Orangutans are the only exclusively Asian genus of extant great ape. The largest living arboreal animals, they have proportionally longer arms than the other, more terrestrial, great apes. They are among the most intelligent primates 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 and Malaysia, orangutans are currently found only in rainforests on the islands of Borneo and Sumatra, though fossils have been found in Java, the Thai-Malay Peninsula, Vietnam and Mainland China. There are only two surviving species, both of which are endangered: the Bornean Orangutan (Pongo pygmaeus) and the critically endangered Sumatran Orangutan (Pongo abelii). The word "orangutan" comes from the Malay words "orang" (man) and "(h)utan" (forest); hence, "man of the forest".
The two orangutan species are the only extant members of the subfamily Ponginae. This subfamily also included the extinct genera Lufengpithecus, which lived in southern China and Thailand 2–8 million years ago (mya), and Sivapithecus, which lived India and Pakistan 12.5–8.5 mya. These apes likely lived in drier and cooler enviroments then orangutans do today. It is Khoratpithecus piriyai, which lived in Thailand 7–5 mya, that is believed to have been the closest known relative of the orangutans. Another notable member of Ponginae was Gigantopithecus, which lived in China, India and Vietnam 5 million to 100,000 years ago. It was the largest known primate. The orangutans likely split off from gorillas, chimpanzees and humans around 11–14 mya.
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