The world’s largest group of wild chimpanzees split into two factions and began killing one another after decades of harmony. Researchers were astonished when the 200-strong Ngogo chimps of Kibale National Park, Uganda, whom they had observed for more than 20 years, turned on one another, leaving 28 dead, all from one side. Lead author, Aaron Sandel, of the University of Texas wrote in Science: “Biting, pounding the victim with their hands, dragging them, kicking them.” “It is hard for me to wrap my head around the fact that yesterday’s friend turned into today’s foe. Males in the two groups grew up with each other, knew each other their entire lives,” said senior author John Mitani of the University of Michigan. Researchers attributed the split to several factors, including the group becoming too successful and too large, which led to competition for food and mates. In 2014, seven died from illness, which Reuters reports could have disrupted social relationships. Then, in 2015—around the time relations began to fray—there was a change in leadership, as the old boss was deposed by a chimp called Jackson. By 2017, two clear groups had formed, and violence broke out in 2018. The violence has continued with one adult male, one adolescent male, and two infants killed in the past two years.
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