historically called the pygmy chimpanzee and less the dwarf or gracile chimpanzee, is an endangered great ape and one of the two species making up the genus Pan. Although bonobos are not a subspecies of chimpanzees, 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; the bonobo is distinguished by long legs, pink lips, dark face and tail-tuft through adulthood, parted long hair on its head. The bonobo is found in a 500,000 km2 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 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.
Because the two species are not proficient swimmers, the formation of the Congo River 1.5–2 million years ago led to the speciation of the bonobo. Bonobos live south of the river, 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 live 40 years in captivity. Despite the alternative common name "pygmy chimpanzee", the bonobo is not 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 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 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, 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, elevated it to species status; the American psychologist and primatologist Robert Yerkes was 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 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 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, 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. There still is controversy, however. Scientists such as Jared Diamond in The Third Chimpanzee, Morris Goodman of Wayne State University in Detroit suggest that the bonobo and common chimpanzee are so related to humans that their genus name should be classified with the human genus Homo: Homo paniscus, Homo sylvestris, or Homo arboreus. An alternative philosophy suggests that the term Homo sapiens is the misnomer rather, that humans should be reclassified as Pan sapiens, though this would violate the Principle of Priority, as Homo was named before Pan.
In either case, a name change of the genus would have implications on the taxonomy of extinct species related to humans, including Australopithecus. Th