© Borneo Nature Foundation
Orangutans were filmed creating their own ointment from leaves to treat aching limbs.
Orangutans may have secret medical knowledge that most humans don't know about, after great apes were filmed turning plants into ointment to soothe their aches and pains.

A study found the animals chewing plants into lather then using this paste on their limbs.

The plants are also used by the orangutan's indigenous human neighbours in the forest.

The bizarre discovery, spotted during more than 20,000 hours of filming by the Borneo Nature Foundation, has researchers wondering if apes may know of medicinal plants that could be used by humans.

In the clips, apes were spotted using their own herbal medicines in the Sabangau Forest in Central Kalimantan, Indonesian Borneo.

Scientists witnessed the apes chewing the leaves into lather, then methodically rubbing it into their upper arm or legs for between 15 and 45 minutes.

They never swallowed the leaves and the remaining pulp was always spat out.
Dracaena cantleyi
© Wikimedia
Researchers conducted tests of the plants being used by the apes and found it to be Dracaena cantleyi - a plant known to locals as beneficial for treating aching limbs.

In the past, gorillas, chimps and bonobos have all been filmed swallowing the bitter juices of plants to control parasite infections.

However, this is the first time apes have been seen creating their own ointments and has set the scientific world buzzing.

Authors of a recent report say the findings are "the first time, to our knowledge, the external application of an anti-inflammatory agent in animals."

Dr Helen Morrogh-Bernard of the University of Exeter and Co-Director of Borneo Nature Foundation is the lead author of the Scientific Reports paper.

She said: "This is very exciting news as it confirms self-medication in orangutans, the first report of self-medication in an Asian ape, and for the first time, to our knowledge, the external application of an anti-inflammatory agent in animals."