[WORLD] Chimpanzees, our closest living relatives, are turning out to be much more fastidious than previously thought. New research from Uganda’s Budongo Forest reveals that these great apes not only care for their wounds with remarkable ingenuity but also practice personal hygiene after defecation and even after sex—a behavior once thought unique to humans.
The study’s findings align with growing evidence that many animals, from birds to elephants, exhibit hygiene-related behaviors. However, chimpanzees stand out due to the intentionality and social dimensions of their actions. Unlike simpler instinctual behaviors, their use of tools (like leaves) and selection of specific plants suggest a higher cognitive process—one that may mirror early human practices.
Chimpanzees’ Hygiene: More Than Just Grooming
A team of researchers from Oxford University, working alongside local scientists, spent months observing the Sonso and Waibira chimpanzee communities in the Budongo Forest. Their findings, published in Frontiers in Ecology and Evolution, are based on four months of direct observation and over 30 years of archival video and logbook data. The study documents a rich repertoire of hygiene and healthcare behaviors among chimpanzees, including:
- Wiping their genitals with leaves after mating
- Cleaning their anus with leaves after defecation
- Treating wounds with chewed plant material, leaf dabbing, and wound licking
- Prosocial care, where chimps help others—sometimes unrelated individuals—with hygiene and injury treatment
These behaviors suggest that hygiene is not just a human concern but has deep evolutionary roots.
Interestingly, the researchers noted that younger chimpanzees often observed and mimicked these hygiene behaviors from older group members, hinting at a form of cultural transmission. This learning process mirrors how human children acquire hygiene practices, further blurring the line between human and animal behavior.
Post-Coital and Post-Defecation Cleanliness
Perhaps the most striking finding is that chimpanzees regularly clean themselves after sex and after using the toilet. Researchers observed both males and females using leaves to wipe their genitals following mating, and similar leaf-wiping after defecation. In some cases, chimps even helped each other with these tasks, demonstrating a level of social cooperation and empathy that parallels human behavior.
"We also documented hygiene behaviors, including the cleaning of genitals with leaves after mating and wiping the anus with leaves after defecation — practices that may help prevent infections," said Dr. Elodie Freymann, lead researcher on the project.
Medicinal Knowledge and First Aid
Chimpanzees do not select leaves at random. The study found that they often choose plant species known for their antibacterial, antifungal, and anti-inflammatory properties, such as Senna spectabilis, Acalypha, and Alchornea floribunda. These plants are also used in traditional human medicine, suggesting that chimps have developed a form of pharmacological knowledge through generations of experience.
The researchers also discovered that chimpanzees occasionally reused the same leaves for multiple cleanings, raising questions about whether they recognize the importance of minimizing contamination. This behavior, if confirmed, would add another layer to our understanding of their cognitive abilities and environmental awareness.
Wound care behaviors include:
- Licking wounds to clean them and potentially apply antimicrobial saliva
- Pressing fingers or leaves to wounds to stop bleeding
- Chewing plant material and applying the paste to injuries
All observed individuals recovered from their wounds, though researchers note it’s unclear what might have happened without such care.
Empathy and Prosocial Care
The research highlights not only self-care but also prosocial behaviors—chimpanzees helping others with hygiene and medical needs. Instances were recorded where chimps assisted unrelated individuals, such as helping to remove snares or tending to wounds. This extends to hygiene, with rare but notable cases of one chimpanzee cleaning another’s genitals after mating.
Such acts suggest a capacity for empathy and social solidarity, traits that were once considered uniquely human.
Implications for Human Evolution
These findings challenge the notion that humans are unique in their concern for hygiene and healthcare. The observed behaviors in chimpanzees provide crucial insights into the evolutionary origins of medicine, self-care, and social support systems.
“Our research helps illuminate the evolutionary roots of human medicine and healthcare systems,” said Dr. Freymann.
The study also opens new avenues for biomedical research. By identifying plants used by chimpanzees for their medicinal properties, scientists may discover novel compounds for treating infections and wounds in humans.
A New Perspective on Animal Intelligence
The hygiene habits of chimpanzees underscore the complexity of their social lives and cognitive abilities. From wound care to post-coital cleanliness, these behaviors reflect a sophisticated understanding of health and wellbeing—one that bridges the gap between humans and our primate cousins.
As Dr. Freymann concluded, “The more we learn about chimpanzee behavior and intelligence, the more we come to realize how little we as humans know about the natural world.”
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