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updated: 6/28/2011 10:03 AM

Rubbing sticks together really can create fire

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  • John Shea makes replicas of Acheulean large cutting tools in East Turkana, Kenya.

      John Shea makes replicas of Acheulean large cutting tools in East Turkana, Kenya.
    Photo courtesy of John Shea

 

You wanted to know

Students in Elise Diaz's fifth-grade class at O'Plaine School in Gurnee asked, "If you rub two sticks together, does it really make fire, and why?"

For tens of thousands of years, people have ignited tinder and crafted fires using sticks.

When two sticks are rubbed together, the action creates friction, which causes heat. Heat coaxes the wood into a smoldering charcoal, which is fed tinder and dry sticks to become a full-fledged fire.

Common tools found in nature that can be used to start a fire are wood and flint. Flint, a quartz rock, creates sparks when struck with pyrite. The sparks that result from striking the one stone against the other are hot and can be used for fire.

"Making fire by friction is the most common preindustrial way of making fire," said John Shea, associate professor of Paleolithic anthropology at Stony Brook University in New York.

"It is found everywhere. This suggests that it is either a very ancient technique, or one that is easily rediscovered if forgotten."

Shea is an expert flintknapper -- he can manufacture tools like axes and spear tips by using stones to chip at stones, making them flat, pointy or sharp. His work has taken him to archaeological digs throughout Africa and the Middle East in search of ancient stone tools.

His recreations are on display at the Smithsonian Institution and the American Natural History Museum.

"Flint-on-stone percussion, of the kind that sometimes occurs in making stone tools, does not routinely create hot enough sparks to ignite vegetal matter," Shea said.

"If you strike flint, whose major component is quartz, against iron-rich rocks, like pyrite, you will get more and hotter sparks, but kindling fire this way is a lot of work."

Shea fabricates stone tools to gain an understanding of how humans lived as many as 100,000 years ago. He teaches his students the art of flintknapping so they can identify stone tools when sifting through archaeological digs.

Professor Shea has been featured on NOVA and "The Human Spark."

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