Orang-utans Self-Medicating

Siobhan Pestano 19 August 2019

In recent years, wild orang-utans (Pongo pygmaeus) have been observed utilising a particular wild-growing plant for medicinal purposes - specifically as an anti-inflammatory to sooth aching joints or swellings.

The plant, Dracaena cantleyi, has been clearly shown to have naturally-occurring anti-inflammatory properties when the chemical constituents were analysed.

Why is this considered so important? For two reasons:

Firstly, because these studies record what they believe are the first documents cases of Asian Great Apes exhibiting “secondary self-medication” (where medicinal substances are applied topically, rather than ingested, which is termed “primary self-medication”).

Secondly, because the local indigenous people have been using the same plant, for the same purpose, for many years. They make a balm from the crushed leaves and rub in on sore bones or muscles. The lead researcher and author, Dr Helen Morrogh-Bernard, feels this correlation “links apes and humans directly”.

Orang-utans have been observed self-medicating, using plants with anti-inflammatory properties topically

Orang-utans have been observed self-medicating, using plants with anti-inflammatory properties topically

For the first time ever, self-medication activities of orangutans have been confirmed through this research.
— Dr Ivona Foitova, Project researcher and co-author

The orangutans make their own “balm” - by masticating the leaves, which releases saponins, which have “soapy” or foam texture when mixed with water - or in this case - their saliva. They then rub the resulting liquid with care and deliberation on the parts of the body where is it needed, taking between 15 - 45 minutes.

Like many medicinal plants, the leaves taste bitter, which the orangutans tolerate in order to make their “medicine” - but they spit out any remaining chewed leaves from their mouth, electing not to swallow them.

Ten such incidences were recorded in a study that took place between 2003 - 2015, and the behaviour was described as “very rare”. It was observed almost exclusively in adult females, with most applications focused on arms rather than legs. One suggested theory for this is possible strain caused by the extra weight from carrying young offspring.

This is indeed exciting and important research, but there is nothing to indicate that it is a new behaviour - it is more likely a long-exhibited behaviour by orangutans that has only relatively recently been observed and documented by humans.

As Morrogh-Bernard observes, rather than the orangutans copying the medicinal use of the plant by local people, in true ethnobotanical style, is it more likely that the local people observed the orangutans use of the plant, and copied them?