Orangutan
Overview
Orangutans are the only exclusively Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

n genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of extant great ape. The largest living arboreal
Arboreal locomotion
Arboreal locomotion is the locomotion of animals in trees. In every habitat in which trees are present, animals have evolved to move in them. Some animals may only scale trees occasionally, while others are exclusively arboreal. These habitats pose numerous mechanical challenges to animals...

 animals, they have proportionally longer arms than the other, more terrestrial, great apes. They are among the most intelligent primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...

s and use a variety of sophisticated tools, also making sleeping nests each night from branches and foliage. Their hair is typically reddish-brown, instead of the brown or black hair typical of other great apes.

Native to Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

 and Malaysia, orangutans are currently found only in rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...

s on the islands of Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....

 and Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...

, though fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

s have been found in Java
Java
Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...

, the Thai-Malay Peninsula
Malay Peninsula
The Malay Peninsula or Thai-Malay Peninsula is a peninsula in Southeast Asia. The land mass runs approximately north-south and, at its terminus, is the southern-most point of the Asian mainland...

, Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...

 and Mainland China
Mainland China
Mainland China, the Chinese mainland or simply the mainland, is a geopolitical term that refers to the area under the jurisdiction of the People's Republic of China . According to the Taipei-based Mainland Affairs Council, the term excludes the PRC Special Administrative Regions of Hong Kong and...

.
Unanswered Questions
Encyclopedia
Orangutans are the only exclusively Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

n genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of extant great ape. The largest living arboreal
Arboreal locomotion
Arboreal locomotion is the locomotion of animals in trees. In every habitat in which trees are present, animals have evolved to move in them. Some animals may only scale trees occasionally, while others are exclusively arboreal. These habitats pose numerous mechanical challenges to animals...

 animals, they have proportionally longer arms than the other, more terrestrial, great apes. They are among the most intelligent primate
Primate
A primate is a mammal of the order Primates , which contains prosimians and simians. Primates arose from ancestors that lived in the trees of tropical forests; many primate characteristics represent adaptations to life in this challenging three-dimensional environment...

s and use a variety of sophisticated tools, also making sleeping nests each night from branches and foliage. Their hair is typically reddish-brown, instead of the brown or black hair typical of other great apes.

Native to Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

 and Malaysia, orangutans are currently found only in rainforest
Rainforest
Rainforests are forests characterized by high rainfall, with definitions based on a minimum normal annual rainfall of 1750-2000 mm...

s on the islands of Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....

 and Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...

, though fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

s have been found in Java
Java
Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...

, the Thai-Malay Peninsula
Malay Peninsula
The Malay Peninsula or Thai-Malay Peninsula is a peninsula in Southeast Asia. The land mass runs approximately north-south and, at its terminus, is the southern-most point of the Asian mainland...

, Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...

 and Mainland China
Mainland China
Mainland China, the Chinese mainland or simply the mainland, is a geopolitical term that refers to the area under the jurisdiction of the People's Republic of China . According to the Taipei-based Mainland Affairs Council, the term excludes the PRC Special Administrative Regions of Hong Kong and...

. There are only two surviving species, both of which are endangered
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

: the Bornean Orangutan
Bornean Orangutan
The Bornean orangutan, Pongo pygmaeus, is a species of orangutan native to the island of Borneo. Together with the slightly smaller Sumatran orangutan, it belongs to the only genus of great apes native to Asia....

 (Pongo pygmaeus) and the critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...

 Sumatran Orangutan
Sumatran Orangutan
The Sumatran orangutan is one of the two species of orangutans. Found only on the island of Sumatra, in Indonesia, it is rarer and smaller than the Bornean orangutan. The Sumatran orangutan grows to about tall and in males...

 (Pongo abelii). The subfamily Ponginae
Ponginae
Ponginae is a subfamily in the hominidae family. It contains a number of genera, all but one extinct:*Pongo *†Gigantopithecus*†Sivapithecus*†Lufengpithecus*†Ankarapithecus*†Ouranopithecus*†Griphopithecus...

 also includes the extinct genera Gigantopithecus
Gigantopithecus
Gigantopithecus is an extinct genus of ape that existed from roughly one million years to as recently as three hundred thousand years ago, in what is now China, India, and Vietnam, placing Gigantopithecus in the same time frame and geographical location as several hominin species...

 and Sivapithecus
Sivapithecus
Sivapithecus is a genus of extinct primates. Fossil remains of animals now assigned to this genus, dated from 12.5 million to 8.5 million years old in the Miocene, have been found since the 19th century in the Siwalik Hills in what is now India, Nepal, and Pakistan...

. The word "orangutan" comes from the Malay
Malay language
Malay is a major language of the Austronesian family. It is the official language of Malaysia , Indonesia , Brunei and Singapore...

 words "orang" (man) and "(h)utan" (forest); hence, "man of the forest".

