Chimpanzees in the forests of West Africa are exhibiting unprecedented behavior. Chimpanzees tactically move to higher ground to gain a better view and gather information to spy on rival groups. This “intelligence” is used to decide further steps. Humans have been using this combat tactic for centuries, but this behavior has never been reported in chimpanzees.
This fascinating behavior was documented in Taï National Park in Ivory Coast during a three-year study by the University of Cambridge and the Max Planck Institute for Evolutionary Anthropology.
The team collected GPS data and over 21,000 hours of tracking records on two neighboring western chimpanzee groups, totaling 58 monkeys. Because the territory of these two chimpanzee groups borders each other, they often have to compete for resources, and this struggle can turn violent. The researcher’s observations showed that chimpanzees regularly patrol borders to control their poorly defined territory.
Lead author of the study and biological anthropologist from the Department of Archeology at the University of Cambridge, Dr. Sylvain Lemoine said in a statement: “Patrolls are generally carried out in subgroups that stay close and limit the sound. As an observer, you sense that the patrol has begun. “They move and stop at the same time, just like prey,” he said.
A common feature of these patrols was that the chimpanzees often traveled upwards through higher, rugged terrain as they moved towards the border where border disputes occurred. However, when returning to their own lands from here, they tended to avoid these hills and preferred easier and flatter routes.
It was also revealed that the chimpanzees’ next moves were determined by the information they collected from above. After gathering information on their opponents, the probability of advancing into “enemy territory” increased from 40 percent when the opponents were 500 meters away, to 50 percent when they were 1,000 meters away, to 60 percent when they were 3,000 meters away.
TACTICAL FIGHTING FORCE
“Tactical warfare is considered a driver of human evolution,” says Dr Lemoine. “This chimpanzee behavior requires complex cognitive abilities that help protect or expand their territories and has been favored by natural selection. Using land for territorial control has deep roots in our evolutionary history. “In chimpanzees’ use of this war-like strategy, we see traces of early small-scale warfare that probably existed in prehistoric hunter-gatherer populations.”
The new study was published in the journal PLOS Biology.
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