Modern sports all have rich histories full of tradition. Horrible, horrible tradition.
Yes, if you delve back far enough, "tradition" quickly takes a back seat to bizarre custom and wanton brutality. All in the name of good fun, though.
5Football: Basically a Town-Wide Riot
American football was cobbled together from a bunch of different sports, as you can pretty much tell by watching it. It's got some rugby, some soccer, some attempted murder. Probably the oldest ancestor was mob football, which was played throughout the Middle Ages and was really closer to a spirited match of Calvinball than anything else.
This medieval football distinguished itself from the modern game by doing away with those silly and pointless conventions we know as "rules." Teams could be as large as they wanted and occasionally involved entire villages, and the only thing expressly forbidden was the killing of opposing players (although many agree this is a fine strategy if it can be done without attracting the attention of the refs).
Anything else was fair game. Unsurprisingly, matches often dissolved from "rioting" into "rioting while things are on fire." The goal of the game was to get the ball to the other team's goal line, which were often put at opposite ends of the town. As a result the field was huge and littered with troublesome obstacles like buildings and the elderly.
Needless to say, there were some accidental deaths and the game was banned no less than 30 times in England over the course of three centuries.
Who's winning? All of us.
Over time, they steadily changed the game as people decided they wanted less murder in their sports. By the 16th and 17th centuries, it was civilized enough to make its way onto university campuses, and a few centuries after that it was all about pads and rules and not stabbing people. Still, to this day after their team wins a big game, some fans like to take to the streets and reenact the old days.