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Violent split in Ngogo chimpanzee community
Scientists have documented a prolonged and brutal conflict within the Ngogo chimpanzee group in Uganda's Kibale National Park, marking one of the longest recorded instances of intra-group violence among wild chimpanzees. The once-unified community of nearly 200 individuals has been divided since 2018, resulting in at least 24 killings, including 17 infants.
From harmony to hostility
For decades, the Ngogo chimpanzees coexisted peacefully, despite being informally split into Western and Central subgroups. Lead researcher Aaron Sandel, an anthropologist at the University of Texas and co-director of the Ngogo Chimpanzee Project, described the group as closely bonded, with individuals often holding hands. However, tensions first surfaced in June 2015 when Western chimpanzees fled after being chased by the Central group.
Initially, the conflict followed typical chimpanzee behavior-screaming, chasing, and eventual reconciliation through grooming. But after the 2015 incident, interactions became rare and increasingly aggressive. By 2018, the division solidified, with the Western group launching targeted attacks on Central chimpanzees.
Death toll and possible causes
The study, published in Science, reports at least seven adult males and 17 infants from the Central group killed in 24 attacks. Researchers suspect the actual death toll is higher. While the exact trigger remains unclear, several factors may have contributed:
- Competition for resources due to the group's large size.
- Male-male rivalry for mating opportunities.
- Three specific catalysts identified by the research team, though not detailed in the study.
Implications for understanding human conflict
The findings challenge assumptions about the roots of human warfare. Sandel and his colleagues argue that the Ngogo chimpanzees' shift from cooperation to lethal aggression-despite sharing no human constructs like religion, ethnicity, or political ideologies-suggests that relational dynamics may play a more significant role in conflict than previously thought.
"In the case of the Ngogo fission, individuals who lived, fed, groomed and patrolled together for years became targets of lethal attacks on the basis of their new group membership," the researchers wrote.
James Brooks, a researcher at the German Primate Center, emphasized the broader lesson in a commentary for Science:
"Humans must learn from studying the group-based behaviour of other species, both in war and at peace, while remembering that their evolutionary past does not determine their future."
James Brooks, German Primate Center
Unanswered questions and ongoing research
The study raises critical questions about the nature of group dynamics and violence in primates. While the researchers have identified patterns, the precise reasons for the Ngogo chimpanzees' sudden descent into conflict remain unclear. Further observations may shed light on whether similar divisions occur in other large primate communities and what mechanisms drive such drastic behavioral shifts.
