Week 3: Primate Diversity (part 2)


Along with the Coquerel’s sifaka I have decided to write up on the Orangutan as well! Ever since taking Human Evolution I have had interest with the Orangutan, they always seemed interesting and a little different than most other great apes. Because they are!

orangutan_img01-lThe Orangutans, as we know them by, can actually be classified into two separate species, based on their geographic location. The Orangutan primarily lives in Borneo (Pongo pygmaeus) and also in Sumatra (Pongo abelii). Although it used to be considered a single species, taxonomists have made the distinction between the two since 1996. I will discuss the Orangutan generally, only including important distinctions between the two. The Orangutan is considered a Great Ape, native to Indonesia and Malaysia, and lives in rainforests on Borneo and Sumatra, as stated above.

The Orangutan primarily eats fruit of the rain forest. It will, however, supplement its diet with other things such as insects, tree bark, honey, and other vegetation. The Orangutans particularly like sugary or pulpy fruits. Don’t we all… It is also important to note that digestion of fruit is much easier than digestion necessities of highly fibrous leaves. Because of it’s diet and the way it retrieves its food, the Orangutan is considered to be a forager; which also means that its diet will vary based on the time of year. Orangutans clearly enjoy fruit:


The Orangutans, compared to the rest of the great apes, actually are the most arboreal, despite their size. One of the most interesting facts about the Orangutans, in my opinion, was that they are the largest arboreal animal in the whole world! I already mentioned that their diet consisted mainly of foraged foods, and the Orangutan spends most of its day in the tree foraging for food. I particularly loved how Orangutans used their weight as a means of locomotion to sway tree branches.


The Orangutan is actually the most solitary of the Great Apes. The strongest bond is that of the mother and child. The dependent child will stay with its mother for about two years, but this relationship can last much longer. Some Orangutans remain breast-fed until they are eight years old! The Orangutan child takes quite a long time to grow up and they reproduce very slowly. Adult males will actually prefer to live alone than in any social groups. Social interaction between adult Orangutans mostly occurs when females’ home ranges overlap with others, most likely their immediate family. These interactions can be anywhere in between pleasant, ignorant, or aggressive, aggression particularly occurring between males with overlapping home ranges. This social structure is difficult to understand, but most simply put, they are semi-solitary with some degree of sociability. And here – for you, dear reader – is a picture of a baby Orangutan and its mother. Because the only thing cuter than a baby Orangutan is a baby sifaka.


Orangutans are considered highly intelligent primates, especially compared to other great apes; researchers have noted that they create nests from tree branches and other vegetation, and have a sophisticated tool set. Some of these tools even represent cultural variation and tradition, something that I – as an anthropologist – found really, really cool. I also thought it was fascinating that, despite their large size, Orangutans could build and sleep in nests up to 100 feet off the ground! Many researchers believe that the extensive culture of the Orangutans is one of the reasons why baby Orangutans remain with their mothers for such a long period of time: because there is so much for them to learn. This is a smart Orangutan:



Both Pongo pygmaeus and Pongo abelii are considered to be endangered. Major threats to Orangutan populations include human activities such as deforestation and illegal hunting for animal trading. Though I didn’t know much about Orangutans before starting this project, I found them to be extremely fascinating and gentle creatures. I would love the opportunity to get to know more about them, and it pleased me to be able to read so much about various conservation efforts directed to the rain forests of Sumatra and Borneo! Plus, the Orangutan is our closest living relative that has red hair!


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