Chimpanzees in Uganda locked in rare vicious “civil war”

A group of African chimpanzees are giving Game of Thrones a run for its money.

Scientists believe they’ve documented the first observed “civil war” in a group of wild chimpanzees, in a study published Thursday in Science.

This behavior, featuring lethal conflict between two groups that were once closely affiliated, had previously thought to be unique to humans.

How things went down

The Ngogo chimpanzees in Uganda make up the largest known group of wild chimps on Earth. For about 20 years (1995-2015), the group coexisted in harmony, forming social hierarchies and generally keeping the peace.

But starting around 2015, cracks started to form. By 2018, the group had split into two factions: the Western and Central communities, with their formerly shared home turf turning into a border routinely patrolled by chimps.

• Over the next seven years, the smaller group began launching coordinated, lethal attacks that started off targeting rival adult males, but later expanded to younger chimps too.
• Researchers have recorded at least 24 chimpanzee deaths in the ongoing conflict, though they believe the true number is higher.

What sparked the split?

One leading theory is that the chimps became victims of their own success after the group grew unusually large, with members starting to feel competition for resources and mates from within their own community despite abundant resources.

Another centers around a series of three surprisingly human-like catalysts in the lead-up to all-out civil war.

1. Six adults mysteriously died in 2014, which could have disrupted social networks and weakened social ties across the subgroups.
2. The following year there was a change in the alpha male, which researchers say coincided with the first Western-Central community split.
3. A respiratory epidemic in 2017 killed 25 chimps across both groups, with one adult male who died being "among the last individuals to connect the groups," per the study.

History repeats itself: Researchers say genetic evidence suggests that a similar chimpanzee “civil war” probably happens once every 500 years among the animals.