An orangutan was observed using medicinal plants to heal an injury. Image source: Wilfredor, via Wikimedia Commons
A Sumatran orangutan has become the first wild animal observed to use a medicinal plant to topically heal a wound.
The subject, a male orangutan named Rakus, has been observed in the area since 2009 and is estimated to have been born in the late 1980s.
Rakus was observed to have a wound on his face on 22 June 2022.
How the wound occurred is unknown though researchers suggested he may have fought with another male. It was noted that vocal evidence of a fight between orangutan males was reported earlier that day.
On 25 June, Rakus was seen feeding on the leaves of a liana called Fibraurea tinctoria, or ‘Akar Kuning’, which is used in traditional medicine in the area to reduce fever, relieve pain, and treat diseases.
F. tinctoria is also known for its antibacterial, anti-inflammatory, anti-fungal, and antioxidant properties.
Rakus was seen chewing the leaves into a paste which he applied directly to his wound. He repeated this behaviour the following day.
By 30 June, the wound had closed without any signs of infection, and after a month, the only indication left of the injury was a scar.
Dr Isabella Laumer, a biologist at the Max Planck Institute in Germany and lead author of the research, discussed the possibility of the behaviour being coincidental.
“It could be that he accidentally touched his wound with his finger that had the plant on it. And then because the plant has quite potent pain relieving substances he might have felt immediate pain relief, which made him apply it again and again,” said Dr Laumer.
Despite this possibility, the researchers concluded Rakus’s actions were deliberate because orangutans rarely eat F. tinctoria and he spent the days after the injury resting longer than usual, potentially recuperating.
“He repeatedly applied the paste, and he later also applied more solid plant matter. The entire process lasted really a considerable amount of time—that’s why we think that he intentionally applied it,” said Dr Laumer.
The report discussed other self-medication behaviour in wild animals, such as the phenomenon of chimpanzees ingesting whole leaves that have potential health benefits.
“This possibly innovative behaviour presents the first systematically documented case of active wound treatment with a plant species known to contain biologically active substances by a wild animal and provides new insights into the origins of human wound care”, said the report.
Scientists will continue to observe orangutans in the area for future similar behaviours.