Taxonomy and nomenclature

The genus Pongo was erected by Lacépède in 1799, for what was then the sole species of Orangutan.
  • Genus Pongo
    • Bornean Orangutan
      Bornean Orangutan
      The Bornean orangutan, Pongo pygmaeus, is a species of orangutan native to the island of Borneo. Together with the slightly smaller Sumatran orangutan, it belongs to the only genus of great apes native to Asia....

       (Pongo pygmaeus)
      • Pongo pygmaeus pygmaeus - northwest populations
      • Pongo pygmaeus morio - east populations
      • Pongo pygmaeus wurmbii - southwest populations
    • Sumatran Orangutan
      Sumatran Orangutan
      The Sumatran orangutan is one of the two species of orangutans. Found only on the island of Sumatra, in Indonesia, it is rarer and smaller than the Bornean orangutan. The Sumatran orangutan grows to about tall and in males...

       (Pongo abelii)

The populations on the two islands were classified as subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 until recently, when they were elevated to full specific level, and the three distinct populations on Borneo were elevated to subspecies. The population currently listed as P. p. wurmbii may be closer to the Sumatran Orangutan than the Bornean Orangutan. If confirmed, abelii would be a subspecies of P. wurmbii (Tiedeman, 1808). Regardless, the type locality of pygmaeus has not been established beyond doubts, and may be from the population currently listed as wurmbii (in which case wurmbii would be a junior synonym of pygmaeus, while one of the names currently considered a junior synonym of pygmaeus would take precedence for the northwest Bornean taxon
Taxon
|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...

). To further confuse, the name morio, as well as various junior synonyms that have been suggested, have been considered likely to all be junior synonyms of the population listed as pygmaeus in the above, thus leaving the east Bornean populations unnamed.
In addition, a fossil species, P. hooijeri, is known from 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. abeli or, in fact, represent distinct species.

Anatomy and physiology

An orangutan's standing height averages from 4 to 5 ft (1.2 to 1.5 m). On average, an orangutan weighs between 73 lbs. Males can weigh up to 250 lbs or more. Orangutan hands are similar to humans' hands; they have four long fingers and an opposable thumb. Their feet have four long toes and an opposable big toe. Orangutans can grasp things with both their hands and their feet. The largest males have an arm span of about 7.5 ft (2 m).

Orangutans have a large, bulky body, a thick neck, very long, strong arms, short, bowed legs, and no tail. They are mostly covered with long reddish-brown hair, although this differs between the species: Sumatran Orangutans have a more sparse and lighter coloured coat.

The orangutan has a large head with a prominent mouth area. Adult males have large cheek flaps (which get larger as the ape ages) that show their dominance to other males and their readiness to mate. The age of maturity for females is approximately 12 years. On average, orangutans may live about 35 years in the wild, and up to 60 years in captivity (though it is unknown what the typical lifespan of the orangutan in the wild is and many would certainly live much longer). Both sexes have throat pouches located near their vocal chords that make their calls resonate through the forest, although the males' pouches are more developed. There is significant sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...

: females can grow to around 4 ft 2 in or 127 cm and weigh around 100 lbs while flanged adult males can reach 5 ft 9 in or 175 cm in height and weigh over 260 lbs.

The arms of orangutans are twice as long as their legs, and an adult orangutan's arms can be well over seven feet from fingertip to fingertip. Much of the arm's length has to do with the length of the radius
Radius (bone)
The radius is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna, which exceeds it in length and size. It is a long bone, prism-shaped and slightly curved longitudinally...

 and the ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...

 rather than the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....

. Their fingers and toes are curved, allowing them to better grip onto branches. Orangutans have less restriction in the movements of their legs than humans and other primates, due to the lack of a hip joint ligament which keeps the femur
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...

 held into the pelvis
Pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...

. Unlike gorillas and chimpanzees, orangutans are not true knuckle-walkers, and are instead fist-walkers.

Ecology and behavior

Orangutans live in primary and old secondary forests, particularly dipterocarp forests and peat swamp forest
Peat swamp forest
Peat swamp forests are tropical moist forests where waterlogged soils prevent dead leaves and wood from fully decomposing, which over time creates a thick layer of acidic peat...

s. Both species can be found in both mountainous and lowland swampy areas. Sumatran orangutans live in elevations as high as 1500 m (4921 ft), while Bornean orangutans live no higher than 1000 m (3281 ft). The latter will sometimes enter grasslands, cultivated fields, gardens, young secondary forest, and shallow lakes. Orangutans are the most arboreal of the great apes, spending nearly all of their time in the trees. Most of the day is spent feeding, resting, and moving between feeding and resting sites. They start the day feeding for 2–3 hours in the morning. They rest during midday followed by traveling in the late afternoon. When evening arrives, they begin to prepare their nest for the night. Tiger
Tiger
The tiger is the largest cat species, reaching a total body length of up to and weighing up to . Their most recognizable feature is a pattern of dark vertical stripes on reddish-orange fur with lighter underparts...

s are the major predatory threat to orangutans in Sumatra. Orangutans may also be preyed on by clouded leopards and crocodile
Crocodile
A crocodile is any species belonging to the family Crocodylidae . The term can also be used more loosely to include all extant members of the order Crocodilia: i.e...

s. The former can kill adolescents and small adult females but have not been recorded killing adult males. In Borneo, orangutans are not threatened by tigers and seem to descend to the ground more often than their Sumatran relatives. Orangutans do not swim, although least one population at a conservation refuge on Kaja island in Borneo have been photographed wading in deep water.

