Wild chimpanzees seek medicinal plants to treat illness and injury, study finds

Chimpanzees appear to consume plants with medicinal properties to treat their ailments, according to a study published June 20 in the open access journal PLUS ONE by Elodie Freymann of the University of Oxford, UK, and colleagues.

Many plants produce compounds that have therapeutic effects on humans and other animals. Wild chimpanzees eat a variety of plant materials, including some that are low in nutrients but can treat or reduce the symptoms of illness. However, it is difficult to determine whether chimpanzees self-medicate, by intentionally seeking out plants with properties that help their specific ailments, or indirectly consume plants that are therapeutic.

The authors of this study combined behavioral observations of wild chimpanzees (Pan troglodytes) with pharmacological testing of potential medicinal plants they eat. They monitored the behavior and health of 51 chimpanzees from two habituated communities in Uganda’s Budongo Central Forest Reserve.

Next, they collected plant extracts from 13 species of trees and herbs in the reserve that they suspected the chimpanzees might use for self-medication and tested them for anti-inflammatory and antibiotic properties.

These included plants that they saw sick or injured chimpanzees eating, but were not part of their normal diet, and plants that previous studies have suggested chimpanzees may consume for their healing purposes.

The researchers found that 88% of the plant extracts inhibited bacterial growth, while 33% had anti-inflammatory properties. Dead wood from a tree in the dogbane family (Alstonia boonei) showed the strongest antibacterial activity and also had anti-inflammatory properties, suggesting that it can be used to treat wounds.

Bark and resin from the East African mahogany tree (Khaya anthotheca) and leaves from fern (Christella parasitica) showed potent anti-inflammatory effects. The researchers observed a male chimpanzee with an injured hand reaching up and eating the leaves of the fern, which may have helped reduce pain and inflammation. They also recorded a person with a parasitic infection who consumed the bark of the cat’s thorn tree (Scutia myrtina).

The results suggest that chimpanzees seek out specific plants for their medicinal effects. The study is one of the first to provide both behavioral and pharmacological evidence of the therapeutic benefits of feeding on bark and dead wood to wild chimpanzees.

The medicinal plants growing in Budongo Central Forest Reserve could also be useful in the development of new drugs to address the challenges of antibiotic-resistant bacteria and chronic inflammatory diseases, the authors say.

The authors add: “In this paper, we demonstrate how watching and learning from our primate cousins ​​can accelerate the discovery of new drugs, while highlighting the importance of protecting our forest pharmacy.”