A community of approximately 200 chimpanzees in Uganda’s Kibale National Park has fractured into two rival factions, leading to a years-long, deadly conflict.
The Ngogo chimpanzees have been under continuous study for three decades, yet scientists have recently observed the violent split unfold in slow motion.
Starting around 2015, this previously unified group began to polarize. Social bonds weakened, neighborhoods within the community solidified into distinct factions, and once-shared territory became hotly contested. By 2018, this division had become permanent.
What transpired next was both surprising and alarming. The smaller faction, known as the western chimpanzees, initiated targeted raids on the territory of their larger rivals, the central group. Over the following six years, they killed at least seven adult males and 17 young children.
This count is likely an underestimate. An additional 14 adolescent and adult male chimpanzees went missing or died unexpectedly between 2021 and 2024, none showing any prior signs of illness.
Today, the Western group has emerged as the dominant force within the jungle.
Recent findings, published in Science, have drawn comparisons to civil wars. Unlike conflicts between strangers, the events at Ngogo involved former allies, groomers, and long-term social partners turning against one another.
Researchers involved in this study estimate that such conflicts occur only once every 500 years.
“One of the most intriguing aspects of this conflict is the so-called ‘friend-to-foe’ transformation,” stated Professor Aaron Sandel from the University of Texas at Austin in an interview with BBC Science Focus. “This provides a rare glimpse into the minds of chimpanzees.”
This research supports the notion that group identities can change, undermining long-held social bonds without the ethnic, religious, or ideological markers typically associated with collective violence.
“It almost facilitates wars between factions,” Sandel commented. “But we remain troubled by civil strife, as it’s often neighbors turning against neighbors.”
He added that insights from chimpanzee behavior could help researchers formulate hypotheses about the factors that drive humans toward or away from similar conflicts.
“By focusing on human interactions and conflict resolution, we may uncover more effective avenues for promoting peace,” he concluded.
Once a cohesive group, the Ngogo chimpanzees have divided, leading to escalation in violence and conflict. Researchers suggest this division might indicate that warfare is an innate aspect of our nature, rather than a recent development linked to our evolving culture.
According to Aaron Sandel and his team from the University of Texas at Austin, a comprehensive analysis of 24 years of social networks, 10 years of GPS tracking, and 30 years of demographic data on the chimpanzees (Pan troglodytes) in Kibale National Park, Uganda, was conducted.
Sandel emphasizes caution with terminology: “These are chimpanzees. Terms like war and civil war carry specific meanings for humans. While the conflict is not a civil war, there exist notable parallels, particularly regarding the shifts in group identity that precipitate lethal conflict.”
Chimpanzees are notorious for violence, predominantly targeting infants of rivals or outsider males.
The Ngogo population, comprising 150 to 200 individuals, is closely related to bonobos (Pongo niger), recognized as humans’ nearest relatives.
Between 1995 and 2015, the Ngogo chimpanzees were known for their cooperative behavior, showcasing fission-fusion dynamics, where individuals form temporary associations throughout the day and regroup each evening.
During puberty, female chimpanzees typically leave the group, while males remain for life. Prior to 2015, adult males formed alliances with females, facilitating hunting and territory patrols.
However, on June 24, 2015, a pivotal confrontation occurred when one faction, known as the central group, violently expelled the western group from their shared territory.
Following this event, the unity among the chimpanzees deteriorated. By 2018, the groups had permanently separated. During the ensuing years, the western group undertook 24 attacks, resulting in the deaths of seven adults and 17 infants from the other faction.
Chimpanzees from the Western Group on Patrol
Aaron Sandel
Sandel noted that the central chimpanzees were the first to pursue the western group; yet, the initial aggressors remain unclear. “As new factions emerged and divisions solidified, both groups engaged in territorial disputes,” he explained. “However, the western group has become the dominant aggressor, responsible for all fatal attacks.”
Various factors are believed to have contributed to the conflict’s escalation. Initial disagreements over food resources may have sparked tensions. In 2014, the deaths of five males and one female likely weakened the social structure. Changes in alpha male dynamics further exacerbated the situation, culminating in an outbreak of respiratory disease.
