The Stone Age is the first and longest stage of human technology, beginning with the first recognizable stone tools around 2.5 million years ago (in Africa, on present evidence) and continuing until the advent of metals. Its duration varies in different parts of the world. It is generally divided into three stages: the Palaeolithic (Old Stone Age), Mesolithic (Middle), and Neolithic (New). The concept arose because stone tools, being virtually indestructible, dominate the archaeological record throughout this period, but it is known that many of them were in fact used in the procurement and use of long-vanished organic materials, such as wood — Dr Paul Bahn