In the legend "Shennong tastes hundreds of herbs", he discovered different herbs that could cure diseases. This may be part of folklore, however, the use of herbs for treating ailments is indeed a long-standing practice among humans. As it turns out, many animals in nature also engage in similar behaviours as well. They not only use leaves, roots, and bark, but also employ insects, soil, and minerals for healing purposes. Perhaps even animals have their own Lord Shennong! This behaviour of using nature’s resources for self-medication is called "zoopharmacognosy".
"Zoopharmacognosy" is derived from "zoo" (meaning "animal"), "pharma" (meaning "medicine"), and "cognosy" (meaning "knowledge"). Relevant research began in the 1960s when scientists observed different groups of chimpanzees across the globe and found unusual behaviours. There were some groups that ingested leaves of no nutritional value, while others swallowed leaves whole without chewing, and these feeding behaviours did not actually provide any nutritional benefits to the chimpanzees. Consequently in 1996, biologist Michael Huffman proposed the idea that these chimpanzees were actually engaging in self-medication.
He observed this unusual behaviour in a chimpanzee in Tanzania that was suffering from constipation due to a parasitic infection. It ingested the leaves of a toxic plant, and on the next day, the constipation resolved. Huffman’s theory was that the chimpanzee ingested the rough leaves to scrub its intestines and expel the parasites.
Based on Huffman's research, scientists have been using his four criteria to determine if an animal is using a plant for self-medication. These criteria include:
1. The plant is not part of the animal's regular diet.
2. The plant has little or no nutritional value.
3. The animal only consumes the plant during a specific time of year (such as during the rainy season when animals are more prone to parasitic infections).
4. Other members of the same species do not feed on the same plant.
Nature's Pharmacy
In addition to ingesting leaves, animals know how to use different parts of plants and even insects and soil to treat ailments, heal wounds, kill parasites, or promote digestion, etc., either by applying them topically or ingesting them. For example, lemurs rub millipedes on their bodies and fur, causing the millipedes to secrete a toxin that contains cyanide, which acts as an insect repellent. Some birds also engage in similar behaviours using ants.
Another example is African elephants, which will ingest the leaves and bark of a specific shrub during their late stage of pregnancy to aid when in labour. Sometimes, they will even travel long distances just to find this shrub. Interestingly, women in Kenya collect the same plant to brew a kind of tea as an aid when giving birth.
Additionally, animals in South America such as parrots, macaws, spider monkeys, and peccaries consume clay with high kaolin content. The leaves and fruits they consume in tropical rainforests often contain toxins, and kaolin absorbs these toxins, helping with detoxification and alleviating digestive discomfort. In China, South America and Africa, kaolin is also traditionally used as a medicine to treat gastric pain and diarrhoea.
First Known Case of Treating Wounds with Topical Application
In 2022, a Sumatran orangutan named Rakus was observed applying sap from the leaves of Akar Kuning (Fibraurea tinctoria), a climbing plant native to India and Southeast Asia and belonging to the Menispermaceae family, to a wound on its face. It also chewed on the leaves to create a "salve", which it used to treat the wound over a considerable period of time. This plant is widely used in traditional medicine by locals to treat various ailments such as dysentery, diabetes and malaria, and it possesses antibacterial, anti-inflammatory, antifungal, and antioxidant properties and other components that promote wound healing. This was the first observed instance of a wild animal using a plant with known medicinal value to treat a wound topically.
