At the study site in Uganda’s Kibale National Park, researchers have seen chimps eating dirt – a practice known as geophagy. Often the behaviour is seen along with eating particular plants. To work out the possible purpose of this peculiar behaviour, soil and leaf samples were taken for analysis. Along with being examined separately and together, the samples went through a process similar to chewing and digestion.

 

The soil turns out to be similar to kaolinite clay, used locally as a diarrhea treatment and resembling western medicines like Kaopectate. One of the sampled plants is Trichilia rubescens, which has shown anti-malarial and antiparasitic properties in the lab. When the leaves and soil were combined and put through digestion simulation, they had increased anti-malarial properties. A number of other plants eaten by chimps also demonstrate biologically active ingredients.

 

It is possible that geophagy evolved to enhance self-medication with certain medicinal plants (known as zoopharmacognosy). Malaria affects mammals such as apes, but in a form that cannot be exchanged directly with humans. Primates are often involved in the development and testing on anti-malarial medications for people, due to their physiological and genetic similarities. The plants eaten by chimps also shed light on new sources of medication for pharmaceutical research.