The human use of solid materials began when a prehistoric ancestor of modern man picked up a stone and used it as a tool. The Paleolithic period, or Old Stone Age, represents the longest phase in human development. Scientists often divide this large expanse of time up into three smaller periods: the Lower Paleolithic period, the Middle Paleolithic period, and the Upper Paleolithic period. The most important development to occur during the Paleolithic period was the evolution of the human species from a near-human apelike creature (referred to as Homo erectus) into a modern human being (or Homo sapien). Supported by a generous quantity of full-color illustrations and interesting sidebars, Solid Matter introduces the basic characteristics and properties of solid matter. It briefly describes the cosmic connection of the elements, leading readers through several key events in human pre-history that resulted in more advanced uses of matter in the solid state.