‘Civil war’ among chimpanzees recorded for the first time

They were once a convivial, unified group that lived, fed, groomed, and patrolled together, with may be the odd scuffle. But then one day, on June 24, 2015, their social fabric began to fray. And very soon, an organised lethal conflict, akin to a ‘civil war’, ensued among one of our closest relatives — chimpanzees — in Kibale National Park, Uganda. Then the Ngogo chimpanzee group, as they are known, split then forever.

After three decades of observation of the group’s behaviour and demographics, researchers observed that in 2015, the community began fracturing into two polarised clusters, as they report in a paper in Science . By 2018, the fission, both spatial and social, was irrevocably complete; but the aggression escalated between the western and central groups.

The western group’s coordinated attacks on the central one resulted in the death of several adult male chimps, and the severe injury of an alpha male in 2017. By 2021 there were reports of frequent infanticide too. In all, seven attacks on adult males and 17 on infants were recorded by scientists between 2018 and 2024.