Chimpanzees in Uganda's jungles are waging the bloodiest war in recorded history. No one knows why.
In the forests of Kibale National Park in Uganda, a drama is unfolding that is forcing scientists to rethink their understanding of the origins of human aggression.
Chimpanzees of Kibale National Park. Photo: Danita Delimont / Getty Images
When primatologists began working in Kibale in 1995, they were struck by the number of chimpanzees: over 100 individuals in an area of about 26 square kilometers. Over the years, the group continued to grow and eventually increased to 200 animals. Years of observations of this population, named the Ngogo group – after the hill around which they live – have brought a deep understanding of the lives of our closest relatives.
One of the scientific sensations was the discovery that Ngogo females experience menopause – a phenomenon previously never recorded in primates other than humans. This underscores the uniqueness of this group and its immense value to science.
This community existed as small groups that roamed the forest in search of food. Social boundaries between them were very transparent: an animal could leave one group and join another several times a day. When two such groups met, it was always a pleasant reunion – the monkeys would start grooming each other, communicating, and acting as a single unit.
Despite such mobility, each individual had the strongest ties to one of three informal groups – the Western, Central, or Eastern clusters. However, for a long time, they remained part of a single social organism: males and females from different clusters mated freely, and all males hunted together and formed common patrols. They even jointly fought against external neighbors, driving away strangers and expanding the common Ngogo territory.
Unexpected Split
The situation radically changed in June 2015. Researchers witnessed for the first time an open violent clash between two parts of the community – the Central and Western. Instead of the usual joyful meeting, the chimpanzees began to scream, attack each other, and engage in a fierce fight. As a result, the Western group retreated, and the Central group began to pursue it. The New York Times introduces the details.
Initially, scientists considered it an accident. But in subsequent years, conflicts became regular. The tension escalated to such an extent that young chimpanzees became nervous just hearing the screams of adult males in the distance. By 2018, the confrontation had entered a deadly phase.
Photo: imageBROKER / Moritz Wolf / Getty Images
"Civil War" in the Primate World
Gradually, scientists came to a disturbing conclusion: they were not witnessing a series of random skirmishes, but a real protracted conflict. To date, at least 28 chimpanzees have been killed, including 19 infants. For observations of these animals, this is an unprecedented level of violence.
Prior to this case, only once, in the mid-1970s, in Tanzania's Gombe National Park, legendary Jane Goodall and her colleagues documented a similar violent split in a chimpanzee group. However, for a long time, researchers doubted the naturalness of those events. Some believed that the "war" was provoked by humans, as Goodall had been giving the animals bananas for years.
Scientists hypothesized that the monkeys were fighting over food, which would not have happened under natural conditions. The conflict in Ngogo, however, proved that Jane Goodall was not mistaken: chimpanzees are capable of organized bloodshed without any human intervention and on a much larger scale.
The peculiarity of this war is its obvious asymmetry. The initiators of aggression were chimpanzees from the Western cluster: although their group was initially smaller in number, they began to behave much more aggressively and attack first. As a result, the conflict took on the character of one-sided destruction – absolutely all recorded victims belong precisely to the more numerous Central cluster, which was unable to withstand the pressure of the "Westerners".
Meanwhile, there is also a third party – the Eastern cluster. Although they remain allies of the affected Central group, they do not engage in the fighting themselves and effectively take the position of observers. Scientists do not know when the clashes will subside and do not rule out that the Western group may eventually completely destroy the Central group.
Photo: Danita Delimont / Getty Images
What Triggered the Conflict?
The main mystery remains unanswered: how did it happen that yesterday's friends turned into mortal enemies? According to observations, the first alarming signals appeared as early as 2014. Ties between the groups began to slowly disintegrate: contacts became increasingly rare, mating occurred predominantly within their own clusters, and the groups themselves gradually diverged and settled in different parts of the forest.
One of the key hypotheses links this turning point to the death of five adult males in the same year – possibly due to illness. It is possible that they were the "social bridges" that connected different parts of the large community. When these bridges disappeared, the internal equilibrium was disturbed – and local tensions began to escalate into open conflict.
These observations are of immense significance for understanding human nature. They prove that the origins of war may lie not in ideology, language, or cultural differences, but in the very structure of social relationships. The Ngogo chimpanzees have shown how our ancestors could have been involved in years of deadly battles without any beliefs or cultural identity – for this, only a change in social ties proved sufficient.
This provides humanity with an important lesson: caring for social ties can help counteract violence. According to scientists, if friendship and "bridges" between groups restrain aggression, then conflict management in our own lives becomes a civic duty for creating a more peaceful world.