The circus animal tradition probably started whenever humans figured out that a dog could sit on command or a monkey looked funny riding a bicycle. (The former probably happened first, but only history knows for sure.) We do at least have a record of the Greeks and Romans having a grand old time watching animals perform for them [source: Speaight]. Many of us think the "circus" started at Circus Maximus — the huge amphitheater of Rome — but it's important to remember that animals were largely used there for gladiatorial sacrifice, not performance. Not exactly friendly fare for us modern families.
By the time we arrived in the Middle Ages and Renaissance, performing animals were quite popular and — a little unlike the circus today — the animals were used as tools for propaganda, as well. One historical act had an ape that jumped for the King of England but sat stock still when someone claimed the same command was from the Pope [source: Speaight]. And while chimps or apes proved popular, it was two other animals that gave us a favorite circus nickname.