200 Chimpanzees Are Waging a Civil War, And It Has Been Going On for E

The largest known community of wild chimpanzees has fractured into two warring factions, and the killing has not stopped since 2015. A landmark study published in Science on April 9, 2026, documents the conflict as the first clearly confirmed permanent fission and civil war in wild chimpanzees, with devastating implications for understanding the evolutionary roots of organized violence.

A Community Too Large to Hold

The Ngogo chimpanzee community in Uganda's Kibale National Park, made famous by Netflix's Chimp Empire, was once a cohesive group of roughly 200 individuals, about four times the size of a typical chimpanzee community. Two main social clusters, Central (larger) and Western (smaller), coexisted for two decades. Males from both clusters hunted together, cooperated on territorial patrols, and mated across groups.

The first cracks appeared in 2014, when five adult males and one adult female died within about a month, likely from disease. These individuals had been crucial "bridge" animals whose relationships spanned both clusters and held the community together.

On June 24, 2015, researcher Aaron Sandel of the University of Texas at Austin observed something unprecedented: Western chimps approached Central chimps and then fled upon hearing them. The Central group gave chase. In 20 years of observation, nothing like this had ever happened.

Systematic Killing

Since the split, the breakaway Western group has launched 24 coordinated attacks on the Central group, killing at least 7 adult males and 17 infants, with an additional 14 adolescent and adult males disappearing and presumed dead.

Among the most documented killings was that of Basie, a 36-year-old gregarious male from the Central group. A patrol of approximately 13 Western adults surrounded him. Three cornered him. Ten piled onto him on the ground. His friend BF, a 53-year-old male, stayed with him through the night. The next morning, BF extended his hand, wanting Basie to follow. Basie died.

What Makes This Different from Gombe?

The only previous documented case of chimpanzee "civil war" was the Gombe Stream war of 1974–1978, observed by Jane Goodall. But critics argued that Goodall's team had been feeding the chimpanzees bananas, possibly distorting natural behavior. The Ngogo chimps were never provisioned. Their conflict unfolded in a fully natural context, with 30 years of baseline data. Lead author Sandel stated: "This is the first time that you could say definitively that the civil war is actually happening."

Implications for Understanding Human Conflict

The Ngogo data enters a long-running debate on the evolutionary origins of warfare. Luke Glowacki of Boston University observed: "This study demonstrates that the social dynamics of group fissioning and subsequent war can happen without any of the cultural markers that we often attribute human war to, differences in beliefs, language, religion, dress."

However, genetic modeling suggests permanent fissions of this kind occur in chimpanzee populations only about once every 500 years.