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Orangutans are
great apes
The Hominidae (), whose members are known as the great apes or hominids (), are a taxonomic family of primates that includes eight extant species in four genera: '' Pongo'' (the Bornean, Sumatran and Tapanuli orangutan); '' Gorilla'' (the ...
native to the rainforest
Rainforests are forests characterized by a closed and continuous tree Canopy (biology), canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropi ...
s of Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...
and Malaysia
Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...
. They are now found only in parts of Borneo
Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...
and Sumatra
Sumatra () is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the list of islands by area, sixth-largest island in the world at 482,286.55 km2 (182,812 mi. ...
, but during the Pleistocene
The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
they ranged throughout Southeast Asia
Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...
and South China
South China ( zh, s=, p=Huá'nán, j=jyut6 naam4) is a geographical and cultural region that covers the southernmost part of China. Its precise meaning varies with context. A notable feature of South China in comparison to the rest of China is ...
. Classified in the genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
''Pongo'', orangutans were originally considered to be one species. In 1996, they were divided into two species: the Bornean orangutan
The Bornean orangutan (''Pongo pygmaeus'') is an orangutan species endemic to the island of Borneo. It belongs to the only genus of great apes native to Asia and is the largest of the three ''Pongo'' species. It has a coarse, reddish coat and up ...
(''P. pygmaeus'', with three subspecies) and the Sumatran orangutan
The Sumatran orangutan (''Pongo abelii'') is one of the three species of orangutans. Critically endangered, and found only in the north of the Indonesian island of Sumatra, it is rarer than the Bornean orangutan but more common than the recently ...
(''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
Ponginae , also known as the Asian hominids, is a subfamily in the family (biology), family Hominidae. Once a diverse lineage of Eurasian apes, the subfamily has only one Neontology, extant genus, ''Pongo (genus), Pongo'' (orangutans), which con ...
, which diverged genetically from the other hominids (gorilla
Gorillas are primarily herbivorous, terrestrial great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or five su ...
s, chimpanzee
The chimpanzee (; ''Pan troglodytes''), also simply known as the chimp, is a species of Hominidae, great ape native to the forests and savannahs of tropical Africa. It has four confirmed subspecies and a fifth proposed one. When its close rel ...
s, and human
Humans (''Homo sapiens'') or modern humans are the most common and widespread species of primate, and the last surviving species of the genus ''Homo''. They are Hominidae, great apes characterized by their Prehistory of nakedness and clothing ...
s) between 19.3 and 15.7 million years ago.
The most arboreal
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...
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. Adult males weigh about , while females weigh about . 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
Bark may refer to:
Common meanings
* Bark (botany), an outer layer of a woody plant such as a tree or stick
* Bark (sound), a vocalization of some animals (which is commonly the dog)
Arts and entertainment
* ''Bark'' (Jefferson Airplane album), ...
, honey
Honey is a sweet and viscous substance made by several species of bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of pl ...
, insects and bird eggs. They can live over 30 years, both in the wild and in captivity.
Orangutans are among the most intelligent primate
Primates is an order (biology), order of mammals, which is further divided into the Strepsirrhini, strepsirrhines, which include lemurs, galagos, and Lorisidae, lorisids; and the Haplorhini, haplorhines, which include Tarsiiformes, tarsiers a ...
s. 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 Birutė Galdikas
Birutė Marija Filomena Galdikas or Birutė Mary Galdikas, OC (born 10 May 1946), is a Lithuanian-Canadian anthropologist, primatologist, conservationist, ethologist, and author. She is a professor at Simon Fraser University. In the field of ...
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
An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...
. Human activities have caused severe declines in populations and ranges. Threats to wild orangutan populations include poaching
Poaching is the illegal hunting or capturing of wild animals, usually associated with land use rights.
Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set against the huntin ...
(for bushmeat
Bushmeat is meat from wildlife species that are Hunting, hunted for human consumption. Bushmeat represents a primary source of animal protein and a cash-earning commodity in poor and rural communities of humid tropical forest regions of the worl ...
and retaliation for consuming crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. In other words, a crop is a plant or plant product that is grown for a specific purpose such as food, Fiber, fibre, or fuel.
When plants of the same spe ...
s), habitat destruction
Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...
and deforestation
Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...
(for palm oil
Palm oil is an edible vegetable oil derived from the mesocarp (reddish pulp) of the fruit of oil palms. The oil is used in food manufacturing, in beauty products, and as biofuel. Palm oil accounted for about 36% of global oils produced from o ...
cultivation and logging
Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidder, skidding, on-site processing, and loading of trees or trunk (botany), logs onto logging truck, truckspet trade. Several conservation and rehabilitation organisations are dedicated to the survival of orangutans in the wild.
Orangutans display significant 
Orangutan hands have four long fingers but a dramatically shorter
Orangutans are primarily fruit-eaters, which can take up 57–80% of their foraging time. Even during times of scarcity, fruit is 16% of their feeding time. Fruits with soft pulp,
The social structure of the orangutan can be best described as solitary but social; they live a more solitary lifestyle than the other great apes. Bornean orangutans are generally more solitary than Sumatran orangutans. Most social bonds occur between adult females and their dependent and weaned offspring. Resident females live with their offspring in defined home ranges that overlap with those of other adult females, which may be their immediate relatives. One to several resident female home ranges are encompassed within the home range of a resident male, who is their main mating partner. Interactions between adult females range from friendly to avoidance to antagonistic. Flanged males are often hostile to both other flanged males and unflanged males, while unflanged males are more peaceful towards each other.
Orangutans disperse and establish their home ranges by age 11. Females tend to live near their birth range, while males disperse farther but may still visit their birth range within their larger home range. They enter a transient phase, which lasts until a male can challenge and displace a dominant, resident male from his home range. Both resident and transient orangutans aggregate on large fruiting trees to feed. The fruits tend to be abundant, so competition is low and individuals may engage in social interactions. Orangutans will also form travelling groups with members moving between different food sources. They are often consortships between an adult male and a female.
Orangutans build nests specialised for either day or night use. These are carefully constructed; young orangutans learn from observing their mother's nest-building behaviour. In fact, nest-building allows young orangutans to become less dependent on their mother. From six months of age onwards, orangutans practise nest-building and gain proficiency by the time they are three years old.
Construction of a night nest is done by following a sequence of steps. Initially, a suitable tree is located. Orangutans are choosy about sites, though nests can be found in many tree species. To establish a foundation, the ape grabs the large branches under it and bends them so they join. The orangutan then does the same to smaller, leafier branches to create a "mattress". After this, the ape stands and braids the tips of branches into the mattress. Doing this increases the stability of the nest. Orangutans make their nests more comfortable by creating "pillows", "blankets", "roofs" and "bunk-beds".
