Uganda Chimpanzee Community Fractures into Lethal Civil War

Key Takeaways

• Researchers confirm eight years of lethal conflict has split Uganda's largest chimp group into warring factions.
• Since 2018, 24 killings occurred, including 17 infants, as former allies turned into lethal enemies.
• Three specific catalysts, including disease and leadership changes, drove the social collapse of the Ngogo community.
• This News highlights how group divisions among close genetic relatives can lead to human-like warfare patterns.

The world's largest known group of wild chimpanzees has fractured, locking in a vicious civil war for eight years. Located within Uganda's Kibale National Park, the once close-knit community of Ngogo chimpanzees has descended into lethal hostilities. Since 2018 alone, scientists have recorded 24 killings, a shocking statistic that includes the deaths of 17 infants. The intensity and duration of this violence have prompted researchers to publish their findings in the journal Science, suggesting that the events may offer critical insights into how early human conflict developed.

Lead author Aaron Sandel, an anthropologist from the University of Texas and co-director of the Ngogo Chimpanzee Project, noted the stark contrast between the past and present. He described the subjects as chimps that previously held hands, now trying to kill each other. While the exact cause of the split remains unclear, Sandel explained that chimpanzees are naturally territorial and usually have hostile interactions with outsiders. However, the Ngogo group, consisting of nearly 200 individuals, lived in harmony for decades, divided only into Western and Central sets that operated as a cohesive unit.

The polarization began in June 2015, when Western chimpanzees fled and were chased by the Central group. Unlike usual arguments that involved screaming followed by grooming and cooperation, this dispute led to a six-week avoidance period. Interactions became less frequent and significantly more aggressive. By 2018, two distinct groups had emerged, and Western members began attacking Central chimpanzees. In 24 targeted attacks, at least seven adult males and 17 infants from the Central group were killed, though researchers suspect the actual death toll is even higher.

The Catalysts of Conflict

Researchers have identified three likely catalysts that precipitated the fission of this massive community. The first event occurred in 2014 with the unexplained deaths of five adult males and one adult female. This loss disrupted social networks and weakened the ties across the subgroups. The following year, a change in the alpha male coincided with the first period of separation, a shift in dominance hierarchy that likely increased aggression and avoidance behaviors.