Chimpanzees losing traits in areas of high human impact, study claims

Chimpanzees are losing their distinctive behaviours in areas of high human activity, new research suggests.

A study of 144 different wild groups in 15 countries found the range of behaviours shown by the animals was reduced in areas where humans had made the biggest mark.

The international team of researchers warned that some traits, which have yet to be noticed in the animals, could disappear without intervention.

The behaviours of chimpanzees, for example the tools they use and gestures they communicate with, vary between groups.

Existing research suggests they may learn from members of their community, meaning each group is culturally different, much like humans.

Male chimpanzees groom one another (Tobias Deschner/Loango Chimpanzee Project/ PA)
Male chimpanzees groom one another (Tobias Deschner/Loango Chimpanzee Project/ PA)

Data on 31 chimpanzee behaviours across the groups was compiled for the study.

The study found that chimpanzee communities in areas with a high degree of human impact were on average 88% less likely to exhibit the behaviours than groups in areas with the least human impact.

These included the extraction and consumption of termites, ants, algae, nuts and honey, as well as the use of tools for hunting and digging.

The use of stones, pools and caves was also considered.

Human impact was measured using factors such as human population density, roads and rivers.

“The analysis revealed a strong and robust pattern – chimpanzees had reduced behavioural diversity at sites where human impact was high,” lead author Dr Ammie Kalan said.

“This pattern was consistent, independent of the grouping or categorisation of behaviours.

“On average, chimpanzee behavioural diversity was reduced by 88% when human impact was highest compared to locations with the least human impact.”

The researchers suggest that chimpanzee populations in areas with high human activity may be smaller, making it hard to pass on certain traits between generations.

The animals may stop displaying some behaviours to avoid attracting human attention and climate change could also be impacting behaviours, they said.

Chimpanzees crack nuts with a stone hammer (Liran Samuni/ Taï Chimpanzee Project/ PA)
Chimpanzees crack nuts with a stone hammer (Liran Samuni/Tai Chimpanzee Project/ PA)

“Our results suggest that chimpanzee populations are losing their characteristic sets of behavioural traits and that a number of not yet discovered behaviours may be lost without having ever been described,” the authors wrote.

They suggest “chimpanzee cultural heritage sites” are needed to protect these diverse sets of behaviours.

“Specific interventions are needed to protect their natural resources and tool-use sites in order to maintain behavioural plasticity and safeguard their capacity for cultural evolution,” the authors wrote.

The study, led by the Max Planck Institute for Evolutionary Anthropology and the German Centre for Integrative Biodiversity Research, has been published in the journal Science.