The Director of the British Museum, Neil MacGregor, retells the history of human development from the first stone axe to the credit card, using 100 selected objects from the Museum. In this programme, Neil goes back two million years to the Rift Valley in Tanzania, where a simple chipped stone marks the emergence of modern humans.One of the characteristics that mark humans out from other animals is their desire for, and dependency on, the things they fashion with their own hands. This obsession has long roots and, in today's programme, Neil introduces one of the earliest examples of human ingenuity. Faced with the needs to cut meat from carcasses, early humans in Africa discovered how to shape stones into cutting tools. From that one innovation, a whole history human development springs.Neil MacGregor tells the story of the Olduvai stone chopping tool, with contributions from Sir David Attenborough and African Nobel Prize winner Dr Wangari Maathai