This outbreak, which claimed 25 Ngogo chimpanzees in January 2017, including the last surviving males of both factions, extinguished hopes for reconciliation.
Sandel and his team propose that the patterns observed in chimpanzee conflicts could provide insights into the evolutionary foundations of human warfare. While contemporary human conflicts are often attributed to ethnic, religious, and political divisions, this perspective may overlook the fundamental social dynamics shared with our primate relatives.
“In specific scenarios, the path toward peace may stem from simple, everyday acts of reconciliation,” the researchers articulated in their findings.
Maud Muzino from Boston University emphasizes that there are two predominant theories regarding the origins of human conflict. The first posits that war is a recent cultural innovation stemming from agrarian society and the establishment of nation-states. The alternative viewpoint asserts that the roots of warfare trace back through human evolution. “Ngogo’s findings significantly contribute to understanding the deep-seated origins of human conflict,” Muzino notes.
This study reveals that social fragmentation and subsequent conflicts can arise independently of the cultural differences often presumed to trigger human wars, be it in beliefs, language, or religious practices, states Luke Glowacki, also from Boston University.
For many years in Uganda’s Kibale National Park, two groups of chimpanzees coexisted, engaging in grooming, socializing, and territory patrols within their communities.
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Then, in a shocking turn of events, one group violently attacked the other, igniting years of conflict likened to human civil wars.
When the violence erupted in 2015, John Mitani, a professor emeritus of anthropology at the University of Michigan with over 20 years of research on chimpanzees, described the chaos: “It was just chaos. They started screaming and chasing each other.”
In the three years following the outbreak, Mitani and his colleague Aaron Sandel, an associate professor of anthropology at the University of Texas, documented how the chimpanzees’ social networks began to erode. By 2018, the two factions known as Western Ngogo and Central Ngogo chimpanzees “stopped sharing territory and began engaging in aggressive behavior, even killing each other,” Mitani reported.
At least 28 chimpanzees, including 19 infants, have been killed in this period, according to the initial research published in Science.
Mitani remarked, “Individuals who once aided each other now view one another as enemies.”
Basie, a central chimpanzee, is attacked by two males from the western subpopulation. Aaron Sandel
This marks the second observed instance of chimpanzee factions splitting and turning violent. Given that chimpanzees and bonobos are humans’ closest genetic relatives, the findings may offer insights into human behavior.
“Civil wars afflict people. How can you turn a neighbor against you? This study of chimpanzees highlights how group identity evolves and how lethal aggression arises,” Sandel noted.
Infants were torn from their mothers and killed.
Following the social collapse, one-sided violence escalated. The Western chimpanzees, initially a minority group, were responsible for all subsequent attacks post-split in 2018. While their numbers rose from 76 to 108, the Central chimpanzee population has steadily decreased.
Attacks have been brutal, with a Western chimpanzee reportedly tearing an infant from its mother’s arms and killing it.
Sandel highlighted that chimpanzees often utilize gang violence when targeting adult or adolescent males.
“Five or ten chimpanzees will overwhelm an individual, holding them down, biting, beating, and dragging them,” he explained. “The violence can be horrifying.”
Mitani remarked, “It’s distressing to witness.”
“The situation deeply troubles me,” he expressed.
Researchers seek answers regarding the reasons behind the collapse of social structures.
Since 1995, chimpanzees at Ngogo have been closely monitored, with structured documentation of their behavior. The recent study utilized 10 years of GPS tracking, 30 years of demographic data, and 24 years of detailed observations.
The team examined chimpanzee social networks by observing individual males for an hour, recording proximity, interactions, and grooming behaviors. They noted recurring patterns of overlapping social dynamics that ultimately led to a breakdown.
Mitani and Sandel propose that the group’s large size might have played a role in the violent divide. While typical chimpanzee groups consist of around 50 individuals, the Ngogo community boasted about 200, possibly straining social connections and heightening competition for resources.
Additionally, the death of five adult males from disease prior to the split could have disrupted critical social ties. Following this, a new alpha male emerged in 2015, further complicating social dynamics.
“That’s a significant factor,” Mitani explained, noting that such shifts typically occur every 6-8 years, often increasing aggression and altering relationships.
