Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genus Pongo, orangutans were originally considered to be one species. In 1996, they were divided into two species: the Bornean orangutan (P. pygmaeus, with three subspecies) and the Sumatran orangutan (P. abelii); a third species, the Tapanuli orangutan (P. tapanuliensis), was identified definitively in 2017. The orangutans are the only surviving members of the subfamily Ponginae, which diverged genetically from the other hominids (gorillas, chimpanzees, and humans) between 19.3 and 15.7 million years ago.
The most arboreal of the great apes, orangutans spend most of their time in trees. They have proportionally long arms and short legs, and have reddish-brown hair covering their bodies. Dominant adult males develop distinctive cheek pads or flanges and make long calls that attract females and intimidate rivals; younger subordinate males do not and more resemble adult females. Orangutans are the most solitary of the great apes: social bonds occur primarily between mothers and their dependent offspring. Fruit is the most important component of an orangutan's diet, but they will also eat vegetation, bark, honey, insects and bird eggs. They can live over 30 years, both in the wild and in captivity.
Orangutans are among the most intelligent primates. They use a variety of sophisticated tools and construct elaborate sleeping nests each night from branches and foliage. The apes' learning abilities have been studied extensively. There may be distinctive cultures within populations. Orangutans have been featured in literature and art since at least the 18th century, particularly in works that comment on human society. Field studies of the apes were pioneered by primatologist Biruté Galdikas and they have been kept in captive facilities around the world since at least the early 19th century.
All three orangutan species are considered critically endangered. Human activities have caused severe declines in populations and ranges. Threats to wild orangutan populations include poaching (for bushmeat and retaliation for consuming crops), habitat destruction and deforestation (for palm oil cultivation, and logging), and the illegal pet trade. Several conservation and rehabilitation organisations are dedicated to the survival of orangutans in the wild.
Etymology Most Western sources attribute the name "orangutan" (also written orang-utan, orang utan, orangutang, and ourang-outang) to the Malay words , meaning 'person', and , meaning 'forest'. The Malay used the term to indicate forest-dwelling humans; the first recorded Malay use of "" referring to the ape identifies it as a Western term. There is, however, some evidence to suggest that the term may have been used in regard to apes in premodern Old Malay.
In Western sources, the first printed attestation of the word for the apes is in Dutch physician Jacobus Bontius's 1631 . He reported that Malays claimed that the ape could talk but preferred not to "lest he be compelled to labour". The word appeared in several German-language descriptions of Indonesian zoology in the 17th century. It has been argued that the word comes specifically from the Banjarese variety of Malay, but the age of the Old Javanese sources mentioned above makes Old Malay a more likely origin for the term. Cribb and colleagues (2014) suggest that Bontius's account referred not to apes (as this description was from Java where the apes were not known to be from) but to humans suffering some serious medical condition (most likely cretinism) and that his use of the word was misunderstood by Nicolaes Tulp, who was the first to use the term in a publication a decade later.
The word was first attested in English in 1693 by physician John Bulwer in the form Orang-Outang, and variants ending with -ng are found in many languages. This spelling (and pronunciation) has remained in use in English up to the present but has come to be regarded as incorrect. The loss of "h" in and the shift from -ng to -n has been taken to suggest the term entered English through Portuguese. In Malay, the term was first attested in 1840, not as an indigenous name but referring to how the English called the animal. The word '' in modern Malay and Indonesian was borrowed from English or Dutch in the 20th century—explaining the missing initial 'h' of ''.
The name of the genus, Pongo, comes from a 16th-century account by Andrew Battel, an English sailor held prisoner by the Portuguese in Angola, which describes two anthropoid "monsters" named Pongo and Engeco. He is now believed to have been describing gorillas, but in the 18th century, the terms orangutan and pongo were used for all great apes. French naturalist Bernard Germain de Lacépède used the term Pongo for the genus in 1799. Battel's "Pongo", in turn, is from the Kongo word or other cognates from the region: Lumbu , Vili mpungu, or Yombi yimpungu.
Taxonomy and phylogeny
The orangutan was first described scientifically in 1758 in the Systema Naturae of Carl Linnaeus as Homo troglodytes. It was renamed Simia pygmaeus in 1760 by his student Christian Emmanuel Hopp and given the name Pongo by Lacépède in 1799. The populations on the two islands were suggested to be separate species when P. abelii was described by French naturalist René Lesson in 1827. In 2001, P. abelii was confirmed as a full species based on molecular evidence published in 1996, and three distinct populations on Borneo were elevated to subspecies (P. p. pygmaeus, P. p. morio and P. p. wurmbii). The description in 2017 of a third species, P. tapanuliensis, from Sumatra south of Lake Toba, came with a surprising twist: it is more closely related to the Bornean species, P. pygmaeus than to its fellow Sumatran species, P. abelii.
