Orangutans: Scientists spot wild ape using medicinal plant on its wound for first time ever

A critically endangered orangutan has stunned biologists, by applying a plant known to have pain-killing properties directly onto a nasty face wound.

In a new report, published this week in Scientific Reports, scientists detailed how they witnessed a wild Sumatran orangutan chewing the leaves of a climbing plant known as Akar Kuning - or Fibraurea tinctoria - and applying the juicy mixture to an injury on his cheek. The team believe this to be the first time a non-human animal has been seen using a medicinal plant to directly treat a wound - and say it could help shed light on how we developed our own medical knowledge.

Sumatran orangutans, one of three subspecies of the great ape, are classified as critically endangered by the International Union for Conservation of Nature (IUCN), and are only found on the northern end of the Indonesian island of Sumatra. About 150 of them live around the Suaq Balimbing research site, a protected rainforest area, including Rakus - a male.

Rakus was believed to have suffered the facial injury three days earlier, before biologists saw him smearing the chewed leaves onto his wound until it was fully covered - a process that lasted more than 30 minutes. The researchers said there were no signs of infection, and the wound closed up over the next five days, with Rakus making a full recovery.

The researchers said it was likely that Rakus knew what he was doing as he only used the plant on his injury - and did not apply it anywhere else on his body. Dr Isabelle Laumer, a primatologist and cognitive biologist at the Max Planck Institute of Animal Behaviour, told PA: “During daily observations of the orangutans, we noticed that a male named Rakus had sustained a facial wound, most likely during a fight with a neighbouring male.”

She said the Akar Kuning plant, found across the tropical forests of Southeast Asia, was known for its pain relieving and anti-inflammatory effects - and was often used in traditional medicine to treat diseases such as dysentery, diabetes and malaria. “Analyses of plant chemical compounds show the presence of furanoditerpenoids and protoberberine alkaloids, which are known to have antibacterial, anti-inflammatory, anti-fungal, antioxidant, and other biological activities of relevance to wound healing,” Dr Laumer said.

Rakus was also observed resting more than usual after being wounded. “Sleep positively affects wound healing as growth hormone release, protein synthesis and cell division are increased during sleep,” she added.

Her colleague Dr Caroline Schuppli, an evolutionary biologist at the Max Planck Institute, added that seeing this behaviour in great apes - our closest relatives - suggested it could have arisen from a common ancestor. “The treatment of human wounds was most likely first mentioned in a medical manuscript that dates back to 2200 BC, which included cleaning, plastering, and bandaging of wounds with certain wound care substances,” she said.

“As forms of active wound treatment are not just human, but can also be found in both African and Asian great apes, it is possible that there exists a common underlying mechanism for the recognition and application of substances with medical or functional properties to wounds, and that our last common ancestor already showed similar forms of ointment behaviour,” she said.

However, the researchers said there was also a possibility that Rakus may have found out about the healing properties of Akar Kuning by accident. “Orangutans at the site rarely eat the plant,” Dr Schuppli continued.

“However, individuals may accidentally touch their wounds while feeding on this plant and thus unintentionally apply the plant’s juice to their wounds. As Fibraurea tinctoria has potent analgesic effects, individuals may feel an immediate pain release, causing them to repeat the behaviour several times.”

Other animals have also been observed eating plants known to have medicinal properties over the years - although Rakus is the first to be seen directly applying it to an injury. These include bears, deer, elk, and other great apes.

Some lizards are believed to respond to a bite by a venomous snake by eating a certain root to counter the venom, a Proceedings of the National Academy of Sciences article from 2014 claimed, while pregnant elephants in Kenya eat the leaves of a tree thought to help induce delivery. Red and green macaws have been observed eating clay to help digestion, while baboons in Ethiopia eat the leaves of a plant which helps combat flatworms.