Wild chimpanzee communities use different strategies when it comes to termite fishing, indicating varying degrees of cultural diversity that could lend further insight into the evolution of human behavior.
More than a half-century ago, observations of wild chimpanzees using sticks to fish for termites became the first recorded evidence of tool use in a species besides our own. Chimpanzees exhibit a large diversity of behaviors when it comes to using tools, and among one of the best-studied is termite fishing. The practice consists of breaking a twig off of a tree, removing its leaves, and poking its end into a nest to collect protein-rich ants and termites. Until now, it was previously thought that the foraging strategy was limited and did not widely vary.
An international team of scientists including those at the Max Planck Institute for Evolutionary Anthropology now describe in Nature Human Behavior how separate communities of wild chimpanzees have developed different approaches to harvesting ants, indicating cultural diversity among the groups. To come to their conclusions, the researchers operating under the 2010-established Pan African Programme studied camera trap videos of chimpanzees across 10 communities void of human interference and located far enough in distance that individuals could not mingle. The team then created an ethogram, or catalogue of behaviors, which indicated at least 38 different technical elements that comprise how an individual might fish for termites.
By and large, the most generalizing difference between groups was their practice to either fish in ant nests above the ground or below it. More nuanced behaviors were also observed. For example, a community known as the Kayan group only fished in aboveground nests using soft sticks, biting off one end of it and leaning on a forearm to poke it into the nest. On the other hand, the Goualougo group only used rigid sticks after first scratching at the tunnel surface with their fingers and used both hands to pull the stick out.
"The diversity of techniques seen in chimpanzee termite fishing was a huge surprise to me. Not only does each community have a very unique way of fishing, they also combine a number of different elements into specific termite fishing etiquettes," said study author Christophe Boesch in a statement.
"The most striking examples of this are how the Wonga Wongue chimpanzees of Gabon usually lie down on their sides to termite fish, while the Korup chimpanzees in Cameroon lean on their elbows, and the ones from Goualougo in the Republic of Congo sit while fishing."
The researchers describe the variations in techniques as those seen in how humans use chopsticks differently based on cultural preference or learning. All chimps in the study live in similar habitats with the same resources, suggesting that groups of individuals likely learn through cumulative cultural evolution where groups of individuals learn from one another, expanding and building upon that knowledge over generations.
“This supports the idea that chimpanzees are capable of imitating social techniques in 'how to termite fish' which goes beyond alternative explanations such as each individual reinventing termite fishing each time they learn it,” said study co-author Ammie Kalan.
Cultural studies largely focus on human behavior, which has limited the study of other species’ cultural behaviors and evolution. The scientists note that further analysis of videos and other data will help to better illuminate how termite fishing may relate to certain aspects of the evolution of human culture.