This is Otto, an adult flanged male orangutan, avoiding fires and traveling through a smoke-filled forest in the Tuanan Orangutan Research Station in Indonesian Borneo. Disclaimer: AAAS and ...

Orangutans do this a lot when they’re mad ... In the forests of northern Sumatra, only one dominant flanged male maintains control over a local group of females. Many males in the area retain ...

Researchers in Indonesia documented a male Sumatran orangutan with a facial wound ... he selectively treated his facial wound ...

Both reproduce and an unflanged male can change to a flanged male for reasons that are not yet fully understood. Orangutans are the only primate in which this biological phenomenon occurs. Male ...