Diet

Fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

 makes up 65–90 percent of the orangutan diet. Fruits with sugary or fatty pulp are favored. Ficus
Ficus
Ficus is a genus of about 850 species of woody trees, shrubs, vines, epiphytes, and hemiepiphyte in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extending into the semi-warm temperate zone. The Common Fig Ficus is a genus of...

 fruits are commonly eaten, because they are easy to harvest and digest. Lowland dipterocarp
Dipterocarpaceae
Dipterocarpaceae is a family of 17 genera and approximately 500 species of mainly tropical lowland rainforest trees. The family name, from the type genus Dipterocarpus, is derived from Greek and refers to the two-winged fruit...

 forests are preferred by orangutans because of their plentiful fruit. Bornean orangutans consume at least 317 different food items that include young leaves, shoots, bark, insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s, honey
Honey
Honey is a sweet food made by bees using nectar from flowers. The variety produced by honey bees is the one most commonly referred to and is the type of honey collected by beekeepers and consumed by humans...

 and bird egg
Bird egg
Bird eggs are laid by females and incubated for a time that varies according to the species; a single young hatches from each egg. Average clutch sizes range from one to about 17...

s.

Orangutans are opportunistic forage
Forage
Forage is plant material eaten by grazing livestock.Historically the term forage has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animals, especially...

rs, and their diets vary markedly from month to month. Bark is eaten as a last resort in times of food scarcity; fruits are always more popular.

A decade-long study of urine and faecal samples at the Gunung Palung Orangutan Conservation Project in West Kalimantan
West Kalimantan
West Kalimantan is a province of Indonesia. It is one of four Indonesian provinces in Kalimantan, the Indonesian part of the island of Borneo. Its capital city Pontianak is located right on the Equator....

 has shown that orangutans give birth during and after the high fruit season (though not every year), during which they consume various abundant fruits, totalling up to 11,000 calories per day. In the low fruit season they eat whatever fruit is available in addition to tree bark and leaves, with daily intake at only 2,000 calories. Together with a long lactation
Lactation
Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process occurs in all female mammals, however it predates mammals. In humans the process of feeding milk is called breastfeeding or nursing...

 period, orangutans also have a long birth interval.

Orangutans are thought to be the sole fruit disperser for some plant species including the climber species Strychnos ignatii which contains the toxic alkaloid
Alkaloid
Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...

 strychnine
Strychnine
Strychnine is a highly toxic , colorless crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine causes muscular convulsions and eventually death through asphyxia or sheer exhaustion...

. It does not appear to have any effect on orangutans except for excessive saliva
Saliva
Saliva , referred to in various contexts as spit, spittle, drivel, drool, or slobber, is the watery substance produced in the mouths of humans and most other animals. Saliva is a component of oral fluid. In mammals, saliva is produced in and secreted from the three pairs of major salivary glands,...

 production.

Geophagy
Geophagy
Geophagy is the practice of eating earthy or soil-like substances such as clay, and chalk. It exists in animals in the wild and also in humans, most often in rural or preindustrial societies among children and pregnant women...

, the practice of eating soil or rock, has been observed in orangutans. There are three main reasons for this dietary behavior; for the addition of minerals nutrients to their diet; for the ingestion of clay minerals that can absorb toxic substances; or to treat a disorder such as diarrhea.

Orangutans use plants of the genus Commelina
Commelina
Commelina is a genus of approximately 170 species commonly called dayflowers due to the short lives of their flowers. They are less often known as widow's tears. It is by far the largest genus of its family, Commelinaceae...

 as an anti-inflammatory balm.

Social life

Orangutans live a more solitary lifestyle than the other great apes. Most social bonds occur between adult females and their dependent and weaned offspring. Adult males and independent adolescents of both sexes tend to live alone. The society of the orangutan is made up of resident and transient individuals of both sexes. Resident females live with their offspring in defined home ranges that overlap with those of other adult females, who may be their relatives like mothers and sisters. One to several resident female home ranges are encompassed within the home range of a resident male, who is their primary breeder. Transient males and females range broadly. They usually travel alone, but as sub-adults they may travel in small groups. However this behavior does not extend to adulthood. The social structure of the orangutan can be best described as solitary but social
Solitary but social
"Solitary but social" is a type of social organization where individuals forage separately, yet some individuals sleep in the same location or share nests. Female home ranges usually overlap while those of males do not. Males usually do not associate with other males, and male offspring are usually...

. As the ranges of males and females overlap, they commonly encounter each other while traveling and feeding and brief social interactions may occur. Interactions between adult females range from friendly, to avoidance to antagonistic. Resident males may have overlapping ranges and interactions between them tend to be hostile.

