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Do Gorillas Use Plants as Medicine?

August 2009

Do Gorillas Use Plants as Medicine?

Mountain gorillas and humans share more then just genetics. Scientists have begun to compare the ways both gorillas and humans use plants. African traditional healers have been using indigenous plants for many years to treat certain ailments, and now researchers are starting to discover that gorillas include many of the same plants in their diet.

A botanical bounty

From its grassy savannahs to its high mountains, the African continent is home to an amazing diversity of habitats, home to many thousands of known plant species. To date, over a thousand plants have been identified just in the Volcanoes National Park in Rwanda, which is home to the mountain gorillas, and more are being discovered all the time.

"We study the entire habitat of the gorillas, which includes plants," says Katie Fawcett, Ph. D., director of the Dian Fossey Gorilla Fund International's Karisoke Research Center, which monitors and protects mountain gorillas in the park. Medicinal plants are of particular importance to Karisoke for two reasons: the possibility that they are used by gorillas, and also to help predict where people might search for plants in the park illegally. Karisoke's 40 years of research provide a solid foundation for exploring these questions.

Prosper Uwingeli, chief park warden for ORTPN, the Volcanoes National Park authority, adds, "As part of the entire biodiversity, it is extremely important to study plants, especially to understand the carrying capacity of the park," in other words, how many individuals of various species the park can support. As information about the plants is gathered, ORTPN uses it to help manage the park.

Ever since the time of Dian Fossey, Karisoke researchers have been interested in the plant species used by the gorillas. It was during Fossey's lifetime that a herbarium was set up to begin cataloguing and identifying local plant species. Karisoke staff press and record plant samples and send copies to the National Herbarium at Rwanda's Institute of Scientific Research and Technology.

In 2005, Aimable Nsanzurwimo, a research assistant with the Fossey Fund, began studying bamboo ecology for Karisoke. Since then he has helped to increase the number of plant species known to occur in the park from 245 to 1,034, including plants new to science and new to Rwanda. Some groups of plants have yet to be studied, so the number of newly discovered plant species is expected to increase.

"We want to document the plants before they disappear," said Nsanzurwimo. "The herbarium at Karisoke will be a major resource for future scientists who want to study Rwandan plants."

Plants that heal

Research supported by the Fossey Fund has begun to explore the exciting question of medicinal use of plants by human and, possibly, gorilla populations. Nsanzurwimo and Alphonse Nahayo, a National University of Rwanda student working on his thesis, are studying the medicinal plants.

The most common medical problems that affect mountain gorillas are respiratory infections, diarrhea, and intestinal parasites. The main disease challenges for the local human population are similar. Surveys have shown that traditional healers who live near the park use up to 183 different plants, of which 110 grow wild in Volcanoes National Park and the remaining 73 are cultivated by people in their gardens. Of the 110 medicinal plants found in the park, 55 are known to be consumed by gorillas.

Over a six-month period, Nahayo collected plants eaten by gorillas, for analysis and screening. He narrowed his selection to three of the gorillas' favorite species, which were analyzed for their chemical properties and then tested for their medical effects on bacteria and parasites.

Researchers discovered, by using chromatography, that similar plant species contained a number of organic properties known to have positive effects against bacteria and parasites that cause diarrhea and respiratory diseases. These findings led to more questions for researchers: "Do the gorillas treat themselves by seeking specific plants, or does their constant intake of a variety of plant material end up being a preventive measure?"

This is just the beginning of the questions the researchers are asking. Another 52 plants known to be used by traditional healers and also consumed by gorillas have not yet been analyzed for medicinal properties. What about the other plants eaten by gorillas that are not used by traditional healers? For the future, how does climate change effect the plant population? Protection of areas such as Volcanoes National Park and their biodiversity can lead to amazing benefits for mankind.

Photos: Dean Jacobs/DFGFI