Today’s Wonder of the Day was inspired by edward. edward Wonders, “why is tug of war a game” Thanks for WONDERing with us, edward!

At summer camps around the United States, kids of all ages square off in a battle of strength that dates back centuries. Is the water balloon toss really that old? No! We're talking about tug of war!

Tug of war is a sport that pits two teams against each other to test their strength using nothing more than a rope and pure muscle. Although we can't be sure exactly when the first-ever tug of war match took place, we do know that it was a long, long time ago.

Ancient Chinese texts claim that military commanders used tug of war (then called “hook pulling") to train warriors 7,000 to 10,000 years ago. Archaeologists have also found evidence that tug of war was popular in India in the 12th century.

There is also evidence that tug of war was common in ancient Egypt. Old Egyptian legend holds that the sun and the moon played tug of war over light and darkness.

The phrase “tug of war" didn't always refer to the game we know today, though. The Oxford English Dictionary indicates that “tug of war" used to mean “the decisive contest; the real struggle or tussle; a severe contest for supremacy." It wasn't until the 19th century that “tug of war" became associated with the sport between two teams tugging on the ends of a rope.

To play tug of war, you really only need a rope — or anything with opposite ends to tug on — and at least two people. Of course, the more people involved, the more fun it is.

The number of people who can play is really only limited by how long the rope is. Serious tug of war contests usually pit two teams of eight players against each other.

The winning team is the one that pulls the other team past a predetermined point. Often this point is marked on the ground.

Flags are spaced equally along the rope from the center point. As soon as one team pulls the other team far enough for their flag to cross the line, they win.

To make things even more fun, there are many variations that can be included. Sometimes teams play tug of war on either side of a small body of water, with the losers getting pulled into the water. Even more fun is playing on either side of a mud pit!

Tug of war is played in probably every country in the world. Many countries have even set up national governing bodies to oversee the sport. Today, there are more than 50 countries associated with an international tug of war governing body, known as the Tug of War International Federation (TWIF).

Although tug of war was included in the Olympic Games from 1900 to 1920, it is no longer an Olympic sport. Tug of war is currently played in the World Games, and the TWIF regularly organizes tug of war world championships. So, yes, even grown-ups still play tug of war!

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