Orangutans Use Plants to Ease Pain

Humans are not the only species of animal that self-medicate. Cats and dogs, for example, chew grass to address gastrointestinal issues. Many animals ingest plants, fermented fruits and other agents from nature's pharmacy to aid digestion, to kill parasites, and to improve mood (think catnip and felines). Bears, deer, elephants, chimpanzees, lizards, birds, bees, cats, dogs, and even woolly bear caterpillars do it. Now, for the first time, researchers have observed orangutans taking their self-care a step further. Behavioral ecologist Helen Morrogh-Bernard of the Borneo Nature Foundation and her team watched 10 orangutans for more than 20,000 hours interact with a plant called Dracaena cantleyi. Although this shrubby plant isn't on the orangutan's regular menu, they were occasionally seen to chew on its leaves to produce a moist lather, which they applied to their upper arms and legs much like an analgesic rub. Intrigued by this behavior, Morrogh-Bernard's co-authors at the Czech Academy of Sciences, Palacký University Olomouc and the Medical University of Vienna analyzed the plant's constituents. Using human skin cells synthesized in vitro and stimulated to produce inflammatory cytokines, the researchers found that the level of cytokines were reduced when extracts from the plant were introduced. The research team reported these findings in Scientific Reports in November 2017. But not all orangutans are necessarily hip to this pain-killing trick. In fact, it appears that this behavior in orangutans is only seen in south-central Borneo, indicating it was a local discovery by one orangutan who then passed it on to others in the group watching nearby. The implication from this for humans is that previously unknown plant substances with medicinal value may be found by observing animals. The study of animal self-medication is known as zoopharmacognosy. Apparently, there's a lot to study out there...

• North American brown bears make a paste of saliva and chewed Osha root to repel insects and to ease bites. Osha root contains more than 100 insect-repelling agents.

• Lizards sometimes eat certain roots to counter snake bites.

• In Madagascar, pregnant lemurs nosh on tamarind and fig leaves to promote a healthy delivery and increase milk production.

• In Kenya, pregnant elephants seek out and consume certain tree leaves to induce labor.

• Fruit flies protect their offspring from parasitoid wasps by laying eggs in plants that contain high levels of ethanol.

• More than 200 species of songbirds engage in "anting," in which they roll in ant hills constructed by ants that produce high levels of formic acid to prevent lice from attaching to their feathers.

• Honeybees seek out certain plant resins with which to line the interior of their hives to deter fungal parasites.

References H. C. Morrogh-Bernard, I. Foitová, Z. Yeen, P. Wilkin, R. de Martin, L. Rárová, K. Doležal, W. Nurcahyo & M. Olšanský, Self-medication by orang-utans (Pongo pygmaeus) using bioactive properties of Dracaena cantleyi, Scientific Reports, volume 7, Article number: 16653 (Nov. 2017) https://www.nature.com/articles/s41598-017-16621-w