During dispersal, females tend to settle in home ranges that overlap with their mothers. However, they do not interact with them any more than the other females and they do not seem to form social bonds. Males disperse much farther from their mothers and enter into a transient phase. This phase lasts until a male can challenge and displace a dominant, resident male from his home range. There are dominance hierarchies between adult males that regularly encounter each other with the most dominant males being the largest and having the best body conditions. Adult males dominate sub-adult males. 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 benefit from social contacts. Orangutans will also form travelling groups in which members coordinate travel between food sources for a few days at a time. These groups tend to be made of only a few individuals. They also tend to be mating consortships, each made of an adult male and female traveling and mating.

Reproduction and parenting

Male orangutans exhibit arrested development. They mature at around 15 years of age by which they have fully descended testicles and can reproduce. However they do not develop the cheek pads, pronounced throat pouches, long fur or long-calls of more mature males until they gain a home range, which occurs when they are between 15 and 20 years old. These sub-adult males are known as unflanged males in contrast to the more developed flanged males. The transformation from unflanged to flanged can occur very quickly. Unflanged and flanged males have two different mating strategies. Flanged males use long calls to advertise their location which attract estrous females. Unflanged males wander widely in search of estrous females and upon finding one, will force copulation on her. Both strategies are successful, however females prefer to mate with flanged males and will seek them out for protection from unflanged males. Resident males may form consortships with females that can last days, weeks or months after copulation.
Female orangutans experience their first ovulatory cycle between 5.8 and 11.1 years. These occur earlier in larger females with more body fat than in thinner females. Like other great apes, female orangutans have a period of adolescent infertility which may last for 1–4 years. Female orangutans also have a 22-30 day menstrual cycle. Gestation lasts for nine months with females giving birth to their first offspring between 14 and 15 years old. Female orangutans have the longest interbirth intervals of the great apes, having eight years between births.

Male orangutans play almost no role in raising the young. Females are the primary caregivers for the young and are also instruments of socialization for them. A female often has more than one offspring with her, usually an adolescent and an infant, and the older of them can also help in socializing their younger sibling. Infant orangutans are completely dependent on their mothers for the first two years of their lives. The mother will carry the infant during traveling, as well as feed it and sleep with it in the same night nest. The infant doesn’t even break physical contact with its mother for the first four months and is carried on her belly. The amount of physical contact soon wanes in the following months. When an orangutan reaches the age of two, its climbing skills are more developed and will hold the hand of another orangutan while moving through the canopy, a behavior known as "buddy travel". Orangutans are juveniles from about two to five years of age and start to exploratory trips from their mothers. Juveniles are usually weaned at about four years of age. Adolescent orangutans seek peers and play and travel with peer groups while still having contact with their mothers. Infanticide
Infanticide (zoology)
In animals, infanticide involves the killing of young offspring by a mature animal of its own species, and is studied in zoology, specifically in the field of ethology. Ovicide is the analogous destruction of eggs. Although human infanticide has been widely studied, the practice has been observed...

 has not been recorded in the two orangutan species like it has in other primate species. Paternity uncertainty, the range patterns of female dispersals and the fact that the ovulation of females depends on food availability may make infanticide by males ineffective.

Tool use and culture

Like the other great apes, orangutans are among the most intelligent primates. Wild chimpanzee
Chimpanzee
Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...

s have been known since the 1960s to use tools. Tool use in orangutans was observed by Birutė Galdikas
Birute Galdikas
Birutė Marija Filomena Galdikas, OC , is a primatologist, conservationist, ethologist, and author of several books relating to the endangered orangutan, particularly the Bornean orangutan. Well known in the field of modern primatology, Galdikas is recognized as a leading authority on orangutans...

 in ex-captive populations.

Evidence of sophisticated tool manufacture and use in the wild was reported from a population of orangutans in Suaq Balimbing (Pongo pygmaeus abelii) in 1996. These orangutans developed a tool kit for use in foraging that consisted of insect-extraction tools for use in the hollows of trees, and seed-extraction tools which were used in harvesting seeds from hard-husked fruit. The orangutans adjusted their tools according to the nature of the task at hand and preference was given to oral tool use. This preference was also found in an experimental study of captive orangutans (P. pygmaeus).

Carel P. van Schaik from the University of Zurich
University of Zurich
The University of Zurich , located in the city of Zurich, is the largest university in Switzerland, with over 25,000 students. It was founded in 1833 from the existing colleges of theology, law, medicine and a new faculty of philosophy....

 and Cheryl D. Knott from Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...

 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 (P. abelii) were found to be avid users of insect and seed-extraction tools when compared to other wild orangutans. The scientists suggested that these differences are cultural. The orangutans at Suaq Balimbing live in dense groups and are socially tolerant; this creates good conditions for social transmission. Further evidence that highly social orangutans are more likely to exhibit cultural behaviors came from a study of leaf-carrying behaviors of ex-captive orangutans that were being rehabilitated on the island of Kaja in Borneo. The above evidence is consistent with the existence of orangutan culture as geographically distinct behavioral variants which are maintained and transmitted in a population through social learning.

