A rare and deadly conflict has erupted among chimpanzees in Uganda's Kibale National Park, with researchers comparing the violence to a human civil war. The conflict began in 2015 when a large, cohesive chimpanzee community split into two distinct subgroups, leading to sustained aggression and fatalities. At least 28 chimpanzees, including 19 infants, have been killed since the division, according to a study published in the journal Science. The research, conducted by scientists from the University of Texas and the University of Michigan, provides the most detailed documentation of such intra-group violence in chimpanzees to date.
The Ngogo chimpanzee community, one of the largest known groups of wild chimpanzees, had been studied continuously since 1995. For the first two decades, the group existed as a single, interconnected community with overlapping clusters of individuals. However, between 1998 and 2014, researchers observed the formation of more stable cliques within the group. By 2015, these cliques had solidified into two distinct subgroups—the Western and Central clusters—which began to behave aggressively toward one another.
The violence escalated rapidly, with chimpanzees attacking and killing members of the opposing subgroup. Infants were often torn from their mothers, and males were observed engaging in brutal fights. By 2018, the two subgroups had stopped using the same territory and treated each other as enemies. Researchers note that this is only the second documented case of such a division and subsequent lethal conflict within a chimpanzee community, the first being observed by primatologist Jane Goodall in Tanzania in the 1970s.
The study's authors suggest that the findings offer insights into human conflict, as chimpanzees and bonobos are our closest genetic relatives. The research highlights how group identities can shift and lethal aggression can arise, even among individuals who were once allies. The long-term implications of this conflict for the chimpanzee population remain unclear, but researchers emphasize the importance of continued monitoring and conservation efforts.