It’s easy to blame war on religion, ethnicity or politics. But chimpanzees in Uganda just experienced a civil war without any of those things – and the incident may reshape how we think about peace.
A new study published in Science documents how a once-unified group of roughly 200 chimpanzees in Kibale National Park fractured into two warring factions, with lethal violence following.
The cause wasn’t territory or resources. Instead, scientists are likening it to the collapse of social bonds.
Lead author Aaron Sandel of the University of Texas at Austin and colleagues argue the discovery “encourages a reevaluation of current models of human collective violence.”
Researchers Studied the Chimpanzees Since 1995
For more than 30 years, scientists have tracked the Ngogo chimpanzees in Uganda.
Between 1995 and 2014, the chimps maintained long-standing friendships across three distinct clusters that mated, hunted and protected each other. Highly social individuals acted as “social bridges,” connecting different cliques and holding the larger group together.
Then, in 2014, five adult males died – likely from disease. Those males had served as key connectors between groups. Once they vanished, low-level tensions escalated into a full rupture. Around 2015, the community split into two factions.
Between 2018 and 2024, chimps from one cluster killed several dozen chimps from the other.
“Although an alpha male change alone does not explain why the Ngogo group split, it may have amplified tensions between the two clusters,” the authors wrote.
What Humans Can Learn From the Chimpanzees
Humans share about 98.8% of their DNA with chimpanzees, and the two species share common ancestors from about 6 million years ago.
The once-strong friendships – and eventual fracture – of the Ngogo chimps could give researchers key insights into why wars start, even between humans.
The dominant theory holds that war stems from cultural differences, and peace efforts typically focus on cultural diplomacy. The Ngogo findings challenge that assumption.
“Relational dynamics may play a larger causal role in human conflict than often assumed,” Sandel writes.
Primatologist Sylvain Lemoine of the University of Cambridge, who was not involved in the study, emphasized the broader evolutionary implications.
“These findings tell us indeed that these civil-war-like types of conflicts were possible in the course of human evolution,” said Lemoine, per the New York Times.
In an accompanying perspective in Science, James Brooks offered a pointed takeaway.
“Humans must learn from studying the group-based behavior of other species, both in war and at peace, while remembering that their evolutionary past does not determine their future,” he wrote.
Researchers Send a Hopeful Message to Humans
If the roots of conflict are simpler than ideology, the path to peace may be simpler too – though not necessarily easier.
Sandel frames the lesson in strikingly personal terms. The study suggests that what prevents communities from fracturing isn’t grand diplomacy but the everyday work of maintaining relationships.
“What we have to do is maintain interpersonal relationships,” Sandel wrote, per the Scientific American. “In our own daily lives with the people that we interact with, if we can reunite-even in the face of conflict-then I think that’s a recipe for maintaining peace.”
He frames this kind of everyday conflict management as nothing less than a civic obligation.
“If that’s the case, then conflict management in our own lives becomes a civic duty to bring about a more peaceful world,” Sandel says.
“In some cases, it may be in the small, daily acts of reconciliation and reunion between individuals that we find opportunities for peace,” he added.
Despite sharing 98.8% of their DNA with chimps, humans are not prisoners of biology. The Ngogo study shows that relationships can drive deadly divisions – but they can also foster cooperation.
The same social bonds that fractured under pressure are the ones that held the group together for decades.
The lesson from a Ugandan forest may be deceptively straightforward: the people who connect us to one another matter. When those bridges disappear, conflict can follow.
Protecting those bonds isn’t just good manners. It may be essential to keeping the peace.