A part of the Olduvai Gorge, famous for its fossil records of human origins. Named by the Maasai Oldupai after the wild sisal plant, Sansevieria (in the foreground), Olduvai displays a unique evolutionary trail spanning ten million years. A fast-flowing river cut the gorge half a million years ago; a million years previously a large lake covered the entire area and was regularly visited by our human ancestors.  .