Chimpanzees used insects to heal their wounds

Plant substances found in the forest are an important source of therapeutic care for chimpanzee communities. In 2003, the team of Sabrina Krief, a primatologist at the National Museum of Natural History in Paris, listed 23 plant species known for their pharmacological properties, which are consumed by these great apes. The ingestion of rough leaves, bark, stems and flowers with antiparasitic or antimicrobial properties is a common practice of self-medication (use of non-nutritive substances to fight pathogens) among our close phylogenetic cousins. However, Simone Pika, a researcher at Osnabrück University in Germany, and her colleagues have just published observations suggesting the existence of a new medication technique used by certain chimpanzees in the Rekambo community in Loango Park, Gabon: Apply insects to your own wounds or to the wounds of other humans.

Chimpanzees are the closest primate speciesHomo sapiens, with whom they share 98% of their DNA. Chimpanzee populations are distributed in equatorial Africa with a very complex social organization. In this picture, two individuals (Roxy and Thea) from the community of Rekambo, Gabon, are preparing each other to eliminate their parasites.

© Tobias Deschner – Ozouga Chimpanzee Project

Self-medication behaviors are not unique to humans and great apes. They are also common in many species such as dolphins, elephants, bears but also starlings and certain reptiles. It is also common to rub animals or animal secretions (ants, myriapods, etc.) on their fur or plumage. However, the application of insects to open wounds had never been documented in the animal kingdom. In 22 chimpanzees in the Rekambo community, the research team reported 76 cases of this behavior. For example, they observed a chimpanzee mother catching flying insects with her mouth and then placing them in the open wound of her calf. In another event, an adult male had applied flying insects to his own wound and then several individuals had come to help him clean the insects with his fingers or lips.

In traditional medicine, humans use many species of insects that have antibiotic, antiviral, and deworming functions. What is the role of chimpanzees in insects? Scientists have not yet identified them. Therefore, the next step will be to collect the insects in the field, identify the species to which they belong and study their potential therapeutic properties, especially in the healing of open wounds. “All these steps are necessary before we can confirm that this is a behavior of care linked to the chemical compounds present in the insect,” said Sabrina Krief. In fact, chimpanzees occasionally use the leaves to “clean” their wound without chewing. They are sometimes passed into the mouth before being applied with saliva to the wound. In this case, this use is similar to that of a tablet that has no medicinal properties per se.

This finding could testify to the existence of complex self-medication behaviors, but even more so to all-medication, i.e., peer intervention to treat a congener. If there is still no consensus on the cognitive ability of great apes to have empathy, the observation of these prosocial behaviors tends to prove otherwise. Just as local traditions for feeding emerge in certain individuals in a group, the application of insects to wounds could result from cultural transmission with important implications for better understanding the phenomenon of animal culture and its evolution in human societies.

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