Orangutan

Most Western sources attribute the name "orangutan" (also written orang-utan, orang utan, orangutang, and ourang-outang{{Cite web |date=March 2022 |title=orangutan, n. |url=https://www.oed.com/view/Entry/132186 |url-access=subscription |access-date=2022-08-04 |website=Oxford English Dictionary |language=en}}) to the Malay words orang, meaning "person", and hutan, meaning "forest".{{cite journal |author=Sastrawan, Wayan Jarrah |year=2020 |title=The Word 'Orangutan': Old Malay Origin or European Concoction |journal=Bijdragen tot de Land-, Taal- en Volkenkunde |volume=176 |issue=4 |pages=532–41 |doi=10.1163/22134379-bja10016 |s2cid=228828226 |url=https://brill.com/view/journals/bki/176/4/article-p532_5.xml?language=en |access-date=12 April 2021 |archive-date=12 April 2021 |archive-url=https://web.archive.org/web/20210412015647/https://brill.com/view/journals/bki/176/4/article-p532_5.xml?language=en |url-status=live |doi-access=free }}{{cite web|title=Orangutan|url=http://www.etymonline.com/index.php?term=orangutan|author=Harper, Douglas|website=Online Etymology Dictionary|access-date=4 May 2012|archive-date=4 November 2012|archive-url=https://web.archive.org/web/20121104100601/http://www.etymonline.com/index.php?term=orangutan|url-status=live}} The Malay used the term to indicate forest-dwelling humans; the first recorded Malay use of "orang-utan" referring to the ape identifies it as a Western term.{{rp|12}} (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 Historiae naturalis et medicae Indiae orientalis. He reported that Malays claimed that the ape could talk but preferred not to "lest he be compelled to labour".{{cite journal|author=Dellios, Paulette|year=2008 |title=A lexical odyssey from the Malay World |journal=Studia Universitatis Petru Maior. Philologia |volume=4 |issue=4|pages=141–44}} 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,{{cite book |author=Mahdi, Waruno |year=2007 |title=Malay Words and Malay Things: Lexical Souvenirs from an Exotic Archipelago in German Publications Before 1700 |volume=3 |series=Frankfurter Forschungen zu Südostasien |publisher=Otto Harrassowitz Verlag |pages=170–81 |isbn=978-3-447-05492-8}} 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.{{cite book |author=Cribb, Robert |first2=Helen|last2= Gilbert |first3=Helen |last3=Tiffin |year=2014 |title=Wild Man from Borneo: A Cultural History of the Orangutan|publisher=University of Hawai'i Press|isbn=978-0-8248-3714-3}}{{rp|10–18}}

The word was first attested in English in 1693 by physician John Bulwer in the form Orang-Outang,{{Cite book |last=Bulwer |first=John |url=http://archive.org/details/anthropometamorp00jbjo |title=Anthropometamorphosis: man transform'd: or, The artificiall changling, historically presented, in the mad and cruel gallantry, foolish bravery, ridiculous beauty, filthy finenesse, and loathsome loveliness of most nations, fashioning and altering their bodies from the mould intended by nature; with figures of those transformations. To which artificial and affected deformations are added, all the native and national monstrosities that have appeared to disfigure the humane fabrick. With a vindication of the regular beauty and honesty of nature |publisher=W. Hunt |others=Internet Archive |year=1653 |edition=2nd |location=London |pages=437 |language=en}} 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.{{cite web |url=http://www.alphadictionary.com/goodword/word/orangutan |title=Orangutan |website=Alpha Dictionary |access-date=20 December 2006 |archive-date=7 July 2016 |archive-url=https://web.archive.org/web/20160707192419/http://www.alphadictionary.com/goodword/word/orangutan |url-status=live }}{{cite journal|first=Peter|last= Tan |date=October 1998 |title=Malay loan words across different dialects of English |journal=English Today |volume=14 |issue=4 |pages=44–50 |doi=10.1017/S026607840001052X|s2cid= 144326996 }}{{cite journal |author=Cannon, Garland|year=1992|title=Malay(sian) borrowings in English |journal=American Speech |volume=67 |issue=2 |pages=134–62|jstor=455451 |doi=10.2307/455451}} The loss of "h" in hutan 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 'orangutan' in modern Malay and Indonesian was borrowed from English or Dutch in the 20th century—explaining the missing initial 'h' of 'hutan'.

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.{{cite book | first = Colin P.| last = Groves | author-link = Colin Groves | year = 2002 | chapter-url = http://arts.anu.edu.au/grovco/Gorilla%20Biology.pdf | chapter = A history of gorilla taxonomy | title = Gorilla Biology: A Multidisciplinary Perspective | editor1-first = Andrea B. | editor1-last = Taylor | editor2-first = Michele L. | editor2-last = Goldsmith | publisher = Cambridge University Press | pages = 15–34 | doi = 10.1017/CBO9780511542558.004 | isbn = 978-0521792813 | url-status = dead | archive-url = https://web.archive.org/web/20090326001207/http://arts.anu.edu.au/grovco/Gorilla%20Biology.pdf | archive-date = 26 March 2009}}{{rp|24–25}} Battel's "Pongo", in turn, is from the Kongo word mpongi{{cite web|website=Etymology Online|url=https://www.etymonline.com/word/pongo|title=pongo|access-date=4 December 2018|archive-date=5 December 2018|archive-url=https://web.archive.org/web/20181205103307/https://www.etymonline.com/word/pongo|url-status=live}}{{cite web|title=pongo|website=Merriam-Webster|url=https://www.merriam-webster.com/dictionary/pongo|access-date=4 October 2018|archive-date=5 December 2018|archive-url=https://web.archive.org/web/20181205145724/https://www.merriam-webster.com/dictionary/pongo|url-status=live}} or other cognates from the region: Lumbu pungu, Vili mpungu, or Yombi yimpungu.{{cite web|title=pongo, n.1.|website=OED Online|publisher=Oxford University Press|url=https://www.oed.com/view/Entry/147630|url-access=subscription|access-date=4 October 2018|archive-date=19 August 2021|archive-url=https://web.archive.org/web/20210819071419/https://www.oed.com/start;jsessionid=8035670788D957535F9C0B1733D19F62?authRejection=true&url=%2Fview%2FEntry%2F147630|url-status=live}}

{{see also|Orangutan–human last common ancestor}}

The orangutan was first described scientifically in 1758 in the Systema Naturae of Carl Linnaeus as Homo troglodytes.{{rp|20}} It was renamed Simia pygmaeus in 1760 by his student Christian Emmanuel Hopp and given the name Pongo by Lacépède in 1799.{{rp|24–25}} The populations on the two islands were suggested to be separate species when P. abelii was described by French naturalist René Lesson in 1827.{{cite book|last= Lesson| first= René-Primevère |author-link= René Lesson|title= Manuel de mammalogie ou Histoire naturelle des mammifères|url= https://archive.org/details/manueldemammalo00lessgoog|page= [https://archive.org/details/manueldemammalo00lessgoog/page/n85 32]|year=1827|language= fr|publisher= Roret, Libraire}} In 2001, P. abelii was confirmed as a full species based on molecular evidence published in 1996,{{cite journal|last1= Xu|first1= X.|last2= Arnason|first2= U.|title= The mitochondrial DNA molecule of sumatran orangutan and a molecular proposal for two (Bornean and Sumatran) species of orangutan|journal= Journal of Molecular Evolution|volume= 43|issue= 5|year= 1996|pages= 431–37|doi= 10.1007/BF02337514|pmid= 8875856|bibcode= 1996JMolE..43..431X|s2cid= 3355899}}{{rp|53}} and three distinct populations on Borneo were elevated to subspecies (P. p. pygmaeus, P. p. morio and P. p. wurmbii).{{cite journal | last1 = Bradon-Jones | first1 = D. | last2 = Eudey | first2 = A. A. | last3 = Geissmann | first3 = T. | last4 = Groves | first4 = C. P. | last5 = Melnick | first5 = D. J. | last6 = Morales | first6 = J. C. | last7 = Shekelle | first7 = M. | last8 = Stewart | first8 = C. B. | year = 2004 | title = Asian primate classification | url = http://www.gibbons.de/main/papers/pdf_files/2004asianprimates.pdf | journal = International Journal of Primatology | volume = 25 | pages = 97–164 | doi = 10.1023/B:IJOP.0000014647.18720.32 | s2cid = 29045930 | access-date = 1 May 2011 | archive-date = 6 December 2010 | archive-url = https://web.archive.org/web/20101206230755/http://www.gibbons.de/main/papers/pdf_files/2004asianprimates.pdf | url-status = live }} 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.{{Cite journal|last1=Nater|first1=A.|last2=Mattle-Greminger|first2=M. P.|last3=Nurcahyo|first3=A.|last4=Nowak|first4=M. G.|display-authors=etal|date=2 November 2017|title=Morphometric, Behavioral, and Genomic Evidence for a New Orangutan Species|journal=Current Biology|volume=27|issue=22|pages=3487–3498.e10|doi=10.1016/j.cub.2017.09.047|pmid=29103940|doi-access=free|hdl=10230/34400|hdl-access=free}}

File:Bornean, Sumatran & Tapanuli orangs (horizontal).jpg, Sumatran and Tapanuli orangutans]]

