“Sometimes I feel like I’ve chosen the most difficult thing in the world to study,” Cheryl Knott tells me as we sit beneath the rain forest canopy at her orangutan research station in western Borneo. The high-pitched, dental-drill sound of cicadas fills the air, at times forcing us to pause our conversation. As we talk, Knott’s associates are at work in the surrounding forest of Indonesia’s Gunung Palung National Park with GPS units and iPads, following orangutans in their daily wanderings, recording what they’re doing, what they’re eating, and how they’re interacting with others of their species.
Unlike gorillas and chimpanzees—fellow great apes that live in groups and can be followed and observed relatively easily—orangutans live mostly solitary lives. They spend nearly all their time in the treetops, they wander widely, and for the most part they inhabit rugged forest or swampy lowland that’s hard for humans to traverse. As a result, orangutans long remained among the least known of Earth’s large land animals. Only during the past 20 years or so has scientific evidence begun to outweigh speculation as a new generation of researchers has tracked the elusive apes across the islands of Borneo and Sumatra, the only places orangutans live.
For more than two decades Knott has supervised the research at Gunung Palung, looking at many aspects of orangutan life history but focusing especially on the way the availability of food affects female hormones and reproduction. “At the time we started here, no one had really worked on hormones in wild apes,” she says. “People said I was crazy.”