Tool use in orangutans was observed by primatologist
Orangutans were known to the native people of Sumatra and Borneo for millennia. The apes are known as ''maias'' in Sarawak and ''mawas'' in other parts of Borneo and in Sumatra. While some communities hunted them for food and decoration, others placed taboos on such practices. In central Borneo, some traditional folk beliefs consider it bad luck to look an orangutan in the face. Some folk tales involve orangutans mating with and kidnapping humans. There are even stories of hunters being captured by female orangutans.
Europeans became aware of the existence of the orangutan in the 17th century. Explorers in Borneo hunted them extensively during the 19th century. In 1779, Dutch anatomist Petrus Camper, who observed the animals and dissected some specimens, gave the first scientific description of the orangutan. Camper mistakenly thought that flanged and unflanged male orangutans were different species, a misconception corrected after his death.
Little was known about orangutan behaviour until the field studies of Birutė Galdikas, who became a leading authority on the apes. When she arrived in Borneo in 1971, Galdikas settled into a primitive bark-and-thatch hut at a site she dubbed Camp Leakey, in Tanjung Puting. She studied orangutans for the next four years and developed her PhD thesis for UCLA. Galdikas became an outspoken advocate for orangutans and the preservation of their rainforest habitat, which is rapidly being devastated by logging industry, loggers,
Orangutans first appeared in Western fiction in the 18th century and have been used to comment on human society. Written by the pseudonymous A. Ardra, ''Tintinnabulum naturae'' (The Bell of Nature, 1772) is told from the point of view of a human-orangutan hybrid who calls himself the "metaphysician of the woods". Around 50 years later, the anonymously written work ''The Orang Outang'' is narrated by a pure orangutan in captivity in the US, writing a letter critiquing Boston society to her friend in Java.
Thomas Love Peacock's 1817 novel ''Melincourt (novel), Melincourt'' features Sir Oran Haut Ton, an orangutan who lives among English people and becomes a candidate for Member of Parliament (United Kingdom), Member of Parliament. The novel satirises the class and political system of Britain. Oran's purity and status as a "natural man" stands in contrast to the immorality and corruption of the "civilised" humans. In Frank Challice Constable's ''The Curse of Intellect'' (1895), the protagonist Reuben Power travels to Borneo and captures an orangutan to train it to speak so he can "know what a beast like that might think of us". Orangutans are featured prominently in the 1963 science fiction novel ''Planet of the Apes (novel), Planet of the Apes'' by Pierre Boulle and the Planet of the Apes, media franchise derived from it. They are typically portrayed as bureaucrats like Dr. Zaius, the science minister.
Orangutans are sometimes portrayed as antagonists, notably in the 1832 Walter Scott novel ''Count Robert of Paris'' and the 1841 Edgar Allan Poe short story ''The Murders in the Rue Morgue''. The Walt Disney Company, Disney's 1967 The Jungle Book (1967 film), animated musical adaptation of ''The Jungle Book'' added a jazzy orangutan named King Louie, who tries to get Mowgli to teach him how to make fire. The 1986 horror film ''Link (film), Link'' features an intelligent orangutan which serves a university professor but has sinister motives; he plots against humanity and stalks a female student assistant. Other stories have portrayed orangutans helping humans, such as The Librarian (Discworld), The Librarian in Terry Pratchett's fantasy novels ''Discworld'' and in Dale Smith (poet), Dale Smith's 2004 novel ''What the Orangutan Told Alice''. More comical portrayals of the orangutan include the 1996 film ''Dunston Checks In''.
By the early 19th century, orangutans were being kept in captivity. In 1817, an orangutan joined several other animals in London's Exeter Exchange. He rejected the company of other animals, aside from a dog, and preferred to be with humans. He was occasionally taken on coach rides clothed in a smock-frock and hat and even given drinks at an inn where he behaved politely for the hosts. The London Zoo housed a female orangutan named Jenny (orangutan), Jenny who was dressed in human clothing and learned to drink tea. She is remembered for her meeting with Charles Darwin who compared her reactions to those of a human child.
Zoos and circuses in the Western world would continue to use orangutans and other simians as sources for entertainment, training them to behave like humans at Chimpanzees' tea party, tea parties and to perform tricks. Notable orangutan "character actors" include: Jacob and Rosa of the Tierpark Hagenbeck in Hamburg, Germany, in the early 20th century; Joe Martin (orangutan), Joe Martin of Universal City Zoo in the 1910s and 1920s; and Jiggs (orangutan), Jiggs of the San Diego Zoo in the 1930s and 1940s. Animal rights groups have urged a stop to such acts, considering them abusive. Starting in the 1960s, zoos became more concerned with education and orangutans' exhibits were designed to mimic their natural environment and let them display their natural behaviours. Ken Allen, an orangutan of the San Diego Zoo, became world famous in the 1980s for multiple escapes from his enclosures. He was nicknamed "the Harry Houdini, hairy Houdini" and was the subject of a fan club, T-shirts, bumper stickers and a song titled ''The Ballad of Ken Allen''.
Galdikas reported that her cook was sexually assaulted by a captive male orangutan. The ape may have suffered from a skewed species identity and forced copulation is a standard mating strategy for low-ranking male orangutans. American animal trafficker Frank Buck (animal collector), Frank Buck claimed to have seen human mothers acting as wet nurses to orphaned orangutan babies in hopes of keeping them alive long enough to sell to a trader, which would be an instance of human–animal breastfeeding.
Birutė Galdikas wrote that orangutans were already threatened by
Orangutan Foundation International
AZA's Orangutan Conservation Education Center
Orangutan Language Project
The Orangutan Foundation
Orangutan Land Trust
{{featured article Orangutans, Primates of Indonesia Articles containing video clips Species that are or were threatened by the pet trade Tool-using mammals Fauna of Southeast Asia Taxa named by Bernard Germain de Lacépède Taxa described in 1799
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 premodernOld Malay
Malay language, Malay was first used in the first millennia known as Old Malay, a part of the Austronesian languages, Austronesian language family. Over a period of two Millennium, millennia, Malay has undergone various stages of development th ...
.
