A massive once-in-500-years chimpanzee civil war has broken out

The largest-known group of wild chimpanzees has split in two. The aftermath has been brutal

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A community of around 200 chimpanzees living in Uganda's Kibale National Park has fractured into two warring factions, with one group launching a years-long campaign of lethal attacks against the other.

The Ngogo chimpanzees have been studied continuously for three decades, but in recent years, scientists have watched as a violent split unfolded in slow motion. From around 2015, what had been a single cohesive group began to polarise. Social ties frayed and shared territory became a contested border. By 2018, the break was permanent.