The Nile River flows north from Lake Victoria and Lake Albert. Its rate of flow, its direction of flow, and even its course have varied greatly over time; these variations likely influenced early human evolution and, more recently, have affected the development of early civilizations, the chemistry in the Mediterranean Sea, and the evolution of endemic fish populations in the African Rift Valley. Nineteenth century explorers identified the source of the White Nile as Lake Victoria. In order to resolve the uncertainty over the beginning of the outflow from Lake Victoria (to form the modern Nile), Talbot et al. measured Sr isotopes in fossil shells and fish bones and thus mapped the late Pleistocene history of Nile River flow. Lake Victoria provides waters with distinctive Sr isotope ratios, and this signature is seen in Nile River fossil deposits starting from about 13,000 years ago (11,500 radiocarbon years ago).—BH
Geology28, 343 (2000).