Chimpanzees Self-Medicate with Healing Plants
The Chimps Seek Out Unappetizing Plants with Medicinal Value, Providing Insights for Human Medicine
Wild chimpanzees in Uganda have been observed consuming plants with pain-relieving and antibacterial properties to heal themselves, according to a recent study. This discovery not only highlights the chimps' sophisticated use of natural resources but also opens potential pathways to novel human medicines.
Observing Self-Medication in the Wild
Scientists conducted extensive "detective work" in Uganda's Budongo Central Forest Reserve, observing chimpanzees that appeared injured or sick. They meticulously tracked these animals to determine whether they were self-medicating with specific plants.
When an injured chimpanzee sought out and consumed a particular plant, researchers collected samples of that plant for analysis. Remarkably, most of these plants exhibited antibacterial properties, suggesting a deliberate selection by the chimps for their healing benefits.
Research Findings
The study, published in the journal PLOS One1, offers compelling evidence that chimpanzees can help in the search for new medicines. Dr. Elodie Freymann, the lead researcher from the University of Oxford, explained the rationale:
"We can't test everything in these forests for their medicinal properties. So why not test the plants that we have this information about—plants the chimps are seeking out?"
Over the past four years, Dr. Freymann has spent extensive periods observing two communities of wild chimpanzees. The team paid close attention to signs of pain or illness, such as limping or unusual body posture, and collected samples of droppings and urine to check for infection.
Particularly noteworthy were instances where injured or ill chimpanzees sought out unusual food items, such as tree bark or fruit skin, which are not typically part of their diet. These behaviors suggested the plants might have medicinal properties.
A Case Study: Christella Parasitica
One striking observation involved a male chimpanzee with a severely wounded hand.
"He wasn't using the hand to walk, he was limping,"
Dr. Freymann recalled. While the rest of the group ate normally, the injured chimp limped away to seek out ferns.
"He was the only chimp to seek out and eat these ferns."
The researchers collected and analyzed the fern, identified as Christella parasitica, which revealed potent anti-inflammatory properties.
Broad-Spectrum Medicinal Properties
In total, the team collected 17 samples from 13 different plant species and sent them for testing at Neubrandenburg University of Applied Sciences in Germany. The analysis, led by Dr. Fabien Schultz, showed that almost 90% of the extracts inhibited bacterial growth, and a third had natural anti-inflammatory properties.
Dr. Freymann reported that all the injured and ill chimpanzees in the study fully recovered.
"The one who ate ferns was using his hand again within the next few days,"
…she explained. Although it is not possible to prove definitively that recovery was due to these plants, the observations strongly suggest a medicinal benefit.
Implications for Human Medicine
These findings underscore the potential medicinal knowledge that can be gained from observing other species in the wild. Dr. Freymann emphasized the importance of preserving these "forest pharmacies" for future generations.
"It 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."
Chimpanzees' use of medicinal plants demonstrates a sophisticated understanding of their natural environment, one that could inspire new approaches in human medicine. By studying the self-medicating behaviors of these primates, scientists hope to discover new compounds and treatments that could benefit human health.
Freymann, E., Carvalho, S., Garbe, L. A., Dwi Ghazhelia, D., Hobaiter, C., Huffman, M. A., Muhumuza, G., Schulz, L., Sempebwa, D., Wald, F., Yikii, E. R., Zuberbühler, K., & Schultz, F. (2024). Pharmacological and behavioral investigation of putative self-medicative plants in Budongo chimpanzee diets. PloS One, 19(6), e0305219. https://doi.org/10.1371/journal.pone.0305219