Decades ago, Jane Goodall witnessed similar violence
Approximately 50 years ago, the late Jane Goodall and her team observed a series of assaults that led to group fragmentation in Tanzania’s Gombe National Park. The main group hunted down and killed all males from the splinter group.
Researchers subsequently termed this conflict the “Four Years’ War.”
Anne Pusey, a professor emeritus of evolutionary anthropology at Duke University, studied these interactions until 1975, and noted that conditions preceding the killings were “remarkably similar” to those seen in Ngogo.
In Gombe, changes in alpha leadership, a shortage of mating females, and the deaths of amicable older males precipitated violent behavior.
Pusey remarked, “These social bonds deteriorated, leading to hostility.”
Joseph Feldblum, an evolutionary anthropologist with experience studying Gombe, stated that the recent findings align with historical observations.
“Such behavior is infrequent, yet exists within the natural repertoire of chimpanzees,” he noted.
Mitani expressed concern over the future of the Ngogo central group, suggesting they may be “doomed” based on past events at Gombe.
“The signs are evident,” he stated.
With the ongoing violence against infants and exclusion of females, Mitani concluded, “We might be witnessing an extinction event.”
Impact on humans
What can we learn from the violent behaviors displayed by our closest relatives?
Sandel emphasized that while cultural differences are often blamed for human warfare, this explanation does not apply to chimpanzees.
“Chimpanzees lack ethnicity, religions, and political ideologies, which are often identified as causes of human conflicts, especially internal strife like civil wars.”
Instead, researchers believe the violence is rooted in the breakdown of friendships and rivalry escalation. Sandel suggested that these dynamics may play a more pivotal role in human civil wars than commonly recognized, proposing that small gestures of reconciliation could be vital for peace.
Mitani reminded us that humans diverged from chimpanzees 6 to 8 million years ago. He cautioned against viewing violence against neighbors as an inherent human trait simply because it is observed in chimpanzees.
“We have evolved,” Mitani asserted. “As a species, we have become increasingly cooperative and socially inclined, often helping not only our neighbors but even strangers. This capability is not shared by chimpanzees.”
In a groundbreaking analysis of spontaneous performances by a male chimpanzee named Ayumu, researchers discovered that the chimp’s rhythmic prowess and expressive “playful face” provide insights into how early humans might have transformed vocal emotions into musical instrument sounds.
Chimpanzee Ayumu exhibited long, multi-element musical displays by drumming and manipulating objects. The analysis of his rhythmic transitions revealed structured sequences, primarily isochronous timing, and a more stable tempo with tools compared to body drumming. His playful expressions suggest heightened arousal and positive emotions, reinforcing the concept that emotional vocal expressions can manifest through instrumental sounds. Image provided by: Hattori et al., doi: 10.1111/nyas.70239.
In February 2023, Ayumu, a 26-year-old male chimpanzee at the Center for Research on the Origins of Human Behavior and Evolution at Kyoto University, showcased a spontaneous musical performance that intrigued researchers.
He creatively removed floorboards to use as drums, generating complex sounds reminiscent of vocal expressions.
Dr. Yuko Hattori of Kyoto University noted, “Ayumu’s drumming is not unprecedented.” Chimpanzees are indeed recognized for their musical talents, especially in drumming.
However, Dr. Hattori emphasized that Ayumu’s unique combination of drumming and vocalizations introduced multiple rhythmic elements, marking a novel instance.
Between February 2023 and March 2025, researchers documented a total of 89 spontaneous performances by Ayumu.
The recordings reveal him ripping floorboards apart to create music through innovative tool use.
“Observing chimpanzees utilize tools to produce diverse sounds and express vocal emotions was fascinating,” remarked Dr. Hattori.
The researchers aimed to determine if vocal expressions could transition to instrumental sounds based on Ayumu’s performances.
They meticulously categorized his actions into elements such as hitting, dragging, and throwing.
Transition analysis was utilized to differentiate between random occurrences and intentional actions.
Finally, they assessed the rhythmic stability of tool use versus hand and foot drumming by analyzing intervals between strikes.
Notably, they found that the order of sounds produced was structured, with isochronous intervals that maintained a constant tempo, akin to a metronome.