The Sumatran orangutan genome was sequenced in January 2011.{{Cite journal | last1 = Locke | first1 = D. P. | last2 = Hillier | first2 = L. W. | last3 = Warren | first3 = W. C. | last4 = Worley | first4 = K. C. | last5 = Nazareth | first5 = L. V. | last6 = Muzny | first6 = D. M. | last7 = Yang | first7 = S. P. | last8 = Wang | first8 = Z. | last9 = Chinwalla | first9 = A. T. | last10 = Minx | doi = 10.1038/nature09687 | first10 = P. | last11 = Mitreva | first11 = M. | last12 = Cook | first12 = L. | last13 = Delehaunty | first13 = K. D. | last14 = Fronick | first14 = C. | last15 = Schmidt | first15 = H. | last16 = Fulton | first16 = L. A. | last17 = Fulton | first17 = R. S. | last18 = Nelson | first18 = J. O. | last19 = Magrini | first19 = V. | last20 = Pohl | first20 = C. | last21 = Graves | first21 = T. A. | last22 = Markovic | first22 = C. | last23 = Cree | first23 = A. | last24 = Dinh | first24 = H. H. | last25 = Hume | first25 = J. | last26 = Kovar | first26 = C. L. | last27 = Fowler | first27 = G. R. | last28 = Lunter | first28 = G. | last29 = Meader | first29 = S. | last30 = Heger | first30 = A. | title = Comparative and demographic analysis of orang-utan genomes | journal = Nature | volume = 469 | issue = 7331 | pages = 529–33 | year = 2011 | pmid = 21270892| pmc =3060778 | display-authors = 29 | bibcode = 2011Natur.469..529L }}{{cite journal |doi=10.1038/news.2011.50 |title=Orang-utans join the genome gang |journal=Nature |last=Singh |first=Ranjeet |url=http://www.nature.com/news/2011/110126/full/news.2011.50.html |date=26 January 2011 |access-date=27 January 2011 |archive-date=27 January 2011 |archive-url=https://web.archive.org/web/20110127224645/http://www.nature.com/news/2011/110126/full/news.2011.50.html |url-status=live }} 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 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. Similarly to gorillas and chimpanzees, orangutans have 48 diploid chromosomes, in contrast to humans, which have 46.{{rp|30}}

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.{{Cite journal|last1=Israfil |first1=H. |last2=Zehr |first2=S. M. |last3=Mootnick |first3=A. R. |last4=Ruvolo |first4=M. |last5=Steiper |first5=M. E. |title=Unresolved molecular phylogenies of gibbons and siamangs (Family: Hylobatidae) based on mitochondrial, Y-linked, and X-linked loci indicate a rapid Miocene radiation or sudden vicariance event |doi=10.1016/j.ympev.2010.11.005 |journal=Molecular Phylogenetics and Evolution |volume=58 |issue=3 |pages=447–55 |year=2011 |pmid=21074627 |pmc=3046308 |url=http://www.gibboncenter.org/publications/MolecularPhylogeneticsIsrafil_etal_2011_MPE.pdf |url-status=dead |archive-url=https://web.archive.org/web/20120510084118/http://www.gibboncenter.org/publications/MolecularPhylogeneticsIsrafil_etal_2011_MPE.pdf |archive-date=10 May 2012 }}{{rp|at=Fig. 4}} 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.{{Cite news|url=https://news.nationalgeographic.com/2017/11/new-orangutan-species-sumatra-borneo-indonesia-animals/|title=New Species of Orangutan Is Rarest Great Ape on Earth|last=Goldman|first=Jason G.|date=2 November 2017|access-date=6 November 2017|publisher=National Geographic Society|archive-date=23 July 2018|archive-url=https://web.archive.org/web/20180723230041/https://news.nationalgeographic.com/2017/11/new-orangutan-species-sumatra-borneo-indonesia-animals/|url-status=dead}}

File:Sivapithecus sivalensis.JPG

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;{{rp|50}} 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.{{cite journal|first1=A.|last1=Bhandari|first2=R. F.|last2=Kay|first3=B. A.|last3=Williams|first4=B. N.|last4=Tiwari|first5=S.|last5=Bajpai|first6=T.|last6=Heironymus|year=2018|title=First record of the Miocene hominoid Sivapithecus from Kutch, Gujarat state, western India|journal=PLOS ONE|volume=13|issue=11|page=10.1371/journal.pone.0206314|doi=10.1371/journal.pone.0206314|pmc=6235281|pmid=30427876|bibcode=2018PLoSO..1306314B|doi-access=free}} 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.{{rp|50}} The largest known primate, Gigantopithecus, was also a member of Ponginae and lived in China, from 2 mya to 300,000 years ago.{{cite journal|last1=Zhang|first1=Yingqi|last2=Harrison|first2=Terry|year=2017|title=Gigantopithecus blacki: a giant ape from the Pleistocene of Asia revisited|journal=Yearbook of Physical Anthropology|volume=162|issue=S63|pages=153–77|doi=10.1002/ajpa.23150|pmid=28105715|doi-access=free}}{{rp|50}}

The oldest known record of Pongo is from the Early Pleistocene of Chongzuo, consisting of teeth ascribed to extinct species P. weidenreichi.{{Cite journal|last1=Harrison|first1=Terry|last2=Jin|first2=Changzhu|last3=Zhang|first3=Yingqi|last4=Wang|first4=Yuan|last5=Zhu|first5=Min|date=December 2014|title=Fossil Pongo from the Early Pleistocene Gigantopithecus fauna of Chongzuo, Guangxi, southern China|journal=Quaternary International|language=en|volume=354|pages=59–67|doi=10.1016/j.quaint.2014.01.013|bibcode=2014QuInt.354...59H}}{{Cite journal|last1=Wang|first1=Cui-Bin|last2=Zhao|first2=Ling-Xia|last3=Jin|first3=Chang-Zhu|last4=Wang|first4=Yuan|last5=Qin|first5=Da-Gong|last6=Pan|first6=Wen-Shi|date=December 2014|title=New discovery of Early Pleistocene orangutan fossils from Sanhe Cave in Chongzuo, Guangxi, southern China|journal=Quaternary International|language=en|volume=354|pages=68–74|doi=10.1016/j.quaint.2014.06.020|bibcode=2014QuInt.354...68W}} 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.{{cite journal|author1=Schwartz, J. H. |author2=Vu The Long |author3=Nguyen Lan Cuong |author4=Le Trung Kha |author5=Tattersall, I. |year=1995 |title=A review of the Pleistocene hominoid fauna of the Socialist Republic of Vietnam (excluding Hylobatidae) |journal=Anthropological Papers of the American Museum of Natural History|issue=76 |pages=1–24|hdl=2246/259 }} 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.{{Cite journal |last1=Liao |first1=Wei |last2=Harrison |first2=Terry |last3=Yao |first3=Yanyan |last4=Liang |first4=Hua |last5=Tian |first5=Chun |last6=Feng |first6=Yuexing |last7=Li |first7=Sheng |last8=Bae |first8=Christopher J. |last9=Wang |first9=Wei |date=September 2022 |title=Evidence for the latest fossil Pongo in southern China |url=https://linkinghub.elsevier.com/retrieve/pii/S0047248422000938 |journal=Journal of Human Evolution |language=en |volume=170 |pages=103233 |doi=10.1016/j.jhevol.2022.103233|pmid=36030625 |s2cid=251879262 }} 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.{{Cite journal|last1=Ibrahim|first1=Yasamin Kh.|last2=Tshen|first2=Lim Tze|last3=Westaway|first3=Kira E.|last4=Cranbrook|first4=Earl of|last5=Humphrey|first5=Louise|last6=Muhammad|first6=Ros Fatihah|last7=Zhao|first7=Jian-xin|last8=Peng|first8=Lee Chai|date=December 2013|title=First discovery of Pleistocene orangutan (Pongo sp.) fossils in Peninsular Malaysia: Biogeographic and paleoenvironmental implications|journal=Journal of Human Evolution|language=en|volume=65|issue=6|pages=770–97|doi=10.1016/j.jhevol.2013.09.005|pmid=24210657}}

File:Pongo tapanuliensis male female.jpg

Orangutans display significant sexual dimorphism; females typically stand {{cvt|115|cm}} tall and weigh around {{cvt|37|kg}}, while adult males stand {{cvt|137|cm}} tall and weigh {{cvt|75|kg}}. Compared to humans, they have proportionally long arms, a male orangutan having an arm span of about {{cvt|2|m}}, 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. Though largely hairless, males' faces can develop some hair, giving them a beard.{{cite journal|last1=Groves|first1=Colin P.|title=Pongo pygmaeus|journal=Mammalian Species|date=1971|issue=4|pages=1–6|doi=10.2307/3503852|jstor=3503852}}{{cite book|author1=Payne, J |author2=Prundente, C |year=2008|title=Orangutans: Behaviour, Ecology and Conservation|publisher=New Holland Publishers|isbn= 978-0-262-16253-1}}{{rp|13–15}}

Orangutans have small ears and noses; the ears are unlobed. The mean endocranial volume is 397 cm³.{{cite book |last1=Aiello|first1= L. |last2=Dean|first2= C. | year=1990 | title=An Introduction to Human Evolutionary Anatomy | publisher=Academic Press | page=193 | isbn=0-12-045590-0}} The cranium is elevated relative to the face, which is incurved and prognathous. Compared to chimpanzees and gorillas, the brow ridge of an orangutan is underdeveloped.{{cite journal|last1=Hilloowala|first1=R. A.|last2=Trent|first2=R. B.|year=1988|title=Supraorbital ridge and masticatory apparatus I: Primates|journal=Human Evolution|volume=3|issue=5|pages=343–50|doi=10.1007/BF02447216|s2cid=83923845}} 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.{{rp|14}} The cheek pads are made mostly of fatty tissue and are supported by the musculature of the face.{{cite journal|author=Winkler, L. A.|year=1989|title=Morphology and relationships of the orangutan fatty cheek pads|journal=American Journal of Primatology|volume=17|issue=4|pages=305–19|doi=10.1002/ajp.1350170405|pmid=31964053|s2cid=83661029}} The throat pouches act as resonance chambers for making long calls.

