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

Chimpanzees appear to be consuming medicinal plants to treat illnesses, according to a study published June 20 in the open access journal Nature. ProSone By Elodie Freyman of the University of Oxford in the UK and her colleagues.

Many plants produce compounds that have medicinal properties for humans and other animals. Wild chimpanzees eat a wide variety of plants, including some that have little nutritional value but may be useful for treating diseases or alleviating symptoms. However, it is difficult to determine whether chimpanzees intentionally seek out plants with specific anti-pathogenic properties and self-medicate, or whether they passively ingest plants that happen to have medicinal properties.

The authors of this study combined behavioural observations of wild chimpanzees (Pan troglodytes) with pharmacological testing of medicinal plants that chimpanzees might eat. They monitored the behaviour and health of 51 chimpanzees from two habituated communities in Budongo Central Forest Reserve, Uganda.

Next, the team tested plant extracts from 13 trees and herbs in the sanctuary that the chimpanzees suspected of using to self-medicate for anti-inflammatory and antibiotic properties.

These included plants that sick or injured chimpanzees had been observed eating but that are not part of a chimpanzee’s normal diet, as well as plants that previous studies had suggested chimpanzees might ingest for medicinal properties.

The researchers found that 88 percent of the plant extracts inhibited bacterial growth and 33 percent had anti-inflammatory properties. Alstonia boonei had the strongest antibacterial and anti-inflammatory properties, suggesting that it may be used to treat wounds.

The bark and resin of the East African mahogany tree (Khaya anthotheca) and the leaves of the fern (Christella parasitica) have powerful anti-inflammatory properties. Researchers have observed male chimpanzees with injured hands seek out and eat fern leaves, which may have helped relieve pain and swelling. Individuals with parasitic infections have also been recorded eating the bark of the cat tree (Scutia myrtina).

The findings suggest that chimpanzees seek out specific plants with medicinal properties, and this study is one of the first to provide behavioral and pharmacological evidence that wild chimpanzees derive medicinal benefits from eating bark and dead wood.

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

“This paper shows how observing and learning from our primate cousins ​​can accelerate new drug discovery, and also highlights the importance of protecting forest pharmacies,” the authors add.