In June 2015, primatologist Aaron Sandel was silently studying a small group of Ngogo chimpanzees in Uganda’s Kibale National Park when he observed unusual behavior. As other chimpanzees from their larger community approached, the individuals in front of him exhibited signs of anxiety, such as grimacing and seeking comfort from one another, suggesting they were more apprehensive about encountering strangers than interacting with familiar companions.<\/p>\n
Reflecting on this experience, Sandel identified it as the initial indication of a protracted and violent conflict within a previously harmonious chimpanzee group.<\/p>\n
A recent study published in the journal Science presents what could be the first documented instance of “civil war” among wild chimpanzees. While it has been established that chimpanzees can engage in lethal aggression against outsiders, witnessing a cohesive group turn against itself is a novel and striking phenomenon that mirrors aspects of human behavior.<\/p>\n
“The occurrence of neighbor-on-neighbor violence is particularly concerning, as it resonates more closely with the human experience. It raises questions about our capacity for cooperation alongside our propensity to betray one another,” Sandel explained.<\/p>\n
The researchers analyzed over thirty years of behavioral data from this well-documented group of chimpanzees to understand the permanent division within the largest known population of wild chimpanzees. From at least 1995 until 2015, the group exhibited social unity, but by 2018, a split had emerged, resulting in two distinct factions: the western chimps and the central chimps.<\/p>\n
Once these groups were established, the western faction executed 24 coordinated assaults against the central group over the next seven years, resulting in the deaths of at least seven adult males and 17 infants.<\/p>\n
Scientists suspect that a similar internal conflict may have taken place in the 1970s among the chimpanzees in Gombe, Tanzania, as documented by the esteemed primatologist Jane Goodall. However, at that time, the understanding of chimpanzee behavior was insufficient to recognize the significance of such in-group violence.<\/p>\n
According to the researchers, a shift in social hierarchies may have led to the fracture of the Ngogo chimpanzee group, leading to organized aggression. Notably, on the day Sandel witnessed the unusual behavior, the alpha male of the group had displayed submissive grunts to another chimp earlier that morning. Additionally, the deaths of several key older members in the years leading up to the division likely destabilized the group’s social fabric.<\/p>\n
“The sudden loss of these individuals might have weakened the ties among subgroups, rendering the community susceptible to polarization following the alpha male’s change in status,” Sandel stated. “Moreover, a disease outbreak in 2017 likely accelerated this division.” <\/p>\n
This situation raises concerns for primate conservation, given that chimpanzees are facing extinction. The study indicates that these “civil wars” among chimpanzees are believed to occur only once every 500 years. However, human activities that impair social cohesion, such as deforestation, climate change, or disease outbreaks, could increase the likelihood of such conflicts, according to Sandel.<\/p>\n
Brian Wood, an evolutionary anthropologist at UCLA, who has researched the Ngogo chimpanzees but was not part of the current study, emphasized the importance of understanding the motivations behind one group’s attack on another. In the context of Darwinian fitness\u2014an assessment of an organism’s success in passing on its genes\u2014Wood noted that enhancing one’s own survival, increasing reproductive success, or diminishing that of competitors can all contribute to evolutionary advantage.<\/p>\n
“This is precisely what the western chimps have achieved. Following the assaults by the western group, the central chimps are now experiencing the lowest survival rates ever recorded in a wild chimpanzee population,” Wood remarked.<\/p>\n
Sylvain Lemoine, a biological anthropology professor at the University of Cambridge, highlighted the significance of this study, stating, “This represents the first well-documented instance of what can be classified as civil warfare in chimpanzees. It illustrates that, even in the absence of cultural identifiers, social bonds and connectivity are crucial for group cohesion, and such ties can be fragile under certain conditions, especially when they depend on a few key individuals.” <\/p>\n
For further coverage on extinction issues, visit our dedicated section, and follow biodiversity reporters Phoebe Weston and Patrick Greenfield in the Guardian app for more environmental updates.<\/p>\n","protected":false},"excerpt":{"rendered":"
In June 2015, primatologist Aaron Sandel was silently studying a small group of Ngogo chimpanzees in Uganda’s Kibale National Park when he observed unusual behavior. As other chimpanzees from their larger community approached, the individuals in front of him exhibited signs of anxiety, such as grimacing and seeking comfort from one another, suggesting they were […]<\/p>\n","protected":false},"author":2,"featured_media":6149,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[639,1489,177,525,447,640,641,1487,175,1488,88,448,571],"tags":[],"class_list":["post-6150","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uk-africa","category-uk-animal-behaviour","category-uk-animals","category-uk-biology","category-uk-endangered-species","category-uk-environment","category-uk-global-development","category-uk-primatology","category-uk-science","category-uk-uganda","category-uk","category-uk-wildlife","category-uk-world-news"],"yoast_head":"\n