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The Newly Discovered And Nearly Extinct Tapanuli Orangutan Species

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Tapanuli orangutan (Credit: Maxime Aliaga)

Tapanuli orangutan (Credit: Maxime Aliaga)

Up to today, there were two known Orangutan species, both critically endangered. There are about 4,000 more Sumatran orangutans (Pongo abelii) than Bornean orangutans (Pongo pygmaeus) currently living in the Indonesian rainforest. A new orangutan family member, the Tapanuli orangutans (Pongo tapanuliensis), was described in a paper published Thursday in Current Biology. And with less than 800 individuals, that makes them most endangered great ape species in the world.

Michael Krützen, an anthropologist at the University of Zurich was the senior author of the study. He comments on how remarkable it is to find a new species of great ape, as only seven that have ever been defined,

“We decided to look at genomic DNA, which would allow us to probe back in time to see what really happened in the past with these orangutan populations. Once we did this, we realized there are three deep, independent evolutionary lines among orangutans and it was very interesting because we had only two species described [at the time].”

This orangutan skull has large upper teeth and a shallow face, which differs from the two previously known species. (Credit: Matthew G. Nowak)

This orangutan skull has large upper teeth and a shallow face, which differs from the two previously known species. (Credit: Matthew G. Nowak)

Krützen and his team correlated their findings with the skeletal and behavioral evidence. These Batang Toru Sumatra skeletons stood out, with distinct features from other known species of orangutans, including large upper teeth and a shallower face depth. In the wild, these same orangutans had unique mating calls that could last up to twice as long as others. Even more interestingly, the Tapanuli orangutan may be the direct descendant of the first orangutan species that migrated from Asia to Sumatra. Using computer models the Tapanuli population split in Sumatra, leading to the creation of the Sumatran species more than 3 million years ago,then, about 670,000 years ago, the Sumatran species split, creating the Bornean species.

The Tapanuli’s already small habitat range, some 380 square miles, is threatened by increasing habitat conversion for roads, agriculture, mining, geothermal development and hydro-electric development. Top that with a culture that’s known to hunt and poach orangutans, and the new species’ future looks pretty bleak.

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