Earlier, in 1978, one of his orangutans, Clyde, appeared in Every Which Way but Loose with Clint Eastwood.
Situated approximately 86 km north-west of Medan, Bukit Lawang is known for the largest animal sanctuary of Sumatran orangutan (around 5,000 orangutans occupy the area), and also the main access point to the Gunung Leuser National Park from the east side.
His book Among Orangutans: Red Apes and the Rise of Human Culture tells the story of his discovery of a group of orangutans in northern Sumatra and the challenge their tool use and sociality pose to theories of primatology and the insights they offer into key moments in human evolution.
Founded by Dr. Birute Galdikas, one of three anthropologists (The Trimates) to study great apes under the guidance of Dr. Louis Leakey, OFI continues to rescue and rehabilitate orangutans, preparing them for release back into protected areas of the Indonesian rain forest.