By 2400 B.C., Sumerians had stepped up their game to devise a pseudo-monthly calendar. This set up 12 periods of 30 days, reflecting our modern 30-day months and 12-months-a-year system.

Each year in the Chinese calendar is linked to one of 12 zodiac animals: rat, ox, tiger, rabbit, dragon, snake, horse, goat, monkey, rooster, dog and pig. These animals represent different traits. For ...