In Western sources, the first printed attestation of the word for the apes is in Dutch physician Jacobus Bontius
Jacobus Bontius (Jacob de Bondt) (1592, in Leiden – 30 November 1631, in Batavia, Dutch East Indies) was a Dutch physician and a pioneer of tropical medicine. He is known for the four-volume work ''De medicina Indorum''. His 1631 work "Historiae ...
'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 make 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
John Bulwer (baptised 16 May 1606 – buried 16 October 1656)
was an English people, English physician and early Baconian method, Baconian natural philosopher who wrote five works exploring the Body and human communication, particularly by gest ...
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 'Angola
Angola, officially the Republic of Angola, is a country on the west-Central Africa, central coast of Southern Africa. It is the second-largest Portuguese-speaking world, Portuguese-speaking (Lusophone) country in both total area and List of c ...
, which describes two anthropoid "monsters" named Pongo and Engeco. He is now believed to have been describing gorilla
Gorillas are primarily herbivorous, terrestrial great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or five su ...
s, but in the 18th century, the terms orangutan and pongo were used for all great apes
The Hominidae (), whose members are known as the great apes or hominids (), are a taxonomic family of primates that includes eight extant species in four genera: '' Pongo'' (the Bornean, Sumatran and Tapanuli orangutan); '' Gorilla'' (the ...
. French naturalist Bernard Germain de Lacépède
Bernard-Germain-Étienne de La Ville-sur-Illon, comte de Lacépède or La Cépède (; 26 December 17566 October 1825) was a French natural history, naturalist and an active freemason. He is known for his contribution to the Comte de Buffon's g ...
used the term ''Pongo'' for the genus in 1799. Battel's "Pongo", in turn, is from the Kongo word or other cognates
In historical linguistics, cognates or lexical cognates are sets of words that have been inherited in direct descent from an etymological ancestor in a common parent language.
Because language change can have radical effects on both the soun ...
from the region: Lumbu , Vili ''mpungu'', or Yombi ''yimpungu''.
Taxonomy and phylogeny
The orangutan was first described scientifically in 1758 in the ''Systema Naturae
' (originally in Latin written ' with the Orthographic ligature, ligature æ) is one of the major works of the Sweden, Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the syste ...
'' of Carl Linnaeus
Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...
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
René Primevère Lesson (20 March 1794 – 28 April 1849) was a French surgery, surgeon, natural history, naturalist, ornithologist, and herpetologist.
Biography
Lesson was born at Rochefort, Charente-Maritime, Rochefort, and entered the Naval ...
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
Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...
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
Lake Toba (, Toba Batak: ᯖᯀᯬ ᯖᯬᯅ; romanized: ''Tao Toba'') is a large natural lake in North Sumatra, Indonesia, occupying the caldera of the Toba supervolcano. The lake is located in the middle of the northern part of the island of ...
, 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 chimpanzee
The chimpanzee (; ''Pan troglodytes''), also simply known as the chimp, is a species of Hominidae, great ape native to the forests and savannahs of tropical Africa. It has four confirmed subspecies and a fifth proposed one. When its close rel ...
s, the Sumatran orangutan became the third species of great ape
The Hominidae (), whose members are known as the great apes or hominids (), are a taxonomic family of primates that includes eight extant species in four genera: '' Pongo'' (the Bornean, Sumatran and Tapanuli orangutan); '' Gorilla'' (the ...
whose genome was sequenced. Subsequently, the Bornean species's genome was sequenced. Bornean orangutans (''P. pygmaeus'') exhibit less genetic diversity
Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species, and can be correlated to the span of survival for a species. It is d ...
than Sumatran orangutans (''P. abelii''), despite the latter'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
A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosome abnormality. Although polygenic disorders are ...
. Similarly to gorillas and chimpanzees, orangutans have 48 diploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...
chromosomes, in contrast to humans, which have 46.
According to molecular evidence, within apes (superfamily Hominoidea), the gibbon
Gibbons () are apes in the family Hylobatidae (). The family historically contained one genus, but now is split into four extant genera and 20 species. Gibbons live in subtropical and tropical forests from eastern Bangladesh and Northeast Indi ...
s diverged during the early Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
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
A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used ...
, Y-linked
Y linkage, also known as holandric inheritance (from Ancient Greek ὅλος ''hólos'', "whole" + ἀνδρός ''andrós'', "male"), describes traits that are produced by genes located on the Y chromosome. It is a form of sex linkage.
Y ...
, and X-linked
Sex linkage describes the sex-specific patterns of inheritance and expression when a gene is present on a sex chromosome (allosome) rather than a non-sex chromosome ( autosome). Genes situated on the X-chromosome are thus termed X-linked, and ...
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 bridge
In biogeography, a land bridge is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and colonize new lands. A land bridge can be created by marine regression, in which sea le ...
s 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.
Fossil record
The three orangutan species are the only extant members of the subfamilyPonginae
Ponginae , also known as the Asian hominids, is a subfamily in the family (biology), family Hominidae. Once a diverse lineage of Eurasian apes, the subfamily has only one Neontology, extant genus, ''Pongo (genus), Pongo'' (orangutans), which con ...
. This subfamily
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...
also includes extinct ape
Apes (collectively Hominoidea ) are a superfamily of Old World simians native to sub-Saharan Africa and Southeast Asia (though they were more widespread in Africa, most of Asia, and Europe in prehistory, and counting humans are found global ...
s such as ''Lufengpithecus
''Lufengpithecus'' () is an Extinction, extinct genus of ape, known from the Late Miocene of East Asia. It is known from thousands of Dental anatomy, dental remains and a few skulls and probably weighed about . It contains three species: ''L. luf ...
'', 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
''Gigantopithecus'' ( ) is an extinct genus of ape that lived in southern China from 2 million to approximately 300,000–200,000 years ago during the Early Pleistocene, Early to Middle Pleistocene, represented by one species, ''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
The Early Pleistocene is an unofficial epoch (geology), sub-epoch in the international geologic timescale in chronostratigraphy, representing the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently esti ...
of Chongzuo
Chongzuo (; ) is a prefecture-level city in the south of Guangxi, Guangxi Zhuang Autonomous Region near the Sino-Vietnamese border. It is home to one of China's largest Zhuang people, Zhuang populations.
Geography and climate
Chongzuo is locate ...
, 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
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
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. During the Pleistocene, ''Pongo'' had a far more extensive range than at present, extending throughout Sundaland
Sundaland (also called Sundaica or the Sundaic region) is a biogeographical region of Southeast Asia corresponding to a larger landmass that was exposed throughout the last 2.6 million years during periods when sea levels were lower. It inc ...
and mainland Southeast Asia and South China. Teeth of orangutans are known from Peninsular Malaysia
Peninsular Malaysia, historically known as Malaya and also known as West Malaysia or the Malaysian Peninsula, is the western part of Malaysia that comprises the southern part of the Malay Peninsula on Mainland Southeast Asia and the list of isla ...
