A new study conducted by scientists from the National Museums of Kenya, Smithsonian National Museum of Natural History and Queens College has discovered tools used by early humans to butcher hippos and plant materials 2.9 million years ago.  Fossil remains were discovered in a site called Nyayanga, located on the Homa Peninsula in western Kenya.  According to the study, the tools are likely the oldest examples of Stone Age innovations known as the Oldowan toolkit.