Orangutans are the only great apes that did not originate in Africa. These large primates are indigenous to Asia, where there are two species. The Bornean orangutan (Pongo pygmaeus) is located on the island of Borneo, which is divided among three different countries: Brunei, Indonesia, and Malaysia. This orangutan has also been divided into three subspecies: Northwest Bornean orangutan (P. p. pygmaeus), Central Bornean orangutan (P. p. wurmbii), and Northeast Bornean orangutan (P. p. morio). The second species is the Sumatran orangutan (Pongo abelii) which can be found on the island of Sumatra.
The Bornean orangutan is the largest of the two orangutan species, weighing up to 100 kg (220 lbs). Sumatran orangutans are slightly smaller, with a weight up to 90 kgs (200 lbs). Female orangutans are notably smaller than males with an average maximum weight of 50 kgs (110 lbs).
Orangutans are the only great ape species that spend the majority of their time in trees. However, when they do descend to the ground they are not knuckle-walkers like chimpanzees and gorillas; instead, they are fist-walkers. The key difference between knuckle-walking and fist-walking is how the weight of the body is distributed by the supporting hand. Knuckle-walkers touch the surface of the ground with the middle phalanges, or middle segments of the ﬁngers. In fist-walking, the ground touches the proximal phalanges, or the segment of finger closest to the hand.
Orangutans live more solitary lives than the other great apes. It has long been considered that most interactions occur during mating and between mother and offspring. However, there has been evidence of vocal communication between orangutans in the same general area and it was hypothesized that they may have been keeping track of each other’s locations. Also, in captivity settings, orangutans have been known to groom and play with each other.
Just like their cousins in Africa, some orangutans have been taught to communicate with humans using symbols and sign language. In one of the only studies of its kind, zoologist Gary Shapiro taught two orangutans, Princess and Rinnie, how to sign while in their natural environment, not in captivity. Princess learned 40 signs while Rinnie learned 30 over a two year study.
Like the other great apes, orangutans also tackled the use of tools. A common use of tools for any species is to crack hard nuts with the assistance of rocks, while using sticks for extraction purposes. Orangutans prefer to use their stick extract technique on honey rather than insects.
While orangutans are the least social great ape, they are still interactive enough to learn techniques from each other, which can show culture. Tool usage can vary by region. In captive settings, orangutans from different areas were all capable of quickly learning tool-usage techniques they were shown, proving that they were capable of learning new techniques and that this wasn’t genetically derived behavior.
Chimpanzees have Jane Goodall, gorillas had Dian Fossey, and orangutans have Birute Galdikas. These three researchers have been nicknamed ‘Leakey’s Angels’ as they were all sent to study their respective primates by the archeologist Louis Leakey. With the aid of her former husband, Galdikas created the Orangutan Research and Conservation Project, now named the Orangutan Foundation International (OFI). This project and foundation has aided in both the research and conservation of orangutans. Galdikas’ research on wild orangutans in their natural environment was the first of its kind for the species. She was able to convince many people that kept orangutans as pets to give them to her for rehabilitation and reintroduction back into the wild. The Project aided in protecting the Tanjung Puting National Park, the volunteers looking out for poachers as well as illegal loggers.
Galdikas and the Orangutan Foundation International are devoted to researching and protecting the lives of orangutans. Orangutan conservation is a constant struggle that consists of educating the public, protecting forests, and rehabilitation. As with Goodall’s and Fossey’s organization, the OFI can be followed on Facebook and they are able to accept donations from anyone that wishes to assist them on their mission. Dr. Galdikas can be found on Twitter. You can even volunteer with the OFI, which would be a great and worthwhile experience to aid the conservation of our orangutan cousins.