A team of researchers concludes our perceptions of the orangutan overlooks how humans have shaped this critically endangered species—a misperception that hampers conservation efforts to protect it.

Orangutan mother and infant in East Malaysia
A team of researchers concludes our perceptions of the orangutan overlooks how humans have shaped this critically endangered species—a misperception that hampers conservation efforts to protect it. Above, orangutan mother and infant in East Malaysia. Image courtesy of HUTAN/KOCP (Kinabatangan Orangutan Conservation Programme).

Researchers Call for Re-Assessment of Species Centering on Impact of Modern Humans

A team of anthropologists, primatologists, and conservationists concludes our perceptions of the orangutan overlooks how humans have shaped this critically endangered species—a misperception that hampers conservation efforts to protect it.

In research published in the journal Science Advances, the scientists call for a multi-faceted approach to orangutan conservation that incorporates human-dominated landscapes, reduces hunting, and increases habitat quality and connectivity.

“Current conservation efforts have focused on minimally disturbed habitats, but growing evidence shows that orangutans are ecological and behaviorally resilient, and are able to live in human influenced environments,” explains Professor Terry Harrison, director of NYU’s Center for the Study of Human Origins and one of the paper’s co-authors. “This offers the possibility to develop new conservation strategies that will increase the potential for the future survival of these critically endangered great apes.”

Orangutans—one of human’s closet living relatives—have interacted with modern humans for at least 70,000 years—interactions that have likely affected the orangutan known today.

“It was often assumed that environmental factors like changes in fruit availability were primarily responsible for most features of modern-day orangutans, such as the fact that they usually live at low densities and have a restricted geographic distribution,” observes Stephanie Spehar, an associate professor at the University of Wisconsin Oshkosh, who led the study. “However, the orangutan that existed before modern humans arrived in Southeast Asia 70,000 years ago may have been quite different. Our synthesis of fossil, archeological, genetic, and behavioral evidence indicates that long-term interactions with humans shaped orangutans in some pretty profound ways.”

The team’s study shows that orangutans were once far more widespread and abundant, with orangutan teeth among the most common animal remains in prehistoric sites in China, Thailand, and Vietnam. The researchers also found that these orangutans overcame many environmental changes—and possibly survived a wider range of environments than their modern counterparts experience.

The researchers’ videos of orangutans in the wild may be viewed here (credit: Andrew Marshall, University of Michigan).

Notably, a widespread reduction in orangutan numbers, which occurred around 20,000 years ago, appears to be correlated with indicators of human impact, especially the appearance of projectile weapons that make hunting tree-living prey easier.

“It suggests that Paleolithic humans were probably hunting orangutans regularly—and as orangutans reproduce very slowly, it doesn’t take much to put a dent in their populations,” says Spehar.

Today, orangutans are found only on the islands of Borneo and Sumatra in Southeast Asia. The ecology and behavior of modern orangutans, the scientists posit, represents an adaptation to environmental factors and long-term human pressures, especially hunting.

“Acknowledging how orangutans were affected by humans in the past can help us better understand how they respond to human threats now,” says Erik Meijaard, co-director of NGO Borneo Futures and a co-author on the paper, who adds that recent studies indicate that orangutan adaptability may be greater than previously thought. “For example, we always thought that orangutans were mostly arboreal, but when we started putting camera traps in the forest, it turned out that they also walk extensively on the ground in some areas.”

Other recent studies have shown that orangutans living in a human-dominated habitat, such as oil palm and forestry plantations, can adjust their behavior to survive in such areas, at least in the short term—but they also underscore how our lack of knowledge of the species has resulted in missed conservation opportunities.

“These insights are important because they show us how even well-studied species can be misunderstood due to our preconceptions,” explains Douglas Sheil, a tropical ecologist at the Norwegian University of Life Science and a co-author on the paper. “This also is a crucial realization for orangutan conservation. If we had known sooner that orangutans survive in selectively logged forests, we could have developed conservation strategies that incorporate these habitats much earlier. This could have saved many thousands of orangutans.”