In a Malay dialect, orangutan means “man of the forest”. Red-haired primates are unique among mammals in many ways, from their biology to their behavior. Here are 12 facts about these amazing monkeys.
1. Orangutans are native to Southeast Asia.
Orangutans live in the tropical rainforests of Sumatra and Borneo and are the only great apes in Asia (besides Homo sapiens). There are three known species of orangutans: the Sumatra (Pongo abelii), Borneo (Pygmy pongo) and Tapanuli (Pongo tapanuliensis). The latter was not officially described as a separate species until 2017.
2. Orangutans are the largest tree mammals on Earth.
Orangutans are arboreal and spend about 95% of their time in the canopy of trees. They eat, drink, rest and sleep in the trees. Like other great apes, they build a new nest of branches and twigs in the canopy to sleep in each night, putting them out of reach of predators. They even make their nests cozy with a soft layer of leaves or place a large sling over their heads for protection from the rain.
3. Female orangutans breed about once every eight years.
Orangutans have the longest birth interval of any land mammal. Their babies then breastfeed for up to eight years, longer than any mammal, and can reach their preteen before they live independently from their mothers and reach sexual maturity. Orangutans can live 40 to 50 years in the wild and 60 years in captivity [PDF].
4. An orangutan’s arms are longer than its legs.
Orangutans are perfectly evolved for life in the treetops. Large males can have an arm span of over six feet, which is more than Tom Hanks is tall. Their upper limbs allow them to swing effortlessly among the branches, which they grip with their hands and feet, a method called quadrumane scrambling.
5. Orangutans are very sexually dimorphic.
Like many animals (including humans), male and female orangutans have significantly different physical traits. Adult male orangutans are about 4.5 feet tall and weigh between 130 and 200 pounds; adult females are 4 feet tall and weigh around 90 to 110 pounds [PDF]. Mature males have huge, flat cheek pads, called frills, and have larger throat sacs than females. The bags amplify the “long calls” of the males to woo the females, which can be heard for more than a mile. While both sexes can wear a beard, men’s beards are generally more pronounced and can include mustaches.
6. Orangutans eat a lot of fruit.
Monkeys build body mass on a diet consisting primarily of fruits, although they will eat nuts, leaves, bark, and sometimes insects or a bird’s egg. According to the San Diego Zoo, orangutans can eat more than 500 kinds of fruit, with figs and durians the most commonly eaten. Other fruits commonly eaten are lychees, mangoes and mangosteen.
7. Orangutans and humans share 97% of their DNA.
This makes orangutans, descended from their common lineage with humans about 13 million years ago, our most distant relatives among the great apes. Our closest relatives, chimpanzees and bonobos, share 98.7% with us (and 99.6% of their DNA with each other). Gorillas and humans share 98% of their DNA.
8. Orangutans are incredibly intelligent.
Orangutans use tools to forage for food in the wild and are able to observe and then mimic human behavior, such as using hammers and saws, washing clothes, and rowing a canoe. They can also master man-made technology. In the 1960s, a captive orangutan named Fu Manchu kept escaping from his enclosure at the Omaha Zoo in Nebraska; he had learned to pick the lock with a piece of thread.
9. An orangutan was legally considered to be a “non-human person”.
In 2014, lawyers in Buenos Aires, Argentina argued that an orangutan named Sandra at a local zoo was illegally detained and abused. A judge ruled the monkey has a right to basic human rights, such as the right to live free from physical or psychological harm, and should no longer be kept at the zoo. Sandra eventually went to live in a great ape sanctuary in Florida.
10. All three orangutan species are critically endangered.
The main threat to orangutans is habitat loss due to logging, both legal and otherwise; and forest clearing for oil palm plantations and the timber, mining, housing and tourism industries. Tree clearing, especially by fire which can rage uncontrollably, often leaves orangutans orphaned or dead. Conservation measures for orangutans include national and international protection laws, improving the enforcement of existing protections, preserving forests, and reintroducing captive-bred orangutans to the wild.