GEOCHEMISTRY AND CLAY MINERALOGY OF TERMITE MOUND SOIL AND THE ROLE OF GEOPHAGY IN CHIMPANZEES OF THE MAHALE-MOUNTAINS, TANZANIA

Earth from a termite mound in the Mahale Mountains National Park, Tanz ania, eaten by chimpanzees, was analyzed to determine the possible sti mulus, or stimuli, for geophagy. The termite mound sample contains rel atively high aluminum (10.0%), iron (3.0%), and sodium (0.5%). This co rrelates well with the mineralogy of the clay (< 2 mu m) fraction, whi ch is high in metahalloysite, a 1:1 (Si:Al=1:1) clay mineral similar i n chemical composition to the clay mineral kaolinite, and smectite (mo ntmorillonite), which is a 2:1 expandable clay mineral. The combinatio n of metahalloysite and smectite produces a substance much like the ph armaceutical Kaopectate(TM) widely used by humans as an anti-diarrheal agent. These analyses and preliminary observations linking geophagy w ith instances of severe diarrhea, and other signs of gastrointestinal upset in the Mahale chimpanzees, suggest that one function for the ing estion of this substance by chimpanzees may be to help provide tempora ry relief from gastrointestinal ailments. Further detailed investigati ons into the relationship between health and geophagy should provide i mportant insights into the diverse roles of this behavior as a form of self-medication.