The Sumatran orangutan genome was sequenced in January 2011. Following humans and chimpanzees, the Sumatran orangutan became the third species of great ape whose genome was sequenced. Subsequently, the Bornean species's genome was sequenced. Bornean orangutans (P. pygmaeus) exhibit less genetic diversity than Sumatran orangutans (P. abelii), despite the former's population being six to seven times greater. The researchers hope these genetic data may help conservationists preserve the endangered ape, as well as learn more about human genetic diseases. Similarly to gorillas and chimpanzees, orangutans have 48 diploid chromosomes, in contrast to humans, which have 46.
According to molecular evidence, within apes (superfamily Hominoidea), the gibbons diverged during the early Miocene between 24.1 and 19.7 million years ago (mya), and the orangutans diverged from the African great ape lineage between 19.3 and 15.7 mya. Israfil and colleagues (2011) estimated based on mitochondrial, Y-linked, and X-linked loci that the Sumatran and Bornean species diverged 4.9 to 2.9 mya. By contrast, the 2011 genome study suggested that these two species diverged as recently as circa 400,000 years ago. The study also found that orangutans evolved at a slower pace than both chimpanzees and humans. A 2017 genome study found that the Bornean and Tapanuli orangutans diverged from Sumatran orangutans about 3.4 mya, and from each other around 2.4 mya. Millions of years ago, orangutans travelled from mainland Asia to Sumatra and then Borneo as the islands were connected by land bridges during the recent glacial periods when sea levels were much lower. The present range of Tapanuli orangutans is thought to be close to where ancestral orangutans first entered what is now Indonesia from mainland Asia.
Taxonomy of genus Pongo Phylogeny of superfamily HominoideaGenus Pongo Bornean orangutan (Pongo pygmaeus) Pongo pygmaeus pygmaeus – northwest populations Pongo pygmaeus morio – east populations Pongo pygmaeus wurmbii – southwest populations Sumatran orangutan (Pongo abelii – Sumatra northwest of Lake Toba) Tapanuli orangutan (Pongo tapanuliensis – Sumatra south of Lake Toba)
Fossil record The three orangutan species are the only extant members of the subfamily Ponginae. This subfamily also includes extinct apes such as Lufengpithecus, which occurred 8–2 mya in southern China and Thailand; Indopithecus, which lived in India from 9.2 to 8.6 mya; and Sivapithecus, which lived in India and Pakistan from 12.5 mya until 8.5 mya. These animals likely lived in drier and cooler environments than orangutans do today. Khoratpithecus piriyai, which lived 5–7 mya in Thailand, is believed to be the closest known relative of the living orangutans and inhabited similar environments. The largest known primate, Gigantopithecus, was also a member of Ponginae and lived in China, from 2 mya to 300,000 years ago.
The oldest known record of Pongo is from the Early Pleistocene of Chongzuo, consisting of teeth ascribed to extinct species P. weidenreichi. Pongo is found as part of the faunal complex in the Pleistocene cave assemblage in Vietnam, alongside Giganopithecus, though it is known only from teeth. Some fossils described under the name P. hooijeri have been found in Vietnam, and multiple fossil subspecies have been described from several parts of southeastern Asia. It is unclear if these belong to P. pygmaeus or P. abelii or, in fact, represent distinct species. In 2025, two other distinct species from Pleistocene deposists in the Làng Tráng and Kéo Lèng caves in Vietnam were described as P. grovesei and P. nguyenbinheri. During the Pleistocene, Pongo had a far more extensive range than at present, extending throughout Sundaland and mainland Southeast Asia and South China. Teeth of orangutans are known from Peninsular Malaysia that date to 60,000 years ago. The youngest remains from South China, which are teeth assigned to P. weidenreichi, date to between 66 and 57,000 years ago. The range of orangutans had contracted significantly by the end of the Pleistocene, most likely because of the reduction of forest habitat during the Last Glacial Maximum. They may have nevertheless survived into the Holocene in Cambodia and Vietnam.
Characteristics
Orangutans display significant sexual dimorphism; females typically stand tall and weigh around , while adult males stand tall and weigh . The tallest orangutan recorded was a . Compared to humans, they have proportionally long arms, a male orangutan having an arm span of about , and short legs. They are covered in long reddish hair that starts out bright orange and darkens to maroon or chocolate with age, while the skin is grey-black. Males' faces can develop a beard.
Orangutans have small ears and noses; the ears are unlobed. The mean endocranial volume is 397 cm3. The cranium is elevated relative to the face, which is incurved and prognathous. Compared to other great apes, the brow ridge of an orangutan is underdeveloped. Females and juveniles have relatively circular skulls and thin faces while mature males have a prominent sagittal crest, large cheek pads or flanges, extensive throat pouches and long canines. The cheek pads are made mostly of fatty tissue and are supported by the musculature of the face. The throat pouches act as resonance chambers for making long calls.
Orangutan hands have four long fingers but a dramatically shorter opposable thumb for a strong grip on branches as they travel high in the trees. The resting configuration of the fingers is curved, creating a suspensory hook grip. With the thumb out of the way, the fingers (and hands) can grip securely around objects with a small diameter by resting the tops of the fingers against the inside of the palm, thus creating a double-locked grip. Their feet have four long toes and an opposable big toe, giving them hand-like dexterity. The hip joints also allow for their legs to rotate similarly to their arms and shoulders.