Scientists from Arizona State University and The University of Texas at Austin announced on Apr. 9 that the largest known group of wild chimpanzees has permanently divided into two, a phenomenon described as extremely rare. The research, based on three decades of field observations in Kibale National Park, Uganda, follows the Ngogo chimpanzees featured in the Netflix series “Chimp Empire.”
The significance of this study lies in its documentation of not only the split but also subsequent violent encounters between the new groups. Researchers observed that while many primate species often divide to reduce competition for resources, such permanent splits are almost never seen among chimpanzees—occurring roughly once every 500 years according to genetic evidence.
The team reported that prior to 2015, the community maintained cohesion through flexible subgroups and strong social ties. In 2015, polarization began as Western and Central clusters started avoiding each other after changes in male dominance and deaths among key adult males. By 2018, two distinct groups with separate territories had formed. From then until 2024, there were seven lethal attacks on adult males and seventeen on infants by members of the Western group against those from Central.
“What’s especially striking is that the chimpanzees killed former group members,” said Aaron Sandel, associate professor at The University of Texas Austin and lead author. “The new group identities overrode cooperative relationships that existed for years.” Kevin Lee from Arizona State University said: “Interestingly, in the Ngogo study, most of the active aggression has been instigated by the smaller, but more cohesive, of the two daughter groups formed by the fission.” He added that targeted attacks allowed this smaller West group to push out their rivals despite being outnumbered initially.
Yixuan He from ASU led analysis using network science techniques to determine when polarization occurred before full separation: “I led the construction of weighted networks from chimpanzee time series data… After constructing these networks… I tried to see whether polarization was developed before actual split.”
Kevin Langergraber at ASU said: “Chimpanzees have been subject of more long-term studies than perhaps any other animal… This study shows they still have interesting and important things to teach us.”
In related news about Arizona State University’s broader activities,according to a press release, ASU partners with Argos Vision for a pilot program using smart traffic cameras aimed at improving safety in Phoenix locations.
Additionally,Arizona State University was named number one for innovation for eight consecutive years by U.S. News & World Report.
