What plunged these chimps into civil war? A new study traces the breakdown: Decades of observations tracked the fraying of once-friendly relations among Ugandan chimpanzees.

The article focuses on a 30-year study of chimpanzee behavior in Uganda’s Kibale National Park, documenting how peaceful relations between two large chimp groups—Central and Western—deteriorated into lethal violence beginning in 2015. Despite abundant food resources, factors such as overpopulation, loss of key social males, and reproductive competition contributed to the groups’ split and subsequent attacks, with the Western males killing multiple Central group members. The findings suggest that chimpanzee warfare arises from biological and social dynamics rather than cultural or ideological differences, offering insights into the roots of intergroup conflict in primates while highlighting differences from human warfare, such as the absence of revenge killings due to lack of language. [Extracted from the article]