Orangutans are the only great ape outside of Africa and they are uniquely adapted to the tropical forests of Southeast Asia. During the Pleistocene, orangutans ranged throughout forests in Java, Sumatra, Borneo, Vietnam and southern China. As climate slowly changed over nearly 1.8 million years, the orangutan range shifted southward. Orangutan populations have declined dramatically, perhaps by as much as 97%, in the 20th century