An East African savanna landscape of tree-dotted grassland is shown in this image from Samburu National Reserve in Kenya. The more heavily vegetated area in the middle distance is the corridor of the Ewaso Ngiro River. A new University of Utah study concludes that savanna was the predominant ecosystem during the evolution of human ancestors and their chimp and gorilla relatives in East Africa. Photo Credit: Thure Cerling, University of Utah.