Indeed, using tools yielded a more consistent rhythm compared to solely relying on hands and feet.
The researchers also documented Ayumu’s facial expressions, including the “play face,” commonly associated with playfulness and positive emotions.
This type of emotional signaling, typically absent in audio displays, suggests that vocal emotions may have previously been externalized into sounds produced with tools.
“Ayumu’s performance illustrates that non-human primates have the capacity to externalize voice-like expressions through musical instruments,” the authors concluded.
Moving forward, they expressed interest in studying the reactions of other chimpanzees and the influence of Ayumu’s performance within his social group.
For detailed insights, refer to the study published in Annual Report of the New York Academy of Sciences.
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Yuko Hattori et al., 2026. Combination of Instrument Sound Production in Captive Chimpanzees: Evolution of Vocal Externalization. Annual Report of the New York Academy of Sciences 1557 (1): e70239; doi: 10.1111/nyas.70239
Jane Goodall, a renowned researcher who studied chimpanzee behavior and social structures, later emerged as a prominent figure in the animal welfare movement, passed away on Wednesday.
At the age of 91, Goodall died of natural causes in California while on a speaking tour, as reported by the Jane Goodall Institute in a statement.
“Dr. Goodall’s contributions as an ethologist transformed scientific understanding, and she was an unwavering advocate for the preservation and rejuvenation of our natural world,” the statement added.
Jane Goodall participated in the TV special “Miss Goodall and The World of Chimpanzees” in 1965. CBS via Getty Images File
Hailing from the UK, Goodall gained recognition in the 1960s for her groundbreaking research on chimpanzees in Tanzania. She meticulously documented their social interactions over several decades.
The foundation noted that she adopted an “unconventional approach” to chimpanzee research, “immersing herself in their environment to experience their intricate societies as neighbors rather than distant observers.”
Goodall’s research revealed that chimpanzees used sticks to fish for termites, challenging the prevailing notion that tool use was exclusive to humans. She also documented the chimps’ communication methods and complex social behaviors, including their meat-eating habits and occasional aggression.
“They are part of Elizabeth Freyman, a primate specialist and postdoctoral researcher at Brown University,” said:
Robert Seyfers, professor emeritus at the University of Pennsylvania who specialized in primate behavior, remarked that Goodall’s passing signifies “the end of an era.”
“Her thorough and detailed observations have resonated with our entire generation—myself included—and inspired many others interested in this scientific field,” Seyfers stated.
He noted that Goodall was among the first researchers to observe chimpanzees as individual beings with distinct personalities, unlike many of her contemporaries who lacked such observational training.
“Her insights into chimpanzee emotions were groundbreaking,” he conveyed, adding that Goodall was an “authentic chronicler” of animal behavior.
“Her goal was to help people comprehend chimpanzees in all their complexities,” Seyfers shared.
As Goodall’s career evolved, she became aware of the threats posed by habitat destruction and illegal trafficking to chimpanzee survival, leading her to prioritize conservation and animal welfare in her work.
The Jane Goodall Institute, which she founded in 1977, stated, “We entered the forest to study the extraordinary lives of chimpanzees, and she emerged from the forest to advocate for their protection.”
Jane Goodall in Paris during October 2024. Joel Saaget/AFP via Getty Images
Ingrid Newkirk, the founder of People for the Ethical Treatment of Animals, stated that Goodall “played a pivotal role in helping the organization end the confinement of chimpanzees in desolate metal chambers for testing.”
At just 26 years old, Goodall embarked on her first journey to Tanzania to study chimpanzees. She began her career without any formal scientific training. Louis Leakey, a notable Kenyan and British anthropologist, recruited her to document her findings on chimpanzees. Goodall later attained her PhD from Cambridge University.
During an interview on this year’s podcast “Call Her Daddy,” Goodall recounted to host Alex Cooper that her initial expedition was funded through a shoestring budget provided by philanthropists.
With funding for six months, the first four months yielded little success, as primates were too wary for her to observe closely. However, one chimpanzee eventually became accustomed to her presence, leading to her groundbreaking discovery of their use of tools.
“This discovery was exhilarating because, at the time, it was believed in Western science that tool-making was a human-exclusive trait. We defined ourselves as the only tool-using species,” Goodall recollected. “So, when I wrote to my mentor, Louis Leakey, he was thrilled.”
