The Chimp Civil War In Uganda

From the BBC (via AOL): "Chimpanzees in Uganda locked in vicious 'civil war', say researchers." The article begins:

    The world's largest known group of wild chimpanzees has split and been locked in a vicious "civil war" for the last eight years, according to researchers.

    It is not clear exactly why the once close-knit community of Ngogo chimpanzees at Uganda's Kibale National Park are at loggerheads, but since 2018 the scientists have recorded 24 killings, including 17 infants.

    "These were chimps that would hold hands," lead author Aaron Sandel said. "Now they're trying to kill each other."

The death toll is probably higher, as Scientific American relates:

Between 2018 and 2024, the researchers witnessed Western adults kill seven males and 17 infants from the Central group, the paper reports. An additional 14 adolescent or adult Central males disappeared during that time, and their bodies were never recovered—these males hadn’t shown signs of illness, so at least some of them also may have been victims of Western chimpanzee aggression. Sandel’s team has documented at least two more attacks on Central males since the data analysis for this study ended in 2024.    

And from NBC News:

    Since the social breakdown, it’s been a one-sided rout: The Western chimps, which started as the minority group, are responsible for all attacks since the groups split permanently in 2018. Their population has risen from 76 to 108, while the Central chimps’ population has seen a stepwise decline.

    The attacks are vicious. Western chimps have ripped infants from their Central mothers’ chests and battered them to death.

    When attacking adult or adolescent males, Sandel said the chimpanzees use collective violence.

    “There’ll be like five or 10 chimps piled on him, holding him down, biting him, slamming their fists on him, kicking him, dragging him,” he said. “They’ll rip off their testicles.”  

Because the chimpanzees don't suffer from "human constructs" like "religion, ethnicity and political beliefs" the researchers were puzzled at why they would fight. But, again from the NBC article:

    Mitani and Sandel think the group’s size might have played a role in the acrimonious split. Whereas most chimpanzee groups involve 50 animals, Ngogo featured some 200, which might have stretched its members’ ability to maintain social connections and heightened competition for food and mates.

    Additionally, before the split, five adult males died, possibly of sickness, which might have severed key social connections. Then, in 2015, a new alpha male emerged.

    “That’s a big deal,” Mitani said, because it happens perhaps once every six to eight years. “This disrupts matters quite a bit, levels of aggression can increase, social relationships can be altered.” 

This isn't the first time this has happened. The NBC article relates:

    About 50 years ago, the late Jane Goodall and her research team witnessed a series of attacks in Tanzania’s Gombe National Park, in which a group of chimpanzees splintered from the group. The remaining members of the original group then hunted and killed all the males in the splinter group.

    Researchers named it the “Four-Year War.”

    Anne Pusey, a professor emerita of evolutionary anthropology at Duke University, did field work at Gombe until 1975, during beginning of the fighting. She said the circumstances ahead of the split and “gang attacks” there were “similar and shocking” to what was observed in Ngogo.

    In the lead-up to the killings in Gombe, there was a dearth of females ready to mate, some of the friendliest older males died and the group experienced a change in alpha male.

    “Those social bonds broke down and changed to become antagonistic,” Pusey said.

    Joseph Feldblum, an evolutionary anthropologist who has studied the Gombe fighting, said the new findings validate the earlier ones.

    “This sort of behavior, while rare, is part of the natural course of chimpanzee behavior,” he said. ​

    Given what happened at Gombe, Mitani said, he’s concerned that the Central group in Ngogo is “doomed.”

    “The writing is on the wall,” he said.

    Because so many infants have been killed and so many females are defecting, Mitani added, “I think we’re witnessing an extinction event.” 

 The Scientific American article indicates that at the time, the Gombe events were thought to be due to interactions with humans, stating: "But because Gombe chimpanzees frequently ate bananas from humans, some primatologists doubted whether the group fission was a natural behavior." But this event in Uganda doesn't feature any comparable human interactions, which suggests that the Gombe event was also not due to receiving bananas. 

    So what are the implications here? According to the NBC article:

    Researchers often attribute human war to cultural differences, but that’s not the case with chimps, Sandel noted.

    “They don’t have ethnicity and religion and political ideology, all these cultural traits that we often identify as a major cause of conflicts in humans, especially internal conflicts like civil wars.”

    Instead, the researchers think the violence stemmed from a breakdown of friendships and escalations between cliques and rivals. Sandel said this might indicate those factors play a more important role in human civil war than some would expect. The authors suggest small acts of reconciliation and reunion could be the key to peace. 

    However, that doesn't flow from the other information in the article. Both groups--the prior Gombe and this one in Uganda--represent conflicts that arose because the two groups of chimpanzees ceased being united and had split. In the Gombe incident, one group physically broke off from the other group; in this one, the two groups apparently had been united by a shared population and when those individuals in the shared population died, the split between the groups was complete. In other words, it appears that the key factor is whether there was a united single group. 

    Applying it to the modern West, it would suggest that when you have a single dominant culture, it should help reduce conflict. That was the strategy followed in the past where groups immigrating to the United States, for instance, were expected to assimilate. But this study would suggest that when that single dominant culture fractures, conflict is inevitable.