On the boundary of dangerous territory, a troop of about 30 individuals engaging in a border patrol climbs a rocky hill to conduct reconnaissance. Detecting the sounds of adversaries a bit too close for comfort, the squad retreats. There is no reason to risk a fight with the odds against you.

It is a scenario that has unfolded innumerable times in the history of human warfare. But in this case, it involved not people but chimpanzees in Tai National Park in southwestern Ivory Coast, West Africa's largest protected area of rainforest.

Researchers said on Thursday they have documented the tactical use of elevated terrain in warfare situations while observing on a daily basis two neighboring communities of wild western chimpanzees in Tai National Park for three years.