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
The Last Glacial Maximum (LGM), also referred to as the Last Glacial Coldest Period, was the most recent time during the Last Glacial Period where ice sheets were at their greatest extent between 26,000 and 20,000 years ago.
Ice sheets covered m ...
. They may have nevertheless survived into the Holocene in Cambodia and Vietnam.
Characteristics
Orangutans display significant sexual dimorphism
Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...
; females typically stand tall and weigh around , while adult males stand tall and weigh . Compared to humans, they have proportionally long arms, a male orangutan having an arm span
Arm span or reach (sometimes referred to as wingspan, or spelled armspan) is the physical measurement of the length from one end of an individual's arms (measured at the fingertips) to the other when raised parallel to the ground at shoulder h ...
of about , and short legs. They are covered in long reddish hair that starts out bright orange and darkens to maroon
Maroon ( , ) is a brownish crimson color that takes its name from the French word , meaning chestnut. ''Marron'' is also one of the French translations for "brown".
Terms describing interchangeable shades, with overlapping RGB ranges, inc ...
or chocolate
Chocolate is a food made from roasted and ground cocoa beans that can be a liquid, solid, or paste, either by itself or to flavoring, flavor other foods.
Cocoa beans are the processed seeds of the cacao tree (''Theobroma cacao''); unprocesse ...
with age, while the skin is grey-black. Though largely hairless, males' faces can develop some hair, giving them 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 chimpanzees and gorillas, the brow ridge
The brow ridge, or supraorbital ridge known as superciliary arch in medicine, is a bony ridge located above the eye sockets of all primates and some other animals. In humans, the eyebrows are located on their lower margin.
Structure
The brow ri ...
of an orangutan is underdeveloped. Females and juveniles have relatively circular skulls and thin faces while mature males have a prominent sagittal crest
A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are excepti ...
, 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
Resonance is a phenomenon that occurs when an object or system is subjected to an external force or vibration whose frequency matches a resonant frequency (or resonance frequency) of the system, defined as a frequency that generates a maximu ...
chambers for making long calls.
Orangutan hands have four long fingers but a dramatically shorter opposable thumb
The thumb is the first digit of the hand, next to the index finger. When a person is standing in the medical anatomical position (where the palm is facing to the front), the thumb is the outermost digit. The Medical Latin English noun for 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.
Orangutans move through the trees by both vertical climbing and suspension. Compared to other great apes, they infrequently descend to the ground where they are more cumbersome. Unlike gorillas and chimpanzees, orangutans are not true knuckle-walkers, instead bending their digits and walking on the sides of their hands and feet.
Compared to their relatives in Borneo, Sumatran orangutans are more slender with paler and longer hair and a longer face. Tapanuli orangutans resemble Sumatran orangutans more than Bornean orangutans in body build and hair colour. They have shaggier hair, smaller skulls, and flatter faces than the other two species.
Ecology and behaviour
Orangutans are mainlyarboreal
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...
and inhabit tropical rainforest
Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes (in the torrid zo ...
, particularly lowland dipterocarp
Dipterocarpaceae is a family of flowering plants with 22 genera and about 695 known species of mainly lowland tropical forest trees. Their distribution is pantropical, from northern South America to Africa, the Seychelles, India, Indochina, Indo ...
and old secondary forest
A secondary forest (or second-growth forest) is a forest or woodland area which has regenerated through largely natural processes after human-caused Disturbance (ecology), disturbances, such as Logging, timber harvest or agriculture clearing, or ...
. Populations are more concentrated near riverside habitats, such as freshwater
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...
and peat swamp forest
Peat swamp forests are tropical and subtropical moist broadleaf forests, tropical moist forests where waterlogged soil prevents dead leaves and wood from fully decomposing. Over time, this creates a thick layer of acidic peat. Large areas of th ...
, while drier forests away from the flooded areas have fewer apes. Population density also decreases at higher elevations. Orangutans occasionally enter grasslands, cultivated fields, gardens, young secondary forest
A secondary forest (or second-growth forest) is a forest or woodland area which has regenerated through largely natural processes after human-caused Disturbance (ecology), disturbances, such as Logging, timber harvest or agriculture clearing, or ...
, and shallow lakes.
Most of the day is spent feeding, resting, and travelling. They start the day feeding for two to three hours in the morning. They rest during midday, then travel in the late afternoon. When evening arrives, they prepare their nests for the night. Potential predators of orangutans include tiger
The tiger (''Panthera tigris'') is a large Felidae, cat and a member of the genus ''Panthera'' native to Asia. It has a powerful, muscular body with a large head and paws, a long tail and orange fur with black, mostly vertical stripes. It is ...
s, clouded leopards and wild dogs. The most common orangutan parasites are nematode
The nematodes ( or ; ; ), roundworms or eelworms constitute the phylum Nematoda. Species in the phylum inhabit a broad range of environments. Most species are free-living, feeding on microorganisms, but many are parasitic. Parasitic worms (h ...
s of the genus '' Strongyloides'' and the ciliate
The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagellum, eukaryotic flagella, but are in general shorter and present in much larger numbers, with a ...
''Balantidium coli
''Balantidium coli'' is a parasitic species of ciliate Alveolata, alveolates that causes the disease balantidiasis. It is the only member of the ciliate phylum known to be pathogenic to humans, although the main reservoir for this species are ma ...
''. Among ''Strongyloides'', the species ''S. fuelleborni'' and ''S. stercoralis'' are reported in young individuals. Orangutans also use the plant species '' Dracaena cantleyi'' as an anti-inflammatory balm. Captive animals may suffer an upper respiratory tract disease.
Diet and feeding
Orangutans are primarily fruit-eaters, which can take up 57–80% of their foraging time. Even during times of scarcity, fruit is 16% of their feeding time. Fruits with soft pulp, aril
An aril (), also called arillus, is a specialized outgrowth from a seed that partly or completely covers the seed. An arillode, or false aril, is sometimes distinguished: whereas an aril grows from the attachment point of the seed to the ova ...
s or seed-walls are consumed the most, particularly figs but also drupe
In botany, a drupe (or stone fruit) is a type of fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pip'' (UK), ''pit'' (US), ''stone'', or ''pyrena'') of hardened endocarp with a seed ...
s and berries. Orangutans are thought to be the sole fruit disperser for some plant species including the vine
A vine is any plant with a growth habit of trailing or scandent (that is, climbing) stems, lianas, or runners. The word ''vine'' can also refer to such stems or runners themselves, for instance, when used in wicker work.Jackson; Benjamin; Da ...
species ''Strychnos ignatii
''Strychnos ignatii'' is a tree in the family Loganiaceae, native to the Philippines, particularly in Catbalogan and parts of China. The plant was first described by the Moravian (Czech) Jesuit working in the Philippines, brother Georg Kamel ...
