Civil War in the Jungle: Deadly Chimpanzee Split Revealed

A groundbreaking 30-year study published in the journal Science has documented a rare and violent “civil war” within the world’s largest known community of wild chimpanzees. Researchers at the Ngogo research site in Uganda’s Kibale National Park observed a once-unified group of over 200 chimpanzees fracture into two rival factions, leading to years of coordinated and lethal attacks.

The Fracture of the Ngogo Community

The community, which had lived in relative cohesion for decades, began to break down between 2015 and 2018.

• The Split: The group permanently divided into a Western faction (76–108 members) and a Central faction (approx. 100 members).

• Cause of Tension: Researchers suggest the death of “bridge” individuals who linked different cliques, combined with the rise of a new alpha male, destabilized the social network.

• Rare Event: This is only the second time such a permanent “fission” and subsequent war has been rigorously documented; genetic evidence suggests these events may occur only once every 500 years.

The “Chimp War” Tactics

What shocked scientists was not just the violence, but the fact that the attackers were targeting former allies they had previously groomed, fed, and patrolled with.

• Coordinated Raids: Between 2018 and 2024, the Western group launched at least 24 coordinated attacks into Central territory.

• Casualties: The conflict has been described as a “one-sided rout”. As of early 2026, at least 28 members of the Central faction have been killed, including 7 adult males and 19 infants.

• Brutal Methods: The attacks often involved ambushes of isolated individuals, resulting in severe injuries and mutilations.

Why This Matters for Science

This “civil war” challenges existing theories about the origins of group conflict.

• Beyond Culture: The study suggests that lethal polarization can occur based solely on shifting social ties, even without human-like “cultural markers” such as religion, language, or ideology.

• The “Human Connection”: Lead researcher Aaron Sandel noted that seeing neighbors kill neighbors brings chimpanzee behavior closer to the “human condition” than previously thought.

• Conservation Risk: Such internal conflicts can cause a “stepwise decline” in population, threatening the survival of communities already facing extinction.