Pick, chew, scoop and apply when required for relief of inflammation

There have been occasional reports of wild animals using naturally occurring drugs. For example, some species such as chimpanzees chew certain types of rough hairy leaves, apparently to remove intestinal parasites, and one species of lemur has been observed rubbing aromatic leaves into its fur to repel parasites.

Recently, however, Helen Morrogh-Bernard of Cambridge University watched as wild orang-utans in the Sabangau Peat Swamp Forest in Indonesia prepared and used an anti-inflammatory substance.

The apes were observed to pick a handful of leaves which when chewed and mixed with its saliva made a greeny-white lather. This was scooped up in one hand and methodically applied to the back of the other arm from shoulder to wrist just as we would apply a cream.

After use the remaining lather was discarded. This behaviour was recorded on four occasions with different animals.

When discarded lather was collected and analysed, the leaves were found to be from a plant of the dayflower genus (Commelina). This is not a normal food plant for the local people, but they grind it into a balm for muscular pain, sore bones and swellings.

Their ancestors may have learnt how to use this medicine by watching the orang-utans. Further investigation may also show that the animals can teach one another. In any event these self-medicating apes do seem to have gained some useful pharmaceutical knowledge.