'' which contains the toxic alkaloid
Alkaloids are a broad class of natural product, naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids.
Alkaloids are produced by a large varie ...
strychnine
Strychnine (, , American English, US chiefly ) is a highly toxicity, toxic, colorless, bitter, crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine, when inhaled, swallowed, ...
.
Orangutans also include leaves in their diet, which take up 25% of their average foraging time. Leaves are eaten more when fruit is less available, but even during times of fruit abundance, orangutans will eat leaves 11–20% of the time. They appear to depend on the leaf and stem material of '' Borassodendron borneensis'' during times of low fruit abundance. Other food items consumed by the apes include bark
Bark may refer to:
Common meanings
* Bark (botany), an outer layer of a woody plant such as a tree or stick
* Bark (sound), a vocalization of some animals (which is commonly the dog)
Arts and entertainment
* ''Bark'' (Jefferson Airplane album), ...
, honey
Honey is a sweet and viscous substance made by several species of bees, the best-known of which are honey bees. Honey is made and stored to nourish bee colonies. Bees produce honey by gathering and then refining the sugary secretions of pl ...
, bird eggs, insects and small vertebrates including slow loris
Slow lorises are a group of several species of Nocturnality, nocturnal Strepsirrhini, strepsirrhine primates that make up the genus ''Nycticebus''. Found in Southeast Asia and nearby areas, they range from Bangladesh and Northeast India in the ...
es.
In some areas, orangutans may practise geophagy
Geophagia (), also known as geophagy (), is the intentional practice of consuming earth or soil-like substances such as clay, chalk, or termite mounds. It is a behavioural adaptation that occurs in many non-human animals and has been documented i ...
, which involves consuming soil and other earth substances. They will uproot soil from the ground as well as eat shelter tubes from tree trunks. Orangutans also visit the sides of cliffs or earth depressions for their mineral lick
A mineral lick (also known as a salt lick) is a place where animals can go to lick essential mineral nutrients from a deposit of salts and other minerals. Mineral licks can be naturally occurring or artificial (such as blocks of salt that fa ...
s. Orangutans may eat soils for their anti-toxic kaolin
Kaolinite ( ; also called kaolin) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral sheet of alumina (). ...
minerals, since their diet contains toxic tannin
Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...
s and phenolic acid
Phenolic acids or phenolcarboxylic acids ? are phenolic compounds and types of aromatic acid compounds. Included in that class are substances containing a phenolic ring and an organic carboxylic acid function (C6-C1 skeleton). Two important nat ...
s.
Social life
The social structure of the orangutan can be best described as solitary but social; they live a more solitary lifestyle than the other great apes. Bornean orangutans are generally more solitary than Sumatran orangutans. Most social bonds occur between adult females and their dependent and weaned offspring. Resident females live with their offspring in defined home ranges that overlap with those of other adult females, which may be their immediate relatives. One to several resident female home ranges are encompassed within the home range of a resident male, who is their main mating partner. Interactions between adult females range from friendly to avoidance to antagonistic. Flanged males are often hostile to both other flanged males and unflanged males, while unflanged males are more peaceful towards each other.
Orangutans disperse and establish their home ranges by age 11. Females tend to live near their birth range, while males disperse farther but may still visit their birth range within their larger home range. They enter a transient phase, which lasts until a male can challenge and displace a dominant, resident male from his home range. Both resident and transient orangutans aggregate on large fruiting trees to feed. The fruits tend to be abundant, so competition is low and individuals may engage in social interactions. Orangutans will also form travelling groups with members moving between different food sources. They are often consortships between an adult male and a female. Social grooming
Social grooming is a behavior in which social animals, including humans, clean or maintain one another's bodies or appearances. A related term, allogrooming, indicates social grooming between members of the same species. Grooming is a major s ...
is uncommon among orangutans.
Communication
Orangutans communicate with various vocals and sounds. Males will make long calls, both to attract females and to advertise themselves to other males. These calls have three components; they begin with grumbles, peak with pulses and end with bubbles. Both sexes will try to intimidate conspecifics with a series of low frequency noises known collectively as the "rolling call". When uncomfortable, an orangutan will produce a "kiss squeak", which involves sucking in air through pursed lips. Mothers produce throatscrapes to keep in contact with their offspring. Infants make soft hoots when distressed. When building a nest, orangutans will produce smacks or blow raspberries. Orangutan calls display consonant- and vowel-like components and they maintain their meaning over great distances. They also displayrecursion
Recursion occurs when the definition of a concept or process depends on a simpler or previous version of itself. Recursion is used in a variety of disciplines ranging from linguistics to logic. The most common application of recursion is in m ...
via three layers of rhythmic sounds.
Mother orangutans and offspring also use several different gestures and expressions such as beckoning, stomping, lower lip pushing, object shaking and "presenting" a body part. These communicate goals such as "acquire object", "climb on me", "climb on you", "climb over", "move away", "play change: decrease intensity", "resume play" and "stop that".
Reproduction and development
Males become sexually mature at around age 15. They may exhibitarrested development
''Arrested Development'' is an American satire, satirical television sitcom created by Mitchell Hurwitz. It follows the Bluths, a formerly wealthy, dysfunctional family and is presented in a Serial (radio and television), serialized format, inco ...
by not developing the distinctive cheek pads, pronounced throat pouches, long fur, or long calls until a resident dominant male is absent. The transformation from unflanged to flanged can occur quickly. Flanged males attract females in oestrous with their characteristic long calls, which may also suppress development in younger males.
Unflanged males wander widely in search of oestrous females and upon finding one, may force copulation on her, the occurrence of which is unusually high among mammals. Females prefer to mate with the fitter flanged males, forming pairs with them and benefiting from their protection. Non-ovulating
Ovulation is an important part of the menstrual cycle in female vertebrates where the egg cells are released from the ovaries as part of the ovarian cycle. In female humans ovulation typically occurs near the midpoint in the menstrual cycle and af ...
females do not usually resist copulation with unflanged males, as the chance of conception is low. Homosexual behaviour has been recorded in the context of both affiliative and aggressive interactions.