In 2003, researchers from six different orangutan field sites who used the same behavioral coding scheme compared the behaviors of the animals from the different sites. They found that the different orangutan populations behaved differently. The evidence suggested that the differences in behavior were cultural: first, because the extent of the differences increased with distance, suggesting that cultural diffusion was occurring, and second, because the size of the orangutans’ cultural repertoire increased according to the amount of social contact present within the group. Social contact facilitates cultural transmission. Carel P. van Schaik suggests that young orangutans (P. abelii) acquire tool use skills and cultural behaviors by observing and copying older orangutans.

Orangutans do not limit their tool use to foraging, displaying or nest-building activities. Wild orangutans (P. pygmaeus wurmbii) in Tuanan, Borneo, were reported to use tools in acoustic communication. They use leaves to amplify the kiss squeak sounds that they produce. Some have suggested that the apes employ this method of amplification in order to deceive the listener into believing that they are larger animals.

Communication

As noted above, flanged males will emit a long call which is used to attract females but also to alert other males to their presence. It is possible that the long calls suppress development in younger males.
A two year study of orangutan symbolic capability was conducted from 1973-1975 by Gary L. Shapiro with Aazk, a juvenile female orangutan at the Fresno City Zoo (now Chaffee Zoo) in Fresno, California. The study employed the techniques of David Premack
David Premack
David Premack is currently emeritus professor of psychology at the University of Pennsylvania. He was educated at the University of Minnesota when logical positivism was in full bloom. The departments of Psychology and Philosophy were closely allied...

 who used plastic tokens to teach the chimpanzee, Sarah
Sarah (chimpanzee)
Sarah is an enculturated research chimpanzee whose cognitive skills are documented in The Mind of an Ape, by David Premack and Ann James Premack . Sarah was one of nine chimpanzees in David Premack's psychology laboratory in Pennsylvania. Sarah was born in Africa in 1962. She first worked in...

, linguistic skills. Shapiro continued to examine the linguistic and learning abilities of ex-captive orangutans in Tanjung Puting National Park, in Indonesian Borneo, between 1978 and 1980. During that time, Shapiro instructed ex-captive orangutans in the acquisition and use of signs following the techniques of R. Allen and Beatrix Gardner who taught the chimpanzee, Washoe
Washoe (chimpanzee)
Washoe was a chimpanzee who was the first non-human to learn to communicate using American Sign Language, as part of a research experiment on animal language acquisition....

, in the late-1960s. In the only signing study ever conducted in a great ape's natural environment, Shapiro home-reared Princess, a juvenile female who learned nearly 40 signs (according to the criteria of sign acquisition used by Francine Patterson with Koko
Koko (gorilla)
Koko is a female western lowland gorilla who, according to Francine "Penny" Patterson, is able to understand more than 1,000 signs based on American Sign Language, and understand approximately 2,000 words of spoken English....

, the gorilla) and trained Rinnie, a free-ranging adult female orangutan who learned nearly 30 signs over a two year period. For his dissertation
study, Shapiro examined the factors influencing sign learning by four juvenile orangutans over a 15-month period.

The first orangutan language study program, directed by Dr. Francine Neago
Francine Neago
Dr. Francine Neago is a primatologist and conservationist specializing in orangutans. In addition to her internationally televised films about orangutans she has lectured worldwide and published several scientific papers in the Journal of Primatology .At UCLA she developed a computer system in...

, was listed by Encyclopædia Britannica in 1988. The Orangutan language project at the Smithsonian National Zoo
Smithsonian National Zoological Park
The Smithsonian National Zoological Park, commonly known as the National Zoo, is one of the oldest zoos in the United States, and as part of the Smithsonian Institution, does not charge admission. Founded in 1889, its mission is to provide leadership in animal care, science, education,...

 in Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

, uses a computer system originally developed at UCLA
University of California, Los Angeles
The University of California, Los Angeles is a public research university located in the Westwood neighborhood of Los Angeles, California, USA. It was founded in 1919 as the "Southern Branch" of the University of California and is the second oldest of the ten campuses...

 by Neago in conjunction with IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

.

Zoo Atlanta has a touch screen computer where their two Sumatran Orangutans play games. Scientists hope that the data they collect from this will help researchers learn about socializing patterns, such as whether they mimic others or learn behavior from trial and error, and hope the data can point to new conservation strategies.

A 2008 study of two orangutans at the Leipzig Zoo showed that orangutans are the first non-human species documented to use 'calculated reciprocity' which involves weighing the costs and benefits of gift exchanges and keeping track of these over time.

Orangutans, along with chimpanzee
Chimpanzee
Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...

s, gorillas, and other apes, have even shown laughter-like vocalizations in response to physical contact, such as wrestling, play chasing, or tickling.

Sexual interest in humans

Male orangutans have been known to display sexual attaction to human women to the point of rape
Rape
Rape is a type of sexual assault usually involving sexual intercourse, which is initiated by one or more persons against another person without that person's consent. The act may be carried out by physical force, coercion, abuse of authority or with a person who is incapable of valid consent. The...