File:Orang-Utan Tournai.jpg

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.{{cite book | author=Rose, M. D.| contribution= Functional Anatomy of the Cheirdia |editor = Schwartz, Jeffrey|editor-link=Jeffrey H. Schwartz |title = Orang-utan Biology | year = 1988 | isbn = 978-0-19-504371-6 | publisher = Oxford University Press | page=301}} 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.{{rp|15}}

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.{{cite journal|last1=Oishi, M.|last2= Ogihara, N.|last3= Endo, H.|last4= Ichihara, N.|last5= Asari, M.|year=2009|title=Dimensions of forelimb muscles in orangutans and chimpanzees|journal=Journal of Anatomy|volume=215|issue=4|pages=373–82|doi=10.1111/j.1469-7580.2009.01125.x|pmid= 19619166|pmc=2766055}}{{cite book | author = Schwartz, Jeffrey | author-link = Jeffrey H. Schwartz | title = The Red Ape: Orangutans and Human Origins | year = 1987 | pages = [https://archive.org/details/isbn_0813340640_0/page/286 6–7] | isbn = 978-0-8133-4064-7 | publisher = Westview Press |url = https://archive.org/details/isbn_0813340640_0/page/286 }}

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.

File:Video wild orangutan Borneo.webm, Malaysia, Borneo island)]]

Orangutans are mainly arboreal and inhabit tropical rainforest, particularly lowland dipterocarp and old secondary forest. Populations are more concentrated near riverside habitats, such as freshwater and peat swamp forest, while drier forests away from the flooded areas have fewer apes. Population density also decreases at higher elevations.{{cite book|author=Rijksen H. D.|last2= Meijaard, E.|year=1999|title=Our vanishing relative: the status of wild orang-utans at the close of the twentieth century|publisher=Springer|isbn=978-0792357551}}{{rp|92}} Orangutans occasionally enter grasslands, cultivated fields, gardens, young secondary forest, and shallow lakes.

Most of the day is spent feeding, resting, and travelling.{{cite book|author=Rodman, P. S.|year=1988|contribution=Diversity and consistency in ecology and behavior|editor=Schwartz, J. H.|title=Orang-utan biology|pages=31–51|publisher=Oxford University Press | isbn=978-0195043716}} 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 tigers, clouded leopards and wild dogs.{{rp|91}} The most common orangutan parasites are nematodes of the genus Strongyloides and the ciliate Balantidium coli. Among Strongyloides, the species S. fuelleborni and S. stercoralis are reported in young individuals.{{cite book|author1=Foitová, Ivona |author2=Huffman, Michael A.|author3=Wisnu, Nurcahyo|author4=Olšanský, Milan|contribution=Parasites and their impacts on orangutan health|editor1-first=Serge A. |editor1-last=Wich |editor2-first=S. Suci Utami |editor2-last=Atmoko |editor3-first=Tatang Mitra |editor3-last=Setia |editor4-last=van Schaik|editor4-first=Carel P. |title=Orangutans: Geographic Variation in Behavioral Ecology and Conservation |year=2009 |url=https://archive.org/details/orangutansgeogra00wich |url-access=registration |publisher=Oxford University Press|page=[https://archive.org/details/orangutansgeogra00wich/page/n198 166]|isbn=978-0199213276}} Orangutans also use the plant species Dracaena cantleyi as an anti-inflammatory balm.{{cite journal |vauthors=Morrogh-Bernard HC, Foitová I, Yeen Z, Wilkin P, de Martin R, Rárová L, Doležal K, Nurcahyo W, Olšanský M |year=2017|title=Self-medication by orang-utans (Pongo pygmaeus) using bioactive properties of Dracaena cantleyi |journal=Scientific Reports |volume=7 |issue=16653 |page=16653|doi= 10.1038/s41598-017-16621-w|pmid=29192145|pmc=5709421|bibcode=2017NatSR...716653M|doi-access=free }} Captive animals may suffer an upper respiratory tract disease.{{cite journal|last1=Zimmermann|first1=N|last2=Pirovino|first2=M|last3=Zingg|first3=R|last4=Clauss|first4=M|last5=Kaup|first5=F. J.|last6=Heistermann|first6=M|last7=Hatt|first7=J. M.|last8=Steinmetz|first8=H. W.|year=2011|title=Upper respiratory tract disease in captive orangutans (Pongo sp.): prevalence in 20 European zoos and predisposing factors|journal=Journal of Medical Primatology|volume=40|issue=6|pages=365–375|doi=10.1111/j.1600-0684.2011.00490.x|pmid=21770970|s2cid=997385}}

File:Orangutan -Zoologischer Garten Berlin-8a.jpg

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, arils or seed-walls are consumed the most, particularly figs but also drupes and berries.{{rp|65}} Orangutans are thought to be the sole fruit disperser for some plant species including the vine species Strychnos ignatii which contains the toxic alkaloid strychnine.{{cite journal | last = Rijksen | first = H. D.| title = A field study on Sumatran orang utans (Pongo pygmaeus abelii, Lesson 1827): Ecology, Behaviour and Conservation | journal = The Quarterly Review of Biology | volume = 53 | issue = 4 | pages = 493–94|date=December 1978 | doi = 10.1086/410942 | jstor=2826733}}

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, honey, bird eggs, insects and small vertebrates including slow lorises.{{cite journal | last = Galdikas |first = Birute M. F. | title = Orangutan Diet, Range, and Activity at Tanjung Puting, Central Borneo | journal = International Journal of Primatology | volume = 9 | year = 1988 | doi = 10.1007/BF02740195 | pages = 1–35 | issue = 1|s2cid = 40513842 }}{{rp|65–66}}

In some areas, orangutans may practise geophagy, 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 licks. Orangutans may eat soils for their anti-toxic kaolin minerals, since their diet contains toxic tannins and phenolic acids.{{rp|67}}

File:Leuser-orangs 09N8683.jpg

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.{{Cite book|author1=van Schaik, C.|author2=MacKinnon, J.|contribution=Orangutans|year=2001|title=The Encyclopedia of Mammals|edition=2nd|editor=MacDonald, D.|publisher=Oxford University Press|pages=[https://archive.org/details/encyclopediaofma00mals_0/page/420 420–23]|isbn=978-0-87196-871-5|url=https://archive.org/details/encyclopediaofma00mals_0/page/420}} 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.{{cite journal | doi=10.1016/S0003-3472(05)80782-1 | title=Residential status and seasonal movements of wild orang-utans in the Gunung Leuser Reserve (Sumatera, Indonesia) |year=1990 | last1=Teboekhorst | first1=I. | last2=Schürmann | first2=C. | last3=Sugardjito | first3=J. |journal=Animal Behaviour | volume=39 | issue=6 | pages=1098–1109| s2cid=54322235 }} Interactions between adult females range from friendly to avoidance to antagonistic.{{cite book|author=Galdikas, B. M. F.|year=1984|contribution= Adult female sociality among wild orangutans at Tanjung Puting Reserve|editor=Small, M. F.|title=Female Primates: Studies by Women Primatologists|publisher=Alan R. Liss|pages=217–35|isbn=978-0845134030}} Flanged males are often hostile to both other flanged males and unflanged males, while unflanged males are more peaceful towards each other.{{cite book |last1=Atmoko |first1=S. Suci Utami|author2=Singleton, Ian |author3=van Noordwijk, Maria A. |author4=van Schaik, Carel P.|author5=Setia, Tatang Mitra |editor1-first=Serge A. |editor1-last=Wich |editor2-first=S. Suci Utami |editor2-last=Atmoko |editor3-first=Tatang Mitra |editor3-last=Setia |editor4-last=van Schaik|editor4-first=Carel P. |title=Orangutans: Geographic Variation in Behavioral Ecology and Conservation |chapter=Male–male relationships in orangutans |year=2009 |publisher=Oxford University Press |isbn=978-0-19-921327-6 |pages=227–29}}

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.{{cite journal | last1 = Singleton | first1 = I. | last2 = van Schaik | first2 = C. P. | year = 2002 | title = The Social Organisation of a population of Sumatran orang-utans| journal = Folia Primatologica| volume = 73 | issue = 1| pages = 1–20 | doi = 10.1159/000060415 | pmid = 12065937| s2cid = 13557435 }}{{cite book|last1=van Noordwijk |first1=Maria A. |author2=Sauren, Simone E.B. |author3=Nuzuar |author4=Abulani, Ahbam|author5=Morrogh-Bernard, Helen C. |author6=Atmoko, S. Suci Utami| author7=van Schaik, Carel P. |contribution=Development of Independence|editor1-first=Serge A. |editor1-last=Wich |editor2-first=S. Suci Utami |editor2-last=Atmoko |editor3-first=Tatang Mitra |editor3-last=Setia |editor4-last=van Schaik|editor4-first=Carel P. |title=Orangutans: Geographic Variation in Behavioral Ecology and Conservation|year=2009|url=https://archive.org/details/orangutansgeogra00wich|url-access=registration|publisher=Oxford University Press|page=199|isbn=978-0199213276}} They enter a transient phase, which lasts until a male can challenge and displace a dominant, resident male from his home range.{{cite journal | last1 = Delgado | first1 = R. A. Jr. | last2 = van Schaik | first2 = C. P. | year = 2000 | title = The behavioral ecology and conservation of the orangutan (Pongo pygmaeus): a tale of two islands | journal = Evolutionary Anthropology: Issues, News, and Reviews| volume = 9 | issue = 1| pages = 201–18 | doi = 10.1002/1520-6505(2000)9:5<201::AID-EVAN2>3.0.CO;2-Y| s2cid = 84778685 }} 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.{{cite journal|author=van Schaik, C. P.|year=1999|title=The socioecology of fission-fusion sociality in orangutans|journal=Primates|volume=40|issue=1|pages=69–86|doi=10.1007/BF02557703|pmid=23179533|s2cid=13366732}}{{cite journal|last1=Mitani|first1=J. C.|last2=Grether|first2=G. F.|last3=Rodman|first3=P. S.|last4=Priatna|first4=D.|year=1991|title=Associations among wild orang-utans: sociality, passive aggregations or chance|journal=Animal Behaviour|volume=42|issue=1|pages=33–46|doi=10.1016/S0003-3472(05)80603-7|s2cid=40824300}} Orangutans will also form travelling groups with members moving between different food sources. They are often consortships between an adult male and a female.{{cite book|last1=van Schaik, C. P.|last2= Preuschoft, S.|last3= Watts, D. P.|year=2004|contribution= Great ape social systems|editor=Russon, A. E. |editor2=Begun, D. R. |title=The Evolution of Thought: Evolutionary Origins of Great Ape Intelligence|url=https://archive.org/details/evolutionthought00russ|url-access=registration|publisher=Cambridge University Press|pages=[https://archive.org/details/evolutionthought00russ/page/n200 193–94]|isbn=978-0521039925}} Social grooming is uncommon among orangutans.

