Self-medicating With Plants

Biological Strategy

Chimpanzee

AskNature Team

Image: Bernard DuPont / Flickr / Some rights reserved

Protect From Animals

Animals–organisms that range from microscopic to larger than a bus–embody a wide variety of harms to living systems, including other animals. They threaten through predation, herbivory, defense, and parasitism, and they compete for resources such as water, nutrients, and space. Any given living organism commonly faces threats from a variety of animals, requiring strategies that effectively defend from each. Trout and other bony fish, for example, escape predators by having scales made of very thin, flake-like pieces of bone covered with slippery mucus. They also have behavioral strategies such as camouflage, fast swimming, and twisting and turning to achieve release from a predator’s grip.

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Protect From Fungi

Fungi–which include molds and mushrooms, amongst others–play important roles in every ecosystem, but can also create diseases in plants and animals. Fungi can rapidly reproduce, so living systems must fend them off early to avoid their spread and potential, physical harm. Living systems use both physical and chemical strategies to protect from fungi, and must ensure that these strategies don’t harm the threatened living system itself. For example, a pumpkin’s skin has antifungal proteins to prevent fungal growth without harming the pumpkin itself.

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Protect From Microbes

In living systems, microbes play important roles, such as breaking down organic matter and maintaining personal and system health. But they also pose threats. Bacteria can be pathogens that cause diseases. Some bacteria create colonies called biofilms that can coat surfaces, reducing their effectiveness–for example, inhibiting a leaf’s ability to photosynthesize. Living systems must have strategies for protecting from microbes that cause disease or become so numerous that they create an imbalance in the system. At the same time, living systems must continue living in harmony with other microbes. Some living systems kill microbes. Others repel without killing to reduce the chances that microbes will adapt to the lethal strategy and become resistant to it. For example, some pea seedlings exude a chemical that inhibits biofilm buildup.

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Mammals

Class Mammalia (“breast”): Bats, cats, whales, horses, humans

Mammals make up less than 1% of all animals on earth, but they include some of the most well-known species. We know first-hand some of the characteristics that make mammals unique, like having hair, being able to sweat, and producing milk through mammary glands. Another critical shared feature is a set of highly-specialized teeth. Unlike sharks or alligators, for example, whose teeth are generally all the same size and shape, mammals have differently shaped teeth in different areas of the jaws to target specific foods or foraging strategies.

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Chimpanzees protect against pathogens by self-medicating with various plants.

“Perhaps the most famous example of an animal herbalist is the common chimpanzee (Pan troglodytes). Those living in Tanzania’s Gombe National Park are often seen pulling leaves off any of three species of Aspilia, a genus of bushy plant related to the sunflower. Instead of simply chewing the leaves, the apes roll them around their mouths for a while, rather like humans sucking medicinal pills, before swallowing them whole.

“Humans living in this area do precisely the same with Aspilia leaves (which taste far too unpleasant to chew, anyway), as they are effective in killing harmful bacteria and fungi because they contain thiarubine A, a powerful antibiotic. They also rid the intestinal tract of parasitic nematodes. In addition, scientists believe that these leaves act as a stimulant for the chimps, since they tend to eat them first thing in the morning, just as humans often drink coffee or tea shortly after waking to benefit from the stimulating effect of caffeine…Another herbal remedy employed by Tanzanian chimps is the bitter-tasting pith of the aptly named bitterleaf shrub (Vernonia amygdalina). This is popularly used by native tribes to counter both parasites and stomach pains, and has been proven to help the recovery of sick chimps.” (Shuker 2001:214)