Unlike females of other non-human great ape species, orangutans do not exhibit sexual swellings to signal fertility. A female first gives birth around 15 years of age and they have a six- to nine-year interbirth interval, the longest among the great apes. Gestation is around nine months long and infants are born at a weight of . Usually only a single infant is born; twins are a rare occurrence. Unlike many other primates, male orangutans do not seem to practise infanticide
Infanticide (or infant homicide) is the intentional killing of infants or offspring. Infanticide was a widespread practice throughout human history that was mainly used to dispose of unwanted children, its main purpose being the prevention of re ...
. This may be because they cannot ensure they will sire a female's next offspring, because she does not immediately begin ovulating again after her infant dies. There is evidence that females with offspring under six years old generally avoid adult males.
Females do most of the caring of the young. The mother will carry the infant while travelling, suckle it and sleep with it. During its first four months, the infant is almost never without physical contact and clings to its mother's belly. In the following months, the amount of physical contact the infant has with its mother declines. When an orangutan reaches the age of one-and-a-half years, its climbing skills improve and it will travel through the canopy holding hands with other orangutans, a behaviour known as "buddy travel". After two years of age, juvenile orangutans will begin to move away from their mothers temporarily. They reach adolescence at six or seven years of age and are able to live alone but retain some connections with their mothers. Females may nurse their offspring for up to eight years, which is more than any other mammal. Typically, orangutans live over 30 years both in the wild and in captivity.
Nesting
Orangutans build nests specialised for either day or night use. These are carefully constructed; young orangutans learn from observing their mother's nest-building behaviour. In fact, nest-building allows young orangutans to become less dependent on their mother. From six months of age onwards, orangutans practise nest-building and gain proficiency by the time they are three years old.
Construction of a night nest is done by following a sequence of steps. Initially, a suitable tree is located. Orangutans are choosy about sites, though nests can be found in many tree species. To establish a foundation, the ape grabs the large branches under it and bends them so they join. The orangutan then does the same to smaller, leafier branches to create a "mattress". After this, the ape stands and braids the tips of branches into the mattress. Doing this increases the stability of the nest. Orangutans make their nests more comfortable by creating "pillows", "blankets", "roofs" and "bunk-beds".
Intelligence
Orangutans are among the most intelligent non-human primates. Experiments suggest they can track the displacement of objects both visible and hidden. Zoo Atlanta has a touch-screen computer on which their two Sumatran orangutans play games. A 2008 study of two orangutans at theLeipzig Zoo
Leipzig Zoological Garden, or Leipzig Zoo () is a zoo in the Leipzig district of Mitte, Germany. It was first opened on June 9, 1878. It was taken over by the city of Leipzig in 1920 after World War I and now covers about and contains approximatel ...
showed orangutans may practise "calculated reciprocity", which involves an individual aiding another with the expectation of being paid back. Orangutans are the first nonhuman species documented to do so.
In a 1997 study, two captive adult orangutans were tested with the cooperative pulling paradigm
The cooperative pulling paradigm is an Scientific control, experimental design in which two or more animals pull incentive salience, rewards toward themselves via an apparatus that they cannot successfully operate alone. Researchers (ethology, e ...
. Without any training, the orangutans succeeded in pulling off an object to get food in the first session. Over the course of 30 sessions, the apes succeeded more quickly, having learned to coordinate. An adult orangutan has been documented to pass the mirror test
The mirror test—sometimes called the mark test, mirror self-recognition (MSR) test, red spot technique, or rouge test—is a behavioral technique developed in 1970 by American psychologist Gordon Gallup Jr. to determine whether an animal posse ...
, indicating self-awareness
In philosophy of self, philosophy, self-awareness is the awareness and reflection of one's own personality or individuality, including traits, feelings, and behaviors. It is not to be confused with consciousness in the sense of qualia. While ...
, while another test with a 2-year-old failed to reveal self-recognition.
Studies in the wild indicate that flanged male orangutans plan their movements in advance and signal them to other individuals. Experiments have also suggested that orangutans can communicate about things that are not present: mother orangutans remain silent in the presence of a perceived threat but when it passes, the mother produces an alarm call to their offspring to teach them about the danger. Orangutans and other great apes show laughter
Laughter is a pleasant physical reaction and emotion consisting usually of rhythmical, usually audible contractions of the diaphragm and other parts of the respiratory system. It is a response to certain external or internal stimuli. Laug ...
-like vocalisations in response to physical contact such as wrestling, play chasing or tickling. This suggests that laughter derived from a common origin among primate species and therefore evolved before the origin of humans. Orangutans can learn to mimic new sounds by purposely controlling the vibrations of their vocal folds, a trait that led to speech in humans. Bonnie
Bonnie is a Scottish given name and is sometimes used as a descriptive reference, as in the Scottish folk song, My Bonnie Lies over the Ocean or Bonnie Dundee about John Graham, 7th Laird of Claverhouse. It comes from the Scots language word "bon ...
, an orangutan at the US National Zoo, was recorded spontaneously whistling after hearing a caretaker. She appears to whistle without expecting a food reward.
Tool use and culture
Tool use in orangutans was observed by primatologist Birutė Galdikas
Birutė Marija Filomena Galdikas or Birutė Mary Galdikas, OC (born 10 May 1946), is a Lithuanian-Canadian anthropologist, primatologist, conservationist, ethologist, and author. She is a professor at Simon Fraser University. In the field of ...
in ex-captive populations. Orangutans in Suaq Balimbing were recorded to develop a tool kit for use in foraging which consisted of both insect-extraction sticks for use in the hollows of trees and seed-extraction sticks for harvesting seeds from hard-husked fruit. The orangutans adjusted their tools according to the task at hand, and preference was given to oral tool use. This preference was also found in an experimental study of captive orangutans. Orangutans have been observed to use sticks to poke at catfish, causing them to leap out of the water so the orangutan can grab them. Orangutan have also been documented to keep tools for later. When building a nest, orangutans appear to be able to determine which branches would better support their body weight.
Primatologist Carel P. van Schaik and biological anthropologist Cheryl D. Knott further investigated tool use in different wild orangutan populations. They compared geographic variations in tool use related to the processing of ''Neesia'' fruit. The orangutans of Suaq Balimbing were found to be avid users of insect and seed-extraction tools when compared to other wild orangutans. The scientists suggested these differences are cultural as they do not correlate with habitat. The orangutans at Suaq Balimbing are closely spaced and relatively tolerant of each other; this creates favourable conditions for the spreading of new behaviours. Further evidence that highly social orangutans are more likely to exhibit cultural behaviours came from a study of leaf-carrying behaviours of formerly captive orangutans that were being rehabilitated on the island of Kaja in Borneo.