That revelation captured the interest and support of National Geographic, ultimately altering the trajectory of Goodall’s career.
As Goodall rose to prominence, she leveraged her visibility to bolster public interest in animal welfare and scientific exploration. She authored numerous books about her experiences with chimpanzees, including several aimed at children.
Primate specialist Freyman reflected that he dressed as Goodall for Halloween in fourth grade. He later mentioned receiving fan mail from children while interning at the Jane Goodall Institute in Washington, D.C., at the age of 19.
“I became a primatologist because I had a hero I admired,” Freyman, now 29, shared.
Correction (October 1, 2025, 11:38pm ET): Due to an editing error, earlier versions of this article referred to primate specialist Elody Freyman using “he.” Freyman is a woman.
WOne of Tim’s eighth graders inquired about his “favorite Italian brain rot animal,” leading to some confusion. “My hearing isn’t the best, so I probably had to ask her to repeat it four or five times,” he reflects.
After instructing the students to continue their work, he opened his laptop and turned to Google.
He learned that “Italian Brain Corruption” involves a series of absurd, AI-generated animal characters with ridiculous Italian names (like Bombomini Gusini and Trippi Troppi), often showcased in TikTok videos with rapid, nonsensical Italian narration.
Essentially, it’s a meme popular among the emerging Generation Alpha (born 2010-2025) and the younger Gen Z (mostly born 1997-2012). For older individuals—whether they are heavily engaged online or consider themselves meme enthusiasts—it might seem perplexing, as Tim discovered while browsing.
As he shared his findings, he appeared horrified. “This one is Chimpanzee Banana: it’s a hybrid of a chimpanzee and a banana. Bombardiro Crocodilo is a crocodile that resembles a bomber plane. There are also characters that are just cappuccinos with legs…”
Ballerina Cappuccina. Photo: tiktok/@aironic.fun
That’s right, Ballerina Cappuccina: female ballet dancers are fused with coffee cups and often depicted in a relationship with Cappuccino Assassin (you can understand that).
“There’s a backstory to all these characters—lore,” Tim adds, pondering. “Some are even at war with each other, and there are songs about them.”
The kids in his class are intensely fascinated by it, unlike any trend Tim has seen before. “Once one person mentions it, the whole class starts buzzing. They’re obsessed with this Italian brain corruption.”
If you’re reading this and finding your own mind bewildered, it’s understandable. If you were born in a year that starts with a “1,” “Italian brain corruption” might not resonate with you.
However, its widespread popularity among the younger crowd is worth trying to understand, at least as a reflection of the evolution of online culture.
Tralala Rotralala. Photo: Tiktok
The first character to gain traction was Shark Sport Nike sneakers (three per fin); Torara Rotorarara. Shortly after, the voice of a male character first appeared, marking the start of Italian expressions on TikTok in early January.
New characters quickly proliferated on TikTok. Don Caldwell, Editor-in-Chief of Know Your Meme, identified Brr Brr Patapim as an example, describing it as a “material monkey that is also a tree.”
Tung Tung Tung Sahur. Photo: Tiktok/@noxaasht
Notably, there’s also brain rot in Indonesia. Tung Tung Tung Sahur (“This features a stick figure on a bat, telling people to wake up for food during Ramadan”) and Boneca Ambalabu (“A frog with a tire and human legs”) are examples.
Both are accompanied by AI-generated voices that, much like their Italian counterparts, aim to confuse rather than clarify.
“Audio is just as crucial, if not more so than visuals,” Caldwell explains. “They really amp it up, like Tra-la-.lero! tra-la-laLA!—that quintessential Italian sound.”
Is this offensive to Italians? “It seems like Italians are in on the joke,” Caldwell suggests. “I don’t think it is.”
The attraction of Italian (and Indonesian) brain corruption isn’t about being derogatory or harmful—it’s simply absurd.
Caldwell, who has been engaged with memes for 15 years, admits he doesn’t track every fleeting online trend. “But I genuinely enjoy this,” he remarks. “In my view, it’s the better side of memes.”
