2023-11-03 10:47:37
Updated Friday, November 3, 2023 – 09:47
To establish and protect their territory, chimpanzees make periodic tours of the periphery and form a kind of “border patrol.”
A cympanic with its young..CAROL GUZYHSUS
Los chimpancs They use hilltops near territorial borders to gather intelligence on rival groups, often before making incursions into enemy territory at times when the risk of confrontation is low.
That is the conclusion of a study carried out by researchers from institutions of Germany, Ivory Coast, United States, France or United Kingdomand published in the journal ‘PLOS Biology’.
Until now, the tactical use of high ground in war situations was considered exclusive to humans. For the first time, one of the oldest military strategies has been observed in chimpanzees, which are the closest evolutionary relatives.
The researchers carried out a three-year study of two groups of neighboring chimpanzees in forests in the Ivory Coast. They tracked the primates as they traversed their respective territories, including an overlapping border zone where occasional skirmishes.
“TACTICAL WAR”
The team found that the chimpanzees were more than twice as likely to climb hills when heading towards this disputed border than when traveling towards the heart of their own territory.
While on top of the border hills, the chimpanzees were more likely to refrain from eating or search for food noisily and they spent time resting quietly, allowing them to hear distant sounds from rival groups, according to the researchers.
The further away the hostile chimpanzees were located, the more likely they were to advance into dangerous territory as they descended the hill. This suggests that these animals They measure the distance of their rivals on high ground and they act accordingly to carry out raids and avoid fights.
Other species of mammals, such as meerkats, they use high ground to watch for predators or call to their mates. However, the researchers point out that this is the first evidence that an animal other than humans makes strategic use of elevation to assess the risks of “intergroup conflict.”
“Tactical warfare is considered an engine of human evolution,” indicates Sylvain Lemoinebiological anthropologist at the Department of Archeology at the University of Cambridge (United Kingdom) and lead author of the study, who adds: “This behavior of chimpanzees requires complex cognitive abilities that help them defend or expand their territories and would be favored by the “natural selection.”
Lemoine emphasizes: “The exploitation of the landscape for territorial control is deeply rooted in our evolutionary history. In this use of warfare strategies by chimpanzees we may be seeing traces of the small-scale ‘protowar’ that probably existed in the populations prehistoric hunter-gatherers.
TA NATIONAL PARK
To carry out the work, teams of researchers spent between 8 and 12 hours a day following four groups that are ‘habituated’ to the presence of humans in the environment. Ta National Park (Ivory Coast), one of the few sites where data is collected simultaneously on multiple wild chimpanzee communities.
Project researchers had GPS trackers, through which they were able to reproduce maps of two border chimpanzee territories, including elevation data. These were compared with old French colonial maps to confirm the topography.
Each group consisted of between 30 and 40 adult chimpanzees. The study used more than 21,000 hours of tracking records from a total of 58 animals recorded between 2013 and 2016.
To establish and protect their territory, chimpanzees performed periodic tours around the periphery and they formed a kind of “border patrol,” according to Lemoine, who emphasizes: “Patrols are usually carried out in subgroups that stay close and limit noise. As an observer, one has the feeling that the patrols have begun. They move and move. stop at the same time, a bit like a hunt.
The type of hills near the border that were used for reconnaissance are known as ‘inselbergs’: isolated rock outcrops that break the forest canopy. The chimpanzees repeatedly returned to some of them, where they spent their time at the top more peacefully.
“These are not so much observation points as listening points. Chimpanzees They drum on tree trunks and emit excitable vocalizations. Panting calls to communicate with group members or assert their territory. “These sounds can be heard more than a kilometer away, even in dense forests,” explains Lemoine.
According to this anthropologist, “chimpanzees may climb to the tops of hills near the edge of their territory when they have not yet heard signs of rival groups.” “Resting quietly on a raised rock formation is an ideal condition for auditory detection of distant adversaries,” she adds.
MORE FOOD AND MATING
The researchers analyzed tactical movements in the half hour after a stop of more than five minutes on a hill near the border and compared them with movements after stops in low-lying border areas.
After a hilltop reconnaissance, the probability of advancing into enemy territory increased from 40% when rivals were 500 meters away, to 50% when rivals were 1,000 meters away, and to 60% when rivals were close. They were at 3,000 meters.
“Chimpanzees often They expand their territory by invading and patrolling that of their neighbors. Gathering information in the hills will help them do this and at the same time reduce the risk of encountering enemies,” says Lemoine, who points out that having more territory can increase food supply and mating possibilities.
#Chimpanzees #humans #high #ground #war #tactic #eye #enemies