Wild chimpanzees recorded waging ‘civil war’ with coordinated attacks between two groups

Key Points:

• Researchers have documented what may be the first observed "civil war" in wild chimpanzees within the Ngogo group in Uganda, where a once unified community split into two hostile factions between 2015 and 2018, leading to lethal conflicts.
• Over seven years, the western subgroup attacked the central subgroup 24 times, killing at least seven adult males and 17 infants, marking unprecedented in-group violence among chimpanzees.
• The split was likely triggered by shifts in social hierarchies, including the submission of the alpha male, deaths of key older individuals, and a disease outbreak, which weakened social cohesion and facilitated polarization.
• This phenomenon, rare in chimpanzees and thought to occur only every 500 years, raises conservation concerns as human activities like deforestation and climate change may increase such violent divisions.
• Experts highlight that the conflict aligns with Darwinian fitness strategies, where one group enhances its survival and reproduction by undermining rivals, and underscores the importance of social ties and network connectivity for group cohesion.