Chimpanzees Use Human-Like Warfare Tactics, Scientists Discover

Chimpanzees use human-like warfare tactics in order to avoid their enemies, scientists have discovered.

Scientists found that chimpanzees—studied across three years in the West African forests of Côte d'Ivoire—often used high ground to keep eyes on rival groups, just like humans in warfare. The findings are described in a study published in the journal PLoS Biology.

This technique is one of the oldest military tactics in human history. Until now, the tactic was thought to be unique to humans. Scientists tracked these chimps across their respective territories, and areas where fighting between them occasionally took place. They found that they were twice as likely to climb to high points when heading to the borders of rival territories, compared to when they were traveling to their territory.

"What was the most surprising is the ability to detect rivals at much longer distances than what was expected given our knowledge on auditive capacities of chimpanzees," Dr. Sylvain Lemoine, a biological anthropologist from the University of Cambridge's Department of Archaeology, and lead author of the study told Newsweek. "High elevation helps in increasing detection distance, but these chimpanzees are still able to detect rivals at more than [1.24 miles]. We also confirm that chimpanzees are able to evaluate their own numbers, but also rivals numbers from a distance, which was also surprising given the long distances between neighbouring communities. Mechanisms of long distance detection of numbers are unclear, but likely act by hearing pant hoots and buttress drumming emitted by distant neighbours."

While on higher ground, the chimps kept quiet and resisted foraging and carrying out other usual behaviors. Both these findings suggest that they were on higher ground purely to seek out the locations of other rival groups, before heading into their territory. This also suggests forethought, as they altered their behavior accordingly, depending on the location of their enemies.

While other animals may use high ground to keep watch—meerkats, for example, do this to warn others about predators—these chimps were clearly using the elevation for tactical and strategic purposes, in order to prevent fights from occurring.

The groups consisted of 30 to 40 adult chimps, who regularly established and guarded their territory by scouting its borders. By doing this they were enforcing some sort of "border patrol," according to Lemoine.

"Patrols are often conducted in subgroups that stay close and limit noise. As an observer, you get a sense that patrolling has begun. They move and stop at the same time, a bit like a hunt," Lemoine said in a release detailing the findings.

Lemoine said that tactical warfare like this is "considered a driver of human evolution."

"Our findings reveal sophisticated tactics in territorial behaviour in chimpanzees, allowed by complex cognition such as anticipation, spatial memory, numerical assessment and ability to weight the costs and benefits of conflict engagement," he told Newsweek. "Regarding human evolution, it also suggests that warfare could have been an important selective pressure throughout our evolution, especially driving cooperative and cognitive skills, and that exploitation and usage of key landscape features could have helped our ancestors to thrive in a competitive environment."

Humans share 98.8 percent of their DNA with chimps. Therefore it is not completely surprising that they display certain behaviors similar to us.

Previous studies have already shown that chimps have complex social societies and structures. While chimps are territorial and can be aggressive when provoked, researchers found that fights between the rival groups were relatively rare. These war-like tactics largely meant confrontation was avoided.

However, fights did occur during the three-year period of research. In fact, violent kidnappings and killings between the groups were occasionally observed. When these fights did occur they were "extremely noisy" and often involved screaming, defecating and "gripping each other's genitals."

Lemoine said that the next step for this research is to assess whether some hilltops are favored and preferred by the chimps.

"And, whether the surrounding terrain make some locations more strategic than others. Another aspect is to investigate other potential changes and modulation in behaviour that could be linked to the presence of hostile rivals," Lemoine said.

Do you have a tip on a science story that Newsweek should be covering? Do you have a question about chimps? Let us know via science@newsweek.com.