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Environment
Apr 09, 2026

Chimpanzees Wage 'Civil War' in Uganda's Kibale National Park

AI Summary
Researchers have documented a 'civil war' among wild chimpanzees in Uganda's Kibale national park, where two groups that were once part of a single, cohesive group have turned on each other, resulting in coordinated attacks and significant loss of life.

For the first time, scientists have observed a 'civil war' in wild chimpanzees, where a once unified group turned on itself, leading to a years-long conflict. In a study published in the journal Science, researchers detail the dramatic shift in behavior among the Ngogo chimpanzee group in Uganda's Kibale national park.

Primatologist Aaron Sandel, who led the research, noted that the conflict began in 2015 when the group's dynamics started to change. A change in social hierarchies, the death of key older individuals, and a disease outbreak in 2017 contributed to the group's fracture. By 2018, two distinct groups had emerged: the western chimps and the central chimps.

The conflict escalated into 24 sustained and coordinated attacks by the western group on the central group over seven years, resulting in the deaths of at least seven adult males and 17 infants. This level of in-group violence is rare in the animal kingdom and has significant implications for understanding human conflict.

Sandel suggests that human activities disrupting social cohesion, such as deforestation, climate change, or disease outbreaks, could make such inter-group conflicts more common among chimpanzees, who are already threatened with extinction. The study highlights the fragility of social ties and the potential for group cohesion to be disrupted under specific circumstances.

Brian Wood, an evolutionary anthropologist, noted that the western chimps increased their Darwinian fitness by decreasing the survival and reproduction of their former community members. This conflict has resulted in the lowest survivorship ever documented in a wild chimpanzee community.