Odd little February, which is named for the Roman god of purification, is the shortest month of the year. Historians aren’t exactly sure why it’s so short. But tracing its evolution gives us a capsule history of the evolution of the modern western calendar.

Our calendar is a descendant of the earliest Roman calendar. It included only 10 months, beginning with March. The year ended with about 60 days that weren’t part of any month.

That system didn’t work very well, though, so two months were added to the end of the year — January and February. They stayed at the end of the year for several centuries, until the start of the year was moved to January.

The lengths of the 10 original months were changed to give the newcomers a total of 56 days. But the Romans feared even numbers, so they added a day to January to give it 29. Since February was the month for repentance and for honoring the dead, it stayed at an unlucky even number.

This version of the calendar contained only 355 days, so an extra month was added every other year. In those years, the last five days of February were dropped.

After that, February remained unchanged until Julius Caesar introduced the basic calendar that we use today — a calendar that includes July, which Caesar named for himself. While updating the calendar, he might have added a day to February. If so, it was taken away by Augustus Caesar, who added it to the month that bears his name: August.

Script by Damond Benningfield