{{listen

| filename = Call-Cultures-in-Orang-Utans?-pone.0036180.s001.ogg

| title = Nest smack

| description = Nest smack, ogg/Vorbis format.

| format = Vorbis

| filename2 = Call-Cultures-in-Orang-Utans?-pone.0036180.s002.ogg

| title2 = Raspberry

| description2 = Raspberry ogg/Vorbis format.

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| filename3 = Call-Cultures-in-Orang-Utans?-pone.0036180.s004.ogg

| title3 = Throatscrape

| description3 = Throatscrape ogg/Vorbis format.

| format3 = Vorbis

}}

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.{{cite web|title=Orangutan call repertoires|publisher=Universität Zürich – Department of Anthropology|url=https://www.aim.uzh.ch/de/orangutannetwork/orangutancallrepertoires.html|access-date=23 April 2020|archive-date=3 October 2020|archive-url=https://web.archive.org/web/20201003083144/https://www.aim.uzh.ch/de/orangutannetwork/orangutancallrepertoires.html|url-status=live}} Orangutan calls display consonant- and vowel-like components and they maintain their meaning over great distances.{{cite journal|last1=Lameira|first1=A. R.|display-authors=etal|year=2021|title=Orangutan information broadcast via consonant-like and vowel-like calls breaches mathematical models of linguistic evolution|journal=Biology Letters|volume=17|issue=9|doi=10.1098/rsbl.2021.0302|pmid=34582737 |pmc=8478518 }}

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".{{cite journal|last1=Knox|first1=A|last2=Markx|first2=J|last3=How|first3=E|last4=Azis|first4=A|last5=Hobaiter|first5=C|last6=an Veen|first6=F. J. F|last7=Morrogh-Bernard|first7=H|year=2019|title=Gesture use in communication between mothers and offspring in wild Orang-Utans (Pongo pygmaeus wurmbii) from the Sabangau Peat-Swamp Forest, Borneo|journal=International Journal of Primatology|volume=40|issue=3|pages=393–416|doi=10.1007/s10764-019-00095-w|s2cid=195329265|doi-access=free|hdl=10023/18054|hdl-access=free}}

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| alt caption1= Male orangutan exhibiting the facial flange and throat pouch

| caption2 = Unflanged male orangutan

|alt caption2 = A male orangutan with no facial flange or throat pouch

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Males become sexually mature at around age 15. They may exhibit arrested development 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.{{cite journal | last1 = Utami | first1 = S. S. | last2 = Goossens | first2 = B. | last3 = Bruford | first3 = M. W. | last4 = de Ruiter | first4 = J. R. | last5 = van Hooff | first5 = J. A. R. A. M. | author-link5 = Jan van Hooff | year = 2002 | title = Male bimaturism and reproductive success in Sumatran orangutans | journal = Behavioral Ecology | volume = 13 | issue = 5| pages = 643–52 | doi = 10.1093/beheco/13.5.643| doi-access = free }}{{rp|100}}

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.{{cite journal | last1 = Fox | first1 = E. A. | year = 2002 | title = Female tactics to reduce sexual harassment in the Sumatran orangutan (Pongo pygmaeus abelii) | journal = Behavioral Ecology and Sociobiology | volume = 52 | issue = 2| pages = 93–101 | doi = 10.1007/s00265-002-0495-x| s2cid = 13583879 }}{{cite journal|last1=Knott|first1=Cheryl Denise|last2=Thompson|first2=Melissa Emery|last3=Stumpf|first3=Rebecca M|last4=McIntyre|first4=Matthew H|year=2009|title=Female reproductive strategies in orangutans, evidence for female choice and counterstrategies to infanticide in a species with frequent sexual coercion|journal=Proceedings of the Royal Society B: Biological Sciences|volume=277|issue=1678|pages=105–13|doi=10.1098/rspb.2009.1552|pmid=19812079|pmc=2842634|doi-access=free}} Non-ovulating 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.{{cite journal|last=Fox|first=Elizabeth A|year=2001|title=Homosexual behavior in wild Sumatran orangutans (Pongo pygmaeus abelii)|journal=American Journal of Primatology|volume=55|issue=3|pages=177–81|doi=10.1002/ajp.1051|pmid=11746281|s2cid=21561581}}

File:Bukit Lawang, orangutans (6785217748).jpg

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.{{cite book|last1=Wich |first1=Serge A. |author2=de Vries, Hans |author3=Ancrenaz, Marc |author4=Perkins, Lori |author5=Shumaker, Robert W. |author6=Suzuki, Akira| author7=van Schaik, Carel P. |contribution=Orangutan life history variation|editor1-first=Serge A. |editor1-last=Wich |editor2-first=S. Suci Utami |editor2-last=Atmoko |editor3-first=Tatang Mitra |editor3-last=Setia |editor4-last=van Schaik|editor4-first=Carel P. |title=Orangutans: Geographic Variation in Behavioral Ecology and Conservation|year=2009|url=https://archive.org/details/orangutansgeogra00wich|url-access=registration|publisher=Oxford University Press|pages=67–68|isbn=978-0199213276}} Gestation is around nine months long and infants are born at a weight of {{convert|1.5|–|2|kg|lb|abbr=on}}.{{rp|99}} Usually only a single infant is born; twins are a rare occurrence.{{cite journal|last1=Goossens|first1=B|last2=Mohd|first2=D|last3=Kapar|last4=Kahar|first4=S|year=2011|title=First Sighting of Bornean Orangutan Twins in the Wild|journal=Asian Primates Journal|volume=2|issue=1|pages=10–12|url=https://www.researchgate.net/publication/245023318}} Unlike many other primates, male orangutans do not seem to practise infanticide. 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.{{cite journal |last1=Beaudrot |first1=LH |last2=Kahlenberg |first2=SM |last3=Marshall |first3=AJ |year=2009 |title=Why male orangutans do not kill infants |journal=Behavioral Ecology and Sociobiology |volume=63 |issue=11 |pages=1549–62 |pmid=19701484 |pmc=2728907 |doi=10.1007/s00265-009-0827-1}} There is evidence that females with offspring under six years old generally avoid adult males.{{cite journal|last1=Scott|first1=A. M.|last2=Knott|first2=C. D.|last3=Susanto|first3=T. W.|year=2019|title=Are Male Orangutans a Threat to Infants? Evidence of Mother–Offspring Counterstrategies to Infanticide in Bornean Orangutans (Pongo pygmaeus wurmbii)|journal=International Journal of Primatology|volume=44|issue=3|pages=435–55|doi=10.1007/s10764-019-00097-8|hdl=2144/39274|s2cid=198190605|hdl-access=free}}

Females do most of the caring of the young. The mother will carry the infant while travelling, suckle it and sleep with it.{{rp|100}} 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".{{cite book |last1=Munn|first1= C. |last2=Fernandez|first2= M.|year=1997|contribution=Infant development |title=Orangutan Species Survival Plan Husbandry Manual |editor-first=Carol |editor-last=Sodaro |publisher=Chicago Zoological Park |pages=59–66 |oclc=40349739}} 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.{{rp|100}} Females may nurse their offspring for up to eight years, which is more than any other mammal.{{cite journal|last1=Smith|first1=Tanya M.|last2=Austin|first2=Christine|last3=Hinde|first3=Katie|last4=Vogel|first4=Erin R.|last5=Arora|first5=Manish|year=2017|title=Cyclical nursing patterns in wild orangutans|journal=Evolutionary Biology|volume=3|issue=5|page=e1601517|doi=10.1126/sciadv.1601517|pmid=28560319|pmc=5435413|bibcode=2017SciA....3E1517S|doi-access=free}} Typically, orangutans live over 30 years both in the wild and in captivity.{{rp|15}}

{{Clear}}

File:Bornean Orangutan in nest.jpg

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.{{cite book |last1=Didik |first1=Prasetyo |author2=Ancrenaz, Marc |author3=Morrogh-Bernard, Helen C. |author4=Atmoko, S. Suci Utami |author5=Wich, Serge A. |author6=van Schaik, Carel P. |editor1-first=Serge A. |editor1-last=Wich |editor2-first=S. Suci Utami |editor2-last=Atmoko |editor3-first=Tatang Mitra |editor3-last=Setia |editor4-last=van Schaik |editor4-first=Carel P. |title=Orangutans: Geographic Variation in Behavioral Ecology and Conservation |chapter-url=https://books.google.com/books?id=ZHsNfZC3DfYC&pg=PA270 |chapter=Nest building in orangutans |year=2009 |publisher=Oxford University Press |isbn=978-0-19-921327-6 |pages=270–75 |access-date=16 December 2015 |archive-date=24 April 2016 |archive-url=https://web.archive.org/web/20160424082644/https://books.google.com/books?id=ZHsNfZC3DfYC&pg=PA270 |url-status=live }}

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".

