A-2- RATE OF TECHNOLOGICAL EVOLUTION
        The rate of technological evolution varies depending upon the nature of the technology, its stage of development, and the evolution environment.

A-2-a- NATURE OF TECHNOLOGY
The degree of sophistication of a technology will impact the rate at which it evolves.
Simple technologies (for example, the bicycle industry) will evolve slower than more complex technologies (for example, microcomputer industry). This rate is always related to the number of variables involved in the technology.
The more variables involved, the more opportunities for new combinations and thus applications to be developed. At some point, however, a technology can become so complex that the rate of evolution begins to slow down.
This would appear to be a result of the complex interlinks ages that occur within sophisticated technologies limiting the number of changes that could occur.

A-2-b- STAGE OF DEVELOPMENT
Technologies go through a series of stages, from introduction to maturity. The stage a technology is in has a strong influence upon its rate of evolution. The early years of development of a new technology will see more rapid evolution than later years.
In the first few decades of the 20th century, aviation technology evolved very rapidly as a series of innovations (for example flaps, retractable landing gear, and metal construction) were integrated into Air Crafts.
As we approach the end of the 20th century, Air Crafts continue to evolve, but the dramatic changes we saw between 1900 and 1945 are from the past, at least for commercial applications.
The early stages of a technology will also tend to see more variation in the form and structure of the technology.
Between 1900 and 1930 we saw a wide variety of Air Crafts with one, two, and three pairs of wings.
By contract, almost all aircraft of the late 20th century have one pair of wings.

A-2-c- EVOLUTION ENVIRONMENT
External forces can have a significant impact on the rate of evolution of a technology. During periods of conflict for example, "survival of the fittest" can drive the pace of technological evolution at a phenomenal rate.
During World War One (1914-1918, military air crafts evolved extremely fast, taking on new forms and functions in a matter of weeks or months.
Similarly, aviation technology evolved very rapidly during World War Two (1939-1945), moving from the use of biplanes to jet aircraft in less than six years. When did technology first exist and where? Following are the last 6000 years in review.