Chimps are losing their culture Tobias Deschner/Loango Chimpanzee Project

Chimpanzee cultures are disappearing. In places where their habitats have been heavily altered by humans, groups are abandoning unique behaviours and reverting to a core set of activities.

The loss of chimpanzee cultural diversity is analogous to the way many human languages are disappearing because so few people speak them. It could make life more difficult for chimps in the long run, because many of the lost behaviours allow the chimps to obtain additional food.

Chimpanzee culture refers to how groups have different behavioural traditions, which are passed on by learning and imitation rather than genes.


For example, some chimps in Uganda have learned to use moss to soak up water, which they can then drink. Chimps elsewhere don’t do this.

In 2002, Carel van Schaik at the University of Zurich in Switzerland suggested that human interference could destroy this cultural diversity. Now a decade-long study has found strong evidence that van Schaik was right.

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A team co-led by Hjalmar Kühl at the German Centre for Integrative Biodiversity Research in Leipzig, Germany, tracked 31 cultural behaviours, such as using twigs to catch termites, in 144 chimpanzee communities across Africa.

They used camera traps to record behaviours, scouted for the remains of tools, and studied faeces to see if the chimps had eaten things like termites that can be obtained only by using tools.

The team then placed the different communities on a map and overlaid a measure of human disturbance, which combined factors like the density of the human population and the amount of infrastructure.

They found that, in areas with a greater human footprint, the chimps perform fewer cultural behaviours. Each behaviour was 88 per cent less likely to occur in these human-dominated landscapes.

“In those places, we find the chimpanzees have suffered a loss in behavioural or cultural diversity,” says study co-leader Ammie Kalan at the Max Planck Institute for Evolutionary Anthropology in Leipzig.

Saving chimpanzee culture

“This is a very impressive study, with sample sizes that were unimaginable just a few years ago and very careful analyses that controlled for all the obvious confounds,” says van Schaik.

“It is a discouraging finding,” says Jill Pruetz at Texas State University. “Those of us who work in disturbed areas kind of had these thoughts before, but to see it demonstrated like that is especially significant.”

Losing some of the behaviours poses a real risk to the chimps, says Pruetz, because if they stop fishing for termites or cracking nuts, they lose access to those foods.

Conservationists must now ensure that, as well as keeping animal populations up, they also preserve behavioural diversity, says Kühl. He says living near humans need not be disastrous.

In a study published in February, he and his colleagues showed that chimps living in human-modified landscapes can do fine provided people don’t actively harm them, such as by hunting them for meat. Chimps in these areas may ultimately invent new behaviours to suit their altered homes.

Another crucial step will be to create corridors so that chimps can move from one group to another. “The community I study is cut off on both sides,” says Pruetz. “The fact you don’t have the exchange of individuals leads not only to a lack of genetic diversity but also a lack of behavioural diversity.”

Other species with culture may also be losing cultural diversity. “This is not just specific to chimpanzees,” says Kühl. Other primates like orangutans and capuchin monkeys are obvious examples, as are cetaceans like whales, dolphins and orcas.

Journal reference: Science, DOI: 10.1126/science.aau4532