Chimpanzees use topography tactically to see where their rivals are.Credit: Neurobite/ iStock/ Getty Images Plus
Chimpanzees, like humans, move to higher elevations to gather information about rival groups in territorial conflicts to avoid risky confrontations, a study published in PLOS Biology has found.
Researchers from the Taï Chimpanzee Project examined the behaviour of two neighbouring groups of western chimpanzees (Pan troglodytes verus) in the Taï National Park in Côte d’Ivoire between 2013 and 2016. They found that just as humans have long used high elevation terrain during war, chimpanzees also use topography tactically to see where their rivals are. They adjust their behaviour based on the information gathered, pointing to the use of sophisticated cognitive abilities in coordinated territorial defense.
On hills, the chimpanzees spent more time resting than they did feeding or travelling to better listen to other groups. After descending from a hill, the chimpanzees use the information they collected to make travel decisions. Once back at lower elevations, they were more likely to advance when rivals were distant, and their next move tended to be one that would reduce the risk of encountering enemies.
“Upon leaving hills, based on information gathered, how far rivals were and how many they were, they decide to engage towards rivals only when the situation is safe [in terms of] numerical superiority and rivals being far away. This reveals sophisticated socio-cognitive skills at play to plan, anticipate where and when to go to get relevant information to minimise risks of warfare engagement,” said Sylvain Lemoine, a co-author, from the University of Cambridge.
The idea for the research, Lemoine explains, was based on observations of wild chimpanzees going to high ground before and during border patrols. The researchers wanted to investigate the potential adaptation caused by out-group conflicts and to test the idea that high ground and landscape features can be efficiently used to establish territorial tactics.
“Military tactics of using physical landscape to weigh the odds of dangerous conflicts are deeply rooted in our evolutionary past,” said Lemoine. The group wanted to study whether, like humans, conflict in chimpanzees can drive adaptations, like territorial tactics and cooperation.
