Chimpanzees make tactical use of high elevation in territorial contexts

Area of Science:

• Primate Behavior
• Cognitive Ecology
• Evolutionary Anthropology

Background:

• Tactical warfare, particularly the use of high elevation, is a proposed driver of human cognitive evolution.
• The collective use of high ground for early detection and low-risk maneuvers in territorial conflicts is considered unique to humans.
• It remains unknown if other animal species employ similar topographical tactics.

Purpose of the Study:

• To investigate whether chimpanzees exhibit tactical use of topography for territorial advantage.
• To determine if chimpanzee behavior aligns with strategic elevation use in conflict scenarios.

Main Methods:

• Utilized a unique 3-year dataset of simultaneous behavioral and ranging data from two neighboring western chimpanzee groups.
• Collected data in Taï National Park, Côte d'Ivoire.
• Analyzed travel and activity patterns in relation to territorial borders and topographical features.

Main Results:

• Chimpanzees were more likely to ascend hills when moving towards territorial borders compared to moving away.
• On border hills, chimpanzees engaged in activities that facilitated information gathering about rivals.
• Post-hill movement indicated decisions favoring lower-risk engagement, suggesting elevation use aids in detecting rival presence or absence.

Conclusions:

• Chimpanzee use of elevated terrain supports tactical advantages in territorial defense.
• Topographical strategy in chimpanzees suggests seeking otherwise inaccessible information to modify behavior.
• This points to sophisticated cognitive abilities and selection for cognition in species with coordinated territorial defense.