Locations - Where orangutans live
ORANGUTAN GEOGRAPHICAL RANGE
Orangutans are now found only on the islands of Borneo and Sumatra with the Sumatran species limited to the northern part of the island. Sumatran orangutans are fragmented into 9 separate populations, all of which are located in the Indonesian provinces of Aceh and North Sumatra. Bornean orangutans are much more widely distributed and are found in Kalimantan, Sabah, and Sarawak. No permanent orangutan populations have been reported from Brunei.
Orangutans on both islands primarily inhabit peat swamp forests, tropical heath forests, and mixed dipterocarp forests at altitudes of less than 1,000 meters (3,281 feet) above sea level. Orangutan population density has been shown to correlate positively with the level of fruit availability. This means that in forests where a higher abundance of fruit and fewer or less drastic periods of seasonal fruit shortages occur, orangutans are found to live at much higher densities than in other forests. Generally speaking,since Sumatran forests seem more productive than forests in Borneo, Sumatran orangutan populations are denser than Bornean orangutan populations. Orangutans living in peat swamp forests live at higher densities than in other forest types
HISTORY - WHERE DID THEY ORIGINATE?
It is believed that orangutans ranged throughout Southeast Asia all the way into southern China. They were also once found on the island of Java.
Their precise origin is not agreed on however some believe that they originated from Lufengpithecus (a genus of extinct ape found in fossils in Yunnan province, China) while other maintain that they originated from Sivapithecus (another extinct ape whose fossils have been found in the Siwalik hills of Nepal, India and Pakistan).
A third theory is that the orangutan was related to the Lufengpithecus chiangmuanensis (fossils discovered in Thailand in 2002 dating back 10 to 13.5 million years ago). The discovery consists of both an upper and lower jaw with similar dental structure as today's orangutan and they consider it to be an ancestor of the new form. This discovery would place the development of the earlier orangutan in a similar habitat as today's tropical forest home on Sumatra and Borneo. More fossils need to be found and studied to complete the picture of its evolutionary history.
Fossils from a million years ago indicate that there were giant sized orangutans in Indochina. Fossils from 40,000 years ago, found on Borneo and Sumatra, show the orangutan as 30% larger than today's species. It is conjectured that early orangutans may have been more terrestrial than today's species. However what we see today is a species that has been arboreal (tree dwelling) for a very long time and has completely adapted physically.