Fire

I

Introduction

Fire, chemical reaction involving fuel and oxygen that produces heat and light (see Combustion). Early humans used fire to warm themselves, cook food, and frighten away predators. Sitting around a fire may have helped unite and strengthen family groups and speed the evolution of early society. Fire enabled our human ancestors to travel out of warm, equatorial regions and, eventually, spread throughout the world. But fire also posed great risks and challenges to early people, including the threat of burns, the challenge of controlling fire, the greater challenge of starting a fire, and the threat of wildfires (see Forest Fires).

As early civilizations developed, people discovered more uses for fire. They used fire to provide light, to make better tools, and as a weapon in times of war. Early religions often included fire as a part of their rituals, reflecting its importance to society. Early myths focused on fire’s power. One such myth related the story of Vesta, the Roman goddess of the hearth. To honor Vesta, the high priest of the Roman religion periodically chose six priestesses, called Vestal Virgins, to keep a fire going in a community hearth. Keeping a controlled fire burning played a central part in communal life. Before the invention of modern implements, starting a fire, especially in adverse weather, usually required much time and labor to generate sufficient friction to ignite kindling. If people let their fire go out, they had to spend considerable time to start it again before they could eat and get warm.

Today people naturally focus not on starting fires but on using fire productively and on preventing or extinguishing unwanted fires. We use fire to cook food and to heat our homes. Industries use fire to fuel power plants that produce electricity. At the same time, fire remains a potentially destructive force in people’s lives. Natural fires started by lightning and volcanoes destroy wildlife and landscapes. Careless disposal of cigarettes and matches or carelessness with campfires leads to many wildfires. Fires in the home and workplace damage property and cause injury and death. Fires usually cost the United States and Canada more each year than floods, tornadoes, and other natural disasters combined.

Scientists and fire protection engineers work together to help people use fire safely and productively. Smoke detectors and automatic sprinklers in homes and the workplace have reduced property loss, deaths, and injuries due to fire. Engineers continue to develop more fire-resistant materials for use in furniture, clothing, electronics, buildings, automobiles, subway cars, aircraft, and ships. The development of new engineering approaches and new building codes and standards has led to safer buildings without dramatically increasing costs of construction.

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II

Early Use of Fire

The earliest use of fire by humans may have occurred as early as 1.4 million years ago. Evidence for this was found in Kenya—a mound of burned clay near animal bones and crude stone tools, suggesting a possible human campsite. However, this fire could have resulted from natural causes. Homo erectus, a species of human who lived from about 1.8 million to about 30,000 years ago, was the first to use fire on a regular basis. Evidence of a fire tended continuously by many generations of Homo erectus, dating to about 460,000 years ago, has been found in China. Scientists have also found evidence of tended hearths dating back as many as 400,000 years in several parts of France.

Homo erectus was the first human species to leave equatorial Africa in large numbers and spread to other continents. Many scientists believe that the use of fire enabled Homo erectus to adapt to new environments by providing light, heat, and protection from dangerous animals. Tending fires probably helped foster social behavior by bringing early humans together into a small area. Fires may have tightened family groups as the families congregated around a fire to protect their young. Homo erectus may have used fire to cook food.

The use of fire became widespread throughout Africa and Asia about 100,000 years ago. By this time anatomically modern humans, Homo sapiens, had evolved and existed alongside their near relatives, the Neandertals (Homo neanderthalensis). Clear indications of hearths have been found in Israel in Neandertal settlements that date from 60,000 years ago. The Neandertals died out about 28,000 years ago.

III

Early Fire-Making Techniques

Sometime after people began to use stone for tools, they found that by rubbing together pieces of flint they could produce sparks that would set fire to wood shavings. Scientists have found evidence that people used pieces of flint and iron to produce sparks for fires 25,000 to 35,000 years ago.

Early people also learned to make fires by rubbing together pieces of wood until the wood produced a hot powder that could light kindling. Later, people made fires by using wood devices that had been developed for other purposes. The fire drill was an adaptation of the bow and the drill. It consisted of a block of wood and a stick that was fixed in the looped string of a small, curved bow. The fire builder moved the bow in a sawing motion, with one end of the stick against the block of wood. This motion rotated the stick rapidly against the wood block, creating friction between the end of the stick and the block of wood. The friction produced a glowing wood powder that could be fanned into a flame and used to light a fire.

Early people of southeastern Asia produced fire another way. They used a wood piston to compress air inside a bamboo tube that contained wood shavings. The compressed air became increasingly hotter, eventually igniting the shavings.

The people of ancient civilizations improved on methods of fire-making. Glassmaking among the Greeks led to the development of lenses, which the Greeks used to focus sunlight on, and thereby ignite, bundles of dry sticks. As the use of metals in toolmaking increased, people developed the tinderbox. This moisture-proof, metal carrying case held tinder, usually charred cotton or linen cloth, and pieces of steel and flint. Striking the steel and flint together produced a spark that lighted the tinder. Later the Japanese devised a tinderbox that operated like a present-day cigarette lighter, in which the rotary motion of a metal wheel against flint set off sparks in tinder. Finally, in the mid-19th century, a reliable form of the phosphorus match was developed.

IV

Fire and the Advance of Civilization

As early people began to live in larger communities and to develop more advanced technologies, fire became a central part of their lives. Fire continues to be essential to humans today, although its presence may be hidden in gas-fired ovens and furnaces and thus less noticeable than before.

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