10 Fascinating Facts About Orangutans

A baby orangutan in a forest
A baby orangutan in a forest / KiltedArab/iStock via Getty Images

In a Malay dialect, orangutan means “man of the forest.” The ginger-haired primates are unique among mammals in many ways, from their biology to their behavior. Here are 12 facts about these amazing apes.

1. Orangutans are native to Southeast Asia.

Orangutans live in the rainforests of Sumatra and Borneo and are the only Asian great ape (besides Homo sapiens). There are three known species of orangutan: the Sumatran (Pongo abelii), Bornean (Pongo pygmaeus), and Tapanuli (Pongo tapanuliensis). The last one was officially described as a separate species only in 2017.

2. Orangutans are the largest tree-dwelling mammals on Earth.

An orangutan mom and baby, just hangin'
An orangutan mom and baby, just hangin' / Donyanedomam/iStock via Getty Images

Orangutans are arboreal and spend about 95 percent of their time in the tree canopy. They eat, drink, rest, and sleep in trees. Like other great apes, they build a new nest of branches and twigs up in the canopy to sleep in every night, which keeps them out of the reach of predators. They even make their nests comfy with a soft layer of leaves or place a large frond overhead to keep off the rain.

3. Female orangutans reproduce about once every eight years.

Orangutans have the longest interval between births of any terrestrial mammal. Their babies then nurse for up to eight years, longer than any mammal, and can reach their tweens before living independently of their mothers and reaching 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. Big males can have an arm span of over six feet—longer than Tom Hanks is tall. Their upper limbs allow them to swing effortlessly among branches, which they grasp with their hands and feet, a method called quadrumanous scrambling.

5. Orangutans are highly sexually dimorphic.

Male orangutans develop large cheek pads called flanges.
Male orangutans develop large cheek pads called flanges. / Freder/iStock via Getty Images

Like many animals (including humans), orangutan males and females have noticeably different physical traits. Adult male orangutans stand roughly 4.5 feet tall and weigh between 130 and 200 pounds; adult females are 4 feet tall and weigh about 90 to 110 pounds [PDF]. Mature males grow huge, flat cheek pads, called flanges, and have larger throat sacs than females. The sacs amplify males’ “long calls” to woo females, which can be heard for more than a mile. While both sexes can sport a beard, males’ beards are usually more pronounced and might include mustaches.

6. Orangutans eat a lot of fruit.

The apes build up their body mass on a diet of mostly fruit, though they’ll eat nuts, leaves, bark, and sometimes insects or a bird egg. According to the San Diego Zoo, orangutans may eat more than 500 kinds of fruit, with figs and durians the most often consumed. Other commonly eaten fruits include lychees, mangoes, and mangosteens.

7. Orangutans and humans share 97 percent of their DNA.

That makes orangutans, which branched off 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 percent with us (and 99.6 percent of their DNA with each other). Gorillas and humans share 98 percent of their DNA.

8. Orangutans are incredibly smart.

Orangutans know what's up.
Orangutans know what's up. / Zocha_K/iStock via Getty Images

Orangutans use tools to forage for food in the wild, and are capable of observing and then imitating human behavior, such as using hammers and saws, washing clothes, and rowing a canoe. They can also master human-devised technology. In the 1960s, a captive orangutan named Fu Manchu kept escaping his enclosure at the Omaha Zoo in Nebraska; he had learned to pick the lock with a piece of wire.

9. An orangutan was legally ruled a “non-human person.”

In 2014, lawyers in Buenos Aires, Argentina, argued that an orangutan named Sandra at a local zoo was being illegally detained and mistreated. A judge ruled that the ape was entitled to the basic rights of personhood, 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 at a great ape sanctuary in Florida.

10. All three species of orangutan are critically endangered.

The main threat to orangutans is habitat loss from logging, both legal and otherwise; and from clearing forests for palm oil plantations and the timber, mining, housing, and tourism industries. Clearing the trees, especially through fire that can rage out of control, often leaves orangutans orphaned or dead. Conservation measures for orangutans include national and international protection laws, improving the enforcement of existing protections, forest preservation, and reintroducing captive-bred orangutans to the wild.