© Reuters. A group of chimpanzees listen to other chimpanzees heard at a distance in the West African forests of Ivory Coast, studied as part of the Tai Chimpanzee Project’s research, in this undated photograph. Roman M. Wittig/Tai Chimpanzee Project/H
By Will Dunham
(Reuters) – On the edge of dangerous territory, a troop of around thirty individuals engaged in a border patrol climb a rocky hill to carry out reconnaissance. Detecting the sounds of opponents a little too close for comfort, the squad retreats. There’s no reason to risk a fight with the odds stacked against you.
This is a scenario that has occurred countless times in the history of human warfare. But in this case, they were not people but chimpanzees from Tai National Park in southwestern Ivory Coast, the largest protected rainforest area in South Africa. West.
Researchers said Thursday they have documented the tactical use of high terrain in war situations, while observing two neighboring communities of wild western chimpanzees in Tai National Park daily for three years.
According to the study, information obtained during hilltop reconnaissance determines whether chimpanzees make forays into enemy territory, with these apes appearing more likely to do so when the risk of confrontation is lower. According to the researchers, the study records for the first time the use of this centuries-old human military strategy by our species’ closest living relatives.
“It demonstrates sophisticated cognitive and cooperative skills to anticipate where and when to go and to act safely on the information gathered,” said Sylvain Lemoine, a biological anthropologist at the University of Cambridge, lead author of the study published in the journal PLOS Biology.
Violence between groups is ubiquitous among chimpanzees, Lemoine said. Skirmishes sometimes take place in overlapping border areas.
“Chimpanzees compete for space, which includes food resources. Large territories are beneficial because they reduce competition within the group, and female reproductive rates increase in larger territories,” Lemoine said.
The two neighboring groups monitored in this study were of equivalent size, between 40 and 45 individuals, with approximately five to six adult males and 10 to 13 adult females, the remainder consisting of adolescents, juveniles and infants. Males still dominate females, researchers say.
“Chimpanzees are extremely territorial. They carry out regular border patrols, during which individuals move to the periphery of their territory in a very coordinated and coherent manner,” Lemoine said.
“They engage in inter-group encounters that are violent, dangerous and stressful. Inter-group encounters can range from long-distance vocal exchanges, eye contact or physical contact to fighting, biting and chasing. Murders are common and victims can come from all age groups,” Lemoine added.
Climbing hills does not necessarily improve visual detection of members of a rival community, but rather provides improved acoustic conditions for detecting adversaries by sound.
“The hilltops are covered in vegetation and don’t offer good viewpoints,” Lemoine explained.
Atop the border hills, chimpanzees generally refrained from eating or foraging loudly, instead resting and listening.
They were more likely to advance into dangerous territory after going down a hill if rival chimpanzees were further away. Such incursions occurred about 40% of the time when the rivals were about three-tenths of a mile (500 meters) away, 50% when the rivals were about six-tenths of a mile (1 km) away, and 60% when the rivals were about 1.9 km away. miles (3 km).
Chimpanzees and closely related bonobos are the species closest genetically to humans, sharing about 98.8% of our DNA. The evolutionary lineages of humans and chimpanzees split about 6.9 to 9 million years ago, according to a study published in June.
Studying chimpanzee behavior can offer insight into our own species.
“We can better understand where we come from and what makes us human. We can better understand what kinds of behaviors and adaptations were present in the last common ancestor between humans and chimpanzees, and get a better idea of the sociality and behavior of ancient hominid species,” Lemoine said, referring to extinct species in the human lineage.
“It also teaches us what we have in common with our closest living relatives, how similar we are to wild animals and that we differ from our cousins only in degree and not in nature,” added The monk.