After weeks of searching, they caught a glimpse of this.
(leaves rustling) A new species of primate.
A great ape.
(leaves rustling) A Tapanuli orangutan.
(leaves rustling) (orangutan grunting) They are smaller and have paler, thicker fur than their lowland cousins.
Scientists believe these are adaptations for living at altitude.
But like all the orangutans, the bond between an infant and its mother is one of the strongest and longest in the natural world.
(orangutan grunting) A mom is everything to her youngster.
Even a bridge when she needs one.
At this high elevation, it seems that these orangutans need a greater variety of plant foods to survive.
All of which this infant has to learn.
When the Tapanuli orangutan was named in 2017, it became the newest and in the same moment, most endangered great ape on Earth.
(orangutan squeaking) There are only 800 individuals.
Their lost world is no longer a secret.
In fact, it's under immediate threat from logging, mining, and hydropower projects.
The Tapanuli orangutan was isolated.
Hidden for nearly 700,000 years.
It's now thought that within a generation, they could be gone.