MISRYOUM newsroom reported that the world’s largest known community of wild chimpanzees has, over time, done something researchers didn’t expect to see at this scale: it split into two hostile camps and turned lethal.
In Uganda’s Kibale National Park, the Ngogo chimpanzee group—once a cohesive community—has been unraveling for years. At its peak, nearly 200 chimps moved through shared territory in smaller subgroups, known as clusters. Males and females from different clusters intermingled, mated, hunted together, and even fought off outsiders as a kind of larger team.
The moment that echoes in the scientific record goes back decades. In the mid-1970s, primatologist Jane Goodall, during her long work with chimpanzees in Tanzania’s Gombe National Park, witnessed a brutal breakdown among chimps that had previously seemed to live together. Researchers had never really seen anything like it: factions formed, and chimps systematically killed others they’d grown up around. It left Goodall adjusting her view of “one of humanity’s closest relatives,” as she later put it—less gentle than “nicer” once opportunity arose.
Now, in the journal Science, a team of researchers describes a second, ongoing “civil war” inside Ngogo. Misryoum editorial desk noted the report draws on more than 30 years of observations. It starts, researchers say, with subtle signs of tension—then a sudden behavioral rupture. Misryoum analysis indicates the split became unmistakable by 2018, when the clusters were essentially completely separate groups, and after that, killing began.
The lead author, Aaron Sandel, says he can even pinpoint a specific day in June 2015 when things changed. He was observing Western cluster chimpanzees in their territory when they heard other chimps nearby—apparently from the larger Central cluster. The Western chimps “quieted all of a sudden,” and then began touching each other in a kind of reassurance gesture, as if they were nervous. Instead of falling back into the normal pattern of reuniting and intermingling, the Western chimpanzees fled while Central chimpanzees chased them. Then, for roughly six weeks, the groups avoided each other—“very clear, like on the ground,” Sandel said, that “something big has just happened.”
Over the next several years, polarization intensified. By then, researchers say, the first lethal attack involved an adolescent male from the Central cluster named Errol—someone Sandel had watched grow up. After that, Misryoum newsroom reported that over the next seven years the Western group killed at least six other adults and 17 infants from the Central cluster. The fighting continues to this day.
Why Ngogo split, and why relations curdled into violence, still isn’t fully settled. In the paper, Sandel and co-authors suggest multiple contributing factors: group size, competition for food, and male-to-male competition. They also point to a possible social weakening before the break—natural deaths of five adult males and one adult female in 2014, before intergroup divisions took root.
Michael Wilson, a primatologist at the University of Minnesota who wasn’t involved in the study, said the research is uncomfortable in a familiar way: group conflict can emerge without the human-style institutions people usually blame for civil wars. Lions don’t have religion and political parties, Wilson noted; neither do wolves or ants. Chimps, he emphasized, don’t have those things either. And Sandel’s takeaway is partly hopeful. If lethal conflict can arise in the absence of human political ideology, maybe the underlying relationships matter more than we assume. There’s even a personal edge to it: “If you act like a stranger, you become a stranger,” Sandel said. One hopes it’s a lesson that lands, not just in a forest where branches crack softly—but in everyday life, where the distance between “us” and “them” can be decided, sometimes, long before anyone starts running.
Sperm whale clicks mirror human speech patterns