Scientists say that in the wild, chimpanzees eat plants that have pain-relieving and antibacterial properties to soothe themselves.
They described their “detective work” in the forests of Uganda, observing animals that appeared injured or sick and finding out whether they were self-medicating with plants.
When an injured animal sought out something specific in the forest and ate it, the researchers took a sample of the plant and analyzed it. Most of the plants they tested were found to have antibacterial properties.
“We can’t test every plant in these forests for its medicinal properties,” says lead researcher Dr Elodie Freyman from the University of Oxford, “so why not test the plants that chimpanzees seek out, and for which we have information?”
Over the past four years, Dr Freiman has closely monitored two groups of wild chimpanzees in Budongo Central Forest Reserve, following them for months at a time.
She and her colleagues looked for signs of pain, such as the animals limping or supporting themselves in abnormal positions, as well as collecting feces and urine samples to check for disease or infection.
The researchers paid particular attention to injured or sick chimpanzees foraging for foods they wouldn’t normally eat, such as tree bark or fruit peelings.
“We were looking for behavioral clues that the plant might have medicinal properties,” Dr. Freiman explained.
She described one male chimpanzee with severe wounds on his hands.
“He wasn’t using his hands to walk. He was dragging his feet,” she recalled. While the rest of the troop sat and ate, the injured chimp limped off to look for ferns. “He was the only one who found and ate the ferns.”
The researchers collected and analyzed a fern called Cristella parasitica and found it to have powerful anti-inflammatory properties.
In total, the researchers took 17 samples from 13 different plants and sent them to Dr Fabian Schulz of the Neubrandenburg University of Applied Sciences in Germany for testing.
They found that nearly 90% of the extracts inhibited bacterial growth, and a third had natural anti-inflammatory properties, which may reduce pain and promote healing.
Dr. Freiman is pleased to report that all of the injured or sick chimpanzees reported in the study made full recoveries. “The chimpanzees who ate the ferns were able to use their hands again within a few days,” she explained.
“Of course, we can’t prove 100% that any of these cases were a direct result of consuming these resources,” she told BBC News.
“But it highlights the medical knowledge we can gain from observing other species in the wild, and the urgent need to protect these ‘forest pharmacies’ for future generations.”