when did humans start keeping track of years
History of calendars A number of prehistoric structures have been proposed as having had the purpose of timekeeping (typically keeping track of the course of the solar year). This includes many megalithic structures, and reconstructed arrangements going back far into the Neolithic period.
Prehistory The period when a culture is written about by others, but has not developed its own writing is often known as the protohistory of the culture. By definition,[1] there are no written records from human prehistory, so dating of prehistoric materials is crucial. Clear techniques for dating were not well-developed until the 19th century.[2]