Chimps are losing their behavioral diversity in the wild

Chimpanzees are closest evolutionary relatives and so it’s no surprise that they’re intensely social animals, just as we are. And just as we do, chimps can learn new behaviors from one another, creating “cultures” of sorts within smaller groups.

Yet this behavioral diversity is on the decline because of human activity, new research has shown.

An international research team, led by primatologists at the Max Planck Institute for Evolutionary Anthropology and the German Centre for Integrative Biodiversity Research, examined data on 31 chimpanzee behaviors in 144 social groups or communities from across the entire geographic range of chimpanzees in the wild. The studied behaviors included how chimps in specific groups obtained termites, ants, algae, nuts and honey; how they uses tools for hunting or digging for tubers; and how they employed stones, pools and caves.

The researchers then examined how groups of chimps were affected in such learned behaviors by their close proximity to people. Their findings indicate that the more exposed to human contact the chimps were, the less likely they were to maintain specific behaviors.

“The analysis revealed a strong and robust pattern: chimpanzees had reduced behavioral diversity at sites where human impact was high,” says Ammie Kalan, a researcher at the Max Planck Institute for Evolutionary Anthropology. “This pattern was consistent, independent of the grouping or categorization of behaviors. On average, chimpanzee behavioral diversity was reduced by 88 percent when human impact was highest compared to locations with the least human impact.”

Why this is the case is open to conjecture. The experts speculate that chimps may stop engaging in behaviors, such as cracking nuts with stones, that might alert people of their presence in forests. In addition, degradations in wild habitats as a result of human activities reduce opportunities for chimps to practice certain behaviors whereby these behaviors then fail to be passed down to offspring and this get lost over time.

The results of such research have profound implications for wildlife conservation. It is not enough simply to preserve vestiges of wildlife habitats. Rather, those habitats must be rich enough for highly social species like chimps to practice their whole gamut of social behaviors.

“Our findings suggest that strategies for the conservation of biodiversity should be extended to include the protection of animal behavioral diversity as well,” says Hjalmar Kühl, an ecologist at the Max Planck Institute. “Locations with exceptional sets of behaviors may be protected as ‘Chimpanzee cultural heritage sites’ and this concept can be extended to other species with high degree of cultural variability as well, including orangutans, capuchin monkeys or whales.”