Similar to humans, chimpanzees use communication to coordinate their cooperative behavior—such as during hunting. Researchers at the Universities of Zurich and Tufts have now shown that when chimpanzees emit a specific sound known as a “hunting bark,” they recruit more group members to hunt and capture prey more efficiently.
Not only do chimpanzees forage fruit, they also look for opportunities to obtain protein-rich meat from time to time. To catch agile monkey prey in the tree canopy, chimpanzees are best hunted with a companion next to them. For the first time, scientists have discovered that communication is key to recruiting team members to join the hunt.
Hunting bark makes chases more efficient
By studying more than 300 hunting events recorded in the Kanyawara chimpanzee community in Uganda over the past 25 years, researchers from the University of Zurich (UZH) and Tufts University in Boston have found that by making bark sounds, wild apes facilitate group hunting, enabling this form of cooperative behavior is more effective. “Chimpanzees that produce hunting bark provide nearby people with information about their hunting motivations, which may convince reluctant people to join in, improving overall chances of success,” said Joseph Mine, a doctoral student in UZH’s Department of Comparative Language Sciences, who leads this research.
Hunting monkeys as a group in dense rainforest with limited visibility can be challenging. Vocal communication can improve the efficiency of group work. “Remarkably, as the hunting bark was produced, we observed that more hunters joined, started the chase faster, and had a shorter time to first catch,” said study co-author Zach of Tufts University. Lim Mahonda, who led the study, said. Kanyawara Chimpanzee Project.
While hunting after bark is more effective, more research is needed to find out why bark has this effect. “It is unclear whether these barks were deliberately made to coordinate the precise actions of the group, or whether they were simply advertising individual hunting decisions, which in turn increased the likelihood that others would join them and have The more hunters they are more effective,” added UZH professor Simon Townsend, who helped lead the study.
Co-evolution of communication and cooperation
Evolutionary biologists have considered a range of other factors that could affect hunting outcomes, including the presence of skilled hunters and potential disturbance, but the appearance of hunting bark still plays a key role. “Communication plays a key role in coordinating complex cooperative behaviors in humans, and this is the first indication that vocal communication may also facilitate group cooperation among our closest relatives,” Townsend said.
It is widely believed that human communication and cooperation are closely linked and co-evolved. Over time, one became more and more complex, and so did the other, creating a feedback loop that eventually led to the uniquely complex forms of cooperation that language and modern humans engage in.
Evolutionary roots at least 7 million years old
However, it is unclear how far back in human evolution this relationship between group cooperation and communication goes. Joseph Mine concludes: “Our findings suggest that the relationship between vocal communication and group-level cooperation is ancient. This link appears to have existed for at least 7 million years, since our last common ancestor with chimpanzees.”