Chimpanzee ‘Civil War’ and Lessons About Social Collapse

In the mid-1970s Jane Goodall, after more than a decade observing chimpanzees at Tanzania’s Gombe National Park, recorded something that overturned her earlier impressions: a once-unified community split into two factions that began systematically killing one another. She likened the violence to a civil war and said it revealed a brutal side of chimps she had not expected. Decades later, researchers report a second, prolonged episode of factional violence among wild chimpanzees, this time at Ngogo in Uganda’s Kibale National Park — the largest known chimpanzee community and the subject of more than 30 years of observation. At its height nearly 200 chimps in Ngogo ranged together in intermingling subgroups, or clusters. Individuals from different clusters mated, hunted together and cooperated against outsiders; researchers even filmed males from separate clusters holding hands. That cooperative pattern began to break down in 2015. Primatologist Aaron Sandel, the study’s lead author, points to a day in June when observers watching Western-cluster chimps heard members of the larger Central cluster nearby. The Western animals suddenly went quiet, touched one another in apparent reassurance, then fled — pursued by Central members. The two clusters then avoided one another for six weeks, a behavior never seen before at Ngogo. Over the next few years polarization deepened; by 2018 the clusters were essentially separate groups and lethal clashes followed. The first documented victim was Errol, an adolescent male from the Central cluster whom Sandel had known since he was young. Over the following seven years the Western group killed at least six other adults and 17 infants from the Central cluster, and the fighting has continued. Why Ngogo fragmented and turned violent remains uncertain. The authors list several possible contributors: the community’s large size, increased competition for food, male–male rivalry, and a string of natural deaths in 2014 — five adult males and one adult female — that may have weakened alliances and social networks. Michael Wilson, a primatologist not involved in the study, emphasizes that such conflicts can arise without the cultural trappings humans attach to war: “Lions don’t have religion and political parties or ideologies. Neither do wolves or ants for that matter.” For Sandel, the absence of human-style ideologies in these chimpanzee fights is both sobering and instructive. If great apes can descend into lethal, factional violence without religion, ideology or formal institutions, that suggests interpersonal relationships and the texture of social bonds may play a larger role in human conflict than we often credit. Strengthening ties, forgiving old grievances and preventing people from becoming strangers to one another could help reduce the risk of escalation. As Sandel puts it, “If you act like a stranger, you become a stranger.” The Ngogo episode, like Goodall’s earlier observations, shows that our close relatives can reveal uncomfortable truths about violence and social breakdown — and that attention to everyday connections might be one practical way to lessen the chances of similar fractures among people.