page_title: Orangutan
section_title: Taxonomy and phylogeny
hierarchical_section_title: Orangutan / Taxonomy and phylogeny
caption_attribution_description: English: Various orangutan species: 1. Bornean, 2. Sumatran, 3. Tapanuli
context_page_description: Orangutans are great apes native to Indonesia and Malaysia. They are found in the rainforests of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genus Pongo, orangutans were originally considered to be one species. From 1996, they were divided into two species: the Bornean orangutan and the Sumatran orangutan. In 2017, a third species, the Tapanuli orangutan, was identified. The orangutans are the only surviving species of the subfamily Ponginae, who split from humans, chimpanzees and gorillas 19.3 to 15.7 million years ago.
  The most arboreal of the great apes, orangutans spend most of their time in trees. They have proportionally long arms and short legs and their hair is reddish-brown. Adult males may develop distinctive cheek pads or flanges and make long calls that attract females and intimidate rivals; younger males do not and resemble adult females. Orangutans are the most solitary of the great apes, social bonds occurring primarily between mothers and their dependent offspring, who remain together for the first two years.
context_section_description: The orangutan was first described scientifically in 1758 in the Systema Naturae of Carl Linnaeus as Simia satyrus. It was renamed Simia pygmaeus in 1760 by his student Christian Emmanuel Hopp and given the name Pongo by Lacépède in 1799. The populations on the two islands were suggested to be separate species when P. abelii was described by French naturalist René Lesson in 1827. In 2001, P. abelii was confirmed as a full species based on molecular evidence published in 1996, and three distinct populations on Borneo were elevated to subspecies (P. p. pygmaeus, P. p. morio and P. p. wurmbii). The description in 2017 of a third species, P. tapanuliensis, from Sumatra south of Lake Toba, came with a surprising twist: it is more closely related to the Bornean species, P. pygmaeus than to its fellow Sumatran species, P. abelii.
  The Sumatran orangutan genome was sequenced in January 2011. Following humans and chimpanzees, the Sumatran orangutan became the third species of great ape to have its genome sequenced. Subsequently, the Bornean species had its genome sequenced. Genetic diversity was found to be lower in Bornean orangutans (P. pygmaeus) than in Sumatran ones (P. abelii), despite the fact that Borneo is home to six or seven times as many orangutans as Sumatra. The researchers hope these data may help conservationists save the endangered ape, and also prove useful in further understanding of human genetic diseases. Similarly to gorillas and chimpanzees, orangutans have 48 diploid chromosomes, in contrast to humans, which have 46.
  Within apes (superfamily Hominoidea), the gibbons diverged during the early Miocene (between 24.1 and 19.7 mya, according to molecular evidence) and the orangutans split 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 Borean species diverged 4.9 to 2.9 mya. By contrast, the 2011 genome study suggested that these two species diverged around 400,000 years ago, more recently than was previously thought. Also, the orangutan genome was found to have evolved much more slowly than chimpanzee and human DNA. 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. Orangutans travelled from Sumatra to Borneo as the islands were connected by land bridges as parts of Sundaland during 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.
caption: Flanged male Bornean, Sumatran and Tapanuli orangutans
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