Stone AgeThe developmental stage of humans in prehistory before the use of metals, when tools and weapons were made chiefly of stone, especially flint. The Stone Age is subdivided into the Old or Palaeolithic, when flint implements were simply chipped into shape; the Middle or Mesolithic; and the New or Neolithic, when implements were ground and polished. Palaeolithic people were hunters and gatherers; by the Neolithic period people were taking the first steps in agriculture, the domestication of animals, weaving, and pottery.