The simplicity and speed of creating these videos using tools like ChatGPT have contributed to the meme’s popularity. Users can prompt their AI to visualize something like Bombardiro Crocodilo in their preferred settings. “No prior video editing skills are necessary, nor do you have to use your own voice,” Caldwell notes.
For adults apprehensive of AI advancements, the Italian brain corruption can feel like a harmless indulgence. “It’s a non-threatening application of AI that doesn’t induce existential dread.”
Naturally, young people don’t view it in such a serious light. They spend more time online from an earlier age, significantly influencing digital culture. “You’ve got a super online kid today,” Caldwell remarks. “They grew up around iPads and TikTok, creating content and dictating the biggest cultural trends of the moment.”
Before Italian brain rot, there was the Skibidi Toilet meme, which spread virally from YouTube in 2023, captivating the younger generation of Gen Z, with millions of views.
Tim recalls discussing it in class: “The kids adore it. The term ‘Skibidi’ is now embedded in Gen Z and Gen Alpha vernacular.”
However, its meaning isn’t straightforward and is steeped in ironic ambiguity. “It can signify something good, something bad, or something bizarre… When they refer to it as ‘Skibidi,’ it’s a positive thing, and they’re laughing at it simultaneously.”
Both Skibidi Toilets and Italian brain corruption resist clear definitions, stimulating youthful imaginations with surreal imagery and crude humor while leaving adults scratching their heads with their more subdued humor.
Ebies.
“AI Art” isn’t just a shortcut for older users primarily active on Facebook, Caldwell states. Ebies example (please check). It increasingly cultivates its own lexicon, customs, and meanings that often elude many adults.
It’s intriguing to hear people declare that past memes were superior. Examine the originality of templates such as distracted boyfriends and layered visual jokes demonstrating endless possibilities for meaning-making. However, Caldwell—a millennial himself—suggests that Italian brain corruption represents another evolution in human creativity. “AI produces images, and text-to-speech gives voice, but the humor originates from the real person behind the screen.”
Tim is skeptical, noting that when he sets creative writing tasks for his class, many leap straight into their favorite Italian brain-rotting creatures. “I worry that the AI generation lacks moments for spontaneous imagination, as AI does so much for them. I tell them, ‘This must be entirely our creation. I don’t want chimpanzees bananini.'”
Nevertheless, he has started incorporating the students’ enthusiasm for Italian brain corruption into his lesson plans. In a multiple-choice quiz, one of the options is Tung Tung Tung Sahur.
He now confidently addresses his eighth graders. “My favorite is Blueberrinni Octopussini,” he shares. “It’s an octopus blended with blueberries.”
Primatologists have recorded and examined both previously noted and newly observed instances of self-administered and socially oriented wound care, snare removal, and potential medicinal hygiene behaviors within the Sonso and Waibira chimpanzee communities of the Budonggo forests in Uganda. They documented self-directed wound care actions, such as licking wounds, slapping leaves, pushing fingers against wounds, applying plant material to injuries, and successfully removing snares. The researchers also noted self-guided hygiene behaviors, including cleaning genital areas with koital leaves and wiping foliage post-defense.
Social grooming between two chimpanzees in Budonggo forest, Uganda. Image credit: Elodie Freymann.
“Our research sheds light on the evolutionary origins of human medicine and healthcare systems,” stated the first author of the study, Dr. Elodie Freyman, a researcher at Oxford University.
“By observing how chimpanzees identify and utilize medicinal plants to care for others, we can gain valuable insights into the cognitive and social foundations of human medical practices.”
Dr. Freyman and his team focused their study on the Sonso and Waibira chimpanzee communities in Budonggo forest.
Like all chimpanzees, individuals in these communities face injuries from various causes, including human-instigated fights, accidents, or snares.
Approximately 40% of all Sonso individuals are observed with snare injuries.
The researchers dedicated four months to each community’s observation, employing video evidence from a comprehensive APE dictionary database, a logbook filled with decades of observational data, and research gathered by other scientists who have witnessed chimpanzees treating injuries and illnesses.
Chimpanzees have been noted to use specific plants for external treatment. Some have been identified to possess chemical properties that enhance wound healing and traditional medicinal applications.
During their field observations, scientists noted 12 injuries at Sonso, all likely resulting from group conflicts.