. The cook of noted primatologist Birutė Galdikas
Birute Galdikas
Birutė Marija Filomena Galdikas, OC , is a primatologist, conservationist, ethologist, and author of several books relating to the endangered orangutan, particularly the Bornean orangutan. Well known in the field of modern primatology, Galdikas is recognized as a leading authority on orangutans...

 was raped by an orangutan. An orangutan tried to have sex with actress Julia Roberts
Julia Roberts
Julia Fiona Roberts is an American actress. She became a Hollywood star after headlining the romantic comedy Pretty Woman , which grossed $464 million worldwide...

 but was prevented by a film crew.

Conservation status

The Sumatran species is critically endangered and the Bornean species of orangutans is endangered
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 according to the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

 of mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s, and both are listed on Appendix I of CITES.
The total number of Bornean orangutans is estimated to be less than 14% of what it was in the recent past (from around 10,000 years ago until the middle of the twentieth century) and this sharp decline has occurred mostly over the past few decades due to human activities and development. Species distribution is now highly patchy throughout Borneo: it is apparently absent or uncommon in the south-east of the island, as well as in the forests between the Rejang River in central Sarawak
Sarawak
Sarawak is one of two Malaysian states on the island of Borneo. Known as Bumi Kenyalang , Sarawak is situated on the north-west of the island. It is the largest state in Malaysia followed by Sabah, the second largest state located to the North- East.The administrative capital is Kuching, which...

 and the Padas River in western Sabah
Sabah
Sabah is one of 13 member states of Malaysia. It is located on the northern portion of the island of Borneo. It is the second largest state in the country after Sarawak, which it borders on its southwest. It also shares a border with the province of East Kalimantan of Indonesia in the south...

 (including the Sultanate of Brunei
Brunei
Brunei , officially the State of Brunei Darussalam or the Nation of Brunei, the Abode of Peace , is a sovereign state located on the north coast of the island of Borneo, in Southeast Asia...

). The largest remaining population is found in the forest around the Sabangau River, but this environment is at risk. A similar development have been observed for the Sumatran orangutans.

A 2007 study by the Government of Indonesia noted in 2004 it was estimated that there was a total wild population of 61,234 orangutans, 54,567 of which were found on the island of Borneo. The table below shows a breakdown of the species and subspecies and their estimated populations from the report:
Scientific
name
Common
name
Region Estimated
number
Pongo abelii Sumatran Orangutan
Sumatran Orangutan
The Sumatran orangutan is one of the two species of orangutans. Found only on the island of Sumatra, in Indonesia, it is rarer and smaller than the Bornean orangutan. The Sumatran orangutan grows to about tall and in males...

Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...

6,667
Pongo pygmaeus Bornean Orangutan
Bornean Orangutan
The Bornean orangutan, Pongo pygmaeus, is a species of orangutan native to the island of Borneo. Together with the slightly smaller Sumatran orangutan, it belongs to the only genus of great apes native to Asia....

Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....

P. p. morio Northeast Bornean Orangutan Sabah
Sabah
Sabah is one of 13 member states of Malaysia. It is located on the northern portion of the island of Borneo. It is the second largest state in the country after Sarawak, which it borders on its southwest. It also shares a border with the province of East Kalimantan of Indonesia in the south...

11,017
P. p. morio Northeast Bornean Orangutan East Kalimantan
East Kalimantan
East Kalimantan is the second largest Indonesian province, located on the Kalimantan region on the east of Borneo island. The resource-rich province has two major cities, Samarinda and Balikpapan...

4,825
P. p. wurmbii Central Bornean Orangutan Central Kalimantan
Central Kalimantan
Central Kalimantan is a province of Indonesia, one of four in Kalimantan - the Indonesian part of the island of Borneo. Its provincial capital is Palangka Raya.The province has a population of just over 2.2 million at the 2010 Census...

>31,300
P. p. pygmaeus Northwest Bornean Orangutan West Kalimantan
West Kalimantan
West Kalimantan is a province of Indonesia. It is one of four Indonesian provinces in Kalimantan, the Indonesian part of the island of Borneo. Its capital city Pontianak is located right on the Equator....

 and Sarawak
Sarawak
Sarawak is one of two Malaysian states on the island of Borneo. Known as Bumi Kenyalang , Sarawak is situated on the north-west of the island. It is the largest state in Malaysia followed by Sabah, the second largest state located to the North- East.The administrative capital is Kuching, which...

7,425

This indicates a decline from some estimates between 2000 and 2003 which found 7,300 Sumatran Orangutan individuals in the wild and between 45,000 and 69,000 Bornean Orangutans. Thousands of orangutans don't reach adulthood due to human disruption. Orangutans are killed for food while others are killed because of disruption in people's property. Mother orangutans are killed so their infants can be sold as pets. Many of the infants die without the help of their mother. Since recent trends are steeply down in most places due to logging and burning, it is forecast that the current numbers are below these figures.

Orangutan habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...

 due to logging
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...

