Wild chimpanzees in Uganda are fighting a rare "civil war," which seems to have begun when a huge community divided, leading to sustained and deadly conflict between animals that had previously been allies and friends.

Conflicts between different groups of chimpanzees (Pan troglodytes) are relatively common as they compete for key resources, like fruit trees, water supplies and trees that provide suitable nesting material. However, conflicts within previously unified communities are much rarer.

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Researchers revealed that from about 2015, the huge Ngogo community — which then numbered about 200 chimps — ruptured into two distinct clusters that lived and reproduced separately. The core of one of the groups was the clique of three adult males.

At this stage, there were still ties between many individuals in the two groups, and they still cooperated and bonded, but by 2018, the last social ties disintegrated and aggression grew during border patrols of their separate territories.

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