Chimpanzees ‘self-medicate’ with healing plants

Next, a case of chimp medicine. A new study has found that wild chimpanzees eat plants that have pain-relieving and antibacterial properties to heal themselves. According to scientists who describe their detective work in the forests of Uganda, they observed animals which appeared injured or sick to determine whether they were self-medicating with plants.

When an injured animal sought out something specific from the forest to eat, the researchers collected samples of that plant and had it analyzed. I spoke to the lead researcher on the project, Elodie Freiman, from the University of Oxford, who told me how the study came about.

"This came about as part of my PhD research project. I was interested in expanding what we know about chimpanzee medicinal repertoire. We know chimps self-medicate, but before I began my PhD, we were limited in which species of plants we knew they were using. I wanted to work at my field site in the Budongo Forest in western Uganda to identify some potential new medicines for the chimps."

Freiman explained more about her findings: "I was doing behavioral research with the wild chimps, which meant I was living out in the Budongo Forest for about eight months. I followed the chimps every day, trekking in the forest with them and a team. We wrote down any unusual feeding behaviors we observed and simultaneously kept track of the health of these chimps through non-invasive monitoring methods. We collected samples to determine if they had a bacterial infection, high parasite load, or wounds. From there, we paid closer attention to their diet, what they were eating, and collected any suspect plants we saw them consuming."

What sort of ailments were the plants helping to heal in the chimps? Freiman elaborated, "Our paper runs through several anecdotes of chimps with a wide range of different illnesses. Some had high parasite loads, some showed signs of bacterial infection, and others had wounds or injuries. When we took the plant samples to a lab in Germany and had a team of pharmacologists examine their medicinal properties, we found that 88% showed strong antibacterial properties and 33% showed strong anti-inflammatory properties. With all our evidence compiled together, it looks like the chimps were seeking out these plants with particular medicinal properties to treat their ailments."

Was this a surprise to Freiman? "Yes and no. Yes, in that we had been limited in our knowledge of the ingestion-based plants that chimps eat, their medicinal repertoires. But at the same time, chimps are incredibly smart. They live in the forest, surrounded by these trees and resources, and it makes perfect sense that they would have developed the ability to identify medicines they need to survive."