20,000 B.C.: The invention of arithmetic provides a way to abstractly compute numbers of objects.
15,000 B.C.: The Lascaux cave paintings record some of the first known narrative constructions.
3,800 B.C.: The Babylonian census begins the practice of systematically counting and recording people.
3,500 B.C.: Written language emerges [pictured: an early cuneiform tablet], providing a systematic way to record and transmit knowledge.
2,500 B.C.: The first known calendar system is established in Mesopotamia, creating a 360-day year.
Content courtesy of Wolfram|Alpha