Fire by Friction

by Norm Kidder

Anthropologists debate the proper place in the fossil record to make the jump from apeman (Australopithecus) to man (Homo). The current trend is to base this arbitrary quantum leap on the first appearance of manufactured stone tools. The earliest case for this so far has been named Homo habilis (Handy man), a being otherwise physically identical to nearby apemen. This approach continues the bias toward stone tools inherent in the term stone-age to describe the human condition until the advent of metallurgy. This bias is the natural result of stone tools being all that's left of ancient technologies, and thus serving the needs of archaeologists. Recently chimpanzee groups in the wild have been found using stone tools. Shouldn't they also then be considered human? I suggest a different theoretical approach - the use of fire as a tool.

The ancient tool kit probably consisted of a crude digging stick, a sharp or pointed stone, a stone hammer, and pieces of bark or leaf used as a cup for water. These are little different from the tools known to be used by chimps. This kit did not change for vast stretches of time. I propose that the stimulus for change that jump started the behavioral evolution for our kind was the discovery of fire as a tool.

Pre-human hominids were omnivorous gatherers and scavengers, killing relatively helpless animals if discovered. They lived at a time of drought, when the great forests of the world were shrinking and being replaced by grasslands. They were forced to make dangerous excursions away from the relative safety of the trees out into the more food-rich plains. Foraging required that group size remain small, and lookouts be always alert for the many large predators. Another element of life a few million years ago was occasional fires, started by lightning or volcanoes, which would sweep across large areas unchecked. A burned area would provide a major windfall to hominid groups. The ground would be cleared of dead vegetation exposing seeds and tubers, as well as providing the occasional cooked dead animal (one advantage to cooked meat is its shelf life). Burning also tended to run off most predators, and make it much easier to detect any that returned. For millennia perhaps, our ancestors learned to seek out burning grasslands which might provide food, briefly, for large congregations of hominids (the first conventions).

The great leap forward that I feel justifies a new classification for humans came when the first of these ancestors took a burning branch and set a new fire, taking control of the process. This discovery that fire could be used to make food more readily available, to preserve some of it for the future, and help defend against predators, created the technological base for modern society.

Fire Stick Farmers

A study of aboriginal groups around the world gives clues to the advances in the use of fire as technology. One of the oldest uninterrupted cultural traditions known to science was found in the Australian Aborigines before they were 'introduced to modern civilization. One anthropologist described their food gathering practices as fire stick farming. Using fire to determine the species of plants available to them for food. Specifically, they used fire to reduce less desirable plants, and encourage the most useful ones. The result was that most of the continents plant communities were, until recently, maintained by fire.

The evidence for California Indians indicates a similar use of burning to promote seed production in grasses and wildflowers; thatch removal to favor tuberous growth and other wildflowers; and thinning of brush to improve hunting by both increasing animal browse and decreasing cover.

Fire was also a critical element in the hunting process. Many ancient groups used fire to drive animals into traps (blind canyons, pits, tar pits, marshes, cliffs, etc.). In recent times, fire was being used by California Indians to drive ground squirrels from their burrows, bees and hornets from their hives and grasshoppers into a pit oven. Smoke and fire permeate most aspects of daily life. It is used to straighten arrows and spears, harden digging sticks, bend basket rims, waterproof tanned hides, purify and deodorize and of course to cook.

The importance of fire to all ancient people made it nearly inevitable that eventually someone would discover how to make fire. It is unlikely that anything in the fossil record will enable us to know just when this change took place. Hearthfires started from wildfire are identical to those started by fire sticks. Even if by chance a set of fire sticks were to be found, it would only tell us when conditions for preservation existed, not the earliest use. As to how the secret of fire making was discovered, I have my guess:

The same process that produces fire will also eventually produce a hole. I believe that someone trying to drill a hole in a board discovered fire making accidentally.

The wide range of the fire-drill throughout many continents (Australian aborigines use the same method as American Indians, etc.) implies that it may have been known before the great dispersal of humans carried out by Homo erectus around 1.5 million years ago, or at least by the migrations at the end of the ice ages starting around 40 thousand years ago (although it is possible that it arose separately and identically in many different places).

The basic technique for making fire by friction involves spinning a drill against the bottom of a hole in a hearth board. Friction from rubbing the sticks together produces heat and (if the correct woods are used) fine powdery sawdust, or char. The char is collected in a notch cut into the center of the hole. This concentrates the heat, the wood acting as an insulator. If the char is heated to 800 degrees Fahrenheit it will begin to smolder (data courtesy of Richard Baugh). Placing the smoldering char (ember) into a bed of tinder (fine, dry plant fibers) and blowing gently will cause the tinder to burst into flames. This is much easier to describe than to accomplish. Reaching 800 degrees Fahrenheit requires considerable pressure be applied to the drill.

The hand spun fire drill, the oldest method, accomplishes this through hand pressure against the drill while bearing down with the weight of the body while continuing to spin the drill as fast as possible. With practice, a strong, fairly heavy, well conditioned person can get an ember in a few seconds of hard work, under ideal conditions. Smaller or less experienced people can make fire through cooperative efforts and persistence. Mechanical advantages can be achieved through the use of a cap piece which is used to push down on the drill. To keep the drill spinning with one hand, a bowstring is wrapped around the drill and moved back and forth, spinning the drill. Another variant involves using toggles (and normally a second person) to spin the drill. These methods probably evolved where conditions made fire making difficult.

Three other techniques for friction fire use lateral friction rather than rotational - fire plow (movement up and down a groove), fire saw (the edge of one piece cuts through the middle of another), and the fire cord (a vine is pulled through a notch). Two techniques are known using heating by compression - the fire piston (works like a diesel engine), and flint and steel (iron particles are crushed, and torn away, causing enough heat to ignite them). The last of these is the best known, but was probably not common until iron became available. Modern matches use materials which ignite easily with little friction heat. Lighters use miniature flint and steel sets to light their gas fumes. Three new ways to make fire have been developed in recent years - electric spark, electric resistance, and chemical resistance.

This article was first published in The Bulletin of Primitive Technology (Fall 1994, #8)
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