Wild orangutans in Tuanan, Borneo, were reported to use tools in acoustic communication. They use leaves to amplify the kiss squeak sounds they produce. The apes may employ this method of amplification to deceive
Deception is the act of convincing of one or many recipients of untrue information. The person creating the deception knows it to be false while the receiver of the information does not. It is often done for personal gain or advantage.
Tort of ...
the listener into believing they are larger animals. In 2003, researchers from six different orangutan field sites who used the same behavioural coding scheme compared the behaviours of the animals from each site. They found each orangutan population used different tools. The evidence suggested the differences were cultural: first, the extent of the differences increased with distance, suggesting cultural diffusion was occurring, and second, the size of the orangutans' cultural repertoire increased according to the amount of social contact present within the group. Social contact facilitates cultural transmission.
During a Field research, field observation in 2022, a male Sumatran orangutan, known to researchers as Rakus, chewed ''Fibraurea tinctoria'' vine leaves and Zoopharmacognosy, applied the mashed plant material to an open wound on his face. According to Primatology, primatologists who had been observing Rakus at a nature preserve, "Five days later the facial wound was closed, while within a few weeks it had healed, leaving only a small scar".
Personhood
In June 2008, Spain would become the first country to recognise the rights of some non-human great apes, based on the guidelines of the Great Ape Project, which are that chimpanzees, bonobos, orangutans, and gorillas are not to be used for animal experiments. In December 2014, a court in Argentina ruled that an orangutan named Sandra at the Buenos Aires Zoo must be moved to a sanctuary in Brazil to provide her "partial or controlled freedom". Sandra has since been relocated to Center for Great Apes, The Center for Great Apes in the United States, as it is the only accredited orangutan sanctuary in the Americas. Animal rights groups like Great Ape Project Argentina argued the ruling should apply to all species in captivity, and legal specialists from the Argentina's Federal Chamber of Court of cassation, Criminal Cassatio considered the ruling applicable only to non-human hominids.Orangutans and humans
Orangutans were known to the native people of Sumatra and Borneo for millennia. The apes are known as ''maias'' in Sarawak and ''mawas'' in other parts of Borneo and in Sumatra. While some communities hunted them for food and decoration, others placed taboos on such practices. In central Borneo, some traditional folk beliefs consider it bad luck to look an orangutan in the face. Some folk tales involve orangutans mating with and kidnapping humans. There are even stories of hunters being captured by female orangutans.
Europeans became aware of the existence of the orangutan in the 17th century. Explorers in Borneo hunted them extensively during the 19th century. In 1779, Dutch anatomist Petrus Camper, who observed the animals and dissected some specimens, gave the first scientific description of the orangutan. Camper mistakenly thought that flanged and unflanged male orangutans were different species, a misconception corrected after his death.
Little was known about orangutan behaviour until the field studies of Birutė Galdikas, who became a leading authority on the apes. When she arrived in Borneo in 1971, Galdikas settled into a primitive bark-and-thatch hut at a site she dubbed Camp Leakey, in Tanjung Puting. She studied orangutans for the next four years and developed her PhD thesis for UCLA. Galdikas became an outspoken advocate for orangutans and the preservation of their rainforest habitat, which is rapidly being devastated by logging industry, loggers, palm oil
Palm oil is an edible vegetable oil derived from the mesocarp (reddish pulp) of the fruit of oil palms. The oil is used in food manufacturing, in beauty products, and as biofuel. Palm oil accounted for about 36% of global oils produced from o ...
plantations, gold miners, and unnatural Wildfire, forest fires. Along with Jane Goodall and Dian Fossey, Galdikas is considered to be one of Leakey's Angels, named after anthropologist Louis Leakey.
In fiction
Orangutans first appeared in Western fiction in the 18th century and have been used to comment on human society. Written by the pseudonymous A. Ardra, ''Tintinnabulum naturae'' (The Bell of Nature, 1772) is told from the point of view of a human-orangutan hybrid who calls himself the "metaphysician of the woods". Around 50 years later, the anonymously written work ''The Orang Outang'' is narrated by a pure orangutan in captivity in the US, writing a letter critiquing Boston society to her friend in Java.
Thomas Love Peacock's 1817 novel ''Melincourt (novel), Melincourt'' features Sir Oran Haut Ton, an orangutan who lives among English people and becomes a candidate for Member of Parliament (United Kingdom), Member of Parliament. The novel satirises the class and political system of Britain. Oran's purity and status as a "natural man" stands in contrast to the immorality and corruption of the "civilised" humans. In Frank Challice Constable's ''The Curse of Intellect'' (1895), the protagonist Reuben Power travels to Borneo and captures an orangutan to train it to speak so he can "know what a beast like that might think of us". Orangutans are featured prominently in the 1963 science fiction novel ''Planet of the Apes (novel), Planet of the Apes'' by Pierre Boulle and the Planet of the Apes, media franchise derived from it. They are typically portrayed as bureaucrats like Dr. Zaius, the science minister.
Orangutans are sometimes portrayed as antagonists, notably in the 1832 Walter Scott novel ''Count Robert of Paris'' and the 1841 Edgar Allan Poe short story ''The Murders in the Rue Morgue''. The Walt Disney Company, Disney's 1967 The Jungle Book (1967 film), animated musical adaptation of ''The Jungle Book'' added a jazzy orangutan named King Louie, who tries to get Mowgli to teach him how to make fire. The 1986 horror film ''Link (film), Link'' features an intelligent orangutan which serves a university professor but has sinister motives; he plots against humanity and stalks a female student assistant. Other stories have portrayed orangutans helping humans, such as The Librarian (Discworld), The Librarian in Terry Pratchett's fantasy novels ''Discworld'' and in Dale Smith (poet), Dale Smith's 2004 novel ''What the Orangutan Told Alice''. More comical portrayals of the orangutan include the 1996 film ''Dunston Checks In''.
In captivity
By the early 19th century, orangutans were being kept in captivity. In 1817, an orangutan joined several other animals in London's Exeter Exchange. He rejected the company of other animals, aside from a dog, and preferred to be with humans. He was occasionally taken on coach rides clothed in a smock-frock and hat and even given drinks at an inn where he behaved politely for the hosts. The London Zoo housed a female orangutan named Jenny (orangutan), Jenny who was dressed in human clothing and learned to drink tea. She is remembered for her meeting with Charles Darwin who compared her reactions to those of a human child.