{{further|Primate cognition}}

{{see also|Great ape language}}

File:Orangutanspeech.webm

Orangutans are among the most intelligent non-human primates. Experiments suggest they can track the displacement of objects both visible and hidden.{{cite journal | last1 = Deaner | first1 = R. O. | last2 = van Schaik | first2 = C. P. | last3 = Johnson | first3 = V. | year = 2006 | title = Do some taxa have better domain-general cognition than others? A meta-analysis of nonhuman primate studies | url = https://www.researchgate.net/publication/232522019 | journal = Evolutionary Psychology | volume = 4 | pages = 149–96 | doi = 10.1177/147470490600400114 | s2cid = 16702785 | doi-access = free | access-date = 19 June 2020 | archive-date = 19 August 2021 | archive-url = https://web.archive.org/web/20210819071419/https://www.researchgate.net/publication/232522019_Do_Some_Taxa_Have_Better_Domain-General_Cognition_than_others_A_Meta-Analysis_of_Nonhuman_Primate_Studies | url-status = live }}{{cite journal | last1 = de Blois| first1 = S. T. | last2 = Novak | first2 = M. A. | last3 = Bond | first3 = M. | year = 1998 | title = Object Permanence in Orangutans (Pongo Pygmaeus) and Squirrel Monkeys (Saimiri Sciureus) | journal = Journal of Comparative Psychology| volume = 112 |issue= 2 | pages = 137–52| doi = 10.1037/0735-7036.112.2.137 | pmid = 9642783}} Zoo Atlanta has a touch-screen computer on which their two Sumatran orangutans play games.{{cite web | author = Turner, Dorie | url = https://www.usatoday.com/tech/gaming/2007-04-12-orangutans-games_N.htm | title = Orangutans play video games (for research) at Georgia zoo | date = 12 April 2007 | newspaper = USA Today | access-date = 12 April 2007 | archive-date = 2 July 2007 | archive-url = https://web.archive.org/web/20070702082102/http://www.usatoday.com/tech/gaming/2007-04-12-orangutans-games_N.htm | url-status = live }} A 2008 study of two orangutans at the Leipzig Zoo 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.{{cite journal|author1=Dufour, V.|author2=Pelé, M. |author3=Neumann, M. |author4=Thierry, B. |author5=Call, J. |year=2008|title= Calculated reciprocity after all: computation behind token transfers in orang-utans |journal= Biology Letters |volume=5|issue=2|pages=172–75|doi=10.1098/rsbl.2008.0644|pmid=19126529 |pmc=2665816}}

In a 1997 study, two captive adult orangutans were tested with the cooperative pulling paradigm. 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.{{cite journal|last1=Chalmeau|first1= Raphaël|first2= Karine |last2=Lardeux|first3= Pierre |last3=Brandibas|first4=Alain |last4=Gallo|title=Cooperative problem solving by orangutans (Pongo pygmaeus)|journal= International Journal of Primatology |volume=18|issue= 1 |year=1997|pages=23–32|doi=10.1023/A:1026337006136|s2cid= 44204663}} An adult orangutan has been documented to pass the mirror test, indicating self-awareness.{{cite journal|author1=Suárez, S. D. |author2=Gallup, G. G. |year=1981|title=Self-recognition in chimpanzees and orangutans, but not gorillas|journal=Journal of Human Evolution|volume=10|issue=2|pages=175–88|doi=10.1016/s0047-2484(81)80016-4}} Mirror tests with a 2-year-old orangutan failed to reveal self-recognition.{{cite journal|author=Robert, S.|title=Ontogeny of mirror behavior in two species of great apes|journal=American Journal of Primatology|volume=10|issue=2|pages=109–17|year=1986|doi=10.1002/ajp.1350100202|pmid=31979488|s2cid=85330986}}

Studies in the wild indicate that flanged male orangutans plan their movements in advance and signal them to other individuals.{{cite journal|last1=van Schaik, Carel P.|last2= Damerius, L.|last3= Isler, K.|year=2013|title=Wild Orangutan Males Plan and Communicate Their Travel Direction One Day in Advance|journal=PLoS One|volume=8|issue=9|page=e74896|doi=10.1371/journal.pone.0074896|pmid= 24040357|pmc= 3770631|bibcode= 2013PLoSO...874896V|doi-access=free}} 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.{{cite journal|last1= Lameira|first1= Adriano R.|last2=Call|first2=Josep|year=2018|title=Time-space–displaced responses in the orangutan vocal system|journal=Science Advances|volume=4|issue=11|page=eaau3401|doi=10.1126/sciadv.aau3401|pmid= 30443595|pmc= 6235548|bibcode= 2018SciA....4.3401L|doi-access=free}} Orangutans and other great apes show laughter-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.{{cite journal |doi=10.1016/j.cub.2009.05.028 |volume=19 |issue=13 |title=Reconstructing the Evolution of Laughter in Great Apes and Humans |journal=Current Biology |pages=1106–11|year=2009 |last1=Ross |first1=Marina Davila |last2=Owren |first2=Michael J|last3=Zimmermann |first3=Elke |pmid=19500987|s2cid=17892549 |doi-access=free }} Orangutans can learn to mimic new sounds by purposely controlling the vibrations of their vocal folds, a trait that led to speech in humans.{{cite journal|last1=Lameira, A. R.|last2= Hardus, M. E.|last3= Shumaker, R. W.|last4= Wich, S. A.|last5= Menken, S. B. J.|year=2015|title=Speech-Like Rhythm in a Voiced and Voiceless Orangutan Call|journal=PLOS ONE|volume=10|issue=1|page=e116136|doi=10.1371/journal.pone.0116136|pmid= 25569211|pmc= 4287529|bibcode= 2015PLoSO..10k6136L|doi-access=free}}{{cite journal|last1=Lameira, A. R.|last2= Shumaker, R. W.|year=2019|title=Orangutans show active voicing through a membranophone|journal=Scientific Reports|volume=9|issue= 1|page=12289|doi=10.1038/s41598-019-48760-7|pmid= 31444387|pmc= 6707206|bibcode= 2019NatSR...912289L|doi-access=free}} Bonnie, an orangutan at the US National Zoo, was recorded spontaneously whistling after hearing a caretaker. She appears to whistle without expecting a food reward.{{Cite journal | last1 = Wich | first1 = S. A. | last2 = Swartz | first2 = K. B. | last3 = Hardus | first3 = M. E. | last4 = Lameira | first4 = A. R. | last5 = Stromberg | first5 = E. | last6 = Shumaker | first6 = R. W. | doi = 10.1007/s10329-008-0117-y | title = A case of spontaneous acquisition of a human sound by an orangutan | journal = Primates | volume = 50 | issue = 1 | pages = 56–64 | year = 2008 | pmid = 19052691 | s2cid = 708682 }}

File:Orangutan using precision grip.jpg using a tool to extract orange-juice concentrate|alt=An orangutan using a stick to pick at a hole in a rock with a cup of orange-juice concentrate.]]

Tool use in orangutans was observed by primatologist Birutė Galdikas in ex-captive populations.{{cite journal | last1 = Galdikas | first1 = B. M. F. | year = 1982 | title = Orang-Utan tool use at Tanjung Putting Reserve, Central Indonesian Borneo (Kalimantan Tengah) | journal = Journal of Human Evolution | volume = 10 | pages = 19–33 |doi=10.1016/S0047-2484(82)80028-6}} 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.{{cite book|last1=Fox|first1= E. A.|last2= Sitompul|first2= A. F.|last3= van Schaik|first3= C. P.|date=1999|chapter=Intelligent tool use in wild Sumatran orangutans|editor-last= Parker|editor-first= S|editor2-last= Mitchell |editor2-first=R. W. |editor3-last= Miles|editor3-first= H. L. |title=The Mentality of Gorillas and Orangutans|publisher= Cambridge University Press|pages= 99–116|isbn=978-0-521-03193-6}}{{cite journal | last1 = van Schaik | first1 = C. P. | last2 = Fox | first2 = E. A. | last3 = Sitompul | first3 = A. F. | year = 1996 | title = Manufacture and use of tools in wild Sumatran orangutans – implications or human evolution | journal = Naturwissenschaften | volume = 83 | issue = 4| pages = 186–88 | doi = 10.1007/BF01143062 | pmid = 8643126 | bibcode = 1996NW.....83..186V| s2cid = 27180148 }} This preference was also found in an experimental study of captive orangutans.{{cite journal | last1 = O'Malley | first1 = R. C. | last2 = McGrew | first2 = W. C. | year = 2000 | title = Oral tool use by captive orangutans (Pongo pygmaeus) | journal = Folia Primatologica| volume = 71 | issue = 5| pages = 334–41 | doi = 10.1159/000021756 | pmid = 11093037| s2cid = 19354930 }} 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.{{cite journal|last1=Russon, A. E.|last2= Compost, A.|last3= Kuncoro, P.|last4= Ferisa, A.|year=2014|title=Orangutan Fish Eating, Primate Aquatic Fauna Eating, and Their Implications for the Origins of Ancestral Hominin Fish Eating|journal=Journal of Human Evolution|volume=77|pages=50–63|doi=10.1016/j.jhevol.2014.06.007|pmid=25038033}}{{cite magazine |url=https://www.wired.com/wiredscience/2011/04/orangutan-tools-fishing/ |title=Orangutans use simple tools to catch fish |author=Bower, B. |magazine=Wired |date=18 April 2011 |access-date=5 August 2013 |archive-date=8 July 2013 |archive-url=https://web.archive.org/web/20130708064108/http://www.wired.com/wiredscience/2011/04/orangutan-tools-fishing |url-status=live }} Orangutan have also been documented to keep tools for later.{{cite journal|author=Mulcahy, N. J.|year=2018|title=An Orangutan Hangs Up a Tool for Future Use|journal=Scientific Reports|volume=8|issue=1|pages=1–6|doi=10.1038/s41598-018-31331-7|pmid=30150738|pmc=6110832|bibcode=2018NatSR...812900M|doi-access=free}} When building a nest, orangutans appear to be able to determine which branches would better support their body weight.{{cite journal|last1=van Casteren, A.|last2= Sellers, W. I.|last3= Thorpe, S. K. S.|last4= Coward, S.|last5= Crompton, R. H.|last6= Myatt, J. P.|last7= Ennos, A. R.|year=2012|title=Nest-building orangutans demonstrate engineering know-how to produce safe, comfortable beds|journal=PNAS|volume=109|issue=18|pages=6873–77|doi=10.1073/pnas.1200902109|pmid= 22509022|pmc= 3344992|bibcode= 2012PNAS..109.6873V|doi-access=free}}

