Do any primates self-medicate?

BBC Wildlife contributor Ben Garrod answers your wild question.


Black lemurs seek out millipedes for health – and possibly recreation © Marco Pozzi Photographer / Getty


Yes. Several species have been observed carrying out self-medicating behaviour. White-faced capuchins in Central America, for example, rub themselves with piper leaves, possibly to deter parasites, while African red colobus monkeys eat charcoal to help them digest toxic plants.

One species of lemur in Madagascar appears to have adopted a particularly unusual relationship with a locally available ‘medicinal’ resource. The fruit-eating black lemur Eulemur macaco has been observed picking up and gently biting large red millipedes before dropping them onto the ground.

In response to the nibbling, the invertebrates curl up into defensive coils and exude toxins. These secretions consist of chemical compounds such as benzoquinone and even cyanide, both of which are thought to act as natural insecticides, even warding off malaria-carrying mosquitoes.

In addition to the health benefits, some researchers have suggested that the lemurs gain some sort of narcotic pleasure from their millipede encounters. After inhaling or swallowing the toxins, the primates have been observed drooling heavily and entering an apparent state of intoxication.

The chemical compounds are known to inhibit their monoamine oxidase system, which has been associated with feeling ‘high’ in humans. 

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