In the 1970s, Jane Goodall witnessed an unusual split among chimpanzees in Gombe, Tanzania. But now, researchers have observed a similar event with the Ngogo chimpanzee community in Uganda.

What's striking is that the chimps are killing former group members, showing how new group identities can override long-standing relationships. This raises questions about human nature and social cohesion.

The researchers analysed 24 years of data from social networks, GPS tracking, and demographic records to observe three phases: an abrupt shift into polarised clusters, increased avoidance between groups, and finally a permanent split by 2018. It's a stark reminder that cooperation can break down quickly when group identities are formed.

The authors suggest this may give us insights into our own species' behaviour, highlighting the complexity of social dynamics among both humans and chimps. But it also leaves one wondering: if chimps can do this, is it really such an anomaly for humans?