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Humans threaten chimpanzees' behavioral diversity

Chimpanzees in the Taï National Park, Côte d'Ivoire, vocalize with another party nearby. Photo: Liran Samuni/Taï Chimpanzee Project

Human disturbance that is shrinking the habitat for chimpanzees is also reducing their behavioral diversity, a key component to biodiversity that previous studies had not examined.

Why it matters: Like humans, chimpanzees learn new skills, including the use of tools for feeding and communication gestures, in group settings. By shrinking their habitat in equatorial Africa through deforestation and reducing their numbers through poaching and other activities, a new study published Thursday in Science shows that we may be reducing an under-appreciated aspect of chimpanzee biodiversity: how animals behave.

What they did: In the study, an international team of researchers examined 31 chimpanzee behaviors across 144 chimpanzee communities. This involved field work in more than 40 locations including multiple sites in Uganda.

They measured the degree of human disturbance for each community to try to determine if more disturbed populations show less behavioral biodiversity than populations under less stress.

The behaviors examined in this study include:

  • The extraction and consumption of termites, ants, meat, algae, nuts and honey.
  • The use of tools for hunting or digging for tubers.
  • The use of stones, pools and caves.

What they found: The researchers found that chimpanzees living in areas with high human impact had an 88% reduction in the mean chance of occurrence of the behaviors they were looking for, compared to the areas with lowest human impact.

What they're saying: "The impact of humans on the environment is not only causing the loss of species and populations, but also the loss of unique animal cultures and behavioral diversity," study co-author Ammie Kalan, of the Max Planck Institute for Evolutionary Anthropology, tells Axios.

"Although this has been theoretically predicted, our study provides empirical evidence of this by putting together an unprecedented dataset on one of our closest living relatives."

What's needed: The study suggests that conservationists should consider behavioral and cultural diversity when pursuing conservation management plans. Specifically, the authors put forward the concept of Chimpanzee cultural heritage sites to protect populations with rare or diverse cultural behaviors, Kalan says.