Today marks the first time in almost two decades that new species of great ape was discovered. Scientists have found an isolated population of orangutans in Sumatra, Indonesia, and studies show that it is a new species, and that it has been separated from the other population of Sumatran orangutans for over a million years.

Where did this new species come from? Why hasn’t it been determined to be a new species before now? Well, this group of orangutans was discovered by scientists in about 1997 and since then, studies have been underway (science doesn’t happen overnight, folks). Now that teeth have been measured, and genetic tests run, scientists are confident that this is a completely new species of orangutan which they are calling Pongo tapanuliensis.

What is the most interesting, in my humble opinion, about this orangutan, is what it says about the evolutionary track of the other two species of orangutan.

Orangutans used to be found as far north as Vietnam and China, but as the climate shifted from the Pleistocene to the Holocene (our current geological era), orangutans moved Southward and now are found only on the islands of Sumatra and Borneo.

Now, you might believe that this new orangutan, since it is found on the island of Sumatra, would be more closely related to the Sumatran orangutan. But, now heres the exciting bit, it is actually closer to the Bornean orangutan, who lives an island away.

This means that orangutans came to Northern Sumatra, went to Borneo, and actually came back to Southern Sumatra, with the Sumatran populations never mixing. How might this have happened? Well, a super volcano is to blame of course!

The volcano Toba, which is now usually dormant (at least for the last few hundred years), was once one of the most powerful volcanos in the world. It is this volcano that separates the two species of orangutan found on Sumatra.

Toba’s caldera is now filled with water and called Lake Toba, but about 80,000 years ago it erupted with such force it has been declared to have been the strongest volcanic eruption in 25 million years. It was so powerful that it started a global volcanic winter which plunged the entire planet’s average temperatures by about 6ºF (3.5ºC) for several years.

It was such a major eruption, with such massively far-reaching effects that it is actually believed to have killed off most of the humans living at that time, which caused a genetic bottleneck to occur in central-east Africa and India. This is probably why most genetic ancestry can be traced back to these two places.

This new species current population count stands at only 800 individuals, and is at a serious risk of extinction

What does this have to do with the new species of orangutan? Well this volcano is what prevented orangutans from overtaking the entirety of the island of Sumatra when they first arrived, and it is what kept the populations separated for all those years.

Now just because this is a new population does not mean it is plentiful. Having been described officially as of today, it’s current population count stands at about 800 individuals. It is thought that it used to range over the entirety of Southern Sumatra, but was hunted to extinction.

Orangutans are extremely susceptible to extinction by hunting, as they reproduce so infrequently. It is thought that there is no way to sustainably hunt these animals, and even if they were taken out of the environment at only 2% of their local population per year they would still go extinct from the pressure in only a few generations.

This population is at risk not only from hunting and habitat loss, but by a newly proposed project which would cut a line through their current range to make way for a hydroelectric dam. This construction project could potentially be the kiss of death for this new species, as it would separate populations, which could lead to extinction by lack of genetic diversity, habitat loss, and not to mention, projects like these are known to bring with them a massive increase in hunting.

If you want to learn more about orangutan conservation you can visit Sumatran Orangutan Society. If you want to read the scientific article describing the new species you can find it here. All photos of the new species of orangutan are by Max Aliaga.