Deep in a Ugandan forest, 200 chimpanzees have been at war with each other for nearly ten years. They are not squabbling or playfully scrapping over a mango. Scientists report that it’s a fully coordinated lethal war between chimps who used to be family.

This community is the Ngogo chimpanzee community in Kibale National Park, and their story just got published in the journal Science. It reads like a nature documentary nobody asked for.

For decades, researchers have observed the chimps grooming each other, sharing food, raising the young, and maintaining peace. Then in 2015, something snapped. The group split into two sides, now called the Central and Western factions, and former friends started hunting each other down. Scientists who witnessed the first clash described pure chaos. Screaming, chasing, and bodies crashing through the forest in a chaotic scene. They planned and ambushed each other.

The uncomfortable part is that nobody fully knows why it happened.

The best theory so far points to the large size of the community. Most chimp groups have around 50 members. Ngogo had nearly 200, which may have strained social bonds and turned everyday competition into something darker.

Then in 2014, five key males died within weeks of each other, probably from disease. These were the peacekeepers, the chimps that kept both sides connected and calm. Once they were gone, the whole thing unravelled fast.

What makes Ngogo so significant is that this event has only happened once before in recorded history, in Tanzania in the 1970s under Jane Goodall. That case was long dismissed because researchers had been feeding the chimps, which many felt had distorted their behavior. Ngogo had no such interference. This time, nothing was staged or influenced. It’s just nature doing something brutal, and scientists are watching every second of it.

Since 2018 the scientists have recorded 24 killings, including 17 infants. “These were chimps that would hold hands,” lead author Aaron Sandel told the Science podcast. “Now they’re trying to kill each other.”

Sandel, an anthropologistfrom the University of Texas in the US, and co-director of the Ngogo Chimpanzee Project, acknowledges that chimpanzees are very territorial, with their interactions with those from other groups described as hostile.

However, Sandel cannot fathom why the nearly 200 Ngogo chimpanzees, who had lived in harmony for several decades, suddenly became sworn enemies.

The war is still ongoing. Attacks continued through 2025 and into 2026, long after the study’s data cutoff.

Here is the part that scientists are not openly discussing. We share 98 percent of our DNA with these chimps. For no obvious reason, they went to war with each other. No famine, no invasion, no existential threat. They are just like us humans, going by how we destroy our very own communities.