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Technology keeps changing--the evidence surrounds us. One need not have lived long, for
example, to have seen the spread of personal computers, microwave ovens, and videocassette recorders. These innovations alter how we live, just as life in the early 20th century was altered by, say, automobiles and telephones. Of course, some innovations prove more far-reaching than others; the microwave oven, a welcome convenience, seems unlikely to reshape life to the extent that the automobile has.
Is it possible to identify a class of innovations that are of particular cultural-evolutionary significance? Some anthropologists, following Leslie A. White (1949), believe that breakthroughs in energy use are just such a class. From this perspective, four milestones of technological evolution can be identified: (1) use of tools, (2) control of fire, (3) application of the steam engine, and (4) control of nuclear power (Asimov 1972). Human societies always have relied heavily, for survival, on the making and using of tools. Stone tools date back over two million years; tools of softer materials, such as digging sticks, spears, and clubs may be much older still. Indeed, it is quite possible (as Darwin himself speculated) that an increasing reliance on tools created the evolutionary pressure that made us into upright bipeds: tool users with hands and arms less used for locomotion would have survived and reproduced better than tool users who continued getting around on all four.
Tools allow the body's energy to be concentrated on small areas--points and edges that can cut and penetrate where the unaided body would fail. Teeth are hard and sharp, but very limited. Consider the difference between a stone chopper held in your hand, and an incisor tooth held in your gums. The power of your swinging arm can be transferred to the edge of the chopper; but if you tried to swing your head in a similar arc to cut a branch from a tree or smash open a bone, the results would not be pretty.
The energy driving hand tools is generated in the human body. Use of energy generated outside our bodies originated when humans got control of fire--a milestone probably reached by half a million years ago. Getting energy by burning firewood is chemically similar to getting energy by eating food; but the former allowed our ancestors to expand out of our tropical evolutionary cradle.
Useful as fire was (especially in helping trigger the Bronze Age and Iron Age a few thousand years ago), it began to replace human--or animal--muscle power only with the refinement of the steam engine in the 1700s. As firewood became scarce in England, coal was turned to; and as coal mines deepened, water seepage and flooding of the mines became a chronic problem. Pumping water from coal mines was the necessity that mothered the refinement of the steam engine; because steam engines increasingly were fueled by coal, coal mining itself helped increase the demand for coal. The steam engine, meanwhile, found innumerable industrial applications by converting heat energy to mechanical energy, as in textile factories to drive huge looms; indeed, the steam engine often is considered to have been the most important single innovation for industrialization.
When we burn either firewood or fossil fuel (coal, oil, natural gas), we are indirectly using solar energy "trapped" by photosynthesis. (The same applies when we energize our bodies by eating food.) The first genuine departure, in this respect, occurred only with control over nuclear power achieved a few decades. ago. Fission, used to generate electricity in coal-poor societies, is efficient; but fuel is expensive, and hazardous wastes are produced. Nuclear fusion--the means by which stars produce heat and light--is even more efficient; moreover, fuel is cheap, and wastes are not hazardous. The problem is containing the extremely high temperatures involved: so far, fusion literally is "too hot to handle." In future decades, controlled fusion could become a practical energy source. Cultural evolutionism can suggest that so fundamental a change in energy use could usher in a new stage of cultural evolution; foreseeing what that stage would be like, however, is well beyond its current ability. Meanwhile, we must cope with the fact that nuclear power's unprecedented potential for destruction places our very survival in doubt. As Leslie A. White wrote, in 1949, concerning the advent of nuclear power, this advance may possibly be the last. In the symbolism of an ancient myth, it may indeed be hazardous to eat of the fruit of every tree in the garden. The mastery of terrestrial fire was tolerable, but to create energy by the transformation of matter is to play with celestial fire. Whether it can be done with impunity remains to be seen. The new Prometheus may also be the executioner. [White 1949:362]
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