Entodiniomorph ciliates of genus Troglodytella are overlooked components of the digestive system of great apes with putatively symbiotic role in fiber fermentation taking place in hind gut. Proposed project will be focused on studying fluctuation of Troglodytella abrassarti population in wild chimpanzee population of Kalinzu Forest Reserve in relation to changes in their diet, particularly in fiber intake. If Troglodytella fluctuation depends on changes in intake of dietary fiber then it supports hypothesis of a symbiotic relationship between ciliates and apes. Additionally, we will try to record first occurrence of Troglodytella in infants in connection with their developing feedings habits. Data about feeding behavior of selected chimpanzees will be recorded and fiber analyses of chimpanzee food items will be conducted. Subsequently fiber intake by chimpanzees will be determined. Concurrently with behavioral observations fecal samples will be collected and later examined for Troglodytella load. It has been proposed that Troglodytella species might live in early humans and help in the digestive processes before cooking was invented. Therefore determination of the relationships between Troglodytella species and recent apes is necessary not only for better understanding the digestion and feeding ecology of great apes but also for understanding the evolution of human digestion and dietary practices.