In Wyvila, five chimpanzees were documented as injured—one female from a snare and four males from combat.
Researchers also recognized that care was provided for their offspring rather than Waibira.
“This may be influenced by factors like variations in social hierarchy stability and greater observation opportunities in the well-acquainted Sonso community,” noted Dr. Freyman.
The scientists recorded a total of 41 care instances: seven instances of prosocial care and 34 instances of self-care.
These instances frequently involved various care behaviors, whether addressing different aspects of a wound or indicating the chimpanzee’s personal preferences.
“Chimpanzee wound care involves several techniques, which can remove debris and apply potentially antibacterial substances, possibly even antibiotics from their saliva.”
“All chimpanzees documented in our study exhibited recovery from their wounds, yet we are unable to determine the outcome had they chosen not to address their injuries.”
“We also recorded hygienic behaviors such as using leaves to clean the genitals post-mating and wiping the anus with leaves after defecation—practices that serve to prevent infections.”
Among the seven instances of prosocial care, the researchers noted four instances of wound treatment, two instances of assistance in snare removal, and one instance involving hygiene help for another chimpanzee.
Care was administered without preference towards a specific gender or age group. Attention was given to genetically unrelated individuals in four cases.
“These behaviors contribute to evidence from other areas where chimpanzees appear to acknowledge the needs and sufferings of others and take deliberate actions to alleviate them, even in the absence of direct genetic advantages,” Dr. Freyman stated.
The research team intends to delve deeper into the social and ecological contexts in which care is provided and which individuals are recipients of such care.
“There are some methodological limitations in our study,” Dr. Freyman added.
“The disparity in familiarity between the Sonso and Waibira communities introduces observational bias, particularly regarding rare behaviors like prosocial healthcare.”
“We have documented the plants used in healthcare contexts, but further pharmacological exploration is necessary to confirm their specific medicinal characteristics and efficacy.”
“The relative rarity of prosocial healthcare also complicates the process of identifying patterns related to when and why such care is provided, or when it is withheld.”
“These challenges underscore future research avenues in this burgeoning field.”
Study published in the journal Frontiers in Ecology and Evolution.
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Elodie Freymann et al. 2025. Self-direction and prosocial wound care, snare removal, and hygienic behavior among Budongo chimpanzees. Front. Ecol. Evol. 13; doi:10.3389/fevo.2025.154092
Chimpanzee mother and child in Kibale National Park, Uganda
Dr. Chris Sabbi, Tufts University
When they have less to eat, most chimpanzees stop playing altogether to conserve energy, but mothers continue to spend a lot of time playing with their children. Because play is essential to the physical and psychological development of young chimpanzees, mothers may channel their energy into this behavior to nurture their young, even during difficult times.
Great apes such as gorillas, bonobos, and chimpanzees all tend to engage in play, such as tickling, pecking, and chasing each other. “Play helps develop both motor and social skills,” he says. Zarin Machanda At Tufts University, Massachusetts. “That's really what the baby needs to develop properly.”
For more than a decade, Machanda and colleagues have been observing a community of about 60 Eastern chimpanzees.Pan Troglodytes Schweinfurti) lives in Kibale National Park, Uganda. The team played a total of 3,891 games between 2010 and 2019.
“We had a great summer in 2016 or 2017 when there was nothing but food everywhere on site,” says Manchanda. “And one of the things we noticed was a lot of adult chimpanzees playing with each other.”
When food was abundant, teams recorded at least one play on 97% of observation days, but when food was scarce, this decreased to only 38%.
However, mother chimpanzees continued to play with their children at even higher rates during times of low food availability.
“We were really surprised,” team members say. Chris Sabbi Food is generally more important to female chimpanzees because the energetic cost of reproduction is much higher, according to a Harvard University study.
During periods of food stress, chimpanzees tend to spend more time alone to avoid competing for resources, so mothers are often the only social partners for their babies. As a result, the mother spends even more time playing with her children to compensate for the lack of interaction with her peers and other adults.
“The fact that mothers continue to play with their babies, even at personal sacrifices, shows how important this is to the child's development,” Machanda said. “It's like the hidden cost of being a mother.”
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