Primate Rescue Center

Apes in a Human World

Erika Fleury May 06, 2015

When Jane Goodall first trekked into the Tanzanian forest, in 1960, the chimpanzees that she encountered were so unaccustomed to humans that they fled whenever they saw her. Nearly a year passed, she wrote in her 1999 memoir, “Reason for Hope,” before the animals finally seemed to lose their fear of “this strange white ape.” Since then, wild apes have become much more familiar with their smooth-skinned cousins. Human hunters and poachers now regularly tramp through ape habitats, searching for bushmeat or rare wildlife species to sell on the black market. The forests are also rapidly being cleared—trees are harvested for timber, charcoal, and fuelwood, and the denuded land is pitted with mines and seeded with cash crops. New roads are carving up the remaining patches of wilderness, fragmenting the apes’ home ranges and stranding the animals in islands of trees surrounded by the thrum of human activity.

“Chimpanzees are coming out of the forest in order to look for food, and people are going into the forest in order to look for forest resources,” Catherine Hill, an anthropologist at Oxford Brookes University who studies human-wildlife interactions, told me. “As that starts to happen, we see interactions between humans and chimps becoming more frequent.” The United Nations Environment Programme has estimated that, by 2032, less than ten per cent of the ape habitat in Africa—and less than one per cent in Asia—will remain untouched by human development.

Donald is a chimp at the PRC who was most likely captured in the wild.

Yet when scientists want to study wild apes, they typically do what Goodall did half a century ago: camp out in a piece of “pristine” wilderness, a remote patch of forest that is as far from humans, and as free from their interference, as possible. “Those environments are seen as being more valuable for looking at ape behavior than any others,” Hill said. “There’s been a greater value placed within the scientific fraternity on what is seen as the behavior of animals in undisturbed states.” But a group of anthropologists, primatologists, and psychologists from around the world is now challenging that view. In a paper published last month in the journal Trends in Ecology & Evolution, fourteen researchers, led by Hill, argue that scientists should spend more time analyzing apes’ behavior in precisely those places where humans are disrupting their lives.

Such studies would have an obvious practical benefit; every species and subspecies of great ape is either endangered or critically endangered, and drafting realistic conservation plans will require a detailed understanding of how these animals are coping with anthropogenic change. But studying apes in human-dominated landscapes could also yield basic scientific insights into the animals’ cognition and behavior.

Kimberley Hockings, a postdoctoral researcher in Hill’s lab, has spent more than a decade studying the chimpanzee community that lives in the hills surrounding Bossou, a small town in southeastern Guinea. The chimps there regularly raid farms and orchards, absconding with oranges, bananas, corn, cassava, and other delicacies. But stealing human food is a risky proposition, and farmers who discover the interlopers may harass, chase, or attack them. The Bossou chimps have learned to keep quiet while out on their heists; they vocalize significantly less when pilfering crops than when foraging for wild food, Hockings found. They also form more cohesive groups, staying in closer physical proximity to their comrades when ransacking fields. The chimps are also adept at judging the risks presented by roads, waiting longer to cross a large, busy road than a smaller, less trafficked one. Some of the animals have even learned how to deactivate hunters’ wire snares: a team of Japanese researchers once watched as an alpha male clambered down a tree and shook a snare until it broke. (In Rwanda, mountain gorillas seem to have become similarly savvy about such dangers; they’ve been observed to threaten and even bite younger gorillas that get too close to the traps.) Further study of the Bossou chimps—and other apes that live in human-influenced habitats—may reveal more about how they detect and respond to risks, as well as their behavioral and cognitive flexibility in rapidly changing environments.

It could also shed light on our own evolution. Chimpanzees rarely walk on two legs when carrying wild foods, but the Bossou chimps often choose bipedalism when lugging stolen crops into the forest. Standing upright allows the animals to carry larger loads; one chimp staggered out of an orchard carrying a papaya in each hand and another in his mouth. The researchers who made the discovery—an international team that included Hockings—suspect that the apes shift to a two-legged walk when raiding farms because crops are a more unpredictable food source than wild fruits, nuts, and seeds. “Chimpanzees are actually competing with people for these crops,” Hockings said. “If they return a bit later, that food might not be there. So you just want to get as much as you can, as quickly as you can.” Precisely how and why human bipedalism evolved remains an area of fierce scientific debate, but the sticky-fingered chimps of Bossou suggest that an upright walking style might have given our ancestors an advantage in acquiring scarce but highly valuable foods. Similarly, although chimps rarely share wild plants with one another, they often share stolen crops, a form of altruism more commonly associated with humans. Investigating the new ape behaviors that emerge in the face of radical environmental change could provide clues about the evolutionary origins of these behaviors.


Although Hill and her colleagues focus on apes, scientists who research other species would do well to follow their lead, Erle Ellis, an ecologist at the University of Maryland, Baltimore County, told me. Ellis specializes in studying the ecology of the Anthropocene, the widely used term for the human-dominated epoch in which we are currently living. He has measured and mapped our influence on ecosystems around the world and developed a system for classifying the different types of human-altered landscapes, or anthromes, that now blanket the planet. “This is the ecology that matters now,” he told me. “It’s become the most pervasive context. If you’re interested in working across the span of habitat that species are living in, it’s very likely that most of that habitat is under human influence.” Simply ignoring that fact doesn’t make it any less real. “This process is not slowing down,” he added. “It’s speeding up.”

The notion that humans might be a legitimate part of an area’s ecology, and one deserving of study, is controversial among conservationists. Many are reluctant to investigate, or even discuss, how wildlife might adapt to environments that have been transformed by humans. “A lot of people feel like that’s kind of giving in—that the idea that we could successfully maintain wildlife in human habitats is going to get people to say, ‘Well, we might as well turn everything into parking lots,’ ” Ellis said.

Hill emphasized that the fact that our enormous ecological footprint has created interesting research environments doesn’t imply that we should stop trying to preserve the world’s wilderness. “In no way do we think that this is a justification for not trying to protect habitat,” she said. But those places where humans and animals are already living in close proximity present valuable opportunities to ask, and answer, new scientific questions about ourselves and the species that surround us. Besides, environments are constantly changing, and even landscapes that look undisturbed may have been altered in subtle ways. “I’m not sure I’d know a pristine habitat if it bit me on the nose,” Hill said.

- The New Yorker

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