In the wild, chimpanzees are more motivated to cooperate than bonobos

JUNE 24, 2020

by Max Planck Society

We humans have unique cooperative systems allowing us to cooperate in large numbers. Furthermore, we provide help to others, even outside the family unit. How we developed these cooperative abilities and helping behavior during our evolutionary past remains highly debated. According to one prominent theory, the interdependence hypothesis, the cognitive skills underlying unique human cooperative abilities evolved when several individuals needed to coordinate their actions to achieve a common goal, for example when hunting large prey or during conflict with other groups. This hypothesis also predicts that humans who rely more on each other to achieve such goals, will be more likely to provide help and support to one another in other situations.

"While we cannot study the behavior of our human ancestors," explains Roman Wittig, a senior author and head of the Taï Chimpanzee Project, "we can learn how relying on others may influence helping behavior in our ancestors by studying our closest living relatives, chimpanzees and bonobos." Chimpanzees are more territorial than bonobos and in some populations engage more frequently in group hunts. According to the interdependence hypothesis, chimpanzees should thus have evolved a higher tendency to cooperate and help others in the group.

To test this hypothesis, researchers from the Max Planck Institute for Evolutionary Anthropology, Harvard University and Liverpool John Moores University, presented 82 chimpanzees and bonobos from five different communities with a model of a Gaboon viper, a deadly snake. During the experiment the apes could cooperate with each other by producing alarm calls to inform conspecifics about the snake. This represents the first experimental study ever conducted in wild bonobos. "This experimental study is a novel and promising approach to probe bonobo's mind," says Gottfried Hohmann, a senior author on the study and head of the LuiKotale bonobo project. Martin Surbeck, co-author on the paper adds: "This study should stimulate several more experimental studies on wild bonobo cooperation, cognition, and communication."

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