, mining
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 and forest fires, as well as fragmentation by roads, has been increasing rapidly in the last decade. A major factor in that period of time has been the conversion of vast areas of tropical forest to oil palm
Oil palm
The oil palms comprise two species of the Arecaceae, or palm family. They are used in commercial agriculture in the production of palm oil. The African Oil Palm Elaeis guineensis is native to West Africa, occurring between Angola and Gambia, while the American Oil Palm Elaeis oleifera is native to...

 plantation
Plantation
A plantation is a long artificially established forest, farm or estate, where crops are grown for sale, often in distant markets rather than for local on-site consumption...

s in response to international demand (the palm oil
Palm oil
Palm oil, coconut oil and palm kernel oil are edible plant oils derived from the fruits of palm trees. Palm oil is extracted from the pulp of the fruit of the oil palm Elaeis guineensis; palm kernel oil is derived from the kernel of the oil palm and coconut oil is derived from the kernel of the...

 is used for cooking, cosmetics, mechanics, and more recently as source of biodiesel
Biodiesel
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl esters. Biodiesel is typically made by chemically reacting lipids with an alcohol....

). Some UN scientists believe that these plantations could lead to irreparable damage to orangutan habitat by the year 2012. Some of this activity is illegal, occurring in national parks that are officially off limits to loggers, miners and plantation development. There is also a major problem with hunting and illegal pet trade. In early 2004 about 100 individuals of Bornean origin were confiscated in Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

 and 50 of them were returned to Kalimantan
Kalimantan
In English, the term Kalimantan refers to the Indonesian portion of the island of Borneo, while in Indonesian, the term "Kalimantan" refers to the whole island of Borneo....

 in 2006. Several hundred Bornean orangutan orphans who were confiscated by local authorities have been entrusted to different orphanages in both Malaysia and Indonesia. They are in the process of being rehabilitated into the wild.
Besides preserved animal and bones of Orangutan, Orangutan skulls have also trade silently in souvenir shops in several cities in Kalimantan
Kalimantan
In English, the term Kalimantan refers to the Indonesian portion of the island of Borneo, while in Indonesian, the term "Kalimantan" refers to the whole island of Borneo....

, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

 with price between Rp.500,000 ($58.8) to Rp.2 million ($235) per skull.

Conservation centres and organisations

A number of organisations are working for the rescue, rehabilitation and reintroduction of orangutans. The largest of these is the Borneo Orangutan Survival
Borneo Orangutan Survival
The Borneo Orangutan Survival Foundation is an Indonesian non-profit NGO founded by Dr Willie Smits in 1991 and dedicated to the conservation of the endangered Bornean Orangutan and its habitat through the involvement of local people...

 Foundation, founded by Dr. Willie Smits
Willie Smits
Willie Smits is a trained forester, a microbiologist, conservationist, animal rights activist and social entrepreneur...

, which employs between six hundred and a thousand people at a hundred sites. It operates a number of large projects, including the Samboja Lestari
Samboja Lestari
Samboja Lestari is an area of restored tropical rainforest near the city of Balikpapan in East Kalimantan, Borneo, Indonesia, created by the Borneo Orangutan Survival Foundation led by Dr Willie Smits, with the aim of providing a safe haven for rehabilitated orangutans while at the same time...

 Forest Rehabilitation Program and the Nyaru Menteng Rehabilitation Program managed by Lone Drøscher Nielsen.
Other major conservation centres in Indonesia include those at Tanjung Puting National Park and Sebangau National Park in Central Kalimantan
Central Kalimantan
Central Kalimantan is a province of Indonesia, one of four in Kalimantan - the Indonesian part of the island of Borneo. Its provincial capital is Palangka Raya.The province has a population of just over 2.2 million at the 2010 Census...

, Kutai
Kutai
Kutai is the traditional name of a historic region in East Kalimantan in Indonesia on Borneo, a Dayak people of the region with a language of the same name and their historic states. Today the name is preserved in the names of three regencies in East Kalimantan, the Kutai Kartanegara Regency, the...

 in East Kalimantan
East Kalimantan
East Kalimantan is the second largest Indonesian province, located on the Kalimantan region on the east of Borneo island. The resource-rich province has two major cities, Samarinda and Balikpapan...

, Gunung Palung National Park
Gunung Palung National Park
Gunung Palung National Park lies on the island of Borneo, in the Indonesian province of West Kalimantan, north of Ketapang and east of Sukadana.- Geography:...

 in West Kalimantan
West Kalimantan
West Kalimantan is a province of Indonesia. It is one of four Indonesian provinces in Kalimantan, the Indonesian part of the island of Borneo. Its capital city Pontianak is located right on the Equator....

