<s>[INST] when did humans start adopting the western way to account for years? [/INST] The Gregorian calendar, also called New Style calendar, solar dating system was proclaimed in 1582 by Pope Gregory XIII as a reform of the Julian calendar.  The Julian calendar calculated too many days, and thus a new leap year format was necessary. The Julian calendar was created in 45 B.C. by Julius Caesar. This calendar employed a cycle of three years of 365 days, followed by a year of 366 days (leap year).  When first implemented, the "Julian Calendar" also moved the beginning of the year from March 1 to January 1.</s>