A new study led by the University of Oxford suggests that chimpanzees consume plants with medicinal properties to treat their ailments. The study entitled Pharmacological And Behavioral Investigation Of Putative Self-medicative Plants In Budongo Chimpanzee Diets is thought to be the most comprehensive study of chimpanzee interactions with pharmacalogical plants.

Many plants contain compounds with medicinal properties that can benefit humans and other animals. Wild chimpanzees consume a wide range of plants, some of which are nutritionally poor but may help alleviate symptoms of illness. However, until now, it has been challenging to determine whether chimpanzees actively self-medicate by deliberately selecting plants that address their specific ailments or if they simply consume plants that happen to have medicinal effects.

To explore this, a team of researchers combined behavioral observations of wild chimpanzees (Pan troglodytes) with pharmacological tests of the plants they consume. They monitored the health and behavior of 51 chimpanzees from two communities in the Budongo Central Forest Reserve in Uganda. The chimps were already accustomed to the presence of humans in their habitat.

The researchers then collected plant extracts from 13 species of trees and herbs in the reserve, which they suspected the chimpanzees might be using for self-medication. These plants included those that sick or injured chimpanzees were observed eating - despite not being part of their regular diet - as well as plants previously identified in research as potentially having medicinal properties.

The extracts were then tested for their anti-inflammatory and antibiotic properties at Neubrandenburg University of Applied Sciences, led by Dr Fabien Schultz. The findings revealed that 88% of the plant extracts effectively inhibited bacterial growth, while 33% exhibited anti-inflammatory effects.

Dr Freymann said: "Our study highlights the medicinal knowledge that can be gained from observing other species in the wild and underscores the urgent need to preserve these forest pharmacies for future generations."

Of particular note, dead wood from a tree in the Dogbane family (Alstonia boonei) showed the strongest antibacterial activity and also demonstrated anti-inflammatory properties, suggesting that chimpanzees may use it to treat wounds. Interestingly, Alstonia boonei is also used in East African communities to treat a variety of ailments, including bacterial infections, gastrointestinal issues, snake bites, and asthma.

Bark and resin from the East African mahogany tree (Khaya anthotheca) and leaves from a fern (Christella parasitica) also displayed strong anti-inflammatory effects. The researchers observed a male chimpanzee with an injured hand seeking out and consuming the fern leaves, likely helping to alleviate pain and reduce swelling. They also documented an individual with a parasitic infection eating the bark of the cat-thorn tree (Scutia myrtina), a plant not previously seen in the chimpanzees' diet. Testing confirmed that this bark had both anti-inflammatory and antimicrobial properties.

The results offer strong evidence that chimpanzees actively seek out specific plants for their medicinal properties. This study represents the most comprehensive analysis to date, combining both behavioral observations and pharmacological evidence to demonstrate the medicinal benefits of consuming bark and dead wood for wild chimpanzees.

Lead author Dr Elodie Freymann, from the University of Oxford’s School of Anthropology & Museum Ethnography, said: "To study wild chimpanzee self-medication you have to act like a detective - gathering multidisciplinary evidence to piece together a case. After spending months in the field collecting behavioral clues that led us to specific plant species, it was thrilling to analyze the pharmacological results and discover that many of these plants exhibited high levels of bioactivity."

Given the growing global concerns over antibiotic-resistant bacteria and chronic inflammatory diseases, the research highlights that the medicinal plants found in the Budongo Central Forest Reserve could play a crucial role in the development of new, effective drugs.