, and Bukit Lawang
Bukit Lawang
Bukit Lawang is a small tourist village at the bank of Bahorok River in North Sumatra province of Indonesia. Situated approximately 86 km north-west of Medan, Bukit Lawang is known for the largest animal sanctuary of Sumatran orangutan , and also the main access point to the Gunung Leuser National...

 in the Gunung Leuser National Park
Gunung Leuser National Park
Gunung Leuser National Park is a national park covering 7,927 km² in northern Sumatra, Indonesia, straddling the border of North Sumatra and Aceh provinces. The national park, named after Mount Leuser , protects a wide range of ecosystems. An orangutan sanctuary of Bukit Lawang is located inside...

 on the border of Aceh
Aceh
Aceh is a special region of Indonesia, located on the northern tip of the island of Sumatra. Its full name is Daerah Istimewa Aceh , Nanggroë Aceh Darussalam and Aceh . Past spellings of its name include Acheh, Atjeh and Achin...

 and North Sumatra
North Sumatra
North Sumatra is a province of Indonesia on the Sumatra island. Its capital is Medan. It is the most populous Indonesian province outside of Java. It is slightly larger than Sri Lanka in area.- Geography and population :...

. In Malaysia, conservation areas include Semenggoh Wildlife Centre in Sarawak
Sarawak
Sarawak is one of two Malaysian states on the island of Borneo. Known as Bumi Kenyalang , Sarawak is situated on the north-west of the island. It is the largest state in Malaysia followed by Sabah, the second largest state located to the North- East.The administrative capital is Kuching, which...

 and Matang Wildlife Centre also in Sarawak
Sarawak
Sarawak is one of two Malaysian states on the island of Borneo. Known as Bumi Kenyalang , Sarawak is situated on the north-west of the island. It is the largest state in Malaysia followed by Sabah, the second largest state located to the North- East.The administrative capital is Kuching, which...

, and the Sepilok Orang Utan Sanctuary
Sepilok Orang Utan Sanctuary
Sepilok Orang Utan Rehabilitation Centre is located about 25 kilometers west of Sandakan in the state of Sabah, East Malaysia.The centre opened in 1964 as the first official orangutan rehabilitation project for rescued orphaned baby orangutans from logging sites, plantations, illegal hunting or...

 near Sandakan
Sandakan
Sandakan is the second-largest city in Sabah, East Malaysia, on the north-eastern coast of Borneo. It is located on the east coast of the island and it is the administrative centre of Sandakan Division and was the former capital of British North Borneo...

 in Sabah
Sabah
Sabah is one of 13 member states of Malaysia. It is located on the northern portion of the island of Borneo. It is the second largest state in the country after Sarawak, which it borders on its southwest. It also shares a border with the province of East Kalimantan of Indonesia in the south...

.

Genomics

Orangutans have 48 diploid chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...

s, and its genome was sequenced in January 2011. Following human
Human
Humans are the only living species in the Homo genus...

s and chimpanzee
Chimpanzee
Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...

s, the Sumatran orangutan has become the third species of hominid to have its genome sequenced. The draft of the genome sequence is based on a captive female named Susie.

The researchers also published less complete copies from ten wild orangutans, five from Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....

 and five from Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...

. It was found that genetic diversity
Genetic diversity
Genetic diversity, the level of biodiversity, refers to the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary....

 was lower in Bornean orangutans (Pongo pygmaeus) than in Sumatran ones (Pongo abelii), despite the fact that Borneo is home to six or seven times as many orangutans as Sumatra. The comparison has shown that these two species diverged around 400,000 years ago, more recently than was previously thought. It was also found that the orangutan genome has evolved much more slowly than chimpanzee and human DNA.

The researchers hope that these data may help conservationists save the endangered ape, and also prove useful in further understanding of human genetic diseases.

See also

  • Australian Orangutan Project
    Australian Orangutan Project
    The Australian Orangutan Project is a non-profit registered Australian environmental organisation established in 1998, which raises funds to support the conservation and protection of orangutans and the preservation and rehabilitation of their forest habitats, which are primarily located in...

     (AOP)
  • Borneo peat swamp forests
    Borneo peat swamp forests
    The Borneo peat swamp forests ecoregion, within the Tropical and subtropical moist broadleaf forests Biome, are on the island of Borneo, which is divided between Brunei, Indonesia and Malaysia.-Location and description:...

  • Chantek
    Chantek
    Chantek is a male orangutan raised by anthropologist Lyn Miles at the University of Tennessee at Chattanooga.-See also:* Abang * Great ape language...

  • Human evolutionary genetics
    Human evolutionary genetics
    Human evolutionary genetics studies how one human genome differs from the other, the evolutionary past that gave rise to it, and its current effects. Differences between genomes have anthropological, medical and forensic implications and applications...

     – more information on the speciation of humans and great apes
  • List of apes
  • List of fictional apes
  • List of solitary animals
  • Orang Pendek
    Orang Pendek
    Orang Pendek is the most common name given to a cryptid, or cryptozoological animal, that reportedly inhabits remote, mountainous forests on the island of Sumatra....

  • Orangutans in popular culture
    Orangutans in popular culture
    Orangutans, two species of great apes indigenous to Indonesia and Malaysia, have been the subject of multiple popular culture references.-Famous orangutans:*Ah Meng , Sumatran Orangutan of Singapore...



External links

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