Ages of Man
Giambattista Vico's ricorso: the return of the society to a relatively more primitive condition
JRR Tolkien's fictional "Four Ages"
Modern archaeology: Three-age system (Stone, Bronze and Iron), with each of the stages further divided into substages (e.g. Stone Age comprises Paleolithic, Mesolithic and Neolithic). Lebenstreppe: an artistic tradition that depicts the ages as a series of ascending and descending steps