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.{{cite journal | doi = 10.1002/ajpa.1045 | title = Geographic variation in tool use onNeesia fruits in orangutans | year = 2001 | last1 = van Schaik | first1 = Carel P. | last2 = Knott | first2 = Cheryl D. | journal = American Journal of Physical Anthropology | volume = 114 | issue = 4 | pages = 331–342 | pmid = 11275962}}{{cite journal | last1 = van Schaik | first1 = CP | last2 = Van Noordwijk | first2 = MA | last3 = Wich | first3 = SA. | year = 2006 | title = Innovation in wild Bornean orangutans (Pongo pygmaeus wurmbii) | journal = Behaviour | volume = 143 | issue = 7| pages = 839–76 | doi = 10.1163/156853906778017944}} 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.{{cite journal | last1 = Russon | first1 = AE | last2 = Handayani | first2 = DP | last3 = Kuncoro |first3 = P | last4 = Ferisa | first4 = A. | year = 2007 | title = Orangutan leaf-carrying for nest-building: toward unraveling cultural processes | journal = Animal Cognition | volume = 10 | issue = 2| pages = 189–202 |doi = 10.1007/s10071-006-0058-z | pmid = 17160669| s2cid = 6875716 }}

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 the listener into believing they are larger animals.{{cite journal | last1 = Hardus | first1 = M. E. | last2 = Lameira |first2 = A. R. | last3 = van Schaik | first3 = C. P. | last4 = Wich | first4 = S. A. | year = 2009 | title = Tool use in wild orang-utans modifies sound production: a functionally deceptive innovation? | journal = Proceedings of the Royal Society B | volume = 276 | issue = 1673| pages = 3689–94 | doi = 10.1098/rspb.2009.1027 | pmid=19656794 | pmc=2817314}} 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.{{cite journal |last1=van Schaik |first1=C. P. |last2=Ancrenaz |first2=M. |last3=Borgen |first3=G. |last4=Galdikas |first4=B. |last5=Knott |first5=C. D. |last6=Singleton |first6=I. |last7=Suzuki |first7=A. |last8=Utami |first8=S. S. |last9=Merrill |first9=M.|year=2003 |title=Orangutan cultures and the evolution of material culture |journal=Science |volume=299 |issue=5603 |pages=102–05 |doi=10.1126/science.1078004 |pmid=12511649|display-authors=etal|bibcode=2003Sci...299..102V |s2cid=25139547 }}

During a field observation in 2022, a male Sumatran orangutan, known to researchers as Rakus, chewed Fibraurea tinctoria vine leaves and applied the mashed plant material to an open wound on his face.{{Cite journal|display-authors=3 |last1=Laumer |first1=Isabelle B. |last2=Rahman |first2=Arif |last3=Rahmaeti |first3=Tri |last4=Azhari |first4=Ulil |last5=Hermansyah |last6=Atmoko |first6=Sri Suci Utami |last7=Schuppli |first7=Caroline |date=2 May 2024 |title=Active self-treatment of a facial wound with a biologically active plant by a male Sumatran orangutan |journal=Scientific Reports |language=en |volume=14 |issue=1 |page=8932 |doi=10.1038/s41598-024-58988-7 |pmid=38698007 |pmc=11066025 |issn=2045-2322}} According to 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".{{Cite news |last=Davis |first=Nicola |last2= |first2= |date=2 May 2024 |title=Orangutan seen treating wound with medicinal herb in first for wild animals |url=https://www.theguardian.com/science/article/2024/may/02/orangutan-seen-treating-wound-with-medicinal-herb-in-first-for-wild-animals-max-planck-institute-sumatra |access-date=2 May 2024 |work=The Guardian |language=en-GB |issn=0261-3077 |archive-date=2 May 2024 |archive-url=https://web.archive.org/web/20240502152144/https://www.theguardian.com/science/article/2024/may/02/orangutan-seen-treating-wound-with-medicinal-herb-in-first-for-wild-animals-max-planck-institute-sumatra |url-status=live }}

{{Main|Great ape personhood|Great Ape Project|Great ape research ban}}

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 not to be used for animal experiments.{{cite news |author=Glendinning, L. |url=https://www.theguardian.com/world/2008/jun/26/humanrights.animalwelfare?gusrc=rss&feed=networkfront |title=Spanish parliament approves 'human rights' for apes |newspaper=The Guardian |date=26 June 2008 |access-date=10 November 2008 |archive-date=26 August 2009 |archive-url=https://web.archive.org/web/20090826115218/http://www.guardian.co.uk/world/2008/jun/26/humanrights.animalwelfare?gusrc=rss&feed=networkfront |url-status=live }}{{cite news |author=Singer, P. |url=https://www.theguardian.com/commentisfree/2008/jul/18/animalwelfare.animalbehaviour |title=Of great apes and men |newspaper=The Guardian |date=18 July 2008 |access-date=10 November 2008 |archive-date=13 November 2012 |archive-url=https://web.archive.org/web/20121113090321/http://www.guardian.co.uk/commentisfree/2008/jul/18/animalwelfare.animalbehaviour |url-status=live }} 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 The Center for Great Apes in the United States, as it is the only accredited orangutan sanctuary in the Americas.{{cite web | url=https://centerforgreatapes.org/orangutan/sandra/ | title=Sandra }} 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 Criminal Cassatio considered the ruling applicable only to non-human hominids.{{cite web |url=http://edition.cnn.com/2014/12/23/world/americas/feat-orangutan-rights-ruling/ |title=Argentine orangutan granted unprecedented legal rights |author=Giménez, Emiliano |publisher=CNN |date=23 December 2014 |access-date=15 June 2020 |archive-date=3 April 2021 |archive-url=https://web.archive.org/web/20210403030759/https://edition.cnn.com/2014/12/23/world/americas/feat-orangutan-rights-ruling/ |url-status=live }}

File:Birute Galdikas.jpg presenting her book about the apes]]

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.{{cite journal|last=Rubis|first=June Mary|year=2020|title=The orang utan is not an indigenous name: knowing and naming the maias as a decolonizing epistemology|journal=Cultural Studies|volume=34|issue=5|pages=811–30|doi=10.1080/09502386.2020.1780281|s2cid=221192990}} 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.{{rp|66–71}}

Europeans became aware of the existence of the orangutan in the 17th century.{{rp|60}} 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.{{rp|64–65}} Camper mistakenly thought that flanged and unflanged male orangutans were different species, a misconception corrected after his death.{{cite book|last=Meijer|first=Miriam Claude|year=2014|title=Race and Aesthetics in the Anthropology of Petrus Camper (1722–1789) (Studies in the History of Ideas in the Low Countries)|publisher=Rodopi|page=42|isbn=978-9042004344}}

Little was known about orangutan behaviour until the field studies of Birutė Galdikas,{{Cite news | last = de Waal | first = Frans | date = January 1995 | title = The Loneliest of Apes | url = https://www.nytimes.com/1995/01/29/books/the-loneliest-of-apes.html?scp=3&sq=galdikas%20fossey%20goodall&st=cse | periodical = The New York Times | access-date = 26 February 2012 | archive-date = 4 May 2013 | archive-url = https://web.archive.org/web/20130504180514/http://www.nytimes.com/1995/01/29/books/the-loneliest-of-apes.html?scp=3&sq=galdikas%20fossey%20goodall&st=cse | url-status = live }} 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.{{cite book|author=Oaks, Elizabeth H.|year=2007|title=Encyclopedia of World Scientists: From Around the World|publisher=Facts on File|page=260|isbn=978-0816041305}} Galdikas became an outspoken advocate for orangutans and the preservation of their rainforest habitat, which is rapidly being devastated by loggers, palm oil plantations, gold miners, and unnatural forest fires.{{cite news|title=Palm oil frenzy threatens to wipe out orangutans |url=https://www.marinij.com/2009/01/19/palm-oil-frenzy-threatens-to-wipe-out-orangutans/ |author=McDowell, Robin|agency=Associated Press |date=18 January 2009 |access-date=18 January 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090120192430/http://news.yahoo.com/s/ap/20090118/ap_on_re_as/as_orangutan_s_last_stand |archive-date=20 January 2009 }} Along with Jane Goodall and Dian Fossey, Galdikas is considered to be one of Leakey's Angels, named after anthropologist Louis Leakey.{{cite book | last1 = MacClancy | first1 = J. | last2 = Fuentes | first2 = A. | title = Centralizing Fieldwork: Critical Perspectives from Primatology, Biological, and Social Anthropology | year = 2010 | publisher = Berghahn Books | pages = 6–7 | isbn = 978-1-84545-690-0 | url = https://books.google.com/books?id=zSTT5Ntj9y0C&pg=PA6 | access-date = 16 December 2015 | archive-date = 30 April 2016 | archive-url = https://web.archive.org/web/20160430081033/https://books.google.com/books?id=zSTT5Ntj9y0C&pg=PA6 | url-status = live }}

