By Rowan Hooper
How many ways are there to get a termite to run up a stick? A surprising variety, it turns out. A new analysis of how chimpanzees perform this “termite fishing” has revealed that different groups of the animals have distinct dining cultures, similar to how chopstick use in humans differs across the world.
The idea that non-human animals can even have culture in the sense that humans have it – behaviours and social norms that vary by group – has been controversial. But this study firms up the idea of chimp ethnography, the study of chimp culture, as a viable subject.
Carel van Schaik at the University of Zurich, Switzerland, who wasn’t involved in the research, says the work confirmed beyond any doubt that the variation that has been found among chimpanzees is cultural. “This paper is an absolute milestone in ‘culture in nature’ research,” he says.
Christophe Boesch at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and his colleagues chose to study termite fishing because it is a widespread behaviour, allowing them to make lots of observations in different communities.
The researchers set up camera traps in 39 different wild chimp communities to record them eating termites, which they found occurring in 10 of the groups. It may be that the other communities didn’t have enough termite mounds in the area to display the behaviour, or perhaps simply that the cameras didn’t happen to capture any termite fishing.
They carefully noted each element of the termite fishing behaviour from hundreds of video clips to create an ethogram, which consisted of a behaviour profile for each chimpanzee in the study. It turns out there are 38 different technical elements to the practice, all used in different combinations in each of the chimpanzee communities.
Individuals in the same community used more similar techniques compared with chimpanzees from other groups. In other words, there were local cultural differences. “As in human social conventions, you do it as you see others do,” says Boesch.
Chimpanzees in Korup National Park in Cameroon, for example, lean on their elbows to insert sticks into termite mounds and then shake the ends of the sticks with their mouths to get the termites to bite the sticks.
Meanwhile, chimpanzees in the Wonga Wongué National Park in Gabon lie on their sides and insert their sticks without shaking them. When extracting the sticks, they take the termites directly off them with their mouths.
Van Schaik says the study also raises the intriguing possibility of chimp etiquette. Boesch and his team found that neighbouring chimp communities differ in the details of their fishing techniques, even though they exchange members between groups.
It seems that the differences aren’t functional, in that some methods work better in one place than another, but cultural, and that chimps moving to a new community change their methods the better to fit in with their new social group and hasten social acceptance and integration. We don’t yet know whether the chimps feel pressure to conform or if there are punishments or sanctions for nonconformity, says van Schaik.
Journal reference: Nature Human Behaviour, DOI: 10.1038/s41562-020-0890-1