Self-Medicative Behavior in the African Great Apes: An Evolutionary Perspective into the Origins of Human Traditional Medicine

Abstract

by observing a similarly sick young porcupineingest the roots ofthe plant.Before these opportune obser-vations,Babu Kalunde and the people ofhis village hadavoided this plant,which they knew to be highly poisonous.After telling the villagers his story ofthe porcupine,however—and taking small doses ofthe plant himself—he persuadedthem to use the plant on the sick.To this day,the WaTongweuse the roots ofmulengelele as medicine.Babu’s grandson,Mohamedi Seifu Kalunde,now a respected elder and healerhimself,uses this plant to also treat gonorrhea and syphilis.By comparison with Babu,scientists are latecomers to thestudy ofanimal self-medication and its possible applicationsfor modern medicine.In recent years,however,a growing bodyofscientific evidence has been gathered in support ofanimalself-medication,or zoopharmacognosy (Huffman 1997).Starting with chance observations ofa sick chimpanzee in 1987(Huffman and Seifu 1989),Mohamedi and I have worked to-gether with a growing group ofcollaborators to learn howchimpanzees in the wild deal with parasites and what their be-havior can tell us about treating other diseases.Unnecessary for nutrition,growth,or reproduction,the sec-ondary compounds in a plant have evolved to give protectionfrom insect and mammalian predators.Whereas ecologistswho study animal foraging behavior focus on how animalscope with these secondary compounds in their diet (Freelandand Janzen 1974,Glander 1975,1982,Hladik 1977,Janzen1978,Wrangham and Waterman 1981),the basic premise ofzoopharmacognosy is that animals utilize these secondarycompounds to medicate themselves.Taking a broader per-spective,we are interested in putting these lessons ofevolu-tionary medicine to practical use for humans (Huffman andSeifu 1989,Ohigashi et al.1994,Plotkin 2000).Much ofthe plant material that is consumed by animals inthe wild contains an array ofsecondary compounds.Johns(1990) argues that the herbal medicines and modern phar-maceuticals used by humans today have replaced the non-nutritive chemicals commonly present in our primate an-cestors’diets.In this light,the nonnutritive components ofitems ingested by African great apes—and,indeed,all