{{Main|Orangutans in popular culture}}

File:Daniel Urrabieta y Vierge - The Murders in the Rue Morgue.jpg" by Daniel Vierge]]

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.{{rp|108–09}}

Thomas Love Peacock's 1817 novel Melincourt features Sir Oran Haut Ton, an orangutan who lives among English people and becomes a candidate for 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.{{rp|110–11}} 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".{{rp|114–15}} Orangutans are featured prominently in the 1963 science fiction novel Planet of the Apes by Pierre Boulle and the media franchise derived from it. They are typically portrayed as bureaucrats like Dr. Zaius, the science minister.{{rp|118–19, 175–76}}

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.{{rp|145}} Disney's 1967 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.{{rp|266}} The 1986 horror 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.{{rp|174–75}} Other stories have portrayed orangutans helping humans, such as The Librarian in Terry Pratchett's fantasy novels Discworld and in Dale Smith's 2004 novel What the Orangutan Told Alice.{{rp|123}} More comical portrayals of the orangutan include the 1996 film Dunston Checks In.{{rp|181}}

File:The Female Orang - Utan.png sitting in a chair) {{Circa|1830s}}]]

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.{{rp|64–65}} The London Zoo housed a female orangutan named 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.{{Cite journal|last1=van Wyhe|first1=John|author-link=John van Wyhe|last2=Kjærgaard|first2=Peter C.|date=1 June 2015|title=Going the whole orang: Darwin, Wallace and the natural history of orangutans|journal=Studies in History and Philosophy of Science Part C: Studies in History and Philosophy of Biological and Biomedical Sciences|language=en|volume=51|pages=53–63|doi=10.1016/j.shpsc.2015.02.006|issn=1369-8486|doi-access=free|pmid=25861859}}{{Cite web|url=https://www.nationalgeographic.com/science/phenomena/2015/04/21/when-darwin-met-another-ape/|title=When Darwin Met Another Ape|last=Zimmer|first=Carl|date=21 April 2015|publisher=National Geographic Society|language=en|access-date=24 February 2020|archive-date=7 June 2020|archive-url=https://web.archive.org/web/20200607041644/https://www.nationalgeographic.com/science/phenomena/2015/04/21/when-darwin-met-another-ape/|url-status=dead}}

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 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 of Universal City Zoo in the 1910s and 1920s; and Jiggs of the San Diego Zoo in the 1930s and 1940s.{{rp|187–89, 193–94}}{{Cite book |last=Robeson |first=Dave |title=Al G. Barnes, Master Showman, as told by Al G. Barnes |publisher=The Caxton Printers, Ltd. |year=1935 |location=Caldwell, Idaho |pages=102–103 |language=en-us |chapter= |lccn=35012032 |oclc=598387}} Animal rights groups have urged a stop to such acts, considering them abusive.{{cite web |url=http://www.nomoremonkeybusiness.com/ |title=Animal Actors |publisher=PETA |access-date=28 January 2011 |archive-url=https://web.archive.org/web/20100303121336/http://www.nomoremonkeybusiness.com/ |archive-date=3 March 2010 |url-status=dead}} 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.{{rp|185, 206}} 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 hairy Houdini" and was the subject of a fan club, T-shirts, bumper stickers and a song titled The Ballad of Ken Allen.{{Cite web|url=http://www.bbc.co.uk/newsbeat/article/36745764/the-missing-lynx-and-five-other-animal-escapees-including-ken-allen-the-orangutan|title=The missing lynx and five other animal escapees including Ken Allen the Orangutan|last=Middleton|first=Duncan|date=7 August 2016|website=BBC Newsbeat|language=en-GB|access-date=25 December 2018|archive-date=25 December 2018|archive-url=https://web.archive.org/web/20181225175722/http://www.bbc.co.uk/newsbeat/article/36745764/the-missing-lynx-and-five-other-animal-escapees-including-ken-allen-the-orangutan|url-status=live}}

Galdikas reported that her cook was sexually assaulted by a captive male orangutan.{{Cite book |last1=Wrangham |first1=Richard W |last2=Peterson |first2=Dale |year=1996 |title=Demonic Males: Apes and the Origins of Human Violence |publisher=Houghton Mifflin |isbn=978-0-395-69001-7 | page = [https://archive.org/details/demonicmalesapes00wran/page/137 137] | url = https://archive.org/details/demonicmalesapes00wran|url-access=registration }} The ape may have suffered from a skewed species identity and forced copulation is a standard mating strategy for low-ranking male orangutans.{{cite book|title=Among Orangutans: Red Apes and the Rise of Human Culture|url=https://archive.org/details/amongorangutans00care|url-access=registration|first=Carel |last=van Schaik|publisher=Harvard University Press|year=2004|page=[https://archive.org/details/amongorangutans00care/page/88 88]|isbn=9780674015777}} American animal trafficker 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.{{Cite book |last=Buck |first=Frank |url=https://www.worldcat.org/oclc/43207125 |title=Bring 'em back alive : the best of Frank Buck |date=2000 |publisher=Texas Tech University Press |others=Steven Lehrer |isbn=0-89672-430-1 |location=Lubbock, Tex. |page=37 |oclc=43207125}}

{{Main|Endangerment of orangutans}}

All three species are critically endangered according to the IUCN Red List of mammals.{{cite iucn |author= Singleton, I. |author2= Wich, S. A. |author3= Griffiths, M. |year= 2008|url= https://www.iucnredlist.org/species/121097935/123797627|title= Pongo abelii|access-date= 28 January 2011}}{{Cite iucn | author = Ancrenaz, M. | author2 = Gumal, M. | author3 = Marshall, A. J. | author4 = Meijaard, E. | author5 = Wich, S. A. | author6 = Husson, S. | title = Pongo pygmaeus | volume = 2016 | page = e.T17975A17966347 | date = 2016 | doi = 10.2305/IUCN.UK.2016-1.RLTS.T17975A17966347.en }}{{cite iucn|last1=Nowak|first1=Matthew G.|last2=Rianti|first2=Puji|last3=Wich|first3=Serge A.|last4=Meijaard|first4=Erik|last5=Fredriksson|first5=Gabriella|title=Pongo tapanuliensis|version=2017.3|year=2017|page=e.T120588639A120588662|doi=10.2305/IUCN.UK.2017-3.RLTS.T120588639A120588662.en}} They are legally protected from capture, harm or killing in both Malaysia and Indonesia,{{cite web|author=Neme, Laurel|date=11 October 2014|title=Endangered Orangutans Gain From Eco-Friendly Shifts in Palm Oil Market|publisher=National Geographic Society|access-date=1 July 2020|url=https://www.nationalgeographic.com/news/2014/10/141009-orangutans-palm-oil-malaysia-indonesia-tigers-rhinos/|archive-date=29 June 2020|archive-url=https://web.archive.org/web/20200629034907/https://www.nationalgeographic.com/news/2014/10/141009-orangutans-palm-oil-malaysia-indonesia-tigers-rhinos/|url-status=dead}} and are listed under Appendix I by CITES, which prohibits their unlicensed trade under international law.{{cite web|title=On the edge of extinction|publisher=Sumatran Orangutan Society|access-date=1 July 2020|url=https://www.orangutans-sos.org/crisis/|archive-date=8 May 2020|archive-url=https://web.archive.org/web/20200508013819/https://www.orangutans-sos.org/crisis/|url-status=live}} 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.{{cite journal|author1=Cheyne, S. M. |author2=Thompson, C. J. |author3=Phillips, A. C. |author4=Hill, R. M. |author5=Limin, S. H. |year=2007|title=Density and population estimate of gibbons (Hylobates albibarbis) in the Sabangau catchment, Central Kalimantan, Indonesia|journal=Primates|volume=49|issue=1|pages=50–56|doi=10.1007/s10329-007-0063-0|pmid=17899314|s2cid=1792717 }} 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.

File:Riau palm oil 2007.jpg]]

Birutė Galdikas wrote that orangutans were already threatened by poaching and deforestation when she began studying them in 1971.{{cite web|url=http://factsanddetails.com/asian/cat68/sub430/item2475.html|title=Endangered Orangutans: Fires, Poaching and Palm Oil: Facts and Details|last=Hays|first=Jeffrey|website=factsanddetails.com|access-date=12 May 2019|archive-date=12 May 2019|archive-url=https://web.archive.org/web/20190512083505/http://factsanddetails.com/asian/cat68/sub430/item2475.html|url-status=live}} By the 2000s, orangutan habitats decreased rapidly because of logging, mining and fragmentation by roads. A major factor has been the conversion of vast areas of tropical forest to palm oil 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 trade{{cite web|author=Than, Ker|title=Hundreds of Orangutans Killed Annually for Meat|date=16 November 2011|publisher=National Geographic Society|access-date=11 May 2020|url=https://www.nationalgeographic.com/news/2011/11/111115-orangutans-meat-animals-environment-science/|archive-date=3 October 2020|archive-url=https://web.archive.org/web/20201003172120/https://www.nationalgeographic.com/news/2011/11/111115-orangutans-meat-animals-environment-science/|url-status=dead}} and bones are secretly sold in souvenir shops in several cities in Indonesian Borneo.{{cite web |url=http://www.antaranews.com/en/news/75425/stop-orangutan-skull-trade |title=Stop orangutan skull trade |publisher=Antara News |date=7 September 2011 |access-date=16 January 2012 |archive-date=3 January 2012 |archive-url=https://web.archive.org/web/20120103220530/http://www.antaranews.com/en/news/75425/stop-orangutan-skull-trade |url-status=live }} 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.{{cite journal|last1=Meijaard, E.|last2= Buchori, B.|last3= Hadiprakarsa, Y.|last4= Utami-Atmoko, S. S.|display-authors=etal|year=2011|title=Quantifying Killing of Orangutans and Human-Orangutan Conflict in Kalimantan, Indonesia|journal=PLOS ONE|volume=6|issue=11|page=e27491|doi=10.1371/journal.pone.0027491|pmid=22096582|bibcode=2011PLoSO...627491M|pmc=3214049|doi-access= free}} Locals may also be motivated to kill orangutans for food or because of their perceived danger.{{cite journal|last1=Davis, J. T.|last2= Mengersen, K.|last3= Abram, N. K.|last4= Ancrenaz, M.|last5= Wells, J. A.|last6= Meijaard, E.|year=2013|title=It's Not Just Conflict That Motivates Killing of Orangutans|journal=PLOS ONE|volume=8|issue=10|pages=e75373|doi=10.1371/journal.pone.0075373|pmid= 24130707|pmc= 3793980|bibcode= 2013PLoSO...875373D|doi-access=free}} 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.{{cite web|author=Jacobson, Phillip|date=29 March 2017|title=The military family that kept a pet orangutan in Indonesia|publisher=Mongabay|access-date=11 May 2020|url=https://news.mongabay.com/2017/03/the-ape-who-escaped-indonesias-blackmarket-trade-in-pet-orangutans/|archive-date=14 June 2020|archive-url=https://web.archive.org/web/20200614055134/https://news.mongabay.com/2017/03/the-ape-who-escaped-indonesias-blackmarket-trade-in-pet-orangutans/|url-status=live}}

