can you make about the contents of these cells?

Word Roots and Origins transpiration from the Latin trans, meaning "across," and spirare, meaning "to breathe"

□ IntehMccflfttd Topic: Transpiration Keyword: HM61552 Topic: Transpiration Keyword: HM61552

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rPMJL'C National Science f TO. Teachers Association

Maintained by the rPMJL'C National Science f TO. Teachers Association

Science in Action

Do Wild Animals Self-Medicate?

Many plants have chemical compounds that defend the plants against herbivores. Such compounds are the active ingredients in many familiar medicines. With so many plants in existence, how do scientists know which ones to test for possible medical benefit? Michael Huffman studies animal feeding behavior for clues.

Dr. Michael Huffman

HYPOTHESIS: Chimpanzees Eat Some Plants for Medicinal Purposes

Researchers studying chimpanzees in Africa have noted that chimps have an unusual feeding habit when they are ill. Before eating the shoots of the plant Vernonia amygdalina, chimps carefully remove the outer bark and leaves to chew on the exposed pith, the spongy material found in some vascular plants. The chimps extract juice from the pith, which the researchers found odd because the juice is extremely bitter. Even though the plant is available year-round, chimps rarely eat it. Based on his observations and those of other scientists, Michael A. Huffman, a researcher at the Primate Research Institute in Japan, wanted to find out whether chimps are self-medicating by eating these plants.

METHODS: Observe Behavior, Collect Samples, and Test Plants

Huffman began by collecting chimpanzee fecal samples at Mahale, Tanzania. He also made detailed observations of as many individual chimps as possible. The fecal samples were from chimps seen eating V. amygdalina during times of apparent illness. Huffman collaborated with other scientists already studying chemicals found in V. amygdalina.

RESULTS: Chimps Recover; Fecal Samples Contain Parasites; Plant Analysis Reveals Antiparasitic Compounds

Huffman and his colleagues found that within 24 hours after eating V. amygdalina, chimps regain their appetites, have reduced numbers of parasites, and recover from constipation or diarrhea. Scientists working with Huffman showed that the pith of V. amygdalina contains several bioactive chemicals. Tests revealed that these chemicals are effective against many different parasites. For example, vernonioside B1 and vernoniol B1 were shown to suppress movement and egg laying in Schistosoma japonicum, a parasitic worm. Scientists also found that chemicals from the pith are effective against drug-resistant malarial parasites.

CONCLUSIONS: Chimpanzees

Self-Medicate by Eating Plants with Beneficial Chemical Compounds

Interestingly, a more toxic compound, vernodalin, was found in the leaves. The pith of the plant instead contained large amounts of vernonioside B1. This same pattern was later verified in analyses of other V. amygdalina specimens collected at various locations in Mahale during different seasons. Huffman and his colleagues think that because chimps discard the bark and leaves and just eat the pith, the chimps have learned that certain parts of the plant are harmful and certain parts are beneficial.

Additional research has revealed that V amygdalina has been part of Tanzanian folk medicine for years. The WaTongwe people of this area use V. amygdalina for stomachaches and parasitic infections. Other African tribes use V amygdalina to treat ailments in their livestock, which suggests agricultural applications for other countries.

An adult male chimp with a nematode infection chews on the pith of Vernonia amygdalina.

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