When did we start counting years?

It’s a New Year! And this led me to ask a lot of questions about things I never thought about before, but mainly:

When did years start being numbered?

We mark the passage of time without thinking about it anymore. It’s just a thing we do. There’s a calendar, and we are looking at our watches (and phones), but it was not always the case. At least, I think so, because even if I learned at school why we divided the calendar the way we do it, and why an hour is an hour, I never knew—or asked—how it all started.

As you may know, a year is the orbital period of a planetary body moving in its orbit around the Sun. It takes a year for the Earth to complete a revolution around the Sun.

That said, what we are calling “a calendar year” is really a Gregorian year. Introduced in October 1582 by Pope Gregory XIII, the Gregorian calendar is a solar calendar, 365 days (12 months of 28–31 days each), with a leap day being added to February in the leap years—also, FYI, one goal of the Gregorian calendar was to change the date of Easter.

Kalendarium gregorianum perpetuum, Venice, 1582, later vellum (source)

The Previous Calendars

Before the Gregorian calendar, we had the Julian calendar, proposed by Roman consul Julius Caesar in 46 BC (took effect on 1 January 45 BC, by an edict). It was very similar to its successor but dealt differently with the leap year (the Gregorian reform omitted a leap day in three centurial years every 400 years and left the leap day unchanged).

Designed with the aid of Greek mathematicians and astronomers, the Julian calendar was used in most of the Western world for more than 1,600 years. It was a reform of the Roman calendar inspired by a discussion about the Egyptian calendar. They all had problems dealing with the fact that the year is a bit more than 365 days, but less than 366 days—in the Egyptian calendar, a fixed year of 365 days was in use, drifting by one day against the sun in four years.

As for the Roman calendar, there was more than one. Before the Julian calendar, there was the Flavian, the Republican, a 10-month calendar (only 304 days a year), and a lunar calendar.

A traditional lunisolar Chinese calendar.

A lunar year is 354 days, 8 hours, 48 minutes, 34 seconds—354.36707 days! Apparently, a lunisolar calendar was found at Warren Field in Scotland—most calendars referred to as “lunar” calendars are in fact lunisolar calendars. It’s a mesolithic monument built about 8,000 BCE. It was created by hunter-gatherer peoples, not by sedentary farmers, which is pretty significant.

In conclusion, we start counting years way before we started documenting History. The years may have been of different lengths, but humans were always influenced by the Earth’s rotation around the Sun and the time that passed during each revolution.

Anyway, Happy New Year To You!

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