Estimates in the 2000s found that around 6,500 Sumatran orangutans and around 54,000 Bornean orangutans remain in the wild.{{cite journal |last1=Wich|first1=S A|last2=Meijaard|first2=E|last3=Marshall|first3=A J|last4=Husson|first4=S|display-authors=etal|year=2002|title= Distribution and conservation status of the orang-utan (Pongo spp.) on Borneo and Sumatra: how many remain?|journal= Oryx|volume=42|issue=3|pages=329–39|doi=10.5167/uzh-3914}} A 2016 study estimates a population of 14,613 Sumatran orangutans in the wild, twice that of previous population estimates,{{cite journal|volume=2|issue=3|pages=e1500789|doi=10.1126/sciadv.1500789|pmid=26973868|pmc=4783118|year=2016|last1=Wich|first1=Serge A.|last2=Singleton|first2=Ian|last3=Nowak|first3=Matthew G.|last4=Utami Atmoko|first4=Sri Suci|last5=Nisam|first5=Gonda|last6=Arif|first6=Sugesti Mhd.|last7=Putra|first7=Rudi H.|last8=Ardi|first8=Rio|last9=Fredriksson|first9=Gabriella|last10=Usher|first10=Graham|last11=Gaveau|first11=David L. A.|last12=Kühl|first12=Hjalmar S.|title=Land-cover changes predict steep declines for the Sumatran orangutan (Pongo abelii)|journal=Science Advances|bibcode=2016SciA....2E0789W}} 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.{{cite journal|last1=Voigt|first1=M|last2=Wich|first2=S. A.|last3=Ancrenaz|first3=M|display-authors=etal|year=2018|title=Global demand for natural resources eliminated more than 100,000 Bornean Orangutans|journal=Current Biology|volume=28|issue=5|pages=P761–769.E5|doi=10.1016/j.cub.2018.01.053|pmid=29456144|s2cid=3756682|doi-access=free}} Fewer than 800 Tapanuli orangutans are estimated to still exist, which puts the species among the most endangered of the great apes.{{Cite journal|last1=Nater|first1=Alexander|last2=Mattle-Greminger|first2=Maja P.|last3=Nurcahyo|first3=Anton|last4=Nowak|first4=Matthew G.|last5=Manuel|first5=Marc de|last6=Desai|first6=Tariq|last7=Groves|first7=Colin|last8=Pybus|first8=Marc|last9=Sonay|first9=Tugce Bilgin|date=2 November 2017|title=Morphometric, Behavioral, and Genomic Evidence for a New Orangutan Species|journal=Current Biology|volume=27|language=en|issue=22|pages=3487–3498.e10|doi=10.1016/j.cub.2017.09.047|pmid=29103940|issn=0960-9822|doi-access=free|hdl=10230/34400|hdl-access=free}}{{Cite journal|last=Reese|first=April|date=2 November 2017|title=Newly discovered orangutan species is also the most endangered|journal=Nature|volume=551|issue=7679|pages=151|doi=10.1038/nature.2017.22934|pmid=29120449|bibcode=2017Natur.551..151R|doi-access=free}}

File:FZS Programm Director Peter Pratje working with orangutans in Bukit Tigapulu, Indonesia.jpg, Indonesia.]]

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.{{cite web|title=Willie Smits|url=https://masarang.nl/en/about-masarang/willie-smits/|publisher=Masarang Foundation|access-date=11 May 2020|archive-date=28 September 2020|archive-url=https://web.archive.org/web/20200928175159/https://masarang.nl/en/about-masarang/willie-smits/|url-status=live}}{{cite web | title = 10 Years: Nyaru Menteng 1999–2009 | publisher = Orangutan Protection Foundation | url = http://savetheorangutan.org/splash/nm10.pdf | archive-url = https://web.archive.org/web/20100215031751/http://savetheorangutan.org/splash/nm10.pdf | archive-date = 15 February 2010}}{{cite web | title = Ny projektledare på Nyaru Menteng | website = Save the Orangutan | date = 26 January 2012 | url = http://www.savetheorangutan.se/about-us/news/ny-projektledare-paa-nyaru-menteng/ | access-date = 2 April 2012 | archive-url = https://web.archive.org/web/20140110175957/http://www.savetheorangutan.se/about-us/news/ny-projektledare-paa-nyaru-menteng/ | archive-date = 10 January 2014 | url-status = dead }}

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.{{cite web|title=Orangutan shaved, made up and prostituted to men for six years|newspaper=The Week|date=28 November 2018|access-date=29 April 2020|url=https://www.theweek.co.uk/98117/orangutan-shaved-made-up-and-prostituted-to-men-for-six-years|archive-date=3 October 2020|archive-url=https://web.archive.org/web/20201003151828/https://www.theweek.co.uk/98117/orangutan-shaved-made-up-and-prostituted-to-men-for-six-years|url-status=live}} 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.{{cite web|author=Brady, Heather|date=18 May 2017|title=Extremely Rare Albino Orangutan Found in Indonesia|publisher=National Geographic Society|url=https://www.nationalgeographic.com/news/2017/05/rare-albino-orangutan-found-indonesia/|access-date=29 April 2020|archive-date=17 February 2020|archive-url=https://web.archive.org/web/20200217133615/https://www.nationalgeographic.com/news/2017/05/rare-albino-orangutan-found-indonesia/|url-status=dead}}

Other major conservation centres in Indonesia include those at 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.{{cite web|url=https://sustainabletravel.org/traveler-resources/viewing-orangutans-in-the-wild/|access-date=10 May 2020|title=Viewing Orangutans in the Wild|publisher=Sustainable Travel International|archive-date=3 October 2020|archive-url=https://web.archive.org/web/20201003131636/https://sustainabletravel.org/traveler-resources/viewing-orangutans-in-the-wild/|url-status=dead}} Major conservation centres headquartered outside the orangutans' home countries include Frankfurt Zoological Society,{{cite book|author=Palmer, Alexandra|year=2020|title=Ethical Debates in Orangutan Conservation|publisher=Taylor & Francis|page=127|isbn=978-0429576638}} Orangutan Foundation International, which was founded by Galdikas,{{cite book | last1 = Martinelli | first1 = D. | title = A Critical Companion to Zoosemiotics: People, Paths, Ideas | publisher = Springer | year = 2010 | pages = 218–19 | isbn = 978-90-481-9248-9 | url = https://books.google.com/books?id=mDPr7gVnXi4C&pg=PT485 | access-date = 16 December 2015 | archive-date = 30 April 2016 | archive-url = https://web.archive.org/web/20160430105825/https://books.google.com/books?id=mDPr7gVnXi4C&pg=PT485 | url-status = live }} and the Australian Orangutan Project.{{cite web |url=http://www.environment.gov.au/tax/reo/index.html |publisher=Australian Department of the Environment and Water Resources |title=Tax Deductible Organisations (Register of Environmental Organisations) |url-status=dead |archive-url=https://web.archive.org/web/20070210025946/http://www.environment.gov.au/tax/reo/index.html |archive-date=10 February 2007 |access-date=16 January 2014}} 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.{{cite web | last1 = Butler | first1 = R. A. | title = Rehabilitation not enough to solve orangutan crisis in Indonesia | date = 20 August 2009 | url = http://news.mongabay.com/2009/0820-orangutans.html | publisher = Mongabay | access-date = 26 March 2012 | archive-date = 5 January 2012 | archive-url = https://web.archive.org/web/20120105163042/http://news.mongabay.com/2009/0820-orangutans.html | url-status = live }}{{cite web | last1 = Marusiak | first1 = J. | title = New deal for orangutans in Kalimantan | website = Eco-Business | date = 28 June 2011 | url = http://www.eco-business.com/features/new-deal-for-orangutans-in-kalimantan/| access-date = 3 April 2012}}

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• [http://www.orangutan.org/ Orangutan Foundation International]
• [https://web.archive.org/web/20130830125746/http://engage.aza.org/orangutans/ AZA's Orangutan Conservation Education Center]
• [https://web.archive.org/web/20090318005138/http://nationalzoo.si.edu/Animals/ThinkTank/ResearchProjects/OLP/default.cfm Orangutan Language Project]
• [http://www.orangutan.org.uk/ The Orangutan Foundation]
• [http://www.forests4orangutans.org/ Orangutan Land Trust]

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