Zoos and circuses in the Western world would continue to use orangutans and other simians as sources for entertainment, training them to behave like humans at Chimpanzees' tea party, tea parties and to perform tricks. Notable orangutan "character actors" include: Jacob and Rosa of the Tierpark Hagenbeck in Hamburg, Germany, in the early 20th century; Joe Martin (orangutan), Joe Martin of Universal City Zoo in the 1910s and 1920s; and Jiggs (orangutan), Jiggs of the San Diego Zoo in the 1930s and 1940s. Animal rights groups have urged a stop to such acts, considering them abusive. Starting in the 1960s, zoos became more concerned with education and orangutans' exhibits were designed to mimic their natural environment and let them display their natural behaviours. Ken Allen, an orangutan of the San Diego Zoo, became world famous in the 1980s for multiple escapes from his enclosures. He was nicknamed "the Harry Houdini, hairy Houdini" and was the subject of a fan club, T-shirts, bumper stickers and a song titled ''The Ballad of Ken Allen''.
Galdikas reported that her cook was sexually assaulted by a captive male orangutan. The ape may have suffered from a skewed species identity and forced copulation is a standard mating strategy for low-ranking male orangutans. American animal trafficker Frank Buck (animal collector), Frank Buck claimed to have seen human mothers acting as wet nurses to orphaned orangutan babies in hopes of keeping them alive long enough to sell to a trader, which would be an instance of human–animal breastfeeding.
Conservation
Status and threats
All three species are critically endangered according to the IUCN Red List of mammals. They are legally protected from capture, harm or killing in both Malaysia and Indonesia, and are listed under CITES#Appendix I, Appendix I by CITES, which prohibits their unlicensed trade under international law. The Bornean orangutan range has become more fragmented, with few or no apes documented in the southeast. The largest remaining population is found in the forest around the Sabangau River, but this environment is at risk. The Sumatran orangutan is found only in the northern part of Sumatra, most of the population inhabiting the Leuser Ecosystem. The Tapanuli orangutan is found only in the Batang Toru forest of Sumatra.
Birutė Galdikas wrote that orangutans were already threatened by poaching
Poaching is the illegal hunting or capturing of wild animals, usually associated with land use rights.
Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set against the huntin ...
and deforestation
Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...
when she began studying them in 1971. By the 2000s, orangutan habitats decreased rapidly because of logging, mining and Habitat fragmentation, fragmentation by roads. A major factor has been the conversion of vast areas of subtropical or tropical moist lowland forest, tropical forest to palm oil
Palm oil is an edible vegetable oil derived from the mesocarp (reddish pulp) of the fruit of oil palms. The oil is used in food manufacturing, in beauty products, and as biofuel. Palm oil accounted for about 36% of global oils produced from o ...
plantations in response to international demand. Hunting is also a major problem, as is the illegal pet trade.
Orangutans may be killed for the bushmeat
Bushmeat is meat from wildlife species that are Hunting, hunted for human consumption. Bushmeat represents a primary source of animal protein and a cash-earning commodity in poor and rural communities of humid tropical forest regions of the worl ...
trade and bones are secretly sold in souvenir shops in several cities in Indonesian Borneo. Conflicts between locals and orangutans also pose a threat. Orangutans that have lost their homes often raid agricultural areas and end up being killed by villagers. Locals may also be motivated to kill orangutans for food or because of their perceived danger. Mother orangutans are killed so their infants can be sold as pets. Between 2012 and 2017, the Indonesian authorities, with the aid of the Orangutan Information Center, seized 114 orangutans, 39 of which were pets.
Estimates in the 2000s found that around 6,500 Sumatran orangutans and around 54,000 Bornean orangutans remain in the wild. A 2016 study estimates a population of 14,613 Sumatran orangutans in the wild, twice that of previous population estimates, while 2016 estimates suggest 104,700 Bornean orangutans exist in the wild. A 2018 study found that Bornean orangutans declined by 148,500 individuals from 1999 to 2015. Fewer than 800 Tapanuli orangutans are estimated to still exist, which puts the species among the most endangered of the great apes.
Conservation centres and organisations
Several organisations are working for the rescue, rehabilitation and reintroduction of orangutans. The largest of these is the Borneo Orangutan Survival (BOS) Foundation, founded by conservationist Willie Smits and which operates projects such as the Nyaru Menteng Rehabilitation Program founded by conservationist Lone Drøscher Nielsen. A female orangutan was rescued from a village brothel in Kareng Pangi village, Central Kalimantan, in 2003. The orangutan was shaved and chained for sexual purposes. Since being freed, the orangutan, named Pony, has been living with the BOS. She has been re-socialised to live with other orangutans. In May 2017, the BOS rescued an albino orangutan from captivity in a remote village in Kapuas Hulu, on the island of Kalimantan in Indonesian Borneo. According to volunteers at BOS, albino orangutans are extremely rare (one in ten thousand). This is the first albino orangutan the organisation has seen in 25 years of activity. Other major conservation centres in Indonesia include those at Kumai District#Tanjung Puting National Park, Tanjung Puting National Park, Sebangau National Park, Gunung Palung National Park and Bukit Baka Bukit Raya National Park in Borneo and the Gunung Leuser National Park and Bukit Lawang in Sumatra. In Malaysia, conservation areas include Semenggoh Wildlife Centre and Matang Wildlife Centre also in Sarawak, and the Sepilok Orang Utan Sanctuary in Sabah. Major conservation centres headquartered outside the orangutans' home countries include Frankfurt Zoological Society, Orangutan Foundation International, which was founded by Galdikas, and the Australian Orangutan Project. Conservation organisations such as the Orangutan Land Trust work with the palm oil industry to improve sustainability and encourages the industry to establish conservation areas for orangutans.See also
* International Primate Day * List of individual apes * Monkey Day * Orang Pendek * ''Orangutan Island'' * Skullduggery (1970 film), ''Skullduggery'' (1970 film)References
External links
Orangutan Foundation International
AZA's Orangutan Conservation Education Center
Orangutan Language Project
The Orangutan Foundation
Orangutan Land Trust
{{featured article Orangutans, Primates of Indonesia Articles containing video clips Species that are or were threatened by the pet trade Tool-using mammals Fauna of Southeast Asia Taxa named by Bernard Germain de Lacépède Taxa described in 1799